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