Baseboard thermostat replacement


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Aug 5, 2011
West of the Mississippi
My home is all electric. The downstairs area is heated by three baseboard heaters. The three heaters are wired into a circuit that has two 30 amp breakers hooked together in the electrical panel. They are, I assume, operating on 240 volts.

The heaters are controlled by one centrally located thermostat. It is a simple dial type thermostat show below. The thermostat is getting old and no longer controls the temperature in the house very well. Simply moving the dial 1/4 of an inch can cause the house to overheat (mid to high 70's) or get cold (low 60's). Photo below.

I want to replace it with a new thermostat that will allow me to program it to turn the heat up at about 6 AM and turn it down at 10 PM. I no longer wish to get up on a cold morning, turn the heat up and then run back to bed until the house warms up.

Below is the type of thermostat I am considering. But, I have not purchased it yet as I am not sure it is right for my heaters. Photo below.

I am confused as to what type of thermostat to purchase. I am looking at this one from Home Depot. It is the type I am interested in. But apparently there are several different ways the 240 volt heaters can be wired into the thermostat. For example, my current thermostat does not have an OFF setting, and that is suppose to be important to the wiring. But how? I am also concerned about the wattage the thermostat must handle. Three electric heaters for a downstairs area of about 700 sq ft must take a lot of watts. The new one in the photo handles up to 3500 watts. How do I know that is enough?

Any advice is appreciated.


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See if there are any covers you can remove or panels you can lift up on the baseboards. The current rating is probably printed somewhere on them. Assuming the thermostat runs all three, total up the Amps. That's the capacity you need for your new thermostat.
"two 30 amp breakers hooked together in the electrical panel. They are, I assume, operating on 240 volts. "

I assume you mean there is a bar connecting the two breakers? If so, that's how a 240V circuit is configured in the US. It's two, opposite phase 120V circuits, that add up to 240V. For safety, if either breaker triggers, both open so all voltage is removed from the circuit.

So you have one 30A circuit at 240 V. For continuous use, circuits are de-rated to 80%, so 24A * 240 V = 5760 W max allowed.

As CaptTom says, you'll need to know the rating of the heaters themselves.

Another way to approach this is to see if you can get any information off the current thermostat. Let’s say, for example, that you could determine that it is a Honeywell ABC123 switch. You could then do some research and find a replacement for that switch. Especially if it is a name brand, like Honeywell, you could get hold of them and ask for a current model thermostat that has the same specs as the one you have. Just a thought.
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