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Malfunctioning York Gas Furnace?
My house was built in the early 1990s. I am the second owner and have been in the house for just over 4 years. I still have the original York gas furnace and central air systems. They are still running strong, but I plan on replacing them with newer, more efficient units in the spring when my budget will allow me to do so.
A few minutes after every full heating cycle, the furnace and blower will kick on for a very short period of time and then kick off. Seems like additional wear and tear on the furnace and blower. Is this normal?
Last edited by walds11; 12-07-2009 at 05:23 PM.
If it is continuing to blow after the burners have gone out for a few minutes then this is perfectly normal. It's squeezing the last bit of heat from the heat exchanger which increases efficiency.
I would not worry about wear and tear on a blower. They are incredibly resilient.
The fan control thermostat may not be set properly or not working well. It is normal for the fan to run awhile after the burner turns off. For it to turn back on momentarily implies there's enough heat in the area to trip the thermostat to bring the fan back on momentarily. The fan should run long enough to bring it below that point so the residual heat doesn't trip it again.
Jim DeBruycker
Important note - I'm not a pro
Retired Defense Industry Engineer
Probably your limit switch is bad.
So, you suggest a service call to my local HVAC company? The heating (and cooling) has had a routine service atleast twice each since I moved in about 4 years ago. I usually alternate, so each one gets serviced every other year. It's been doing this ever since I moved in and I never thought of bringing it up to the service guy until now. I can see the blower kicking in after a full heating cycle, but the furnace too? Or maybe it is just the blower? I was never in the basement to check it out. I just hear it in the house. Maybe not worry about it since I plan on replacing the systems next spring?
Originally Posted by jadnashua
The limit switch is a thermostat that turns the blower on when the furnace gets to a certain temperature. It then turns the blower off after it drops below that temperature.
If you plan to replace this unit in a few months I would not bother fixing it unless the problem gets worse.
I plan on replacing the systems late Spring at the earliest, or maybe next Fall, so we are talking a year from now. Or maybe beyond that, if they still run strong. Who knows. I do know that the systems are probably nearing the end of their lives.
I really don't know if it is a problem and it has not gotten worse. It just seems like extra wear and tear (and maybe not normal?) for the blower and I think the whole furnace to kick on briefly after a full cycle. The HVAC guy will be over in a few weeks to install a hot water heater. I'll have him look at it.
Less than 10 minutes on is probably 'short cycling'.
I get 25 yrs +/- 3 yrs for the replacement age of 'resi. HVAC equip.'
Last edited by Thatguy; 12-13-2009 at 03:25 PM.
Here is what happens...
1. full heating cycle
2. about 2 minutes after the full heating cycle, the furnace and blower will kick on for about 15-20 seconds
Is this considered short cycling? Bad? How is it fixed?
My HVAC systems are about 18-19 years old. Maybe no need to rush to replace the new systems even if I have to spend small amounts of money for mainatence and repair each year?
Does the burner actually turn on, or just the fan?
Jim DeBruycker
Important note - I'm not a pro
Retired Defense Industry Engineer
Not sure. It sounds and feels (hot air blows out of the vents) like the burner and fan kick on during that 15-20 second cycle. I'll have to go down in the basement to really check it out.
Bump. Any ideas?
Your ductwork os probably undersized so the furnace retains residual heat after the cycle.
Interesting. How is this fixed? Is it bad for the furnace to run this way?
I would agree especially if this furnace has the old style honeywell limit/fan switch.
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