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.