Line voltage thermostat for garage heater

GymB

GymB

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Heated garage?

 
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Frank C Lyons said:
Honeywell makes one at about half that price that I've used quite a bit. I'll see if I can find it.

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Similar to @Frank C Lyons suggestion, my dad used one of these to direct wire a shop heater. Nice because it is programmable.

This one looks pretty cool if you want a wifi version.

 
I think I can skip the wifi for this application.

It’s a 240v heater, so do I need a thermostat with a DTST switch? I think that’s switch both legs, but not sure.
Jeppo said:
Heated garage?

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lol, it is also dehumidified and only used for woodworking and reloading. Insulated on 2 walls and the ceiling. Used to heat with propane, but electric is nicer!
 
JimB said:
I think I can skip the wifi for this application.

It’s a 240v heater, so do I need a thermostat with a DTST switch? I think that’s switch both legs, but not sure.

lol, it is also dehumidified and only used for woodworking and reloading. Insulated on 2 walls and the ceiling. Used to heat with propane, but electric is nicer!
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A line voltage tstat wouldn’t need another separate relay. Just be sure to get one that can handle the power requirements. The one I linked will do 5.2kW @ 240vac. The programmable above is rated at 4kW @ 240vac.
 
Oops, I meant DPST. A single pole makes sense on a 120v line as you just interrupt the hot wire, but do you need to interrupt both for 240v?

It’s on a 20 amp line, but I’ll open it up to check. I seem to recall that it could be wired internally for different power draw, but I don’t know which I used.
 
Here is the wiring diagram. It looks like I moved the yellow and blue wires up to the A-B terminals to keep the power draw below 15 amps.

3 wires in, 2 hot and a ground. So does it matter which hot line I switch?

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JimB said:
Here is the wiring diagram. It looks like I moved the yellow and blue wires up to the A-B terminals to keep the power draw below 15 amps.

3 wires in, 2 hot and a ground. So does it matter which hot line I switch?

View attachment 430513View attachment 430514View attachment 430515
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See the existing tstat in your diagram? I’d unhook that and reroute the wiring through your wall mounted stat.

Keep in mind I’m a low voltage guy and it ain’t my house. 😀
 
Good point, I’ve got to catch a flight, but I’m gonna delay buying the line voltage thermostat and see if the enclosed one is 24v. If it is then things become a lot easier…or at least less likely to cause a fire.
 
I just realized that you guys may think I’m blind, an idiot, or both. On the wiring diagram there is no transformer, so that must be a single pole 240 thermostat. Think I should be able to disconnect it and connect to an external one. Gonna order that honeywell one.
Thanks, I’ll let you know if the garage burns down.
 
JimB said:
Have a 240v electric heater, I think 3500-5000 watts, need to open it to confirm. Little dial thermostat is crap, want to add an external thermostat.

Thinking something like https://www.amazon.com/TP519-Indust...ine+voltage+thermostat&qid=1643474453&sr=8-86

Is it really as simple as that, just wire this thing in line into the power cord then turn the heater knob to high and let this thing control?
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Just saw this. I’ve used thermostats like the one you linked in garages of mechanics. They are sturdy for line voltage. The cheaper Honeywell old look thermostats never lasted very long even behind lockable covers. Look for a double pole whatever you get.
 
BlackGun said:
Just saw this. I’ve used thermostats like the one you linked in garages of mechanics. They are sturdy for line voltage. The cheaper Honeywell old look thermostats never lasted very long even behind lockable covers. Look for a double pole whatever you get.
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I can get that one for something like $40 in the real world, some amazon seller is just being stupid. But, did you look at the schematic? the current thermostat is 2-wire and it looks like everything is wired so the fan has power even when heater element turns off. I’m pretty sure that the fan doesn’t run all the time. But anyway, I’m thinking of just replacing the existing thermostat rather than adding a new thermostat that cuts power to the whole unit. So need a 20amp 240v 2-wire thermostat.

What do you think?

edit; and what is a pole anyway?
 
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JimB said:
I can get that one for something like $40 in the real world, some amazon seller is just being stupid. But, did you look at the schematic? the current thermostat is 2-wire and it looks like everything is wired so the fan has power even when heater element turns off. I’m pretty sure that the fan doesn’t run all the time. But anyway, I’m thinking of just replacing the existing thermostat rather than adding a new thermostat that cuts power to the whole unit. So need a 20amp 240v 2-wire thermostat.

What do you think?

edit; and what is a pole anyway?
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Each side of relay or contactor.

In the wiring diagram it looks like a thermal device breaks the fan circuit after a drop in heater temperature when thermostat is satisfied. Basically fan runs until heat in elements is gone.

The factory thermostat breaks one side of the line voltage power. As a function to work it is fine. As far as safe, not so much which is why houses have 24vac thermostats. It’s a garage. Not like a kid is going to damage it.
 
@JimB By the way, thanks for the lead on that t-stat. I paid $140 for garage thermostats that were sealed. I used them in Penske rental/garages for gas tube heaters and in car wash locations.
 
BlackGun said:
@JimB By the way, thanks for the lead on that t-stat. I paid $140 for garage thermostats that were sealed. I used them in Penske rental/garages for gas tube heaters and in car wash locations.
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My pleasure. Cheaper here on amazon, the shipping from walmart makes it about the same.
 
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