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DragonFire 01-04-2011 09:05 AM

2 wire thermostats in parallel?
I would like to wire two 240v baseboard heaters to a single 20amp circuit, and have each baseboard on its own thermostat. Wiring is 12/2 (black, white, ground only, no red) and combined wattage of baseboards is 3000w so everything is fine in that regard.

Now... i already have two 2-wire digital wall thermostats.

From my understanding I have 2 options.... install a junction box from the circuit breaker to split a separate 12/2 going to each thermostat and baseboard.


Run the 12/2 to each thermostat in parallel, and then connect each thermostat to its baseboard.

So my question is... If i choose the (supposedly preferred) method of wiring the thermostats in parallel must those thermostats be 4 wire thermostats?

jbfan 01-04-2011 09:41 AM

What you will do is run the feed to the tstat, connect the tstat and the feed in and the feed out to the next tstat.
On the load side of the tstat you feed to the heaters.

DragonFire 01-04-2011 09:53 AM

So you are saying it is possible and acceptable to use 2-wire thermostats wired in parallel?

jbfan 01-04-2011 09:54 AM

You are not wiring them in parallel.
They still control only one heater.
You are just paralleling the feeds to the heaters.

DragonFire 01-04-2011 10:31 AM

ok, now I am getting somewhere. Earlier I specifically read on a google search form another forum posting that thermostats should be wired in parallel for this scenario... which now sounds to be wrong information, and of course creating all sorts of confusion for me trying to visualize things.

I don't suppose there is any simple diagram to help clarify the wiring, or a bit more detailed verbal walk-thru for this type of install? Once I get it clear, I plan to post my working diagram for approval before attempting it.

I can always go with the alternative method of using a junction box and splitting, but would really like to eliminate that especially since what I am wanting to do is a common task.

Thanks for taking the time to post.

jbfan 01-04-2011 10:42 AM

You are doing the same thing with a j box as I said.
You take the feed from the breaker to the first box with the tstat.
You pigtail that wire with the wire that feeds the tstat and the wire that feeds the next tstat.
At each tstat, you run a wire from the controlled side of the tstat to each heater controlled by that tstat.

DragonFire 01-04-2011 11:12 AM

Thanks jbfan,
I am now going to try to diagram as per your directions above and hopefully can post something back for confirmation later.

DragonFire 01-04-2011 12:32 PM

1 Attachment(s)
ok, here we go with my first stab at the diagram. Comments anyone?

jbfan 01-04-2011 01:56 PM

Looks good!

DragonFire 01-04-2011 02:23 PM


Originally Posted by jbfan (Post 562682)
Looks good!

Awesome! Thanks for taking the time to explain everything in greater detail for me.

jbfan 01-04-2011 02:25 PM


Originally Posted by DragonFire (Post 562694)
Awesome! Thanks for taking the time to explain everything in greater detail for me.

Not a problem, cause that what we get paid for!!!!!!!!!!!:laughing:

DragonFire 01-22-2011 12:50 PM

Just a followup and thanks again to jbfan for the information. I was successful in my project and everything is working perfectly. :thumbup:

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