On 14/11/2017 03:28, John Rumm wrote:
On 13/11/2017 16:59, whisky-dave wrote:
On Monday, 13 November 2017 16:24:56 UTC, John RummÂ* wrote:
On 13/11/2017 13:58, whisky-dave wrote:

All we need is a heating engineer that knows stuff, both theory and
in practice
Â*Â* It was 12C @ 9am, now 16C @ 13:45.

This is with 5 of 2KW heaters and 2 ofÂ* 1.5KW heaters.

So if yuo wanted the demp to be 16C before the 10am class how many
heaters would we need in total. ?

You need to do the test with two different total power levels to
determine unambiguously what the thermal capacity and other losses are.

The simplest way out would be to use a couple of 2kW air curtain heaters
over the lab doors which will rapidly warm the *air* inside the lab to a
comfortable temperature instead of these useless convection heaters
heating up the wall behind them and air that immediately rises up to the
ceiling. The room fills with warm air slowly from the top down.

Any kind of fan heater would be way better than oil filled radiators if
you want to get the room habitable in the shortest possible time.

Those propane powered fan flame things for heating big garage spaces are
pretty good and fast if you don't mind the smell of combustion products.
(I find them a bit scary YMMV)

https://www.machinemart.co.uk/c/gas-...space-heaters/

--
Regards,
Martin Brown

On Wednesday, 29 November 2017 11:43:25 UTC, T i m wrote:
On Wed, 29 Nov 2017 02:48:06 -0800 (PST), whisky-dave
wrote:
snip

So why whine that you weren't getting the full 2kW from the heaters?

I'm NOT.

Maybe not now but you went on and on and on about it at the beginning
(till you were told why and the penny finally dropped).

I knew exaclty why.
What I don't understand is why a 1.3KW heater would be better than a 2KW at giving out heat.


I know you're having difficulties in reading and maths but READ the subject line.

And?

"So how much power does an oil filled radiator actually use."

Yeah, and?

So what is the answer .




When you say 'just below 220V' you actually mean 202 (that you told
us)?

No you clueless ****er, that was thew LOWEST I've EVER seen it at

Ok, so that *was* the voltage when you were doing what you needed to
do and have all the heaters on then? eg,

all 5 heaters on the same MCB circuit as a test.
Don;t forget we;d be allocated 20 of these, so if 5 overrated our supply take a guess at what 20 of them would do ?
5 1.6KW heaters arrived a day or so later to add to the 5 2KW ones we had.



I'm not 'clueless' I'm just
quoting *exactly* what you said yourself? It matters not a jot what
the off-load voltage is, it's what it is *on-load* that matters.

So what was teh relivance that yoiu have 239V at home without saying whether you had loaded it or not.
What is the relivance of yuor 239V ?


AND that was when pulling 40 amps from a 32 amp MCB !

And?

I would expect the voltage to drop we've run labs on this soprt of thing in the past to measure the internal impedence/resistance of the supply.
Yes even the mains from the wall socket.
even our leads/cable have a reistance.




I don;t think I"ve EVER measured the lab volage at 240V it's always been around 220V

Yes, of course not, you have some snake-oil 'energy saver' bs in
there.

Yes I know a managment decision to save power probbly the same sort of managers that have invested auto on lights in teh toilets to save money, but they are left on 24/7, how does that save electricity ?


but we have little reason to measure it as the vast majority of labs use low voltage DC and no one gives a **** what the AC voltage is.

Some people seem to be when they want to get 2kW out of a heater
though?

The only reason we want this is because the college has ****ed up the heating system of teh engineering block, the block that was meant to be completed in august is now perhaps due to be almost finished by April.
Having teh lab without heating over the summer I didnlt consider it a problem but having a lab without heating and without windows and no form of air conditioning, in the past after xmas it;s been 5C you can't expect studetns to do labs or lectures at %c without it affect their precious student experience results via the National student survey which we have dbeen told to get the studetn to fill out and suprise suprise the reuslts haven't been favourable.

The labs electrics were NEVER designed to heat the lab.


We have a lab tomorrow where the students design a DC PSU.

Good for them.

We can't give them the mains to play with so we give them a 12 V AC PSU..

So a(n isolating) transformer you mean?

No a transformer a standard transformer.


I;ve had to contact rapid as we need a couple of spares and the ones we brought some 4 years ago have been discontinued.

Did you contacts sates, tech or product support? ;-)

I contacted sales as we wished to purchase products rather than ask technical questions regarding a product we have brought from them.

This is the corect time to contact sales.
You DO NOT contact sales for technical queries



So come on genius tell us what the AC volage should be from one of these..

https://www.rapidonline.com/stontron...daptor-90-2636

If connected in our lab at 215V and yuo can then guess what it might give at your home on 239V

If it was designed for 230V then it would be less (than 12V RMS) on
220 and more on 239 (proportionally)?

So why on ~215V do they all measure 13.xx

NOT one of the dozen measure less than 13V.

And if yuo check the website it says
An unregulated linear plugtop AC power adaptor with an output of 12V AC at 1A and a UK plug.
230V AC mains input

NOT 240V



I did ~1050W so where do you get 1300W from,

Mate. You were the one quoting 700W at the beginning so you know full
well what we are talking about.

But where did you get 1300W from even in my lab it's never gone about 1850W
Rememebr what yuo said I told you our lab voltage was 202V.



Oh yes you've forgotten apparently you believe our standard mains voltage is 202V

I do? (No, I don't), but for the purposes / duration of your power
tests it was.

For the power test YES, remeber this was a TEST of 5 heaters, we were due to recieve another 15.




So you think a 2KW heater on 202V rather than 240V will still consume 2KW irrecspective of the input voltage.

I don't, you do though it seems?

No you do you;re the one that's come up with 1300W tpo add to the 700W to get 2KW, when in the lab we were getting about 1.7-1.8KW.






How comes it didn't occur to you that a 2KW rated heater will give out less than 2KW if placed on a 202V supply, this is why I asked you what;d you''d expect if we ran if from a 9V battery would you STILL expect 2KW ?

And I didn't answer

because you didn't know the answer.

that because the question was (and still is)
childish and stupid. Unless you do actually need to know the answer
because you are thinking of running the heaters on 9V batteries?

So why do yuo expect the heaters to run at 2KW on 202V ?
We already know according to the website it is a 2KW heater and the operating voltage is 230V NOT 240V .
This should be noted on the vast majority of products exported to the UK are for 230V not 239V or 240V.



Anyone with any insight would have known that 202/240 should give you the fraction that you use to multiply by so :-
A heater of 2KW at 240V will consume 2000W
A heater of 2KW at 202V will consume 1683W

Wow, who worked that out for you then?

Me how comes you couldn't work it out all th4e info was there.

A 2KW heater that was running at 1700w when full on and when the 700W 'element'; is switch out what do we get left with according to you it's 1300W ,
but iof yuo take 700 from 1,700 you get 1000 NOT 1300 as you said.
Is this really that ccomplex.




So if it's consuming 700W already we have 1683-700= 983W NOT 1300W that you expected.

Whoosh. If it's a 2kW heater and you *measured* 700W on the low power
element (when the supply voltage would have been higher because of the
reduced load) then it makes sense the 'other' element is 1300W.
However, it doesn't actually matter what it is when you measure it, we
are only talking of those values as a means of identifying the
different settings.

It matters when working out what power the heater is.
But that escaped you didn't it.

If it were 1300W at 240V then the 700W atv 240V would be about 20% higher so NOT 700W be about 840W.
1300+840 would be 2140W not 2KW
They would NOT sell such a thing and rate it at 2KW.

Yep, I wouldn't expect anyone to set the heater to a mid setting to get the maxium heat from it.

Of course you wouldn't because you really don't have a clue how things
work ITRW.

IS that how you operate things setting them to 60% to get the best from them.


Why buy a 2KW heater just to run it at 1300W ?

Because it just might give off more heat over a certain period?

It just might, so why not buy a lower rated heater as that too might give off more heat than a 2KW heater perhaps thats why we brought some 1.6KW heaters because they give out n=more heat than a 2KW heater.
Maybe we should by some 10W heaters maybe they'll give out more heat than my 2.5KW heater at home.



Say you have a 2Kw heater made up from a 700W and 1300W elements and
with an upper limit stat only on the 1300W element. You set the main
stat to full and monitor the current drawn.

The heater draws 2kW for two hours before the overtemp stat kicks in
(out) on the 1300W element when the rad itself is at (say) 100 DegC
and so drops back to the 700W element. At that point it's only a 700W
rad and it will then cool down over (say) another 2 hours with the
surface temperature dropping from 100 DegC to 70 DegC (hysteresis of
the stat) when it cuts back in again and the cycle repeats.


So, the surface temperature of the rad will have gone from ambient,
slowly up to 100 DegC and back to 70 again, over a 4 hour period. The
heating effect WILL be reduced as the differential between the heater
and the ambient air is reduced to it won't heat as well at 70 DegC
than it does at 100 DegC.

The average power consumed will be 1350 W/h.

Is that what you expect from a 2KW heater ?


Now, say you only enabled the 1300W element and let's say the rad only
gets to 90 DegC and stays there, the element won't be cut out by the
upper limit stat and so you will get a constant temperature over the
full 4 hours.

The average power consumed will be 1300W/h but, if the average
temperature remains constant and higher, it may offer a better heating
effect.

Proving it;s a cheap crappy heater as I first suggested as you can't run it at the specified rating.

So tell me how you;'d decide how many heaters yuo;d buy for heating a room.
How would you know that a 2KW heater would cut down to 1300W or 700W for the majoroty of it;s use. ?


what's a room temperature heater ?

A heater the temperature of the room (or whatever you were going on
about above)? I was saying the hooter the surface.
greater the temperature differential between that and the room and the
more efficient it will liberate heat into the room. Also, the higher
the temperature differential the less impact on that differential it
will make when the room goes from 16 to 20 DegC.

That's why air cool engines are often more durable in the desert that
water cooled ones as the running temperature of the air cooled engine
is greater than that of a water cooled.

So how would too design such a system how would you know which heaters to by ?
How do you know whether or not to buy a 500W or 1KW or 1.6KW or a 2KW heater
or a 2.5KW one ?
what would you look at in the ad or datasheet ?


HTF do you think a heater heats a room?

Depends where it's placed.

No it doesn't.

Most heaters are placed near windows to circuiate the air, have you not noticed that the vast of radiators are placed under windows.

You really don't have a clue do you (and don't think
that if you put it by a draughty window it will make a difference
because we aren't talking that sort of thing).

It's a room or which most have windows.
Most rooms have some sort of air as if you placed the heater in a vaccum then it wouldn't heat up the 'room' very well would it.



why did you contact sales ?

Why are you opening up strawmen. Are you really that desperate (you
don't need to answer that btw).

Why did you contact sales, you cliamed to be helping.


and what was sales reply.

That Tech Support needed more details to proceed. Do you have a point
(yet)?

What details ?
Where did they ask for details ?


Go look it up in your email in box

I don't need to mate ... I have a good memory and a good understanding
of the situation.

Yeah sure now what was the voltage you said my lab was.


I'm grateful if they are actually helping, but you passed that point a long time ago.

I know, that was when I took the time to patiently answer your first
stupid questions ...

and you got that wrong too.



John rumm was helping you are NOT.

I think he told you the facts and explained much of the science but as
you didn't understand most of it

Most of it was about how MCBs work, not about the heater.

As yet you are still missing the point after so long.

So how much power does an oil filled radiator actually use.

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

On Wednesday, 29 November 2017 12:28:44 UTC, Martin Brown wrote:
On 29/11/2017 10:48, whisky-dave wrote:

Anyone with any insight would have known that 202/240 should give you the fraction that you use to multiply by so :-

No it doesn't.

Yes it does.


A heater of 2KW at 240V will consume 2000W
A heater of 2KW at 202V will consume 1683W

So if it's consuming 700W already we have 1683-700= 983W NOT 1300W that you expected.

He is more nearly right that you are.

No he is NOT because those are the real world results I get.
This is ONE of the reasons why we run both theory and practicals.



Anyone that understands the basics
of Ohms law will know that the power dissipation in a resistor R is I*V

= V^2/R

OK here's the resitances at cold of the relivant parts.
at 240V at 230V (the speicifed operational volatge)
I 66.4R 867W 797W
II 44.9R 1283W 1178W
III 27.1R 2125W 1952W


The power dissipated in a fixed resistor R scales as the *square* of the
applied voltage V all other things being equal.

Nominal 2kW at 240V = R = 29
So on a 202V supply it will consume 202^2/29 ~ 1.4kW

except it is wrong. Tim said the 1300W for just ONE of the 'resistors'
What I get 202^2 = 40804/44.9=908W NOT 1300W

But normmaly we have a voltage of about 215-220
217.5^2 = 47306/44.9=1054W NOT 1300W




R won't quite be constant but it won't vary by all that much either.
R might be a percent or so lower at 1.4kW since the element is cooler.

which element ? element I or II



Cheap and nasty resistive electric heaters are usually configured
series, single and parallel to present loads of V^2/2R, V^2/R and 2V^2/R
to the mains being low, medium and high heat settings respectively.

Yep and this is what I first suspected of this ~£25 heater.


You perhaps ought to worry if your lab mains voltage is as low as you
say it is something somewhere must be dropping nearly 30V.

I think it's the heaters as the lab was NEVER designed to be heated by heaters connected to the labs mains supply.

It really, is that simple.


Oh and I've run anothe rtest from cold.

with the heater switch to maximium and consuming about 1700W at 212V
I left it on and after 27mins 21 secs it went down to 685W.
Ambient temperature of room 19C .

On Wednesday, 29 November 2017 13:38:14 UTC, Andy Burns wrote:
whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

there's no option of a 1.3KW cycle.


It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

So how would you know this before buying the heater ?
What would you expect if you brought a 2KW oil filled radaitor ?

On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

Bingo.

I've given up with the troll, now *you* have the baton Andy! ;-)

Cheers, T i m

On Wednesday, 29 November 2017 14:47:38 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

Bingo.

I've given up with the troll, now *you* have the baton Andy! ;-)

Cheers, T i m

You lost it big time troll.

On Wed, 29 Nov 2017 06:39:49 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 13:38:14 UTC, Andy Burns wrote:
whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

there's no option of a 1.3KW cycle.

Bwhaha ... the troll thinks it's a washing machine now! ;-)

Cheers, T i m

On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on (and potentially maintaining)
the 1300W element than with them all trying to run both (at ~2kW
total) because of the voltage drop from the crap power supply.

And with that supply he'll probably be getting as much heat out of the
ring main as he will the heaters themselves. ;-)

Cheers, T i m

On Wednesday, 29 November 2017 16:26:19 UTC, T i m wrote:
On Wed, 29 Nov 2017 06:39:49 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 13:38:14 UTC, Andy Burns wrote:
whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

there's no option of a 1.3KW cycle.

yuo were the one to go on about a duty cycle yuo ****wit.


Bwhaha ... the troll thinks it's a washing machine now! ;-)

you were the one to go on about a duty cycle you ****wit.
Are you saying heaters and washing machines are the same because they both heat things, wouldn't suprise me if that was your conclusion.





Cheers, T i m

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?
would it be better or worse at providing heat. ?

So what is the optimium volage for a 2KW heater ?



(and potentially maintaining)
the 1300W element than with them all trying to run both (at ~2kW
total) because of the voltage drop from the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.
But if it does..
back to the 9V battery so it definanlty won't ever overheat.



And with that supply he'll probably be getting as much heat out of the
ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.


Cheers, T i m

On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?



(and potentially maintaining)
the 1300W element than with them all trying to run both (at ~2kW
total) because of the voltage drop from the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

But if it does..
back to the 9V battery so it definanlty won't ever overheat.

What do you think?



And with that supply he'll probably be getting as much heat out of the
ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

Cheers, T i m

On 29/11/2017 13:59, whisky-dave wrote:
On Wednesday, 29 November 2017 12:28:44 UTC, Martin Brown wrote:
On 29/11/2017 10:48, whisky-dave wrote:

Anyone with any insight would have known that 202/240 should give you the fraction that you use to multiply by so :-

No it doesn't.

Yes it does.

No wonder UK engineering is in such a mess if you are typical of the
people who are supposed to be teaching it.

A heater of 2KW at 240V will consume 2000W
A heater of 2KW at 202V will consume 1683W

So if it's consuming 700W already we have 1683-700= 983W NOT 1300W that you expected.

He is more nearly right that you are.

No he is NOT because those are the real world results I get.
This is ONE of the reasons why we run both theory and practicals.

WOW! I knew engineers could be pretty dumb but I didn't think there
would be anyone claiming to be an engineer who couldn't grasp Ohm's law.

Anyone that understands the basics
of Ohms law will know that the power dissipation in a resistor R is I*V

= V^2/R

OK here's the resitances at cold of the relivant parts.
at 240V at 230V (the speicifed operational volatge)
I 66.4R 867W 797W
II 44.9R 1283W 1178W
III 27.1R 2125W 1952W

Don't you think that my estimate of 29R when hot is a rather good
approximation to your case III when the device is providing 2kW?

Hint: 27 is 66 || 45

R won't quite be constant but it won't vary by all that much either.
R might be a percent or so lower at 1.4kW since the element is cooler.

which element ? element I or II

The combination III where the device is supposed to output 2kW on a
decent mains supply.

Cheap and nasty resistive electric heaters are usually configured
series, single and parallel to present loads of V^2/2R, V^2/R and 2V^2/R
to the mains being low, medium and high heat settings respectively.

Yep and this is what I first suspected of this ~£25 heater.

It is the standard way of doing it. Electric blankets have their lowest
setting with a grubby diode in series to make it slightly less deadly in
the event of insulation being compromised and halves the power.

You perhaps ought to worry if your lab mains voltage is as low as you
say it is something somewhere must be dropping nearly 30V.

I think it's the heaters as the lab was NEVER designed to be heated by heaters connected to the labs mains supply.

It really, is that simple.

So we have an engineering lab staffed by people who are too dumb to
figure out for themselves how to make the place comfortably warm! Worse
still they are probably overloading the lab ring main in the process.

No wonder that UK industrial productivity is so pathetic.

If you want to warm the place up quickly you heat the *AIR* in the room
with a powerful fan heater - convection heaters are useless unless you
live on the ceiling where all the warm air accumulates.

--
Regards,
Martin Brown

On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you refer to.
If we ran it out a lower votage the duty cycle would increase to a higher percentage which you claim is bester.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on and that is what they call the operational voltage but that of course depends on other factors.


(and potentially maintaining)
the 1300W element than with them all trying to run both (at ~2kW
total) because of the voltage drop from the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection is applied.


But if it does..
back to the 9V battery so it definanlty won't ever overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe the heater would ever go into it's 'cycle' as you call it.

I also think that runnin git at about 240V of possible would make it less efficiant than running it at 202V



And with that supply he'll probably be getting as much heat out of the
ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct voltage to apply to a heater that says it's operational voltage is 230V.

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle.
Even the 51Hz went down to 50Hz but then again I don't think such small changes mean much as the unit samples at about twice per second.






Cheers, T i m

In article ,
whisky-dave wrote:
On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better
than a 2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty
cycle, but the 2kW keeps hitting its overtemp stat and operates on
less than a 65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you refer
to. If we ran it out a lower votage the duty cycle would increase to a
higher percentage which you claim is bester.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on and
that is what they call the operational voltage but that of course depends
on other factors.


(and potentially maintaining) the 1300W element than with them all
trying to run both (at ~2kW total) because of the voltage drop from
the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection is
applied.


But if it does.. back to the 9V battery so it definanlty won't ever
overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe
the heater would ever go into it's 'cycle' as you call it.

I also think that runnin git at about 240V of possible would make it less
efficiant than running it at 202V



And with that supply he'll probably be getting as much heat out of
the ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct voltage
to apply to a heater that says it's operational voltage is 230V.

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle. Even the 51Hz went down to
50Hz but then again I don't think such small changes mean much as the
unit samples at about twice per second.


If your test meter thought that you boiling a kettle dropped the mains
frequncy from 51Hz to 50Hz, then it's a very strange meter.



Cheers, T i m

--
from KT24 in Surrey, England

On Wed, 29 Nov 2017 12:31:42 +0000, Martin Brown
wrote:

snip

All we need is a heating engineer that knows stuff, both theory and
in practice
** It was 12C @ 9am, now 16C @ 13:45.

This is with 5 of 2KW heaters and 2 of* 1.5KW heaters.

So if yuo wanted the demp to be 16C before the 10am class how many
heaters would we need in total. ?

You need to do the test with two different total power levels to
determine unambiguously what the thermal capacity and other losses are.

John gave him all the help for calculating the room losses but I'm
pretty sure it was more than he could be bothered with (and would
rather bite the hand that feeds him here in the big gaps between
leaning the labs between classes that do that).

The simplest way out would be to use a couple of 2kW air curtain heaters
over the lab doors which will rapidly warm the *air* inside the lab to a
comfortable temperature

He has said fan heaters are not allowed (as it might melt the
snowflakes) but I'm not sure if an air curtain (that I think I also
suggested) would count as such.

instead of these useless convection heaters
heating up the wall behind them and air that immediately rises up to the
ceiling.The room fills with warm air slowly from the top down.

But if they have low ceilings and people moving about?


Any kind of fan heater would be way better than oil filled radiators if
you want to get the room habitable in the shortest possible time.

They do but can't (not allowed).

Those propane powered fan flame things for heating big garage spaces are
pretty good and fast if you don't mind the smell of combustion products.
(I find them a bit scary YMMV)

If fan / convectors heaters aren't allowed ... !

I would still be interested to hear the outcome of the test of leaving
*just* the 1300W element on, to see how long it takes before it
overtemps (if it does at all).

Also, given the 700W element doesn't appear to be protected by the
(same?) overtemp stat, it's possible the rad would cool faster if it
went from 1300W to zero, rather than 2000W to 700. This might get the
heating back on quicker as it's likely the 700W element would slow the
time the heater took to get back down to the point where the overtemp
stat cut back out (in electrically) again (stat hysteresis).

Then I wondered if the alternative 1500W heaters might not overtemp on
full, but noticed they have a smaller surface area (7 as opposed to 9
'fins') and so it would probably be the same issue with them being
'overpowered'.

I've ordered a couple of electronic power controllers to experiment
with my own rads [1]. The aim is to limit the power to that that they
can actually dissipate as they are only going to be used to provide
'background' heating in the bedroom and I'd rather not hear either of
the stats clicking in and out all night. ;-)

Cheers, T i m

[1] And any heat the controllers dissipate will only go into the room
in any case. ;-)

On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:
On 29/11/2017 13:59, whisky-dave wrote:
On Wednesday, 29 November 2017 12:28:44 UTC, Martin Brown wrote:
On 29/11/2017 10:48, whisky-dave wrote:

Anyone with any insight would have known that 202/240 should give you the fraction that you use to multiply by so :-

No it doesn't.

Yes it does.

No wonder UK engineering is in such a mess if you are typical of the
people who are supposed to be teaching it.

I'm not teaching it.


A heater of 2KW at 240V will consume 2000W
A heater of 2KW at 202V will consume 1683W

So if it's consuming 700W already we have 1683-700= 983W NOT 1300W that you expected.

He is more nearly right that you are.

No he is NOT because those are the real world results I get.
This is ONE of the reasons why we run both theory and practicals.

WOW! I knew engineers could be pretty dumb but I didn't think there
would be anyone claiming to be an engineer who couldn't grasp Ohm's law.

You haven't a clue have you.
You got very confused thinking there is a 1300W setting there isn't



Anyone that understands the basics
of Ohms law will know that the power dissipation in a resistor R is I*V

= V^2/R

OK here's the resitances at cold of the relivant parts.
at 240V at 230V (the speicifed operational volatge)
I 66.4R 867W 797W
II 44.9R 1283W 1178W
III 27.1R 2125W 1952W


where's the 1300W you speak off, closest is at 240V,
the highest voltage here is about 219V.
At the operational voltage your 1300W is less than 1200W
So tell me what voltage you'd need to get this 1300W and what would then be the rated power of the heater at that voltage.





Don't you think that my estimate of 29R when hot is a rather good
approximation to your case III when the device is providing 2kW?

My device has NEVER provided 2kW


Hint: 27 is 66 || 45

Yes I know, I sussed that on day ONE.

and V^2/R IS NOT 1300

So come on you claim to know ohns law how about proving it.
In order to get 1300W disapated in a 45R resistor/element what voltage is required.


R won't quite be constant but it won't vary by all that much either.
R might be a percent or so lower at 1.4kW since the element is cooler.

which element ? element I or II

The combination III where the device is supposed to output 2kW on a
decent mains supply.

Define a decent mains supply .
How long would you expect this 2kW output to be maintained from this decent supply. ?




Cheap and nasty resistive electric heaters are usually configured
series, single and parallel to present loads of V^2/2R, V^2/R and 2V^2/R
to the mains being low, medium and high heat settings respectively.

Yep and this is what I first suspected of this ~£25 heater.

It is the standard way of doing it. Electric blankets have their lowest
setting with a grubby diode in series to make it slightly less deadly in
the event of insulation being compromised and halves the power.

Surely you mean halve the voltage by removing either the +ve or -ve cycles.
Are you saying there's a diode in the radiator ?



You perhaps ought to worry if your lab mains voltage is as low as you
say it is something somewhere must be dropping nearly 30V.

I think it's the heaters as the lab was NEVER designed to be heated by heaters connected to the labs mains supply.

It really, is that simple.

So we have an engineering lab staffed by people who are too dumb to
figure out for themselves how to make the place comfortably warm!

It is not our job to make the place comfortably warm

Worse
still they are probably overloading the lab ring main in the process.

They would be if we installed all the 20 2kW convection heaters that were brought for us. It was us the technicain that remined them that those heaters have beeen banned so don't order them.



No wonder that UK industrial productivity is so pathetic.

If you want to warm the place up quickly you heat the *AIR* in the room
with a powerful fan heater

We arentl allowed to use fan heaters than were banned even before convection heaters were.


- convection heaters are useless unless you
live on the ceiling where all the warm air accumulates.

How comes those in charge of the buiding services and building managment didn't know this ?


--
Regards,
Martin Brown

On 30/11/2017 11:45, T i m wrote:
On Wed, 29 Nov 2017 12:31:42 +0000, Martin Brown
wrote:

snip

All we need is a heating engineer that knows stuff, both theory and
in practice
Â*Â* It was 12C @ 9am, now 16C @ 13:45.

This is with 5 of 2KW heaters and 2 ofÂ* 1.5KW heaters.

So if yuo wanted the demp to be 16C before the 10am class how many
heaters would we need in total. ?

You need to do the test with two different total power levels to
determine unambiguously what the thermal capacity and other losses are.

John gave him all the help for calculating the room losses but I'm
pretty sure it was more than he could be bothered with (and would
rather bite the hand that feeds him here in the big gaps between
leaning the labs between classes that do that).

Some much for engineering education in the UK.

The simplest way out would be to use a couple of 2kW air curtain heaters
over the lab doors which will rapidly warm the *air* inside the lab to a
comfortable temperature

He has said fan heaters are not allowed (as it might melt the
snowflakes) but I'm not sure if an air curtain (that I think I also
suggested) would count as such.

It would be by far the simplest solution for a largish laboratory a bit
noisy when heating things up from cold but once the air is warm a
relatively modest heat input from radiators can hold it there
(especially once the room is occupied by a decent number of people).

Our village hall has essentially the same problem of wanting to get it
to working temperature in the shortest time with the least energy usage
and only having electric heating available.

instead of these useless convection heaters
heating up the wall behind them and air that immediately rises up to the
ceiling.The room fills with warm air slowly from the top down.

But if they have low ceilings and people moving about?

Unless they are walking round on the ceiling their feet will freeze.


Any kind of fan heater would be way better than oil filled radiators if
you want to get the room habitable in the shortest possible time.

They do but can't (not allowed).

OK then a cold fan pointed at the useless convection heater(s).
Strange that an organisation that prohibits fan heaters permits
overloading of the lab ring main without a second thought.

Those propane powered fan flame things for heating big garage spaces are
pretty good and fast if you don't mind the smell of combustion products.
(I find them a bit scary YMMV)

If fan / convectors heaters aren't allowed ... !

I would still be interested to hear the outcome of the test of leaving
*just* the 1300W element on, to see how long it takes before it
overtemps (if it does at all).

Chances are that upping the power for some of the time will always
result in more heat output overall. The problem is that they are losing
heat too fast and heating up the wrong things mostly the air against the
ceiling and walls behind the oil filled radiators. Some fans on the
ceiling to push the warm air down would help a bit.

I've ordered a couple of electronic power controllers to experiment
with my own rads [1]. The aim is to limit the power to that that they
can actually dissipate as they are only going to be used to provide
'background' heating in the bedroom and I'd rather not hear either of
the stats clicking in and out all night. ;-)

If you don't mind being dirty about it you could do what the electric
blanket people do with a diode in the supply to halve output on low.

--
Regards,
Martin Brown

On 30/11/2017 11:55, whisky-dave wrote:
On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:

- convection heaters are useless unless you
live on the ceiling where all the warm air accumulates.

How comes those in charge of the buiding services and building managment didn't know this ?

They are probably as dumb as you are. Where is this dodgy university?

--
Regards,
Martin Brown

On Thursday, 30 November 2017 11:39:36 UTC, charles wrote:
In article ,
whisky-dave wrote:
On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better
than a 2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty
cycle, but the 2kW keeps hitting its overtemp stat and operates on
less than a 65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you refer
to. If we ran it out a lower votage the duty cycle would increase to a
higher percentage which you claim is bester.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on and
that is what they call the operational voltage but that of course depends
on other factors.


(and potentially maintaining) the 1300W element than with them all
trying to run both (at ~2kW total) because of the voltage drop from
the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection is
applied.


But if it does.. back to the 9V battery so it definanlty won't ever
overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe
the heater would ever go into it's 'cycle' as you call it.

I also think that runnin git at about 240V of possible would make it less
efficiant than running it at 202V



And with that supply he'll probably be getting as much heat out of
the ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct voltage
to apply to a heater that says it's operational voltage is 230V.

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle. Even the 51Hz went down to
50Hz but then again I don't think such small changes mean much as the
unit samples at about twice per second.


If your test meter thought that you boiling a kettle dropped the mains
frequncy from 51Hz to 50Hz, then it's a very strange meter.

You don't understand much about meters do you.
This is a two digit display so it shows an average over time.
So all it can display 49Hz 50Hz 51Hz etc...

so if the freuency is 50.5Hz it's display 50 for a second then 51 for a second.
At home and work it does the same although at work is only displays 51 for about 1 in 5 or so seconds.

It's similar to the one below but was brought about 10 years or so ago.
https://www.amazon.co.uk/Brennenstuh.../dp/B00I068ZEE

On Thu, 30 Nov 2017 03:32:53 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you refer to.

Agreed.

If we ran it out a lower votage the duty cycle would increase to a higher percentage which you claim is bester.

Correct and I do.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on and that is what they call the operational voltage but that of course depends on other factors.

Correct, 'designed voltage range' so as to either not damage the unit
or it not perform reasonably expected.


(and potentially maintaining)
the 1300W element than with them all trying to run both (at ~2kW
total) because of the voltage drop from the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection is applied.

Agreed.


But if it does..
back to the 9V battery so it definanlty won't ever overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe the heater would ever go into it's 'cycle' as you call it.

Agreed.

I also think that runnin git at about 240V of possible would make it less efficiant than running it at 202V

It wouldn't affect the 'efficiency' (as it will always be ~100%
efficient) but that might indirectly affect it's ability to heat the
room (as) effectively.



And with that supply he'll probably be getting as much heat out of the
ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct voltage to apply to a heater that says it's operational voltage is 230V.

Who said that then?

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle.

So not 202V then?

Even the 51Hz went down to 50Hz

Not because of what you did alone it didn't.

but then again I don't think such small changes mean much as the unit samples at about twice per second.

And that.

So, have you tried running one of the 2kW heaters on just the II
setting yet, just to see what happens?

Cheers, T i m

On Thu, 30 Nov 2017 11:39:17 +0000 (GMT), charles
wrote:

snip

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle. Even the 51Hz went down to
50Hz but then again I don't think such small changes mean much as the
unit samples at about twice per second.


If your test meter thought that you boiling a kettle dropped the mains
frequncy from 51Hz to 50Hz, then it's a very strange meter.

His meter didn't, he did. ;-)

Cheers, T i m

On Thu, 30 Nov 2017 03:55:50 -0800 (PST), whisky-dave
wrote:

On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:
snip

OK here's the resitances at cold of the relivant parts.
at 240V at 230V (the speicifed operational volatge)
I 66.4R 867W 797W
II 44.9R 1283W 1178W
III 27.1R 2125W 1952W


where's the 1300W you speak off, closest is at 240V,

Ding!

See, *everyone else* would refer to such things with their optimum
values, you know, when it was plugged into any other supply here in
the UK (as this is a UK newsgroup), not your substandard setup.

snip

So tell me what voltage you'd need to get this 1300W and what would then be the rated power of the heater at that voltage.

He just did (and you acknowledged)? There is a good chance that this
heater was *designed* to be run from 240V and just re badged to say
220-230. My mini rads say 220-240V.

snip

The combination III where the device is supposed to output 2kW on a
decent mains supply.

Define a decent mains supply .

Any other supply in the country that's not yours?

How long would you expect this 2kW output to be maintained from this decent supply. ?

On a cheap heater and not outside or in front of a fan, about two
hours. What did I win? ;-)

snip

So we have an engineering lab staffed by people who are too dumb to
figure out for themselves how to make the place comfortably warm!

It is not our job to make the place comfortably warm

Just as well eh!


Cheers, T i m

On Thu, 30 Nov 2017 12:03:15 +0000, Martin Brown
wrote:

snip

John gave him all the help for calculating the room losses but I'm
pretty sure it was more than he could be bothered with (and would
rather bite the hand that feeds him here in the big gaps between
leaning the labs between classes that do that).

Some much for engineering education in the UK.

;-)

snip

OK then a cold fan pointed at the useless convection heater(s).
Strange that an organisation that prohibits fan heaters permits
overloading of the lab ring main without a second thought.

Quite.


I would still be interested to hear the outcome of the test of leaving
*just* the 1300W element on, to see how long it takes before it
overtemps (if it does at all).

Chances are that upping the power for some of the time will always
result in more heat output overall.

I guess that depends on the duty cycle. 2000W with a 50:50 duty cycle
won't be as affective as 1750W for 100%?

The problem is that they are losing
heat too fast and heating up the wrong things mostly the air against the
ceiling and walls behind the oil filled radiators. Some fans on the
ceiling to push the warm air down would help a bit.

Agreed.

I've ordered a couple of electronic power controllers to experiment
with my own rads [1]. The aim is to limit the power to that that they
can actually dissipate as they are only going to be used to provide
'background' heating in the bedroom and I'd rather not hear either of
the stats clicking in and out all night. ;-)

If you don't mind being dirty about it you could do what the electric
blanket people do with a diode in the supply to halve output on low.

I had considered that previously and even putting two heaters in the
room with each on one / different half cycle. ;-)

Cheers, T i m

On Thursday, 30 November 2017 12:47:33 UTC, T i m wrote:
On Thu, 30 Nov 2017 03:32:53 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better than a
2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty cycle,
but the 2kW keeps hitting its overtemp stat and operates on less than a
65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you refer to.

Agreed.

and part of the reason (or so I was told) that we had a new voltage conditioner transforms installed for the WHOLE enginneering building not just for our lab or our floor. This building incorperates at least 3 wind tunnels for the aerolab for testing, when they fire those up it sounds like a jet engine outside.
A mechanical enginnering lab with welders and the like, 100s of computers, offices a couple of 100 I'd guess and a number of labs both research and teaching on 4 floors.




If we ran it out a lower votage the duty cycle would increase to a higher percentage which you claim is bester.

Correct and I do.

So isn't it better to have 220V than 240 for this POV.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on and that is what they call the operational voltage but that of course depends on other factors.

Correct, 'designed voltage range' so as to either not damage the unit
or it not perform reasonably expected.

So conencting it to yuor home ~240V would in theory be overrating the heater as it was design for running at 230V NOT 240V


(and potentially maintaining)
the 1300W element than with them all trying to run both (at ~2kW
total) because of the voltage drop from the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection is applied.

Agreed.

So does this make it a more efficient heater ?
Strange that they say 230V then isn't it.



But if it does..
back to the 9V battery so it definanlty won't ever overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe the heater would ever go into it's 'cycle' as you call it.

Agreed.

So does this make it a more efficient heater ?



I also think that runnin git at about 240V of possible would make it less efficiant than running it at 202V

It wouldn't affect the 'efficiency' (as it will always be ~100%
efficient) but that might indirectly affect it's ability to heat the
room (as) effectively.

Why would that be the case if the 'efficiency' was the same ?

remmeber the transformer installed lowers the voltage to increase 'efficiency'.


And with that supply he'll probably be getting as much heat out of the
ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct voltage to apply to a heater that says it's operational voltage is 230V.

Who said that then?

you're the one claiming that 240V is the 'standard' not me.


I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle.

So not 202V then?

No that is our lab when we overrate the MCBs designed current carrying capacity by 8 amps.


Even the 51Hz went down to 50Hz

Not because of what you did alone it didn't.

At first glance I had no way of knowing that, soemtimes I;m just too observant I guess.



but then again I don't think such small changes mean much as the unit samples at about twice per second.

And that.

Yep and with switch on/off spikes and the like.


So, have you tried running one of the 2kW heaters on just the II
setting yet, just to see what happens?

Yes it runs at 1055W or there abouts depending on the input voltage remmeber that small point ?

Today it's running at 1003W at 208V in my office ambient temp 21C,





Cheers, T i m

On Thursday, 30 November 2017 12:29:34 UTC, Martin Brown wrote:
On 30/11/2017 11:55, whisky-dave wrote:
On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:

- convection heaters are useless unless you
live on the ceiling where all the warm air accumulates.

How comes those in charge of the buiding services and building managment didn't know this ?

They are probably as dumb as you are.

No where near as dumb as you for supporting paying nearly half a million to a uni chanceler.

Where is this dodgy university?

http://www.qmul.ac.uk/


The thing is I've been complaining for years aboout the lab adn the running

In article ,
whisky-dave wrote:
On Thursday, 30 November 2017 11:39:36 UTC, charles wrote:
In article ,
whisky-dave wrote:
On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better
than a 2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100%
duty cycle, but the 2kW keeps hitting its overtemp stat and
operates on less than a 65% duty cycle.

The other thing that came to mind is that he would probably get
more heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you
refer to. If we ran it out a lower votage the duty cycle would
increase to a higher percentage which you claim is bester.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on
and that is what they call the operational voltage but that of course
depends on other factors.


(and potentially maintaining) the 1300W element than with them
all trying to run both (at ~2kW total) because of the voltage
drop from the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection
is applied.


But if it does.. back to the 9V battery so it definanlty won't
ever overheat.

What do you think?

it's would depend on the battery whether it could, but I don't
believe the heater would ever go into it's 'cycle' as you call it.

I also think that runnin git at about 240V of possible would make it
less efficiant than running it at 202V



And with that supply he'll probably be getting as much heat out
of the ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct
voltage to apply to a heater that says it's operational voltage is
230V.

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle. Even the 51Hz went down to
50Hz but then again I don't think such small changes mean much as
the unit samples at about twice per second.


If your test meter thought that you boiling a kettle dropped the mains
frequncy from 51Hz to 50Hz, then it's a very strange meter.

You don't understand much about meters do you. This is a two digit
display so it shows an average over time. So all it can display 49Hz 50Hz
51Hz etc...

so if the freuency is 50.5Hz it's display 50 for a second then 51 for a
second. At home and work it does the same although at work is only
displays 51 for about 1 in 5 or so seconds.

The mains frequency doesn't change like that. And it rarely gets to 51.5Hz
except occasionally in the middle of the night to make up for a spell of
49.5 during the day.

--
from KT24 in Surrey, England

On Thursday, 30 November 2017 14:06:55 UTC, charles wrote:

You don't understand much about meters do you. This is a two digit
display so it shows an average over time. So all it can display 49Hz 50Hz
51Hz etc...

so if the freuency is 50.5Hz it's display 50 for a second then 51 for a
second. At home and work it does the same although at work is only
displays 51 for about 1 in 5 or so seconds.

The mains frequency doesn't change like that.

What do you mean like that ? Like what ?



And it rarely gets to 51.5Hz

I;'ve NEVER seen it get to 51.5Hz and I;ve never said it gets to 51.5Hz
so where are you getting those figures from ?

except occasionally in the middle of the night to make up for a spell of
49.5 during the day.

So what would a two digit meter display at these times ?

In article ,
whisky-dave wrote:
On Thursday, 30 November 2017 14:06:55 UTC, charles wrote:

You don't understand much about meters do you. This is a two digit
display so it shows an average over time. So all it can display 49Hz
50Hz 51Hz etc...

so if the freuency is 50.5Hz it's display 50 for a second then 51 for
a second. At home and work it does the same although at work is only
displays 51 for about 1 in 5 or so seconds.

The mains frequency doesn't change like that.

What do you mean like that ? Like what ?

varying by the second

And it rarely gets to 51.5Hz

I;'ve NEVER seen it get to 51.5Hz and I;ve never said it gets to 51.5Hz
so where are you getting those figures from ?

my error, I should have typed 50.5

except occasionally in the middle of the night to make up for a spell
of 49.5 during the day.

So what would a two digit meter display at these times ?

It should show 50.

--
from KT24 in Surrey, England

whisky-dave wrote:

On Thursday, 30 November 2017 11:39:36 UTC, charles wrote:
In article ,
whisky-dave wrote:
On Wednesday, 29 November 2017 17:06:57 UTC, T i m wrote:
On Wed, 29 Nov 2017 08:50:01 -0800 (PST), whisky-dave
wrote:

On Wednesday, 29 November 2017 16:32:58 UTC, T i m wrote:
On Wed, 29 Nov 2017 13:38:10 +0000, Andy Burns
wrote:

whisky-dave wrote:

What I don't understand is why a 1.3KW heater would be better
than a 2KW at giving out heat.

It *might* be better, if. e.g. the 1.3kW can operate at 100% duty
cycle, but the 2kW keeps hitting its overtemp stat and operates on
less than a 65% duty cycle.

The other thing that came to mind is that he would probably get more
heat out of the radS with them all on.

what if we ran it at 240V rather than 215V or 202V ?

What do you think?

I think it would make it a pooreer heater due to this cycling you refer
to. If we ran it out a lower votage the duty cycle would increase to a
higher percentage which you claim is bester.


would it be better or worse at providing heat. ?

What do you think?

So what is the optimium volage for a 2KW heater ?

What do you think?

I would hope that it is the voltage it has been designed to work on and
that is what they call the operational voltage but that of course depends
on other factors.


(and potentially maintaining) the 1300W element than with them all
trying to run both (at ~2kW total) because of the voltage drop from
the crap power supply.

So run it at 110V then it is highly unlikely it'll NEVER cut out.

What do you think?

I doubt it would ever reach the point where the overheat protection is
applied.


But if it does.. back to the 9V battery so it definanlty won't ever
overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe
the heater would ever go into it's 'cycle' as you call it.

I also think that runnin git at about 240V of possible would make it less
efficiant than running it at 202V



And with that supply he'll probably be getting as much heat out of
the ring main as he will the heaters themselves. ;-)

didn;t seem to be the case afer a couple of hours.

Like you, it was a joke mate. ;-)

and thr biggest joke is someone claiming that 240V is the correct voltage
to apply to a heater that says it's operational voltage is 230V.

I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle. Even the 51Hz went down to
50Hz but then again I don't think such small changes mean much as the
unit samples at about twice per second.


If your test meter thought that you boiling a kettle dropped the mains
frequncy from 51Hz to 50Hz, then it's a very strange meter.

You don't understand much about meters do you.
This is a two digit display so it shows an average over time.
So all it can display 49Hz 50Hz 51Hz etc...

so if the freuency is 50.5Hz it's display 50 for a second then 51 for a
second. At home and work it does the same although at work is only
displays 51 for about 1 in 5 or so seconds.

It's similar to the one below but was brought about 10 years or so ago.
https://www.amazon.co.uk/Brennenstuh...attage-current
/dp/B00I068ZEE

I doubt it really reaches either 49.5 or 50.5 Hz. I think your meter is
wrong. Either way, it is an absolute certainty that your kettle did
*not* change the frequency in any way detectable by any practical
instrument.

--

Roger Hayter

On Thursday, 30 November 2017 15:08:20 UTC, charles wrote:
In article ,
whisky-dave wrote:
On Thursday, 30 November 2017 14:06:55 UTC, charles wrote:

You don't understand much about meters do you. This is a two digit
display so it shows an average over time. So all it can display 49Hz
50Hz 51Hz etc...

so if the freuency is 50.5Hz it's display 50 for a second then 51 for
a second. At home and work it does the same although at work is only
displays 51 for about 1 in 5 or so seconds.

The mains frequency doesn't change like that.

What do you mean like that ? Like what ?

varying by the second

I never said it varied by the second.
I have no idea how often it varies it could be far shorter than a second or are you claiming it varies ever hopur or day or week.
I stated what the display read, NOTHING more.

https://wwwhome.ewi.utwente.nl/~ptde...isc/mains.html

This 50 or 60 Hz is not perfectly stable, due to the continuously changing load of the power grid and the generator's reaction to load changes.




And it rarely gets to 51.5Hz

I;'ve NEVER seen it get to 51.5Hz and I;ve never said it gets to 51.5Hz
so where are you getting those figures from ?

my error, I should have typed 50.5

I've never seen it at 50.5Hz either.

I checked gridwatch before sending this and it was 50.0662Hz
now it is at 49.885Hz



except occasionally in the middle of the night to make up for a spell
of 49.5 during the day.

So what would a two digit meter display at these times ?

It should show 50.

yes it should and it does for most of the time.
I understand that the accuracy of such things is limited usualy to the least significant digit ansd it doesnlt suprise me that this fluctuates in teh same way a 9V battery does when it show a voltage of fluctuates between 9.59 and 9.60V on the 20V scale, on the 200V scale it's 09.6V on the 1000V scale 009V
are yuo suggesting there's something wrong with my 9V battery (PP3) ?

or perhaps the meter(s)....
I have about 100 of them but I'm not testing them all and sending back those that don;t agree to the exact mv.

On Thursday, 30 November 2017 15:11:10 UTC, Roger Hayter wrote:
whisky-dave wrote:

It's similar to the one below but was brought about 10 years or so ago.
https://www.amazon.co.uk/Brennenstuh...attage-current
/dp/B00I068ZEE

I doubt it really reaches either 49.5 or 50.5 Hz. I think your meter is
wrong. Either way, it is an absolute certainty that your kettle did
*not* change the frequency in any way detectable by any practical
instrument.

I agree I can't see how it could have other than the meter it's self throwing a wobbley or not being the most accurate ever made.

Now lets see if you can work this out.

Using the maplin power meter I get a voltage of 209V

Using the meter below I get 212V
https://www.rapidonline.com/328a-dig...imeter-86-3177

Using the meter below I get 210V
https://www.rapidonline.com/digital-...8-lcd--85-0721

Using our ~20 year old true RMS meter
Using the meter below I get 207V
https://www.bidspotter.co.uk/en-gb/a...8-a76700e1c839

Using the meter below I get 214V, flickers between 0.04 and 0.05 KHz.
https://www.rapidonline.com/atp-dm-6...imeter-90-6561


So I;m not expecting super accurate results from a 10 year old maplin power meter with two digets for frequency.

On 30/11/2017 13:16, T i m wrote:
On Thu, 30 Nov 2017 12:03:15 +0000, Martin Brown
wrote:

I've ordered a couple of electronic power controllers to experiment
with my own rads [1]. The aim is to limit the power to that that they
can actually dissipate as they are only going to be used to provide
'background' heating in the bedroom and I'd rather not hear either of
the stats clicking in and out all night. ;-)

If you don't mind being dirty about it you could do what the electric
blanket people do with a diode in the supply to halve output on low.

I had considered that previously and even putting two heaters in the
room with each on one / different half cycle. ;-)

I am thinking of doing it to my office cooling fan but it wasn't warm
enough this summer. It has settings called low, medium and high.

Even on "low" it moves sheets of paper off my desk several metres away.
The settings are more accurately gale, strong gale and hurricane.

--
Regards,
Martin Brown

whisky-dave wrote:

On Thursday, 30 November 2017 12:29:34 UTC, Martin Brown wrote:
On 30/11/2017 11:55, whisky-dave wrote:
On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:

- convection heaters are useless unless you live on the ceiling where
all the warm air accumulates.

How comes those in charge of the buiding services and building
managment didn't know this ?

They are probably as dumb as you are.

No where near as dumb as you for supporting paying nearly half a million
to a uni chanceler.

Where is this dodgy university?

http://www.qmul.ac.uk/


The thing is I've been complaining for years aboout the lab adn the
running . last year I complain because 3 female students compalined to me
and asked me why they can't have heaters in the lab as it was 14C (hardly
cold I've worked here when it's been 5C). I sent an email around asking if
athena swan . https://www.ecu.ac.uk/equality-charters/athena-swan/ can
help (as women suffer the cold more than men) the head of department sent
me an email claiming that I am being sexist and that he recieved a
complaint and that he has put on my record that I have been sexist. If I
want to know what he;s said I have to pay £10 to an outside company, and I
can NOT defend the claim that I am sexist. Uni's dont; like critasm
haven;t you noticed check out the Russel group that we are part of .

https://www.theguardian.com/uk-news/...-accused-of-im
porting-sports-direct-model-for-lecturers-pay

Do you have any evidence for your somewhat harmless but undoubtedly
sexist suggestion that women feel the cold more than men? This has not
particularly been my experience. Perhaps at some point in your life
you have identified concern for the health of small children as a
particularly female characteristic? I'm only guessing.


--

Roger Hayter

On Thu, 30 Nov 2017 05:28:47 -0800 (PST), whisky-dave
wrote:

snip

If we ran it out a lower votage the duty cycle would increase to a higher percentage which you claim is bester.

Correct and I do.

So isn't it better to have 220V than 240 for this POV.

It may only be 'better' if it stops it cycling when it otherwise
might.


snip

Correct, 'designed voltage range' so as to either not damage the unit
or it not perform reasonably expected.

So conencting it to yuor home ~240V would in theory be overrating the heater as it was design for running at 230V NOT 240V

No, as I said, the chances are it was *designed* to run at 240V, it's
just been *de-rated* on paper to allow it more compatibility over
Europe.

snip


So does this make it a more efficient heater ?

No. The efficiency will always be roughly the same. eg, ALL the energy
going into the unit *will* come out as heat.

Strange that they say 230V then isn't it.

See above.



But if it does..
back to the 9V battery so it definanlty won't ever overheat.

What do you think?

it's would depend on the battery whether it could, but I don't believe the heater would ever go into it's 'cycle' as you call it.

Agreed.

So does this make it a more efficient heater ?

No (see above). However, if you are talking about how 'effectively' it
will transfer it's heat to the room, then yes, depending on the
voltage applied.


I also think that runnin git at about 240V of possible would make it less efficiant than running it at 202V

It wouldn't affect the 'efficiency' (as it will always be ~100%
efficient) but that might indirectly affect it's ability to heat the
room (as) effectively.

Why would that be the case if the 'efficiency' was the same ?

Because you are trying to mix two different things. You have the
'efficiency' of how the rad converts electricity into heat and the
'effectiveness' of how the rad transfers that heat to the room.

remmeber the transformer installed lowers the voltage to increase 'efficiency'.

I don't need to remember that because I understand it so know that in
some (most) cases it will do no such thing.

The only time it might improve anything will be to reduce the running
costs of things like lights (if designed for 230V and running them at
240V might make them 'overbright') and possibly (refrigeration) pumps,
if being over driven.

Most SMPSU's wouldn't care less (and often automatically fun from 110
to 240V, 50 or 60 Hz) and pure resistive loads won't care either but
just take more or less time to heat your room or heat your tea.

snip

and thr biggest joke is someone claiming that 240V is the correct voltage to apply to a heater that says it's operational voltage is 230V.

Who said that then?

you're the one claiming that 240V is the 'standard' not me.

It is, in the UK (but not in your part of the UK apparently).


I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle.

So not 202V then?

No that is our lab when we overrate the MCBs designed current carrying capacity by 8 amps.

You aren't 'overrating' the MCB (that you were told was an RCBO), you
are overrating the ring / supply. The RCBO is potentially working as
designed, the wiring in the lab less so if the voltage is dropping so
much.


Even the 51Hz went down to 50Hz

Not because of what you did alone it didn't.

At first glance I had no way of knowing that, soemtimes I;m just too observant I guess.

No, too blinkered to understand what is going on behind what you see.

snip


So, have you tried running one of the 2kW heaters on just the II
setting yet, just to see what happens?

Yes it runs at 1055W or there abouts depending on the input voltage remmeber that small point ?

I don't need to remember, because I understand. You don't understand.

So, my question was to be if you have run the rads continuously on the
NoII setting, do they still cycle?

Today it's running at 1003W at 208V in my office ambient temp 21C,

Whilst the few degrees increase from what you find in an unheated lab
and say 21 Degrees may not be enough to impact the rad cycling thing,
it still could. So, 'a good test' would be to set one rad up out in
the (cold) lab on setting II and seeing if it cycles at all. Also,
measure the temperature as you did before and see if it's holding
steady and at what temp?

*IF* it's sitting just under the overtemp stat trip level (98 DegC or
so you said) from cold up to the required (main stat) temperature then
that *is* a more effective solution at heating the lab and allowing
you to have more heaters on at the same time, than trying to run them
at 2kW (more heaters drawing less power and at a higher temperature
more consistently).


Cheers, T i m

On Thu, 30 Nov 2017 16:37:38 +0000, Martin Brown
wrote:

On 30/11/2017 13:16, T i m wrote:
On Thu, 30 Nov 2017 12:03:15 +0000, Martin Brown
wrote:

I've ordered a couple of electronic power controllers to experiment
with my own rads [1]. The aim is to limit the power to that that they
can actually dissipate as they are only going to be used to provide
'background' heating in the bedroom and I'd rather not hear either of
the stats clicking in and out all night. ;-)

If you don't mind being dirty about it you could do what the electric
blanket people do with a diode in the supply to halve output on low.

I had considered that previously and even putting two heaters in the
room with each on one / different half cycle. ;-)

I am thinking of doing it to my office cooling fan but it wasn't warm
enough this summer. It has settings called low, medium and high.

Even on "low" it moves sheets of paper off my desk several metres away.
The settings are more accurately gale, strong gale and hurricane.

;-)

Cheers, T i m

On Thursday, 30 November 2017 17:21:52 UTC, Roger Hayter wrote:
whisky-dave wrote:

On Thursday, 30 November 2017 12:29:34 UTC, Martin Brown wrote:
On 30/11/2017 11:55, whisky-dave wrote:
On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:

- convection heaters are useless unless you live on the ceiling where
all the warm air accumulates.

How comes those in charge of the buiding services and building
managment didn't know this ?

They are probably as dumb as you are.

No where near as dumb as you for supporting paying nearly half a million
to a uni chanceler.

Where is this dodgy university?

http://www.qmul.ac.uk/


The thing is I've been complaining for years aboout the lab adn the
running . last year I complain because 3 female students compalined to me
and asked me why they can't have heaters in the lab as it was 14C (hardly
cold I've worked here when it's been 5C). I sent an email around asking if
athena swan . https://www.ecu.ac.uk/equality-charters/athena-swan/ can
help (as women suffer the cold more than men) the head of department sent
me an email claiming that I am being sexist and that he recieved a
complaint and that he has put on my record that I have been sexist. If I
want to know what he;s said I have to pay £10 to an outside company, and I
can NOT defend the claim that I am sexist. Uni's dont; like critasm
haven;t you noticed check out the Russel group that we are part of .

https://www.theguardian.com/uk-news/...-accused-of-im
porting-sports-direct-model-for-lecturers-pay

Do you have any evidence for your somewhat harmless but undoubtedly
sexist suggestion that women feel the cold more than men?

Yes, from teh TV program looking at the differnce between the sexes which was on the very same week and was a repeat of teh program I saw a year ago.

women feel the cold more because their biological systems are designed (yes you can blame a male god for this) to keep the heat in the central part of the body in order to protect the reproductive organs, this means blood is divered from the limbs and other extremities. It's as much as 2C, this is why women are more likely to pull the duvet off their male partners. They might do this to female partners too, but that would just end in a bitch fight ;-)


http://www.bbc.co.uk/news/magazine-33760845

http://www.dailymail.co.uk/femail/ar...odies-men.html

http://www.slate.com/articles/double...old_hands.html

http://www.independent.co.uk/life-st...-a7998241.html

http://www.sciencefocus.com/article/...-cold-more-men


This has not
particularly been my experience. Perhaps at some point in your life
you have identified concern for the health of small children as a
particularly female characteristic? I'm only guessing.


Of the 4 people that complained to me about the cold conditions 3 of them were female one was mature or rather she had a 8 year old kid and was married and she complained with her hat & coat on when the lab was at 22C

On Thursday, 30 November 2017 18:55:57 UTC, T i m wrote:
On Thu, 30 Nov 2017 05:28:47 -0800 (PST), whisky-dave
wrote:

snip

If we ran it out a lower votage the duty cycle would increase to a higher percentage which you claim is bester.

Correct and I do.

So isn't it better to have 220V than 240 for this POV.

It may only be 'better' if it stops it cycling when it otherwise
might.

I said nothing about stoping, what's wrong with reducing cycling. ?



Correct, 'designed voltage range' so as to either not damage the unit
or it not perform reasonably expected.

So conencting it to yuor home ~240V would in theory be overrating the heater as it was design for running at 230V NOT 240V

No, as I said, the chances are it was *designed* to run at 240V,

So why not state that as the operational voltage rather than 230V ?


it's
just been *de-rated* on paper to allow it more compatibility over
Europe.

And you'd just that would you.
Perhaps the 32A MCB was designed to run at 40 amps.


So does this make it a more efficient heater ?

No. The efficiency will always be roughly the same. eg, ALL the energy
going into the unit *will* come out as heat.

So there's no way of imporving efficieny by say having more fins or larger surface area.


remmeber the transformer installed lowers the voltage to increase 'efficiency'.

I don't need to remember that because I understand it so know that in
some (most) cases it will do no such thing.

How about in the case of heating, after all you;d hardly both with such a thimng to change the power consumption of an oscilloscope.

So what are these things installed for ?(apart from making money from mugs)



The only time it might improve anything will be to reduce the running
costs of things like lights (if designed for 230V and running them at
240V might make them 'overbright') and possibly (refrigeration) pumps,
if being over driven.

But if everything was designed to run at 240V .... this then makes NO sense..



Most SMPSU's wouldn't care less (and often automatically fun from 110
to 240V, 50 or 60 Hz) and pure resistive loads won't care either but
just take more or less time to heat your room or heat your tea.

Yes I know. But there was talk of how installing such a system would spread the load SMPS's run on because the phase of current and voltage weren;t in sysch the way the company measures power didn;t give the correct readings as in the system show'd we were using less billable power than we actually used and installing suchb a transfromer would smooth this out.


and thr biggest joke is someone claiming that 240V is the correct voltage to apply to a heater that says it's operational voltage is 230V.

Who said that then?

you're the one claiming that 240V is the 'standard' not me.

It is, in the UK (but not in your part of the UK apparently).

The UK was meant to reduce it;s voltage to 230V to come more in line with the EU 220V average.



I took the tester home last night and I too got a reading of 238-239V
went down to 237-8 when boiling my kettle.

So not 202V then?

No that is our lab when we overrate the MCBs designed current carrying capacity by 8 amps.

You aren't 'overrating' the MCB (that you were told was an RCBO),

so drawing 40amps isn't overrating a 32a MCB. ?
at what point would you say it's being overrated ?



Even the 51Hz went down to 50Hz

Not because of what you did alone it didn't.

At first glance I had no way of knowing that, soemtimes I;m just too observant I guess.

No, too blinkered to understand what is going on behind what you see.

I guess at what was going on as I've seen it time and time again in labs for years. Itls very difficult to get a cheap circuit to read lopw frequescies so it;s not too accurate when it can only sample 3 times a second it uses averages of algorithms for D-A converers there two main type's I think.



So, have you tried running one of the 2kW heaters on just the II
setting yet, just to see what happens?

Yes it runs at 1055W or there abouts depending on the input voltage remmeber that small point ?

I don't need to remember, because I understand. You don't understand.

I do you don't yuou've proved that.


So, my question was to be if you have run the rads continuously on the
NoII setting, do they still cycle?

No idea don't care.
We did not buy 2KW heaters to run at 1.x KW.
If we wanted 1.2KW we'd have brought cheaper 1KW or 1.5KW heaters rather than 2KW heaters.



Today it's running at 1003W at 208V in my office ambient temp 21C,

Whilst the few degrees increase from what you find in an unheated lab
and say 21 Degrees may not be enough to impact the rad cycling thing,
it still could. So, 'a good test' would be to set one rad up out in
the (cold) lab on setting II and seeing if it cycles at all. Also,
measure the temperature as you did before and see if it's holding
steady and at what temp?

Not practical, too many other variables.
Yesterday a workman has walled himslef in so we had to open the closed doors to let him in he had the full H&S gear on and a hoodie tracksuit because he was so cold those doors remaine dopen or ajar foir teh next hour while he brough rubble through the centre of the lab on sack barrows.
we also have about 100 or so studetns coming and going from 9am to 6pm, depending on the day we can have 100 students or less than a handful we didn't have ANY this morening until after 11am.


*IF* it's sitting just under the overtemp stat trip level (98 DegC or
so you said) from cold up to the required (main stat) temperature then
that *is* a more effective solution at heating the lab and allowing
you to have more heaters on at the same time, than trying to run them
at 2kW (more heaters drawing less power and at a higher temperature
more consistently).

I'd like to see the real world calcualtions for that before I complain that theree;'s not enough heating and they come in to see my 2KW rads set to 1.1KW because I say it's more efficinet they'd laugh all the way to the capincino machine.

whisky-dave wrote:

On Thursday, 30 November 2017 17:21:52 UTC, Roger Hayter wrote:
whisky-dave wrote:

On Thursday, 30 November 2017 12:29:34 UTC, Martin Brown wrote:
On 30/11/2017 11:55, whisky-dave wrote:
On Thursday, 30 November 2017 08:33:15 UTC, Martin Brown wrote:

- convection heaters are useless unless you live on the ceiling where
all the warm air accumulates.

How comes those in charge of the buiding services and building
managment didn't know this ?

They are probably as dumb as you are.

No where near as dumb as you for supporting paying nearly half a million
to a uni chanceler.

Where is this dodgy university?

http://www.qmul.ac.uk/


The thing is I've been complaining for years aboout the lab adn the
running . last year I complain because 3 female students compalined to me
and asked me why they can't have heaters in the lab as it was 14C (hardly
cold I've worked here when it's been 5C). I sent an email around asking if
athena swan . https://www.ecu.ac.uk/equality-charters/athena-swan/ can
help (as women suffer the cold more than men) the head of department sent
me an email claiming that I am being sexist and that he recieved a
complaint and that he has put on my record that I have been sexist. If I
want to know what he;s said I have to pay £10 to an outside company, and I
can NOT defend the claim that I am sexist. Uni's dont; like critasm
haven;t you noticed check out the Russel group that we are part of .

https://www.theguardian.com/uk-news/...-accused-of-im
porting-sports-direct-model-for-lecturers-pay

Do you have any evidence for your somewhat harmless but undoubtedly
sexist suggestion that women feel the cold more than men?

Yes, from teh TV program looking at the differnce between the sexes which
was on the very same week and was a repeat of teh program I saw a year
ago.

women feel the cold more because their biological systems are designed
(yes you can blame a male god for this) to keep the heat in the central
part of the body in order to protect the reproductive organs, this means
blood is divered from the limbs and other extremities. It's as much as 2C,
this is why women are more likely to pull the duvet off their male
partners. They might do this to female partners too, but that would just
end in a bitch fight ;-)


http://www.bbc.co.uk/news/magazine-33760845

http://www.dailymail.co.uk/femail/ar...naturally-cold
er-bodies-men.html

http://www.slate.com/articles/double...heart_cold_han
ds.html

http://www.independent.co.uk/life-st...e-arguments-wo
men-colder-men-thermostat-house-temperature-study-a7998241.html

http://www.sciencefocus.com/article/...feel-cold-more
-men


This has not
particularly been my experience. Perhaps at some point in your life
you have identified concern for the health of small children as a
particularly female characteristic? I'm only guessing.


Of the 4 people that complained to me about the cold conditions 3 of them
were female one was mature or rather she had a 8 year old kid and was
married and she complained with her hat & coat on when the lab was at 22C

More women than men complain of problems with excessively cold hands and
feet.


The rest is just anecdote.


--

Roger Hayter

On Thursday, 30 November 2017 18:55:57 UTC, T i m wrote:




*IF* it's sitting just under the overtemp stat trip level (98 DegC or
so you said) from cold up to the required (main stat) temperature then
that *is* a more effective solution at heating the lab and allowing
you to have more heaters on at the same time, than trying to run them
at 2kW (more heaters drawing less power and at a higher temperature
more consistently).

They must have heard you.

In an email today after we complained that at midday it was still only 14C.
They have said I thought the labs times had changed to 3pm so you could heat up the lab.
It's 2:30pm now and the lab has just reached 15C, this is with 5 2KW heaters and 3 or 4 1,5KW heaters, so maybe they read your email as they have just given us 2 new 1.5KW heaters.

if I die from heat exaustion before 5pm I'm sueing you !