I have a 240V electric baseboard heater (70's vintage?) controlled with a
low voltage (24 VAC) thermostat. The heater has a Honeywell
transformer/relay mounted at one end which supplies the low voltage to the
thermostat circuit and has a heater-resistor/bimetal relay to energize the
heating element when the thermostat demands heat, i.e. completes the low
I just painted the outside surface of the heater with a latex wall paint.
The next day the transformer/relay failed, taking the thermostat with it.
This transformer had been buzzing off and on for the last several months
and may be about thirty years old. So the question is: was this
transformer/relay about to go anyway and the jostling round in pulling the
heater away from the wall to paint, etc., sent it over the edge, or did
painting the outside surface change the heat dissappation characteristics
enough to overheat the transformer and cause it to fail? While in theory
the paint would insulate a little and change the emissivity, I'm having a
hard time believing it would have that much of an effect.
Any electrician/HVAC folks out there familiar with these transformer/relay
systems and know the typical failure modes--with or without the paint
factor? Do these things tend to fail the way this one did (wiping out the
thermostat, too) without homeowner intervention? I have another heater I
haven't painted yet and would like to avoid another failure--if the paint
had anything to do with it. TIA.
Dennis M. Straussfogel, Ph.D.
Aerospace Engineering Consultant