I want to put a wall mounted thermostat in my garage to control the heat better. The heater has a thermostat installed on the unit which is just a knob. I am unsure what type of thermostat I need. Here is the schematic of the heater.



To me it looks like the 4 wires need to be hooked up to operate correctly with the overheat switch. I have a 2 wire thermostat left over from a previous project. Can i use this or do i need a different thermostat?

Thanks in advance

I think you can do what you desire with the thermostat that you already have provided you understand that it will not - cannot - handle this level of power by itself. You will need to use it the same way your home thermostat(s) are used, to control higher-power switching devices known as contactors, or relays, depending on your technical background. Electrically very simple to do but you are definitely going to need a couple of additional components.

Good luck with your project.

Supplyhouse.com sells a 24 volt transformer and contactor module which along with a wall mounted thermostat should do what you want.

One way would be to use a thermostat made for electric heat, it would be a 2 pole rated for 30 amp, 2 wires in 2 wires out,

The same type of wiring used for power to the electric heater (rated for 240 volt 30 amp) would be used for the thermostat wiring

The 240 volt line at L1, L2 would now go to the new thermostat first,

then from the thermostat to the heater and terminate at the L1,L2 terminal

If you did not want to open the heater unit up and wire around its internal thermostat just turn that knob all the way up and leave it that way and the wall thermostat will will control the heat.

Post a picture of the thermostat you have or e-mail me a picture and we can determine if it will be suitable, if you want or need to eliminate the internal thermostat on the unit, it's not very difficult if you can identify the wires.

RC's answer is correct. You need a line voltage thermostat rated for whatever your unit draws. Either bypass integrated t-stat or leave set on highest level. Try to go above the rating of the unit. So if unit draws 20a, don't get 20a, get 30a.

Are the walls open so you can get to wiring and pull slack out to install? If no slack you will need to add junction box to extend wiring to t-stat.

Thermostat, 24V transformer and 30A contactor. You only have to open one side.

Way cheaper and easier to use line voltage t-stat like you'd use for baseboards. Why do you suggest such a complicated set up? Requires enclosure, 120v source for trans, trans, and contractor plus spot to mount the t-stat. Yeah he can reuse only t-stat, but the other materials cost more than line voltage thermostat.

Thank you all. Upon further inspection of the t stat I have, it is rated for 3000 watts. The heater has a low setting at 3k, a medium at 4k, and a high at 5k. To prevent any issues, I will not be using that thermostat. I think I have some stats for the baseboards we tore out of here I can use. I just need to find one. They are around here somewhere...

There are 22 amp 2 pole 240 volt line voltage thermostats made by several companies. These are what I use for 5 kw or less electric heaters. $20 - $30 at the electrical supply house depending on surface or box mount. Also at Grainger.

quote:

Originally posted by Skins2881:
Way cheaper and easier to use line voltage t-stat like you'd use for baseboards. Why do you suggest such a complicated set up? Requires enclosure, 120v source for trans, trans, and contractor plus spot to mount the t-stat. Yeah he can reuse only t-stat, but the other materials cost more than line voltage thermostat.

Several reasons:

Any 24V thermostat, including programmable, touch screen or even wireless.
*Better thermostats with features.

240V heater, so a simple 240V to 24V transformer. Usually room in heater to mount it.
$7.75
https://www.supplyhouse.com/Pa...ary-40VA-Transformer

Simple 30A contactor with 24V coil. As with the transformer, usually room in the heater to mount it.
$4.79
https://www.supplyhouse.com/Pa...Contactor-24V-30-Amp

Or spend $0.60 more for a 2-pole contactor.
*Gives you an extra set of contacts for when the first set become pitted.
https://www.supplyhouse.com/Pa...Contactor-24V-30-Amp

*Now it's easier/cheaper to run 18/2, low voltage wiring to the thermostat location.

quote:

Originally posted by Excam_Man:

quote:

Originally posted by Skins2881:
Way cheaper and easier to use line voltage t-stat like you'd use for baseboards. Why do you suggest such a complicated set up? Requires enclosure, 120v source for trans, trans, and contractor plus spot to mount the t-stat. Yeah he can reuse only t-stat, but the other materials cost more than line voltage thermostat.

Several reasons:

Any 24V thermostat, including programmable, touch screen or even wireless.
*Better thermostats with features.

240V heater, so a simple 240V to 24V transformer. Usually room in heater to mount it.
$7.75
https://www.supplyhouse.com/Pa...ary-40VA-Transformer

Simple 30A contactor with 24V coil. As with the transformer, usually room in the heater to mount it.
$4.79
https://www.supplyhouse.com/Pa...Contactor-24V-30-Amp

Or spend $0.60 more for a 2-pole contactor.
*Gives you an extra set of contacts for when the first set become pitted.
https://www.supplyhouse.com/Pa...Contactor-24V-30-Amp

*Now it's easier/cheaper to run 18/2, low voltage wiring to the thermostat location.

This....I prefer low voltage in the wall, high voltage in the unit w/disconnect.
I'm in the BAS/controls field, they only let me work on 24v and under