Vermont Castings Radiance - shuts off unexpectedly

[mqmurphy]

Hello - new member here - our Radiance fireplace (natural gas) runs well after starting but will shut off after a while. I've read some other posts and my guess is that maybe the thermocouple needs to be repositioned or perhaps replaced. Anyone had a similar experience? Thanks.

 

[DAKSY]

Does the pilot go out, or just the burner? The pilot is controlled by the thermocouple. The burner is controlled by the thermopile. If the pilot stays lit, then I’d suspect the thermopile may be failing. You need to take measurements on the thermopile mV output at the valve terminal block with a multimeter. Set the meter to VDC, & touch the meter’s probes to the TP & TP-TH terminals. Light the pilot & take a reading. Light the burner & take another reading. Keep the probes in contact with the terminals & watch your meter. If the mV numbers begin to drop, that will let you know it’s the thermopile.

 

[mqmurphy]

Does the pilot go out, or just the burner? The pilot is controlled by the thermocouple. The burner is controlled by the thermopile. If the pilot stays lit, then I’d suspect the thermopile may be failing. You need to take measurements on the thermopile mV output at the valve terminal block with a multimeter. Set the meter to VDC, & touch the meter’s probes to the TP & TP-TH terminals. Light the pilot & take a reading. Light the burner & take another reading. Keep the probes in contact with the terminals & watch your meter. If the mV numbers begin to drop, that will let you know it’s the thermopile.

Thank you - I will test those parts in the morning.

 

[mqmurphy]

Does the pilot go out, or just the burner? The pilot is controlled by the thermocouple. The burner is controlled by the thermopile. If the pilot stays lit, then I’d suspect the thermopile may be failing. You need to take measurements on the thermopile mV output at the valve terminal block with a multimeter. Set the meter to VDC, & touch the meter’s probes to the TP & TP-TH terminals. Light the pilot & take a reading. Light the burner & take another reading. Keep the probes in contact with the terminals & watch your meter. If the mV numbers begin to drop, that will let you know it’s the thermopile.

A question for you, Daksy - though I have a multimeter I am not familiar with its settings - which VDC setting should I set the meter at? I see 200m and 2000m and then 20, 200, 600.
My guess is probably the 200m setting? 'm' for milivolts?

 

[mqmurphy]

The readings on the meter rose as the pilot heated up - the readings stayed constant after the burner was lit - when the burner and pilot shut off the readings started to drop.

 

[DAKSY]

What readings did you get with only the pilot on?
How about when the burner was lit?

 

[mqmurphy]

What readings did you get with only the pilot on?
How about when the burner was lit?

With meter set to 2000m I get a steady reading of 257+/- but here's something odd - anticipating that some disassembly was coming I removed all the "logs" - and restarted the flame - it isn't shutting down now.
Is it possible that somehow misplaced "logs" were interfering with the thermopile ?
At loss here - runs fine with "logs"out - reinstalled them bit by bit, still ran - reinstalled front screen, runs and shuts off.
Now screen off and most "logs" out, it runs.

 

[DAKSY]

What does the multimeter tell you when it shuts off? Do the mV numbers drop slowly, or is there a rapid drop?

 

[Millbilly]

Bvent or direct vent?

 

[mqmurphy]

Bvent or direct vent?

Direct vent.

 

[mqmurphy]

What does the multimeter tell you when it shuts off? Do the mV numbers drop slowly, or is there a rapid drop?

I will make that test today, thanks.