# Vermont Castings won't stay lite



## Swanny (Dec 2, 2010)

I have 6 year old Vermont Castings unvented gas heater.  I am able to light the pilot and then am able to turn it on.  It runs for about 20-25 seconds then shuts totally off.  Any suggestions?


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## DAKSY (Dec 2, 2010)

Find the OD sensor & clean it. It's generally located on the side of the pilot tube & looks like a small hole in the tube.
It's probably jammed with dust & if it is, it'll give the sensor a false reading & shut the unit down.
A can of compressed air like the type used for computer keyboards will clean it nicely...


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## jtp10181 (Dec 2, 2010)

If the stove has never had a full service cleaning it is definitely due (5 years overdue).

Vent free fireplaces should be serviced by a professional annually to keep them operating safely and properly.

Any little thing out of place or misaligned can cause more incomplete combustion which can lead to soot or excess CO emissions.


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## Swanny (Dec 2, 2010)

Thanks gentlemen.


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## webbie (Dec 2, 2010)

As above, clean things out first. After that, you have to determine how handy your are...or call a pro.

As a guide to how these things work, check out:
https://www.hearth.com/econtent/index.php/articles/how_gas_works

Basically, the pilot tube sends a small flame out which hits the thermocouple....that generates a small electrical charge which is sent back to the valve and allows it to open when the ON switch is pressed.

If either the pilot will not stay lit...or, the unit shuts off when the burner is turned on, the usual cause is a lack of electric back to the valve. That can be caused by:
1. Some dirt and dust in the pilot tube causing the pilot flame to be smaller or in a wrong direction.
2. A bad thermocouple
3. The connection between the thermocouple and the valve.

#3 - back when I did the work - often was fixed by removing the nut which connects the thermocouple to the gas valve and cleaning the threads of that nut (I remember one owners manual said to use a pencil eraser)...and then making sure it is fairly tight when you put it back in.

Most vent-free units are not designed for you to just replace parts...so if the basics don't fix it, you will want to consult the factory or a knowledgeable source for what particular parts or assemblies are OK to replace. In vent-free, this is often the entire pilot assembly as one piece - that is, they often do not sell the little parts separately.


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