# vermont casting Direct vent wont stay lit



## jwelfeld (Oct 17, 2009)

HI All,

This it the third season of using the stove.  I just turned on the gas and lit the pilot.  The  Pilot will stay lit without any problems.  When I turn on the heater  the gas comes on and I get a good flame.  after a short period of time  the flame and the pilot light go out (i hear a clicking sound).  I can relight the pilot with no problem  and then turn  it on and the same thing happens.. . any suggestions.    FYI It's a Honeywell  system.

Thanks,

Joe W.


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## webbie (Oct 17, 2009)

Chances are that the pilot flame needs to be turned up and/or the thermocouples (those copper things the pilot flame hits) are dirty and/or their connections back to the valve are not tight.

This is an electrical circuit. Here is how it works.

The pilot hits them and creates enough voltage to make the valve stay open. Then, when you turn the burner on the gas pressure to the pilot is slightly reduced and therefore the output falls below what is needed to keep the valve open.

Just a guess from afar. My first course of action would be:
1. Use a can of air or straw to clean the area and pilot tube of dust.
2. Turn the burner on low and try it that way.....maybe that robs less pressure from the pilot and will work...confirming the problem.
3. clean the soot off the thermocouples - with a small brush, etc.
4. Check the tightness of the nuts which connect the thermocouples to the valves....tighten them slightly.
5. Turn up pilot if there is adjustment for it.

If you don't feel comfortable with this stuff, get a pro.

Note that it could be other things......but these are more likely.


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## jwelfeld (Oct 17, 2009)

So Far So good,   opened it up and just cleaned everything,  it's been working for a while now,  I'll keep an eye on it but it sure seems to be burning better.  

Thanks for the quick response,  ya gotta love this forum


Joe Welfeld


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## ezradams (Oct 29, 2009)

I have a similar problem, but my vermont casting is the basic model without any electrical hookup.  Pilot is ok, but will only hold a flame for about 5-10 minutes and than goes out.


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## DAKSY (Oct 30, 2009)

Probably need to replace the thermopile...


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## jtp10181 (Oct 30, 2009)

Could also be an airflow problem. How old is it, and when was it last serviced?


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## ezradams (Oct 30, 2009)

The unit is about 7 years old but only used a few times each year  (under 10).  It does not operate with any electrical input and does not have a thermostat.  It's a very simple unit.  When it's on, the fire appears to be pretty strong, but seems slightly different than in previous years.....no quite as steady maybe.


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## DAKSY (Oct 30, 2009)

Get yourself a multimeter, set it to Millivolts (Mv) DC & test the thermopile (TP).
It attaches to the valve terminal block with a red & a white wire (usually)...
If the wires are different colors, test at the terminals marked TP & TH-TP (or TP-TH)
Take a reading with the pilot on, by touching the multimeter probes to the terminal block screws.
Should read around 550Mv, but the range can be between 350 & 750Mv.
Turn the burner on & watch the meter. If the Mv readings drop, the TP is failing.
It'll shut the gas flow to the burner off at around 125 Mv (+/-)...
If this is the case, replace it.
Not a definite answer to your problem, but it's a starting point. 
Let us know what you find...


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## ezradams (Oct 30, 2009)

How can there be voltage when there is no electrical source?


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## DAKSY (Oct 30, 2009)

The thermopile is a millivolt generator. 
It is constructed of strands of dissimilar metals 
which expand at different rates when subjected to heat.
The differences in the rates create a small electrical voltage - millivolts...


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## ezradams (Oct 30, 2009)

Got it.....I have a voltmeter and will try this over the weekend.


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## Mr Fixit (Nov 2, 2009)

That sounds like a spill switch to me. It is located at the back of the stove at the exhaust. Looks like a coin shaped disk with 2 wires coming out of it. It's function is to measure the exhaust temperature. If the unit is not exhausting properly, it backs up and the switch is tripped with the rise in temp that the exhaust produces. If you still have access to the multimeter, test the switch by neasuring the ohms (resistance). If you have around 1 ohm or more, the switch needs to be replaced. If it is less, you need to find out why the exhaust is not getting out of the venting. There may be a blockage of some sort. I have found birds nests, dead birds, bats and squirrel nests in fireplace venting. 
Good luck.


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## ezradams (Nov 2, 2009)

This unit vents into the room, so it probably doesn't have that switch.  I'm going to be checking the thermopile with the voltmeter.


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## DAKSY (Nov 2, 2009)

ezradams said:
			
		

> This unit vents into the room, so it probably doesn't have that switch.  I'm going to be checking the thermopile with the voltmeter.



Wait a minute. 
Your original post was titled "vermont casting Direct vent wont stay lit"
Now you say it vents into the room...
Which one is it?


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## ezradams (Nov 2, 2009)

My mistake, I guess.  I assumed direct vent meant into the room.  It is a very simple unit, no electric supply and vents into the room.


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## DAKSY (Nov 2, 2009)

OK, we're talkin a WHOLE different scenario here...
Your problem may be in the pilot/O2 depletion assembly.
These things tend to get dust in em & the O2 sensor
gives a false reading & shuts the unit down.
If you have one of them there keyboard cleaning cans 
of compressed air with the little tube to concentrate the 
airstream on it, use it to clean the pilot asembly...
Concentrate the air on the small hole in the side of the 
pilot hood & the open end of the pilot hood...
You may be able to clear out any debris in there...
If THAT doesn't work, you may hafta replace the whole pilot assembly...


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## ezradams (Nov 2, 2009)

Thanks!  Will try that as soon as I pick up a can of compressed air.  Does that mean the the thermopile scenario is NA?


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## DAKSY (Nov 2, 2009)

Not exactly sure WHAT you have in the O2 depletion system.
Maybe if the air thingie doesn't work, you could post a pic 
of the pilot assembly & we'll take it from there...


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## leester (Nov 4, 2009)

Thank you for all the suggestions. I was having the same issues with the same stove myself.
The replies here have helped.




Regards,
Leester
Simulation pret immobilier


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## jtp10181 (Nov 4, 2009)

IMO a vent free unit is not something to be messed with by a homeowner. Find a local tech who knows how to service vent free fireplaces and setup a service call.

If you insist on fixing it yourself PLEASE get a GOOD carbon monoxide detector.


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