A gas furnace uses either propane or natural gas to heat up an enclosed area. Gas furnaces are better than oil furnaces for controlling temperature because gas burns cleaner than oil and helps the environment. Like oil furnaces, gas furnaces also have mechanical problems that arise when the furnace has not been maintained for long time. However, the mechanical problems in gas furnaces are less frequent than those that occur in oil furnaces. The mechanical problems of gas furnaces are also easier to diagnose and fix compared to oil furnaces. Here you will find some of the most common problems that occur on gas furnaces and how you can fix them.
Not Generating Enough Heat
When gas furnaces are not generating enough heat, it could mean that the blower belt is loose
or damaged. It could also mean that the furnace’s blower is blocked or its filter or burner is too
dirty. Open the furnace and secure the blower belt if it is loose. If the belt is broken, you may
need to take it to a repair shop to get it fixed or buy a new blower belt and install it yourself. If
the filter or burner is too dirty, then clean you need to clean it so that the dust will not block the
air coming out of the furnace. If the furnace is not broken or dirty but it is still not generating
enough heat, check the setting of the thermostat and make sure that it is not too low. If the setting
is too low, raise the temperature setting so that the furnace will generate enough heat.
Another common problem that occurs in gas furnaces is that it suddenly stops generating heat.
When this occurs, it could be the result of a faulty fuse or circuit, closed control valve, knocked
out pilot light, or a non-working thermostat. If the control valve is the problem, then open it
sufficiently so that the gas will be able to flow properly. If there is a problem with the fuse or
circuit, replace them to restore power to the furnace. If the pilot light is knocked out, then light
the pilot flame so that the furnace will work properly. If changing the setting of the thermostat
does not change the temperature, then it may be broken and you need to have it repaired at a
If the furnace keeps switching on and off frequently and produces erratic heat, then the blower
may be clogged. Erratic heating may also be the result of a dirty filter or a motor or blower that
is too dry. You can solve this problem by cleaning the blower or filter in order to remove the dust
that is blocking the air that is passing through it. If the motor or blower is too dry, lubricate them
in their proper port areas. Erratic heating may also be caused by a problem in the thermostat
heat anticipator. To fix the thermostat heat anticipator problem, you will have to reorient the
adjustment arm to the correct position.
Pilot Light with No Light
If the furnace’s pilot light won’t light, it may be caused by lack of gas due to an insufficiently
open valve. The lack of gas may also be the result of a clogged pilot opening. If the valve
is insufficiently open, you will need to adjust the gas valve so that the pilot light will work
properly. If the pilot opening is clogged by debris such as dirt and dust, clear the blockage so that
gas will be able to flow into the pilot light properly.