3 Baseboard heaters, one t-stat

[mark32]

Hi there, I have little experience with baseboard heaters and their configurations. Customer wants to operate three baseboard heaters off one t-stat which according to him would draw 22 amps. I mentioned he could probably use a relay box and feed it with two 20 amp circuits (Have two heaters on one circuit and the third on it's own circuit) but I am unaware how a typical install would go and what's available out there. Do they make a relay box with two or four poles (In order to use two 240v circuits) or would you run all three heaters on a 30a circuit?

 

[480sparky]

They're typically called lighting contactors. You can get as many poles as you like. Just run power through your stat to the coil, and the power for the heaters through the contactors. It's literally an electrically-operated switch. When the stat calls for heat, it will send power to the coil, which closes the contacts and sends power to the heaters.

 

[BryanMD]

If the heaters are not all in the same room then placing the t-stat becomes more of an issue; and using more than one may make the several areas more comfortable.

 

[steve66]

I have two baseboard heaters in my house on a 30 amp thermostat. I don't know anything that prohibits that.
Steve

 

[roger3829]

They make control relays just for electric heat that use low voltage thermostats. (honeywell)

 

[Dennis Alwon]

Hi there, I have little experience with baseboard heaters and their configurations. Customer wants to operate three baseboard heaters off one t-stat which according to him would draw 22 amps. I mentioned he could probably use a relay box and feed it with two 20 amp circuits (Have two heaters on one circuit and the third on it's own circuit) but I am unaware how a typical install would go and what's available out there. Do they make a relay box with two or four poles (In order to use two 240v circuits) or would you run all three heaters on a 30a circuit?

What lengths are the heaters? Typically they are 250 watts/ foot. If he had 3 4' heaters then that would be 3000 watts. This would work on a 20 amp circuit. If indeed he had 22 amps then you could run a #10 to the units and you would be fine. I would prefer running a #10 to using a relay.

 

[LarryFine]

If indeed he had 22 amps then you could run a #10 to the units and you would be fine. I would prefer running a #10 to using a relay.

Same here, but the T-stat has to be rated for the 22a, also.

 

[LarryFine]

They're typically called lighting contactors.

I have found lighting contactors to be extremely expensive, and barely reliable. I would grab a definite-purpose contactor. For example, Grainger has a 4-pole 20a contactor for about $45.

 

[electricmanscott]

Relay and 24v tstat is an option.

http://customer.honeywell.com/techlit/pdf/60-0000s/60-2004.pdf

 

[mdshunk]

Use the Honeywell R841C relay. You can run up to 40 amps of heat off it. Connect it to an ordinary low voltage wall stat, like a T87.

http://customer.honeywell.com/honeywell/ProductInfo.aspx/R841C1227

White Rogers makes one nearly identical, as do several other manufacturers.

 

[BAHTAH]

Thermostat 240v

Thermostat 240v

Hi there, I have little experience with baseboard heaters and their configurations. Customer wants to operate three baseboard heaters off one t-stat which according to him would draw 22 amps. I mentioned he could probably use a relay box and feed it with two 20 amp circuits (Have two heaters on one circuit and the third on it's own circuit) but I am unaware how a typical install would go and what's available out there. Do they make a relay box with two or four poles (In order to use two 240v circuits) or would you run all three heaters on a 30a circuit?

If the circuit is not yet installed you could use a 2-circuit thermostat. They are rated 120-240 44amps. It would help to know the length of the heaters just to be sure what the customer is telling you (22amps)is correct.

 

[hillbilly1]

You could use a power relay, they have ratings of 20 and 30 amps, and can be double pole. around $20, or you can use individual RIB relays (relay in a box) which are self contained. I think the rating on those are 10 and 20 amp. Not quite as hardy for heavy loads as the power relays, but are very compact.

 

[mark32]

Thank you all for your insight, I really appreciate it. According to the customer the load would be 24 amps and not 22 as I incorrectly wrote and if I remember correctly it's three 8 footers. I see some here would forgo the relay, maybe most would take that route as it would be a simpler install.

Marc, please forgive my ignorance, I viewed the specs for that Honeywell relay and it's resistive rating in amps is 22 and 42 for locked rotor. Wouldn't one use the 22a rating for this application?

 

[mdshunk]

Marc, please forgive my ignorance, I viewed the specs for that Honeywell relay and it's resistive rating in amps is 22 and 42 for locked rotor. Wouldn't one use the 22a rating for this application?

Maybe that particular one. I might have prematurely snagged the wrong one off the net, but your supply house will have the one you need.

 

[mark32]

Thanks for clearing that up Marc, I thought I was losing my mind.