Keystoker 90 Chimney Vent Hearth Model Thermostat Buzz

Backstory:
Toward the end of the last burning season (Spring 2019), our Keystoker thermostat started buzzing when calling for heat. So I took to the web and found a couple threads here that indicated the RA89A thermostat relay either needed cleaning or replaced. Being an easy swap and a relatively inexpensive part, I changed out the relay. So the RA89A is new.

Currently:
We still have our buzz when the thermostat calls for heat. Is it possible that the RA89A I got is a dud, or is there something else I can troubleshoot to pinpoint the issue?

Thanks fellow coal burners for any input.

Open thermostat up and try just touching or tying the 2 wires together for just a test. This can show whether the t'stat is the cause.
And let me say, there can only be '1' 24volt transformer in circuit.
Can not have 24volts from Keystoker with 24volts from Honeywell...one or the other, never both...

McGiever wrote: ↑

Fri. Nov. 08, 2019 10:05 am

Open thermostat up and try just touching or tying the 2 wires together for just a test. This can show whether the t'stat is the cause.

Do you mean the two thermostat wires in the thermostat? If I touch them together while the stove is running, will it make the buzz sound if the thermostat is the cause? Sorry, my knowledge and understanding of electrical is very basic. Thanks for chiming in.

I went ahead and crossed the two wires in the thermostat, and there is the buzz. But when I remove the wires from the posts and touch them together, there is no buzz. I plan to pick up a new thermostat at the hardware store tomorrow.

Thank you!

So the buzz is back even with the new thermostat installed. So now I have a new RA89A, new thermostat (standard non-programmable round Honeywell), and no buzz when I connect the two thermostat wires together independent of the thermostat.

Any other thoughts McGiever or anyone else?

McGiever wrote: ↑

Tue. Nov. 12, 2019 9:33 pm

Thanks. How can I remedy that? It's not as though anyone here added a transformer to the circuit last Spring to create the buzz? This setup has ran for several seasons without the issue.

Check voltage at relay coil with voltmeter both with and without thermostat switch closed.
Do the same with checking volts at transformer.
Should be very close to 24 volts, any much less than 24 volts is the reason for the buzz...

Does Keystoker instruct to add the RA89A?

https://forum.heatinghelp.com/discussion/164230/h ... 9a-buzzing

Note *HomerJSmith's* reply...

If it were me, I'd completely bypass the internal transformer in the RA89A and drop in a larger common off the shelf 24v 40va foot mounted transformer and forget the other too small one...

Thanks very much, that's very helpful. I appreciate you taking time to post.