Gas burners cycle on & off while heating - http://www.hvacmechanic.com/ Forums
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| Xenos
Webmaster 
|  "Re(1):Gas burners cycle on & off while heatin"
, posted Mon 3 Nov 21:18  
To be honest I am hoping hvt is going to answer this one. But for the last 20 years of working on furnaces I would say safety feature or not It doesn’t sound right. Did they happen to mention what the safety feature was?
Xenos.
The best way to escape a problem is to solve it.
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| | trespinosranch
| "Re(2):Gas burners cycle on & off while heatin" , posted Mon 3 Nov 21:25
He said it was to keep the heat chamber from overheating. The system is about 9 years old. The other morning it took almost 4 hrs to heat the house. I don't recall it doing that last year.
Today, I replaced the filtrate type filters with regular cheapo filters, thinking that would allow more air flow, but it didn't make a difference.
Peter
Pete
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| | Xenos
Webmaster
| "Re(3):Gas burners cycle on & off while heatin" , posted Mon 3 Nov 21:42
You defiantly have a problem then. Most furnaces are designed for a TD ( temperature difference) of between 40 –70. This means in your case the temperature should never exceed 70. If you were to look on the nameplate of your furnace it will list what the TD should be. Lets just use this maximum for an example lets say it’s 70 in your home and with a TD of 70 this would mean the maximum supply air temperature allowed would be 140. I have yet to see a limit set for less than 180. Therefore you’re either overheating your furnace to 180 and lessening it’s life or the limit is defective.
If your furnace is overheating the evaporator coil for the A/C may be plugged with dirt. I suggest taking a temperature reading of the air between the furnace and the A/C coil. No it wont be easy to access that area but may be very beneficial.
P.S. Do not drill a hole in the duct work unless you know where all the copper pipes are.
Xenos.
The best way to escape a problem is to solve it.
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| | Ad Mech
| "Re(4):Gas burners cycle on & off while heatin" , posted Thu 6 Nov 20:26
furnace is probably shutting down on high temp safety switch
contrary to Sears this is not normal!!
Temperature rise is the indicator!
If your filters are clean, and the return duct is not blocked, then the return duct size is too small.
seen this before in cases where installers don't really care and use available parts instead of the proper parts.
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