multiple baseboards, one thermostat
This diagram from the Baseboard Owner’s Guide, shows how to correctly wire multiple baseboard heaters to one thermostat.

Sometimes we get calls from people who want to know if they can wire multiple heaters to one thermostat. The answer to that question is yes, you can wire multiple heaters to one thermostat — if you’re using 240-volt heaters and a 240-volt breaker. But that doesn’t mean we always recommend it.

Steve in our Tech Support Department says most of the time people want to wire multiple heaters to one thermostat for the sake of convenience. That makes sense if you have a larger room with multiple heaters in it or maybe an open-concept living space where a living room and dining room are one large area. Having one thermostat to control both heaters will work just fine because you’re dealing with one larger space.

It doesn’t work with one thermostat in a bedroom controlling a heater in that room plus another one in a different room. The temperature in both rooms would be determined by the temperate of the bedroom with the thermostat. That just defeats one of the advantages of electric heat: heating rooms independently to maximize individual comfort and minimize the electric bill.

Still reading? That probably means you’re wanting to know how you can hook up multiple heaters to one thermostat. Here’s what you need to know:

Rule #1:

The number of heaters that you can safely wire to one thermostat will depend on the size of your breaker in the electrical box, what type of wiring you are using and the wattage of the individual heaters.

So a 240-volt circuit running on a 20-amp, double-pole breaker, can have any combination of heaters up to 3,840 watts.

For example, using just one thermostat, you can install:

  • Two 1,500 watt heaters, or
  • Three 1,000 watt heaters, or
  • Five 750 watt heaters

This helpful chart provides more information.

Volts 

Size of breaker

Wire size

Maximum watts on circuit

240

20 Amp Double Pole 12/2 with Ground

3840

240

30 Amp Double Pole 10/2 with Ground

5760


Rule #2

All heaters must be wired in parallel. You can either do that by connecting each heater to the thermostat directly, or by connecting each heater to the next — just be sure that each heater is connected to the source wires. (You can also check out the wiring diagram at the top of this post — it shows how to wire multiple baseboards together.)

Multiple heaters
This photo shows how you would connect wires to use multiple Com-Pak heaters to each other. One of the building wire lines (a.k.a. Romex) is going to the next heater, the other is coming from the wall thermostat. The looped copper wire would be connected to the green grounding screw in the heater wall can.

I know that’s a lot to take in. If you’re at all confused, leave a comment and we will get back to you or get in touch with our Tech Support department. They’d be more than happy to walk you through the process over the phone or through an e-mail.