9 Troubleshooting Tips for Furnaces on the Fritz


The furnace is broken! Or is it? Before you pick up the phone to call for help, here are some basic troubleshooting tips you can try first.

Tip 1: Find your owner’s manual

Owner’s manual? Didn’t that come in the box with a bunch of other papers and plastic? Chances are you’ve already thrown it away, misplaced it, or buried it at the bottom of your junk drawer. But never fear! Most manuals are now easy to find online. Check out any tips and pointers that the manual recommends for your particular thermostat and furnace. The solution to your problem could be just a mouse click away.

Tip 2: Check the thermostat to make sure it’s on

Have you ever had problems with your computer or an appliance only to discover later that it wasn’t plugged in or turned on? Sometimes, the easiest solution is the best one. So double-check to make sure your thermostat is on and set correctly.

Move the thermostat setting to “heat” to confirm that it is telling the furnace to turn on. Next, check the temperature setting. Set the temperature 10 degrees warmer than the current room temperature. If the furnace responds by coming on, your problem is solved. If it doesn’t respond, carry on with the following steps.

Replace the thermostat battery! If there is a power outage and your battery is dead, your thermostat will revert to default settings. If your thermostat displays the day and time, be sure that it is showing the correct settings.
Follow the thermostat wires back to the furnace. If you find a break in one of the wires, splice them back together and wrap the wires with electrical tape. Clean the thermostat by gently blowing out any dust or debris. Check that all wires and parts are secure and that the thermostat adheres firmly to the wall.

Tip 3: Check that the furnace is on

You’ve checked, and your thermostat is on—great! Now confirm that your furnace is also on. All furnaces, no matter the brand or type, have a standard wall switch on or near the furnace. If the switch is in the ‘on’ position, then move on to the circuit breaker or fuse to be sure that they are on. Finally, find the front panel that covers the blower motor (this is where your owner’s manual will come in handy!) and make sure it is securely fastened.

Tip 4: Make sure the gas is on

Warm weather arrived, someone turned off the gas and then, of course, forgot to turn it back on. An easy mistake to make, and a straightforward fix! Follow the gas line from the furnace to the meter and observe the handle which should be parallel to the gas pipe. If it’s not, turn it until it is. If you have an older furnace or boiler, then it’s likely you have a pilot light. Check to see if it’s lit.

Tip 5: Change your filters

Did you know that a clogged furnace filter can cause your entire furnace to turn off? Dirty/dusty filters are the most common cause of furnace problems. And it’s such an easy, inexpensive thing to fix. Just remove your old filter and replace it with a new one. Filters should be changed more frequently if you have children, pets, or someone living in your home who has respiratory difficulties.

Tip 6: Check that the chimney exhaust flue is clear

Unfortunately, birds occasionally fall into the chimney exhaust flue because the warm air attracts them. To see if it is clear, turn your furnace off and your thermostat all the way down. Disassemble the duct where it exits the furnace and check for dust, debris, etc. Reassemble when all parts are clean.

Tip 7: Flush out drain lines

In the same way that a dirty filter can wreck a furnace’s efficiency and shut it down, clogged drain lines can do the same. Drain lines are often blocked by sediment or even mold growth (yuck). If your drain hose looks dirty, remove it, fill it with a mixture of 25% bleach and 75% water, wait a few minutes, and then flush it out.

Tip 8: Check your register vents and ducts

The furnace turns on, and your house is warming up—except for one or two rooms which are still cold. The first step is to be sure that all register vents are open. If they are, then it is time to examine ductwork. Look for gaps between sections and seal any gaps or holes with metal duct tape only. Standard cloth duct tape will not hold up over time and may even cause future leaks. Finally, make sure all control dampers are open.

Tip 9: Clean debris from heat pumps or intake and exhaust vents

If your furnace vents out of the side of your house, make sure nothing is blocking the intake or exhaust. It’s normal for leaves and other debris to get caught. If ice is clogging one of the pipes, you have a bigger problem. Clear the ice and call Stuart Pro for assistance. Finally, if you have a heat pump, clear away grass and leaves and hose it down gently to rid it of dirt and debris.

If you have tried all of the above to no avail, then chances are something more serious has gone wrong with your furnace. Pick up the phone anytime, day or night, to get help from Stuart Pro Heating & Air. We’ll have your home warmed up in no time.