Wood Furnace (RSF/Ardent) thermostatic air inlet control

[Peace Meal Farm]

So I bought a super clean and solid RSF 65 (Ardent Energy) wood burner to use in my shop. It has a butterfly valve type air inlet which can be controlled manually, but it also has a 24v 60 hz motor which can be tied to a household thermostat to control the air inlet for you.

On my unit the 2-wires going to the thermostat were cut off, and no thermostat was supplied. I want to use this feature but I don't know exactly how to set it up. This is the stepper motor, which has a chain attached to it behind the stove's heat shroud, which in turn is attached to the butterfly valve in the air intake.



I think what I need to do is purchase a 120v to 24v step down transformer. This will provide the correct voltage supply to both the t-stat and the stepper motor. Like so ...



Obviously the black and white wires would go to my 120v hot and neutral wires, respectively. From there I am unsure ....

I would think that my thermostat becomes a switch on the 'load/r' post, and my 'nec/c' post goes straight to my stepper motor neutral, but I am really unsure on this.

Guidance please!

[ChrisGrohms]

You have it right. Step down transformer to 24v. Wire the thermostat in series with the damper motor. I would try to incorporate a high limit switch in the loop as well.

An issue with the wood boilers is to LOW of a return temp causing the heat exchanger to rust out prematurely. It would be good practice to install either a manual bypass valve or better yet a 4 way mixing valve to keep the return temp within 20F of your supply.

[Peace Meal Farm]

Originally Posted by ChrisGrohms

You have it right. Step down transformer to 24v. Wire the thermostat in series with the damper motor. I would try to incorporate a high limit switch in the loop as well.

An issue with the wood boilers is to LOW of a return temp causing the heat exchanger to rust out prematurely. It would be good practice to install either a manual bypass valve or better yet a 4 way mixing valve to keep the return temp within 20F of your supply.

Thank you for your feedback. I have limited experience with this low voltage AC controls stuff.

My application is not a boiler .... just a giant wood stove with the optional t-stat controlled air inlet, so I am not worried about the pluming side of things.

Your point about a high limit temp switch is interesting as a means of helping to prevent an unattended overfire. I would have to run the stove manually and see what my surface temps I get on the heat shields when I'm at the height of my tolerable stove temps - before the thing starts glowing. If I could find a switch which will open at a high temp like that then I'd definitely put one in.

[Commander B]

As an owner of an RSF furnace you are on the right track. They do make high limit switches. Note if the power fails you can loose heating abilities I will also add a thermostat controlled fire is a creosote monster. Regular chimney maintenance and inspection is a must. Burn it hot once and a while, and good dry wood also

B.

Also convenient to put a power service switch in front of transformer.