Hi guys,


I have been upgrading my thermostats here in the house and I have a little challenge now.

Two baseboard heaters that I assume are wired parallel (you will be able to confirm) had their own unit mounted thermostat. I'd like to upgrade as well but for those two I'd like to use the same thermostat to control them. (same room)

Those 240V baseboards are wired to a 15A breaker with #14 wires.

I've included pictures from the two heaters. Heater 2 is fed from heater 1 to its left side. All wires on heater 1 are located on its right side. Heater 1 is fed to its right side from a third baseboard in another room.

I'm not sure how to connect eveything so the thermostat will control both of them correctly. (thermostat is rated with more than enough watts for the two baseboards.)

I have found similar questions to mine on the web and even here but it didn't address the specific wiring questions here.

Thanks for your help!
Gabriel


Heater 1
http://img697.imageshack.us/img697/7...heater1.th.jpg



Heater 2
http://img29.imageshack.us/img29/286...heater2.th.jpg


Diagram (very rough sketch that I did for myself at first - hope it will do. W=white. B=Black)
http://img694.imageshack.us/img694/4486/diagrame.th.jpg

Confirm a few things:

Heater #2 looks like it has a thermal protector in series with the heater. I suppose heater #1 has on on the other side?

The thermostat that your going to use has 4 wires and is a line powered thermostat?

The existing thermostat isn't pictured. Where does it fit in this picture?

Where did you plan to get power from?

You do realize that wiring for baseboards must be oversized by 1.25 because it's a space heating load.

i.e. if the current was 14 A by dividing watts by 120.. You would have to multiply 14 by 1.25 and get 17.5 amps. This would require 12 AWG wire and a 20 A breaker.

This is done for space heating loads.

Where are you getting power from for these heaters?

What is the wattage of each?

You can post pics directly to this forum using go advanced/manage attachments.

Quote:

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Originally Posted by KeepItSimpleStupid

Confirm a few things:

1) Heater #2 looks like it has a thermal protector in series with the heater. I suppose heater #1 has on on the other side?

2) The thermostat that your going to use has 4 wires and is a line powered thermostat?

3) The existing thermostat isn't pictured. Where does it fit in this picture?

4) Where did you plan to get power from?

5) You do realize that wiring for baseboards must be oversized by 1.25 because its a space heating load.

i.e. if the current was 14 A by dividing watts by 120.. You would have to multiply 14 by 1.25 and get 17.5 amps. This would require 12 AWG wire and a 20 A breaker.

This is done for space heating loads.

Where are you getting power from for these heaters?

What is the wattage of each?

You can post pics directly to this forum using go advanced/manage attachments.

---

Hi Keepitsimple

Just so you know those baseboards have been in use for many years. I'm just upgrading the thermostats. The three baseboards connected to the circuit are 750W, 1000W and 1250W. = 3000W.

A little short of 80% of the 3600W of the 240V 15A breaker. (2880W)
But like I said it's always been like that...

1) Yes. I assume this is what you're talking about?
http://img27.imageshack.us/img27/5379/photovn.th.jpg

2) No. It's a two pole thermostat as are all the other ones in the house, except one.

3) It's been removed. It was a simple dial like this
But again, only two wires. Single pole.

4) What do you mean? Those are already powered. 3 heaters in parallel.

5) Yes. See above.


I hope this shed light on the matter.
What do you suggest?


Thanks!

Sorry I didn't get back to you sooner.

2) A two pole thermostat would have 4 wires and essentially two switches inside. On switch is turned off on a rise in temperature and the other is turned off when the thermostat is turned to the off position. Just like a 2 pole breaker has two connections to the bus and 2 connections to the load, so would a two pole thermostat.

The black thing looks like an overtemperature (OT) device, so for all intents and purposes the side with the OT device and all the wires, we will call black to be the black after the OT device.

The other heater black is black.

What you want to do is connect the reds together and the blacks together to put the heaters in parallel.

One way to do that which may already be done is a cable then runs between the two heaters. Proabaly makes sense to connect black of the cable to black of the heaters and white of the cable to red of the heaters.

Now you have the heaters tied together.

Pick one of the heaters and run a cable to the thermostat load terminals. Connect to the black and white cable that connects both heaters together. You will have all the blacks tied together and 2 whites and 1 red tied together.

Connect power to the line input(s) of the thermostat.

Here is an example single pole and double pole thermostat.

http://www.luxproproducts.com/pdfs/lv1-2_eng.pdf

Note the LV-1 (single pole) should be used on 120 V systems and the LV-2 is intended for 240 V systems.

What I'm getting from you is that your separating the heaters into two heaters and one thermostat and 1 heater and another thermostat.

As it stands, I think, you have one thermostat connecting to all of the heaters, so the cable that goes from one room to the other needs to be removed since it is controlled by the thermostat in the other room.

Your picture didn't make a lot of sense. I hope my wording did.

Somewhere, I think you mentioned that the tstat was on the heater. If that's the case, then you can use the existing wire for power.

It's customary to run power to the switch and then to the heaters for 240. I hope the tstat is not in a "switch loop" where power runs to the heater first and then two wires run to the thermostat. This would be incorrect for the US.

Yep, your right 3600/240*1.25=15.625 A which is slightly over 15 A.

If it's easier, you could just run another wire from the panel for power.