240V heater and low voltage thermostat

AmateurHour

Looking for a little confirmation from the experts on this. I have a 5000W DynaGlo heater in my garage and I'm setting it up for external thermostat control. It has a switch and terminal block for external control with a line voltage stat. I'm using an Aube RC840T-240 transformer/relay and an ecobee 3 lite stat. I've attached a sketch of what I think is how this should be wired in order to retain functionality of the internal thermostat as I believe it controls the fan delay start and cool down run.

Thoughts?

Jamie Hall

Refer to the wiring diagram which is helpfully printed on the case of the RC840T-240 and the heater's diagram. You can have either the heater's thermostat active or the external one -- but not both.

EBEBRATT-Ed

No. You r not hooked up right.

Connect the Blue from the RC840T-240 to L2 on the heater
Connect the Black to #1 terminal external thermostat
Connect the Red to #2 terminal external thermostat

Then attach your thermostat

AmateurHour

How does this look?

EBEBRATT-Ed

looks fine to me

utility01

@AmateurHour : I am doing exactly the same thing as you with a 5000W DynaGlo heater and an Aube RC840T-240 transformer/relay, but with a different thermostat.
Did your corrected wiring diagram work out successfully?
Thank you.

lbartley1959

I tried both ways and it did not work for me.

Jamie Hall

Did you wire it in accordance with the Aube wiring diagram?
https://www.manualslib.com/manual/11515/Aube-Technologies-Rc840t.html
Note that you have a choice: external thermostat or internal thermostat. NOT BOTH.

Jamie Hall

I might add -- you will need a two pole service disconnect for that heater, as the Aube relay only breaks one of the hots, not the other.