If you have a problem with your furnace, it’s quite natural to think it’s too much for you to deal with alone, and that outside help is required. However, there are a number of small and safe adjustments and checks you can make before picking up the phone.
A badly clogged air filter can cause the furnace to overheat and shut off, so replace it if it’s dirty. It can be hard to tell with some filters, so consider installing an air filter gauge that lets you know when it’s time to replace the filter.
Make sure the power is on! The power switch for your furnace looks like a regular light switch and can get bumped and turned off accidentally. If the switch is off, just flip it back on.
Be sure your thermostat is set to “heat” and at a temperature higher than the temperature inside the house.
GAS LINE SHUTOFF
Check the ball valve on the pipe that supplies gas to your furnace and make sure it’s open all the way. When the valve’s handle is parallel to the pipe, it’s open.
INTAKE AND EXHAUST PIPES
Newer high-efficiency furnaces will shut off if something like a bird or ice buildup blocks either the fresh-air pipe or the exhaust pipe. You’ll need to go outside and peek inside the pipes to see. Sometimes a critter can get lodged in the pipe all the way back to the furnace and you won’t be able to see it without taking the pipe apart, a job best left to a pro.
Check the door switch. Whenever you remove the access door on the furnace, a little safety switch shuts everything off. Sometimes this switch will stay turned off if the door isn’t completely closed.
High-efficiency furnaces produce water called “condensate.” If the drain tubing for the condensate gets clogged, the furnace shuts off. Check the tubing and clear any clogs. Or, better yet, just replace the tubing.