4 Silly Reasons Why a Furnace Won’t Turn On

“Help! My furnace won’t turn on!”

It’s a call we get all too often in the winter. However, sometimes when we show up, the problem is so simple to solve that the homeowner could have easily fixed it without calling us.

Let’s prevent that embarrassing situation, shall we?

If your furnace suddenly refuses to turn on, check these 4 things before picking up the phone to call for a furnace tech.

Many of our “no heat” calls turn out to be caused by dead thermostat batteries. That is, since the thermostat isn’t powered, it can’t send a message to the furnace to call for heat.

Digital thermostats usually have a “low battery” message pop up when the battery needs changing.

If you see that message, make sure to change the battery—unless you want to wake up freezing in the middle of the night!

Now, we do want to point out that not all thermostats are powered solely by batteries. Many thermostats are powered by a 24V wire connected to a transformer located inside the furnace.

These thermostats do have small backup batteries, but their purpose is to preserve the thermostat’s settings in case the power goes out.

Regardless, anytime you see a low battery notification, change the batteries as soon as you can.

One of your kids or a really excited dog may have switched your thermostat to COOL. Meaning clearly the thermostat will never call for heat. So, check that setting before picking up the phone.

Near your furnace should be a power switch. Someone may have switched it to off by accident. This is easy to do because it often looks JUST like a light switch.

So if you get no heat, head to the furnace and check the switch.

None of the above will solve the problem if the furnace’s breaker has “tripped” (cut off the flow of electricity). After trying the troubleshooting steps 1-3 discussed above, find your breaker box and see if the furnace’s breaker has tripped (switched to a neutral position). If so, do this:

1. Switch the breaker to “off”
2. Switch the breaker to “on”

If the breaker trips again, you have a more serious problem and need a professional’s touch.