Incomplete ignition/American Standard Freedom 90

[Tman]

Every once in awhile, the furnace locks out upon failing to completely light all 5 burners.
Upon a call for heat, things go normally except when the 4th and 5th burners fail to light fast enough to satisfy the flame sensor. Today I cleaned the burners (they seemed clean) and checked the hot surface ignitor. Seems okay to me. I still have the intermittent problem. Any *

Thank you,
Tman

[clay3636]

check the burner orfices on #4-#5...they may be stopped up

[Tman]

**"theduke03"-* you remove the burners to clean * If not I would suggest that. Once removed you can brush the outlet end of each burner including the slit on either side of each and use a vacuum to really get the crap out. If this doesn't work you may have other problems. Don't touch the ignitor or you'll be sorry!*/-*

Yes, I did remove the burners (except the one by the ignitor....been down that path before w/o a spare)
That thin slit carries the flame from burner to burner (*). Perhaps I should look closer and slide a razor blade (or something) down the slit.
Would our unusually cold Georgia weather affect the pressure in the propane * Pressure to the * Just a thought.
Tman

[MikeInNE]

Hi Guys...I would like to reopen this thread.

I have a Freedom 90 two stage variable speed furnace that was installed when my house was built in '99 - and I've had this EXACT same problem since it was installed. My furnace fails EVERY year, sometimes more than once. The problem usually ends up being crap in the burners, crap in the orifices or a dirty flame sensor. The symptoms are always the same - the flame does not propagate across all 6 burners fast enough to get sensed before the furnace shuts off the gas. The 'funny' part is that it usually lights - just not fast enough to heat up the sensor quickly enough to get sensed before shutting down (the last burner barely gets lit and it all shuts off). If the furnace waited just a half second longer to sense the flame, it would be reliable. Apparently, this 'wait' time is not adjustable.

In addition to my twice annual cleanings, I usually end up paying for one or two emergency repairs throughout the heating season. I've had the burners, the gas valve and various other electronics replaced. I'm on propane, with a 500 gallon buried tank, with regulators on both the tank and just outside the house. I have never serviced the furnace myself - it's always been done by the company that installed it. Every time they send a new rep, he goes through the same checkes, comes up with new theories, and none of them ever pan out. They have resorted to telling me that it's moisture in the propane causing rust and crap buildup, and there's nothing they can do about it. They have gone so far as to tell me that even if I replace the furnace, I'll likely have the same problem.

So the bottom line is that I've been to a pro, with no success. I'm convinced that this furnace has a major design flaw, and as an engineer, I really want to talk to someone at American Standard. Unfortunately, they don't talk to us peasants. They only talk to pros. I keep wondering if there has been an EC that may have already been released that can be applied to my furnace, but since I can't ask them (and my installer keeps telling me that they've talked to AS), I'm at a dead end.

Does anyone have any thoughts or * Does anybody know anyone at American Standard that I can * I'm about ready to call in the DIY network or HGTV and see if they want to do a segment on my furnace...because I'm broke from paying for repairs.

Mike

[MikeInNE]

Yes - every time they do a PM. They check both the high and low pressure, and have even checked and adjusted my regulators. The entire gas valve assembly has been replaced as well.

At today's emergency visit, they came up with a new one. They believe the rust and slight discoloring of the 10 year old wiring for the flame sensor and igniter are signs of a hot burner box - and an indicator that the furnace isn't getting enough air. The intake is IN my basement (meaning it sucks in basement air) - and they think my basement is too tight. I'm REALLY struggling with this one. I have a very large basement, and my house isn't very tight. They want to drill a big hole and route the intake outside. I'm not real enthusiastic about this one.