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 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?

snip

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, 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.

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

And?

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.

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?

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?

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? ;-)

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)?


Which is why I 'set' it to 2KW and not 700W or 1300W .

Yes, I know and I was saying you might also try setting it to Heat
level II and see what happens.

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.

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.

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?

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 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?

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?

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.

That's why I changed from the 700, 1300, 2000W to settings I, II and
III so you didn't keep throwing your trolling toys out of the pram.


eg, If you get 2000W for 2 hours and then it drops to 700W for 2 hours
then the average will be 700W and 2000W for that 4 hour period. IF
putting it on heat level II(1300W) meant it didn't trip the overtemp
stat you might get 1300W continuously for the entire 4 hours.

I think that is unlikely.

But as yet untested eh?

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.

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

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

Can you answer that at least.

I just did, but I'll explain it to you in detail (not that it will
help ...).

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.

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.



We don't want hot radiators we want the room to be hot preferably, that is what efficincy is about.

Bwhahahaha ... you really don't have an effing clue do you? Are you
anywhere near a science teacher to ask them to teach you all about
basic thermodynamics?


Still talking **** I see.

What, that a room temperature heater will heat a room better / quicker
than a hot one (you can't make this stuff up!).

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 of the rad the
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.


HTF do you think a heater heats a room?

Depends where it's placed.

No it doesn't. 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).



Do yuo actually know what these things are used for ?

Yes, that's why I'm trying to teach you.

yuor the one that was suggesting I send working heaters back because you didn't know how they worked.

Liar.

So why did yuo think they were faulty. ?

Why do you keep lying?

why did you contact sales ?

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

and what was sales reply.

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

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.



Why did you contact salesd aledgly to help me and get a wrong result ?

Why are you so ungrateful when people try to help you?

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 ...


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 and still asked further stupid
question I'm not sure exactly how much it helped you. The rest of us
did actually learn things though.

Cheers, T i m