intermittant furnace

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Well-known member
Mar 6, 2006
Mims,Fl, USA (central east coast)
Good morning all,
I have a Hydro Flame furnace, model number 8531-111, It is approximately 14 years old. It has become intermittant. Last year in Novemeber when temp went to 16 deg F,(in Ohio), it wouldn't work. Fan would come on, but gas wouldn't ignite. Plenty of propane and would work stove, water heater, ect. When arriving back in Florida, after a hasty retreat from the cold, the furnace worked fine. Last propane fill up was here in Florida. Possible wrong mix for climate?

Yesterday during our cold snap here in Florida, the fan would come on and the gas ignite momentarily then go out. Finally it stopped cold. All other gas appliances worked OK. Got out my books and started to check on how to trouble shoot. Meantime weather warmed up a little. 50 versus 30. Tried out furnace and it worked fine, after I took one or two wires loose from there respective connect points then reinstall them. These were the wires to the back of the circuit breaker. The furnace worked fine from that point on.

The book states that you must have a least 11 inches of water column pressure in the system at all times. Is there a simple way of measuring this when all the appliances are turned on? I have a manometer that I have used to measure low pressures in the past. My question here is, where can you connect into the system to measure it? I have a Marshal Brass regulator in my system.

Any suggestions? Jerry
Could it be something as simple as a slight mis-alignment of the flame sensor? When the furnace fired up briefly, maybe in cold weather it didn't heat up quickly enough to send a 'flame good' (my terminology) signal back to the control board in enough time to prevent shutdown. If only the furnace was giving you problems, it would seem logical to measure the pressure there. It's the biggest gas user. Also check for a nice, hot, blue flame and not a cool, yellow one. Clean and adjust if necessary.

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