insert fails to ignite

[mattym]

The unit is a Jotul Katahdin GI450DV. It is installed in a brick fireplace with dual liners 20 ft up throught the roof to a high-wind style cap. It was converted at install to LP with the supplied orifice. Sometimes when the thermostat calls for heat, the valve opens, gas flows around the burner, but the flames stay a transparent blue, dance around the burner, then lift off the burner completely and die. The pilot also goes out, so a few seconds later the valve properly shuts off. This happens less than 10% of the time. There are other times you can see it struggle to light. The flames are extremely tall and thin for a few minutes, then settle down to normal.
I've read the different opinions here about opening the glass to see if it will relight, to test for a vent problem. If this sounds like a lack of combustion air, should I try a less restrictive cap? I have the can shaped one, with vertical openings around the cylinder.
Thanks for any help. 13 below zero this morning, and disappointed to see it out again.

 

[DAKSY]

The unit is a Jotul Katahdin GI450DV. It is installed in a brick fireplace with dual liners 20 ft up throught the roof to a high-wind style cap. It was converted at install to LP with the supplied orifice. Sometimes when the thermostat calls for heat, the valve opens, gas flows around the burner, but the flames stay a transparent blue, dance around the burner, then lift off the burner completely and die. The pilot also goes out, so a few seconds later the valve properly shuts off. This happens less than 10% of the time. There are other times you can see it struggle to light. The flames are extremely tall and thin for a few minutes, then settle down to normal.

That's a DEFINITE indication of combustion air blockage or contamination. Has any one checked to make sure the vent is properly attached? I'vr seen this happen where the intake & exhaust get mixed up & mounted to the wrong flue collars.
Sometimes the unit will work correctly. Sometimes it won't...
Have you had this issue since the original install?

I've read the different opinions here about opening the glass to see if it will relight, to test for a vent problem.

This is a TEST & I mean ONLY a test. If it runs well for maybe 5 minutes with the glass off, it's DEFINITELY a venting issue

If this sounds like a lack of combustion air, should I try a less restrictive cap? I have the can shaped one, with vertical openings around the cylinder.

I wouldn't. The Hi-wind cap is the best one I've seen out there & gives us the least amount of issues.

Thanks for any help. 13 below zero this morning, and disappointed to see it out again

I hear that. It was a BALMY -2 here in the Capital District...
Try the glass thingie. If it works, then I'd pull the unit to check the liner attachment.
In order to determine if they're attached correctly, you may need a helper on the roof...
PM me if I can be of further help.

 

[mattym]

thanks for your help. I got to watch it fail again today. I waited 5 minutes for gas to clear, then relit the pilot, cracked the glass open about an inch, switched it on, and it lit off nicely. Flames were tall for about 30 seconds, then settled down. Latched the glass shut and it ran normally.
This has been a problem since installed, maybe they did swap the liners. So now I will try find a way to rig a ladder to get me up my 8/12 pitch steel roof without damaging it. If the liners are correct, and everything else about the install meets the specs in the manual, what are the options other than new cap?
I read you in another thread state that lp appliances should have the air shutter wide open. Surprisingly, the manual for my insert says LP and NG both open 1/8 inch. I have been slowly adjusting it further open to stop sooting on the glass. It is approx 3/4 open now. Would that make a difference here?
thanks again.

 

[jtp10181]

I worked on an insert with a similar problem, except it was doing it much more often. I finally decided the liners must be swapped. I switched them around where they attach to the top of the insert and the customer has not called back that I know of. Unfortunately the exhaust on this unit has a special SS liner for the first few feet, and now that's on the intake. So if its working now, we will have to go back once her roof doesn't have 16" of snow on it and swap it on the roof properly.

 

[Mr Fixit]

You mentioned sooting... I have experienced sooting so bad that it choked the exhaust closed. Soot clogging in the exhaust will also cause the "ghosting" as you described. You need to open the aperature about 1/2 inch for propane for starters. If the flame is a dirty orange or is producing any kind of black, open it more. You may need to allow the burner to run for 10- 15 min while adjusting to allow the flame to "set" ( the flame will change appearance and get more orange or blue after a few minutes). I am not familiar with that model, and they are all different, but usually you would want the flame to be blue at the base and yellowy orange farther up to the tip of the flame. You do not want dirty orange, but a lighter orange flame. You may have to open the aperature all the way to achieve this on a propane model.
If the problem persists, it may be as JTP said above. What I have seen is exhaust being sucked into the intake liner and in turn causing the "ghosting" because of a lack of oxygen. This is rare, but possible.