Replacing electric wall heaters

5 years ago

last modified: 5 years ago

Our wall heater is no longer turning off when the room reaches the temperature in the thermostat. I don't think the issue is the thermostat because it controls another similar heater that is still cycling on and off. When we opened the grate, there were small bits of broken/burnt plastic which seems to indicate there is an overheating problem too.

While looking into replacements, I noticed that our current one oddly has two cans. Does this look to you like the prior owner just wedged a replacement wall heater into the box/grate of the old one? The model on the inner element is King DEC2422. How would you recommend going about replacing this?

We have four others that are similar, would you recommend replacing all at once? I also noticed that none of them are 4" off the floor like they recommend with their new models, do you think we need to cut into the wall to raise them up higher? Thank you!

Edited - to add photos, and to say - we are open to hearing about other heating systems too. We live in a condo HOA so heat pumps with outdoor units aren't a great option but we're interested to learn more about ceramic/infrared heaters and other styles. Thanks

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Comments (5)

wdccruise
5 years ago
"I don't think the issue is the thermostat because it controls another similar heater that is still cycling on and off."

Is the thermostat a UPM HTM311A? If not, what is the thermostat model? The UPM thermostat is a 240 volt thermostat that directly controls a heater. It's not like a low-voltage thermostat used for a typical heat pump or furnace that's connected to a relay to switch the heat pump or furnace on. If the thermostat is a 240 volt model, it's not possible for it to switch on/off one heater while not switching on/off a second.
roentree
Original Author
5 years ago
Hi @wdccruise, thanks for weighing in. It is an old White-Rodgers thermostat - I can't see a model number on it (perhaps on back) but here is a photo. We do have a White-Rodgers relay in our utility room that I believe connects the different heaters with the thermostat. One thermostat in the downstairs controls two heaters, and then each heater upstairs has its own similar thermostat but slightly different look.
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wdccruise
5 years ago
If the thermostat controls a relay which in turn controls the heater and the heater stays on all the time, then the problem is with the relay.
roentree
Original Author
5 years ago
last modified: 5 years ago
Ah got it, thanks @wdccruise. Do you have any tips on troubleshooting the relay? I also noticed that one of the wire nuts and multiple of the terminals' insulation shows signs of melting or overheating - do you know if that would be caused by the relay issue (only had been going on a day or two when we noticed it) or another overheating issue?
wdccruise
5 years ago
You need a VOM (volt ohm meter).

Thermostat A controls Relay 1 and Relay 2. Relay 1 controls Heater 1 and Relay 2 controls Heater 2. Heater 2 is the heater with the problem.
1. Turn Thermostat A to 50 degrees. Confirm that Heater 1 turns off and Heater 2 stays on.
2. Turn Thermostat A to 90 degrees. Confirm that Heater 1 turns on and Heater 2 stays on.
3. Turn Thermostat A to 50 degrees. Locate Relay 1 and Relay 2. For each relay measure the voltage across the wires connected to the thermostat. It should be zero.
4. Turn Thermostat A to 90 degrees. For each relay measure the voltage across the wires connected to the thermostat. It should be non-zero (probably 24 volts).
5. Turn off the heater circuit breaker(s).
6. Remeasure the voltage across the wires connected to the relays. If it is the same as in Step 5, proceed to step 9.
7. Disconnect the relay wires connected to the circuit breakers and heaters.
8. Turn on the heater circuit breaker(s).
9. Turn Thermostat A to 50 degrees. Check the resistance across the terminals that are (or were) connected to the circuit breaker and heater. It should be high because the relay is open (no current passes through the relay).
10. Turn Thermostat A to 90 degrees. Check the resistance across the terminals that are (or were) connected to the circuit breaker and heater. It should be zero because the relay is closed (current passes through the relay).
11. If Relay 2 is closed in Step 9, replace the relay.
I suspect the wire nuts are burned because they're not designed for high heat and they're at the front of the heater where they are heated up.

-- amateur
roentree thanked wdccruise