Hard ignition on Propane unit- help!

[hard ignite]

I have a propane fired unit manufactured by American Standard (Trane) and installed when the house was built in 1991. I have a problem with a what they (service proffesional) calls a "hard ignition". The furnace ignites occasionally with such force that it rattles the pictures on the walls and has twice blown the pilot completly out. I have called out the best local technicians to look at it twice and once they adjusted the pressure (slighly) and the other time they said I had a "lazy" pilot (pliot light was replaced). Both repairs did not resolve the issue. The overall condition of the unit is good to very good for it's age. The furnace is located in the attic. Now here is the confusing part, the hard (and LOUD) ignition only happpens after the unit has been off a while and it has cooled. When there is a demand for heat regularly it works like a champion with a smooth and quite ignition. The burner appears to be clean and in good working order. Clueless
Thanks,
Mark

[lolson]

maybe you need to call another contractor for trouble shooting

if you like to keep your hair on your head, never stick you nose anywhere near the burners at startup, the flame rollout will give you a real nice trim

[m kilgore]

Very bad ignition problem. Call a pro that knows what they are doing. Possible bad heat exchanger. Do not attemp to fix yourself. Get this fixed ASAP!!!!!

[jrbenny]

Nothing for a homeowner to attempt on this one.

You need to call someone besides the guy that was there.

Thread closed.