# Bad Thermopile?



## ferenc5 (Nov 27, 2012)

I have an old vermont castings wonderfire direct vent gas stove.  The pilot fires and stays lit, the stove will fire and run for a minute or so, then something shuts off the gas valve completely.  The stove and pilot both go out. After another minute or so I can then relight the pilot and the stove will refire, but it will again shut down after a minute or so. Does anyone have any ideas on troubleshooting the thermopile  and or gas valve?


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## DAKSY (Nov 28, 2012)

ferenc5 said:


> I have an old vermont castings wonderfire direct vent gas stove. The pilot fires and stays lit, the stove will fire and run for a minute or so, then something shuts off the gas valve completely. The stove and pilot both go out. After another minute or so I can then relight the pilot and the stove will refire, but it will again shut down after a minute or so. Does anyone have any ideas on troubleshooting the thermopile and or gas valve?


 
Take a reading on the TP-TH (or TH-TP) & TP screws on the valve terminal block with a multitester set to milliVolts (mV). With the burner off, the reading should be about 550 (more or less). Turn the burner on & watch the readings. Report back with what you find.


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## mygasfireplacerepair (Dec 2, 2012)

Check the venting.  Does the main burner flame look any different right before it goes out?  If it turns blue and burns up in the air for a second (ghosting), you could have a bees nest or some kind of blockage in your vent or cap.  If you notice the flame looking this way, you could crack the bottom of the glass (to give it more air) and see what happens.  If it runs fine with the glass open its venting related.

Otherwise how does your pilot flame look while running?  If the pilot flame is getting pulled away from your thermopile sensor after the fireplace gets a bit of draft going you may need to replace your pilot assembly.  The pilot flame should be direct and intense on your thermopile and thermocouple sensors (much like a blow torch flame).  If your pilot flame is yellow or "candle-like" it should definitely be cleaned out or better yet- replaced.


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## ferenc5 (Dec 2, 2012)

DAKSY said:


> Take a reading on the TP-TH (or TH-TP) & TP screws on the valve terminal block with a multitester set to milliVolts (mV). With the burner off, the reading should be about 550 (more or less). Turn the burner on & watch the readings. Report back with what you find.


 Thanks for your quick reply, the stove is at camp, three hours north and i may not get back up for a while.  Should I assume that the 550mv reading is with the pilot on and warming up the thermopile?  When i turn on the gas and it runs for a minute should the mv be rising or falling?  What would the proper mv reading be once the main valve opens?


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## ferenc5 (Dec 2, 2012)

mygasfireplacerepair said:


> Check the venting. Does the main burner flame look any different right before it goes out? If it turns blue and burns up in the air for a second (ghosting), you could have a bees nest or some kind of blockage in your vent or cap. If you notice the flame looking this way, you could crack the bottom of the glass (to give it more air) and see what happens. If it runs fine with the glass open its venting related.
> 
> Otherwise how does your pilot flame look while running? If the pilot flame is getting pulled away from your thermopile sensor after the fireplace gets a bit of draft going you may need to replace your pilot assembly. The pilot flame should be direct and intense on your thermopile and thermocouple sensors (much like a blow torch flame). If your pilot flame is yellow or "candle-like" it should definitely be cleaned out or better yet- replaced.


The flame is blue, seems to look just about the way it should, it kind of shrinks down to nothing and goes out completely evenly throughout the burner area.  I removed the vent pipe and refired it wth the same results.  The pilot looks very strong, bright blue on the thermopile and thermocouple.  It burns evenly until the gas valve shuts down. I understand parts are pretty much nonexistent for these old stoves and i'm thinking of replacing the entire gas valve,pilot, thermopile and thermocouple if the thermopile tests good.


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## DAKSY (Dec 3, 2012)

ferenc5 said:


> Thanks for your quick reply, the stove is at camp, three hours north and i may not get back up for a while. Should I assume that the 550mv reading is with the pilot on and warming up the thermopile? When i turn on the gas and it runs for a minute should the mv be rising or falling? What would the proper mv reading be once the main valve opens?


 
550mV is the "pilot only" reading...When the unit is turned on, the mV will drop to around 200. If the mV continues to drop, the thermopile is probably on its way out. Just for grins, what model is your unit?


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## ferenc5 (Dec 3, 2012)

DAKSY said:


> 550mV is the "pilot only" reading...When the unit is turned on, the mV will drop to around 200. If the mV continues to drop, the thermopile is probably on its way out. Just for grins, what model is your unit?


Thanks again it's an old VC Wonderfire I think it's a model 2570.  My camp is up in Stewartstown NH on the Connecticut River where NH, VT, and Canada come together. Across the river from the Ethan Allen plant where they still make American made furniture.  PS I ride a 2010 Electraglide and still have my good old 1992 FXRP.


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## DAKSY (Dec 3, 2012)

ferenc5 said:


> Thanks again it's an old VC Wonderfire I think it's a model 2570. My camp is up in Stewartstown NH on the Connecticut River where NH, VT, and Canada come together. Across the river from the Ethan Allen plant where they still make American made furniture. PS I ride a 2010 Electraglide and still have my good old 1992 FXRP.


 
Some of the older VC units, & I'm not sure about yours, had a spill switch that would shut the unit down if the upper part of the firebox got too hot. If that spill switch failled, or if the sheathing on the wiring to that switch failed (possibly creating a short), the unit might do what your seeing.

Nice rides...sometimes I wish I still had my Sporty...I took the Ultra thru the Tail of the Dragon & it was a workout. I'd like to try it on something with less "SCRAPAGE"


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