I have a late-1980s Bryant forced air gas furnace in the basement that
has acted poorly from the day I bought my split level home in October
2000. Every now and again, when it first comes on, it appears to work
normally: the blower starts, the electronic pilot clicks, the gas
burner flames, and very soon I have warm air coming through the vents.
However, after about 10 minutes, the electronic pilot clicks or
multi-clicks (even though burner flame is still present), which is
followed by flame putting itself out and then relighting. All the
while, the blower is going fine and itself does not also cycle on and
off. And this goes on and on and on, every 5-20 seconds, until I set
the thermostat back at least 1 degree below the current temp in the
That first winter (2000/01) in my house, I had service techs from 2
separate companies check it out at different times. The first one was
unable to suggest a fix other than to try a new thermostat in the
living room. So, I bought a new programmable and a new
non-programmable thermostat, tried them both, and had the same result.
Given this information, the 2nd service tech thought a new "Gas
Furnace Control Center" would be in order (Part No. HH84AA021). When
that didn't fix it he said that, while being inconvenient (takes much
longer to heat the house this way) and disconcerting to hear the pilot
lighting and relighting, it was not dangerous and that eventually I
should buy a new furnace.
In the meantime, I began keeping notes of when this occurred and
environmental factors. Everytime this problem came up, I would note
the indoor vs outside temps, humidity, cloud cover, snow on ground (I
live in D.C. area), etc. I also tracked indoor conditions (when
filter last changed, open/closed position of doors in house), and soon
discovered a correlation between the furnace short-cycling and the
upstairs bathroom door being closed OR if the shower is being used
upstairs. This info did not appear to help my two technicians, but
once I had this understood, I simply heated the house before using the
shower and all was mostly well. No, my furnace problem wasn't solved,
but 80% of the problem appeared to be related to that one door
...that is, until the past 24 hours. Now the heater short-cycles
within 10 minutes of igniting everytime. I will soon begin looking for
a service tech from a 3rd company, but before I do I wanted to query
this on-line community for ideas about my problem.
Your thoughts and suggestions are appreciated!