Lennox Furnance Intermittent Problem


Old 12-20-04, 05:47 PM
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Unhappy Lennox Furnance Intermittent Problem

I have a Lennox G27M Series gas furnance with sureLight Ignition Syetem and a Honneywell weekday/weekend (5 day/2 day) programmable thermostat both thermostat and furnace are 4 years old. The thermostat hardly ever gets above 68 degrees no matter what temp it is set at even if I override and turn it up as high as 78 or 80. The thermostat shows an arrow indicating that the system is on but it is not. Sometimes if I play with the thermostat by turning the temp up high or turning the thermostat off and on I can make the furnace start this works probably 1 out of 10 times sometimes it clicks sometimes it don't when turned on and off. Sometimes I can get the furnace to stay on and heat up to 70 degrees with the thermostat on hold temp. Most times the thermostat reads 66 degrees. I have had two different HVAC companies out and they both are telling me nothing is wrong with the furnace even when they can see I dont have heat they play with the thermostat and get the furnace to come on. One guy told me change the batteries in the thermostat (in one week I changed the batteries 8 times) he said only use Energizer batteries and if that dont work change the thermostat. First guy said the furnance needs to be cleaned (I just had it cleaned in November). The inducer motor comes and and runs and runs then the flame will come up and go out right away this happens several times and then the motor shuts off and there is no way you can get the furnace to start up again. Sometimes the motor runs and runs and no flame will come up. Both furnance people are telling me the LED lights are flashing properly showing the furnance is working properly. I have been watching the lights and both LED 1 and LED 2 simultaneously slow flash which according to my book is power on normal operation when the thermostat is asking for heat they both flash together fast meaing heat demand initiated at thermostat then I get a alternate slow flash in both LED 1 & 2 which means Watchguard - burners failed to ignite. I also think I have seen alternating fast flash on both LED 1 & 2 (not sure) Sometimes I smell faint gas I thought it was coming from the pilot on the hot water heater but now I think it is the furnance. All I know is I have a hard time getting the furnace to start if it starts I just pray it will keep running and heat up to what the thermostat set at. Previously when the thermostat used to ask for heat it made a loud click at the furnace now you can hardly hear it click and most of the time is does not make any noise just shows the arrow pointing to system on and goes out after awhile by itself. I have a third guy coming out this week what should I ask him to check (if he will listen to me) I have had the furnace shut down twice in the last year because birds got caught in the vent one went through the inverter motor last year but the furnace ran fine after it was cleaned and checked out another bird got caught in the vent in November I had the furnace cleaned and checked out again and it seemed to run OK until December. There are no birds or bird parts left anywhere in the furnace except I saw some poop in the vent coming out of the furnace. I change my filters every month too. I am ready for a new furnace because I am freezing to death.
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Old 12-20-04, 06:04 PM
mattison's Avatar
Join Date: Mar 2003
Location: Cinti, OH
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Couple things to check.

1st - What does the flame look like when it does fire ?

2nd - There should be a flame sensor in the burner compartment on the opposite side of the pilot. It's about 2-3 inches long and about as fat as a match stick. Clean it off with steel wool.
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