Space Heater And Thermostat Positioning In A Panel

Why do you need heating? Good ventilation would be a better option.

Heating can induce condensation, a bad thing in my book.

Well Tony, in tropical countries especially, when the switchboard is OFF, the humidity makes the inevitable moisture condense on the cool switchgear, busbars etc, and cause flashovers. So space heaters are provided to prevent condensation, at least here in India.

I stand corrected.

As the hot air rises, the bottom is a good place for the heater. The thermostat at the top also sounds ok, somewhere in the middle would have been better.

Here is what a major European company provides. No mention of where the thermostat should be placed though.

I think its called ACH: Anti Condensation Heater

GA Iris, i stand corrected (to plagiarise TonyS ). i learnt something here, that the thermostat should be at the bottom too, shielded from line-of-sight radiant heat. Awesome ! Thanks.

yes - thermostat at the bottom is a good practice - shielded from radiated heat is a good practice . . .

the next important step for our friend's journey is to determine the thermostat HI cut out set point - this is done by ensuring that the temperature anywhere in the panel does not exceed a safe storage temperature or a safe working temperature (lower of the two) for any component part or sub-assembly . . . this is very complicated design and simulation . . . most people i know do it empirically using experience and learning over years . . . in any case a good rule of the thumb would be to not set the thermostat higher than 45 deg celsius . . . this would ensure that the heater is never switched ON in high ambient temperature or in-panel temperature conditions . . .

a big worry in installations is that the space heater is meant for periods when the panel is not in use (powered off ) - so supply has to be kept connected even when the panel is not in use - safety considerations and indication of HEATER CIRCUIT INPUT CONNECTED are worthy of consideration . . .

a second worry is that heaters or thermostats not working when needed since these get low priority in preventive or routine maintenance checks because they are not directly related to process or production . . . .

http://cr4.globalspec.com/thread/57536

Confused again ! Posts in that thread say that the thermostat should be at the top ???

Thermostat at top, heater at bottom, GAP, no?

I read the info on thermostat placement. If you buy the IC style, you may install a thermostat, and it does not say, but I infer, that it should be as far away from the convective heat current as possible. (ie the top)

If you buy one of the resistance types, the thermostat is inside the box, as shielded as possible, but only by necessity.(because it's one neat little unit)

If I were building one, I would use IC style, with remote thermostat. Heater at bottom, thermostat at the top.

so i m totally confused now...............

which of these combination is the right one for my problem.

1) heater top, thermostat top

2) heater centre, thermostat centre

3) both heater and thermostat at the bottom

4) heater bottom, themostat top

5) heater bottom, thermostat bottom but in the opposite corner

6) heater bottom, thermostat top but in the opposite corner

all these combinations are with respect to the side cover of the panel...........so gentlemen its time to make the right choice.........

if there were two options i would have tolled you to toss a coin . . . since there are six you may roll dice . . . .

narrow it to 5 or 6 and i would a toss a coin with 5 written on both sides . . . the trick if you use either will be to select the right temperature set point

i would use ...

Heater - at the bottom, since natural convection would take the heated air through the panel, preventing condensation.

Thermostat - at the top, since, by the time the heated air has imparted its heat to the various components, it would have cooled a bit, so you need a certain temperature to prevent condensation, so, the coolest the part of the convecting air must be above a certain temperature which you will set...

One side or the other depends on your panel design and its venting system.

KVS! That is what is my perception too! I reproduce my psoting in the other post (57536):

"ACH is mounted at the bottom of the enclosure so that hot air flows to the top. Thermostat is mounted at the top so that the top temperature is monitored to control the ACH On/Off.

As regards the consultant's view that the MCB might trip spuriously due to heat from the ACH, he is also correct, because the overload protcetion device in an MCB is a bi-metal and could operate from external heat too causing spurious triping.

Best way out is to have the ACH at the bottom, the Thermostat at the top but shift the MCBs to an area where there would not be any external heat influence".