7500-watt Garage Heater and Remote Thermostat wiring

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Old 01-02-18, 12:29 PM
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Question 7500-watt Garage Heater and Remote Thermostat wiring

I have two of the ProFusion Heat Ceiling-Mount Shop Heater, 25,590 BTU, 240 Volts, Model# HA24-75M
that I purchased from Northern Tool earlier this year for my 3 car garage build. I am having a little bit of a hard time understanding how an external thermostat would be wired to these units. Here is the wiring diagram that is provided in the manual:



According to the manual, I can wire in an external/remote thermostat to the provided terminal station using >16 AWG wire. So does this mean I can use a smart thermostat that runs off of 24 volts (thinking Nest or Ecobee) or do I need a line-voltage thermostat (240 volts). Since this is a 7500-watt heater, does it have to be a 40-amp line-t or is that why there is contactor coil in the heater already? Just a little confused at what size thermostat would work...manual here doesn't provide much on what can be used: https://www.northerntool.com/images/...uals/44740.pdf

Furthermore, would it be possible to wire both of these identical units up to a single thermostat?

Thanks for the help...I appreciate it!
 
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Old 01-02-18, 12:55 PM
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Welcome to the forums.

As they stand now.... you'd have to use a 120/240v line thermostat for each heater. They tell you to use #16 interconnecting wiring for the stat but that is incorrect. The wiring you're using is energized by the mains line coming in. Any external wiring needs to be protected.

You could control both heaters with one 24vac thermostat. That would required a 24vac transformer and two 24vac relays. You could mount a relay in/to each heater.
 
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Old 01-02-18, 01:14 PM
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Thanks Pete!

If I wanted to use a single 24 volt thermostat, what would be suitable for the 24 volt transformer and the 24 volt relays? Are there any online that I could order that would work with these heaters?
 
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Old 01-02-18, 01:28 PM
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Would the AUBE RC840T-240 relay work with these heaters?...it has a built in 24 volt transformer
 
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Old 01-02-18, 06:56 PM
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Yes.... they would work but be over kill since you'd still need two.

Here's what I would do and have actually already done.

RIB relays are in a plastic enclosure that attach to an electrical knockout. There are many numbers that would work for you. You need a 24VAC coil and a 5A N.O. (normally open) contact. I shop around and buy bargains.

Here's a real bargain.... RIB24C-FA-RD - RIB,Relay In A Box, Functional Device
Here's another bargain company. Functional-Devices-RIB24C-FA-p/rib24c-fa.htm
Otherwise you can search using RIB2421B, RIB2401B.

Two wires go to the remote thermostat terminals and two wires go to the stat.
So you'd need two of these relays.... one for each heater.
Then you could use a basic wall wart 24vac transformer to power an electronic stat and the relays.
amazon_Delectronics&field-keywords=MGT-2440

You could also use the type of 24vac transformer on an electrical cover.
You only need a 20va transformer.
 
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Old 01-03-18, 12:18 PM
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Thank you so much! That really helps laying it out like that. I wired my house and a couple garages and have dealt with transformers for door bells but nothing to do with HVAC so the relays and all are new territory for me. Since I haven't done any wiring and this is for new construction, I may just wire up a doorbell transformer to power those two relays and the t-stat at 24v.

So with the RIB24C-FA, I assume the two white-blue wires would be connected to T1 (in my heater diagram) and two white/yellow wire to T2, followed by the Blue/Nor.Closed wire to t-stat RH, Orang/Nor.Open wire to t-stat W1, and yellow wire to C or common on t-stat. Is that right or do I have it backwards? I know the nest and other thermostats have the W1, Rh, and C wires for heaters. But doesn't the t-stat need power via the C wire...so don't need the Yellow wire then?
 
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Old 01-03-18, 08:05 PM
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It is basically a five wire relay. Some diagrams show two white/blues and two white yellows. You use one pair and cap off the extra pair. So white/blue and white/yellow are the coil wires and go to the 24v stat/transformer.
The yellow and orange are the normally open pair that go to the connections inside the heater. Blue gets capped off.

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This shows a stat needing a C connection. If you use a battery stat you don't the C connection.
 
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Old 01-05-18, 05:57 PM
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Thank you sir! I appreciate that diagram...that helps a lot! Much cheaper setup this way...especially when I need to do multiple heaters.
 
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Old 08-06-19, 05:11 AM
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I am attempting to set my heater

hi I am gonna set up my heater next week and want to connect a nest to it. Wanted to ask how your set up went ?
 
 

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