- Check that the thermostat is set higher than the actual room temperature. If you have a programmable thermostat, make sure it has fresh batteries.
- If equipped with central air, or the system is zoned, Make sure the selector switch is on heat.
- Check the emergency switch( usually a red switch plate at the top of the cellar stairs or on the side of the furnace) to see that it is on.
- If you are familiar with the fuse or circuit breaker panel, see if the fuse is burned or the breaker tripped. Correct the problem once. If it repeats, call a serviceman.
- On standing pilot furnaces, the burner will not light if the pilot has gone out. If you are not familiar with the function of the gas valve or lighting the pilot, call for service.
- Furnaces with electronic ignition have a sequence of safety steps the burner takes to light. Information is usually attached to the inside of the burner or blower access door. Follow the procedure according to the manufacturers guidelines to avoid the risk of fire or explosion.
- Do not disconnect any piping to check for gas supply. An instrument is used to check for pressure, and should be done by a qualified serviceman.
- If the furnace is vented through PVC (white plastic pipe) out the side of the building, examine the ends of the pipe or pipes outside. Blockage of any kind will cause a shutdown.