Burner Problem - Jotul Lillehammer

[Soppin2014]

We have a propane Jotul Lillehammer that was installed this summer. We recently have had problems with the burner staying lit. The unit will run anywhere from 10 minutes to hours. At some point the burner shuts down and extinguishes the pilot light. So far I have done the following:

checked pilot light -- looks good
checked all the wiring -- no loose connections
tested the thermopile -- 600mV with pilot and 300mV when burner on
removed logs and embers
cleaned inside of stove including pilot assembly, thermocouple and thermopile

If there was something wrong with the thermocouple wouldn't the pilot light also go out when the burner isn't running?

Any suggestions as to what to try next would be greatly appreciated.

 

[DAKSY]

Couple things come to mind. How old is the gas line?
Did you try removing the pilot orifice & blowing the gas line clear?
What do you mean the pilot "looks good?" Is it agitated at all?
What is your venting configuration? Horizontal? Vertical? Both?
You could try turning the pilot down so the thermopile reads about 550mV.
Tpiles work on temperature differential & if the bottom gets too hot, the tpile doesn't work correctly...
Also try running it without the logs or repositioning them. If they're too close to the tpile, it can overheat.
Did you take a millivolt reading on the tcouple? What was it?
Keep us informed...

 

[Soppin2014]

Couple things come to mind. How old is the gas line?
Did you try removing the pilot orifice & blowing the gas line clear?
What do you mean the pilot "looks good?" Is it agitated at all?
What is your venting configuration? Horizontal? Vertical? Both?
You could try turning the pilot down so the thermopile reads about 550mV.
Tpiles work on temperature differential & if the bottom gets too hot, the tpile doesn't work correctly...
Also try running it without the logs or repositioning them. If they're too close to the tpile, it can overheat.
Did you take a millivolt reading on the tcouple? What was it?
Keep us informed...

Thanks for the reply. Answers below.
Gas line was installed this summer when the stove was installed
I didn't remove the orifice
Pilot flame is blue and steady. Looks like it is contacting the tpile and tcouple correctly
Vent is horizontal directly out the back of the unit.
I removed the logs and embers a couple days ago and the problems still occurs.
I haven't tested the tcouple yet.

I spoke with the dealer and they said it sounds like that its being starved for air. Would the vent ice up with a huge temperature difference? It was 50 degrees a couple days ago and today it was 13 below when we woke up. I will check the vent when I get home tonight.

 

[DAKSY]

If it runs OK with the glass off but shuts down with it on, I'd look at the venting.
Just don't run it for very long that way. I can be deadly.
Horizontal runs directly into the wind can be problematic.
Is your cap on the West side of the house?

 

[Soppin2014]

Cap is on the south side. It hasn't been windy when the problem has happened. Sometimes it will run for a few minutes then kill. Other times it will run all day with no problems. Seems weird to me with the huge time differences when the problem occurs.

 

[DAKSY]

Hmmm. How long did you monitor the tpile?

 

[Soppin2014]

5-10 minutes after burner was on.
Is there a height adjustment for the tpile? It looks like the pilot flame is contacting the tpile lower then what the manual says it should.

 

[DAKSY]

That should give you a good idea. Was the glass on or off the unit?
It should be on when reading the millivolts.
The pilot flame should engulf the top 3/8 of the tpile...
What color are your flames after the burner heats up?
Is the air shutter all the way open?

 

[Soppin2014]

Glass was on. Flames were blue at the bottom and orangish yellow on the tips. Air shuttle is open all the way. As far as I can see in the vent is clear. I will try post some pictures later.

 

[Soppin2014]

I think we found the problem. I tested the incoming gas pressure. It was set a little below 10". I adjusted it to 13" when pilot is on and 12.5" when burner is turned up all the way.

I retested the tpile after cleaning and adjusting the pressure. It measured 640mV pilot and 240ish mV when burner was on. It seems to be working, but the 240mV seems low?

 

[DAKSY]

Glad you found the issue. Seems your gas company is a little remiss if the pressure was that low.
240mV is good, but 640mV is kinda high. I'd turn the pilot down so the TP reads under 600mV.
Otherwise you may burn it out quickly.