My home has two adjacent thermostats, each one controls a single 1000W 240V baseboard heater. The heaters themselves are on opposite walls of the dining room. I’d like to replace both thermostats with a single smart Mysa thermostat. I’ve already done the replacement in every other room of the house but I’d rather not have two thermostats here, and I can’t fit two Mysas side by side within this space anyway.

What’s the best way to do this in this spot? I think I should be able to wire the loads in parallel to a single thermostat but I’m not sure on the best way to do the wiring. Should I take the load wires out of the top box and move them into the bottom one? Or run a new jumper from one box to the other?

1 Answer 1


There are two different possibilities here:

  • Same Circuit

If the heaters are currently on the same circuit (i.e., turning off one double-breaker turns off both heaters) then this is easy. If you can move the wires from one box to the other, great. If not, run cable from the heater side of one box to the other and pigtail the heater connections together to the heater/load side of the new thermostat.

  • Different Circuits

In general 2 x 1000W heaters can easily fit on a single 240V circuit. 2000W / 240V = 8.33A. Multiple by 1.25 because continuous = 10.4A. Even a 15A circuit can handle that. However, it is possible that you have multiple heaters from different parts of the house on different circuits. For example, if you have 2 20A 240V circuits for heating then each can provide 3,840W of heat. If each of them currently handles 3,000W (3 x 1,000W) and each of the two relevant heaters is on a different circuit then moving one of them to the other circuit is not allowed (one circuit goes from 3,000W to 2,000W but the other goes from 3,000W to 4,000W > 3,840W).

So if they are currently on different circuits, you need to determine the total usage on each of the circuits to figure out if/how to rearrange things to make it work. It may be easy or it may involve moving heaters in other rooms between circuits.

  • They are on the same breaker, 30A Dec 3, 2023 at 15:24

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