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