How to wire baseboard heaters with thermostats

[Fritz2me]

Hello;

Can someone help me? I want to install some electric baseboard heaters in my house. The heaters I have, the thermostats are installed on them so there's no need for the wall thermostats..

My questions are: How does one wire two or three of those heaters together on one 240 amp circuit while keeping the thermostats on each heater?

Or do you have to remove the thermostats from the 2nd/3rd heater, having only one thermostat controlling all three heaters?

Thanks for any help anyone can give me.

Fritz

[joed]

The heaters will have a connection point for power. Connect your power to that point. Unless you modify the heater the thermostat should be already setup and only the two power connections need to be made.

[suemarkp]

You have a lot of options. You could put a "master" thermostat on the wall which can also be a disconnect. If this is off, none of the heaters will run. Or, you could turn it up all the way and let the thermostats on each baseboard control its heater.

Or you can forget the the wall thermostat, and just let each unit control itself.

There is a limit to how many watts you can put on a circuit, and you need to choose the appropriate size wire for the size circuit you run (you have a choice of 15, 20 and 30 amp circuits for heaters). Everything is basically wired in parallel after the main wall thermostat/switch (if you use it). Put black to black, and red to red (or tape the white wire red if using 14-2, 12-2, or 10-2 romex).

You can spider out from a central wall switch/thermostat, or daisy chain from one heater to another -- whichever works easier for your room and which walls are opened up.

How many watts of heaters do you want on the same circuit?

[Fritz2me]

You can spider out from a central wall switch/thermostat, or daisy chain from one heater to another -- whichever works easier for your room and which walls are opened up.

How many watts of heaters do you want on the same circuit?


When you say daisy chain, do you mean to connect to each thermostat on the heater? (I'm assuming this is what you mean but checking to make sure I understand it correctly).

As for wattage... I figured 2 heaters per 20 amp double pole breaker using #12 red coated wiring but I'm not sure how many I can have on one line. I intend to have a 1000 watts per room with 2 rooms on one circuit. Would this be OK or could I have more than two?

I plan on installing a total of 10 heaters and I have exactly 10 slots left in the panel but I also want to install a water heater so if I could add more than 2 heaters then that would free up at least 2 slots for that.

I'm in Canada if this makes a difference.

Thanks again for your help.. it's much appreciated!!

Fritz:boxing:

[suemarkp]

Daisy chain means run a cable to the heater, another cable from that heater to the next heater, and another to the next heater, repeating until you have a cable to the last heater and that's it. At each heater, the blacks of the incoming, outgoing, and heater input are all interconnected. Same with the reds and grounds.

Volts x amps = watts. However, heaters are a continuous load, so you can only load your circuit to 80%. So 80% of 20A is 16A. At 240V, 16A * 240V = 3840 watts. So you could easily do 3500W of heaters per 20A circuit.

I'd encourage a wall thermostat in each room for baseboard heaters -- they are easy to reach and set (but this will cost more). If the baseboards have thermostats too, you could just turn them up all the way, or bypass them, or actually set them to help balance the heat if half the room is hotter or colder than the other (assuming more than one heater per room). If these are wall mounted forced air heaters, they are easier to reach and not usually blocked by furniture, so perhaps a wall thermostat wouldn't be all that helpful there.

Since you're doing multiple room per circuit, run the wire from the breaker to the first room wall thermostat. From there, run a cable to the next room wall thermostat and a cable to the heater for the first room. At the second room, repeat the same concept -- another cable for the heater in that room and another cable to get to the next room. If only one 100W heater per room, then do 3 rooms per circuit. Larger rooms should have multiple heaters (two 500W heaters is nicer than one 1000W heater -- more even heat). But a larger room probably also needs more heating wattage than a small room, so two 1000W heaters may make sense.

At each wall thermostat box, the incoming power cable and cable to the next room thermostat need to be interconnected and go to the LINE side of the wall thermostat. The LOAD side of the wall thermostat goes to the cable to the baseboard heater for that room (either multiple cables if more than one heater in the room, or once cable and daisy chain to the next heater in that room).

[Fritz2me]

Thanks for your help!! I do have two more questions if I may? Upon checking, I realized I have one heater that doesn't have a thermostat installed on it. So my first question is: If I daisy chained from an heater that has a thermostat to one that doesn't, could I control both heaters from that one thermostat?

And question #2: some heaters I have only have two black wires so which one should I put the red wire on?

Thanks again for all your help!

Fritz

[joed]

That could work IF the thermostat in the one heater has a high enough current rating to control both heaters.

[suemarkp]

And also if the output side of the thermostat is accessible to you. There may only be line side wires you're supposed to use in the heater. The LOAD side, which is thermostat controlled, may be on the wrong side of a cover plate.

I still vote for the wall thermostat. Then use the thermostat on the baseboard (if it has one) as a fine tuning mechanism.

[Fritz2me]

That could work IF the thermostat in the one heater has a high enough current rating to control both heaters.

How would I know if it does or not?

Fritz

[Fritz2me]

And also if the output side of the thermostat is accessible to you. There may only be line side wires you're supposed to use in the heater. The LOAD side, which is thermostat controlled, may be on the wrong side of a cover plate.

I still vote for the wall thermostat. Then use the thermostat on the baseboard (if it has one) as a fine tuning mechanism.

Since the house has no basement or upstairs, I may go with your idea of 3 wall thermostats afterall and have it control 3500 watts of heaters per curcuit.

So are there any differences in wall theromstats that I should be aware of?

[junkcollector]

The built in thermostat on baseboard heaters can barely be called a thermostat in my opinion. The heat regulation not very good. You are far better off with a good quality line voltage wall thermostat.

Here is a good digital one:

http://www.google.com/products?q=honeywell+TL7235A1003&hl=en&aq=f

You will find a pretty good selection of other mechanical types at your local home improvement store.

[suemarkp]

So are there any differences in wall theromstats that I should be aware of?

Yes. In order for a thermostat to qualify as a disconnect, it must have a marked OFF position and breaker both wires on 240V heaters. So get one with the OFF position, and make sure it is a double pole thermostat (a 120V thermostat will only break one wire -- will still control your heater just fine, but it will always have one live wire which isn't good if you expected no power when set to OFF during maintenance).

[Fritz2me]

Double pole it is... I've been tweaking my plan a bit and have figured that the porch would probably be better with just an heater thermostat. I'll be using 2 - 500 watt heaters with a double pole thermostat installed on one of them (I already have this so might as well use it lol).

The problem is I'm not sure where the wires from the curcuit and wires to the second heater goes. I have included a diagram I drew to show what wires I see and how they're presently connected.

You guys have been a great help!! Now to get the thermostats and start wiring! Thanks again.

[Fritz2me]

I forgot to ask the question: Do I hook up the incoming and outgoing wires to the two red wires that are left on the diagram?

Thanks

[suemarkp]

Is the thermostat in your drawing part of the heater unit, or a separate one on the wall?

Yes, the incoming power goes to the two red wires. If you want to control another heater via this same thermostat, it would need to connect in parallel with the black wires to the heater. As others have mentioned before, you have to make sure the thermostat is rated to take that additional load. Also, if this thermostat is part of the baseboard heater, can you even tap in to those black wires (i.e. are they wire nut connected), or are they terminal connected?

[Fritz2me]

Yes, the drawing is of a thermostat on the heater itself.

The wires connecting the thermostat to the heater are connected with marinets.

There are also two black wires at the other end of the heater again connected with a marinet.

Also you mentioned to make sure the thermostat is rated to take that additional load.

Here's what I could find written on the heater:
240/208 V.A.C. 1000/750 Watts

And what is written on the thermostat:
277 volts 17 Amps

How do I determine if it can take the extra load?

If you think the heater is rated to take an additional load, which wires do I tap into, to run the second heater?

Sorry for all the questions...

Fritz

[suemarkp]

So it appears you heater is a 1000W heater. At 240V, this is 1000/240 = 4.2 amps. Your thermostat appears to be rated for 17 amps, so you should be able to supply a second heater from this one (two 4.2 amp heaters is 8.4 which is well under 17).

You're using the term marette. Are you in Canada? If so, you may have other restrictions that many of us here don't know about. May want to consider reposting your question in the Canadian electrical forum:

http://www.selfhelpforums.com/forumdisplay.php?f=5

To run a second heater controlled from the thermostat in this first one, undo the marette from each black wire going from the thermostat to the heater internals. Using a new red 12-2 romex cable going to the other heater, connect one additional wire in each marette connection (a red from the romex in one marette, the black from the romex in the other, and bare or green ground to the grounding screw). At the other heater, the red and black wire in that red romex cable would connect to the two power input wires of that heater (and the ground would most likely go onto a green screw).

[Fritz2me]

Yes, I am in Canada and my apology for my spelling... glad you understood what I was referring to.

I will certainly post it there as you suggested for any restrictions.

Thanks Mark, for sharing and for helping me figure this out.

All the best!

Fritz