Gas and Oil Home Heating Furnaces - Fan on furnace
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : Fan on furnace
12-30-00, 01:12 PM
Fan is switching constantly on and off for variable time periods. This is occuring without the gas furnace igniting. Heat is still working.
fjrachel
12-30-00, 04:39 PM
What type of system? Do you have heat pump with gas furnace heat? Need more info.
12-31-00, 08:04 PM
System is fan forced air, no heat pump on a gas furnace. Fan clicks intermittently like it is about to start blowing and sometimes even starts blowing then shuts down. This occurs without the furnace firing and when the temperature on the thermostat is at the required temperature. Thanks
Sharp Advice
12-31-00, 11:18 PM
Hi:mattbillevans
If the furnace has a constant burning <always on> pilot, the pilot flame may be adjusted too high. If so, the heat created by this large pilot flame could cause the firebox to get warm enough to briefly turn on the fan.
Another possibility is a fan switch set at too low a temperature. The on temperature turns the fan on. If the on temperature is set at say 80 degrees, a larger then normal pilot flame will cause the firebox to exceed that temperature and turn the fan on.
The fan ON temperature should be set at 140 to 160 degrees. The fan OFF temperature should be about 120 to 110 degrees.
Should these setting be already correctly set or not recently changed, the fan on/off switch may have become defective and needs to be replaced.
Also check the filter and replace it if there are any doubts about it's condition or should it be dirty.
If the furnace has a constant burning <always on> pilot, the pilot flame may be adjusted too high. If so, the heat created by this large pilot flame could cause the firebox to get warm enough to briefly turn on the fan.
Another possibility is a fan switch set at too low a temperature. The on temperature turns the fan on. If the on temperature is set at say 80 degrees, a larger then normal pilot flame will cause the firebox to exceed that temperature and turn the fan on.
The fan ON temperature should be set at 140 to 160 degrees. The fan OFF temperature should be about 120 to 110 degrees.
Should these setting be already correctly set or not recently changed, the fan on/off switch may have become defective and needs to be replaced.
Also check the filter and replace it if there are any doubts about it's condition or should it be dirty.