Your furnace is a key part of your home. Without one, you wouldn’t be able to keep warm during cold weather. Yet furnaces can have some issues that are more common than others.
Let’s go over these problems and about what they might cost to correct so you know before you contact an HVAC technician. Some of the most common furnace repair issues include:
- Furnace won’t turn on
- Furnace doesn’t stay lit
- Furnace won’t blow hot air
- Furnace won’t turn off
1. Furnace Won’t Turn On
There are a couple of reasons why your furnace won’t turn on, so make sure to go through all of them.
- Is your thermostat set correctly? Make sure it’s on “heat,” “auto” and that your preferred temperature is greater than the room’s current temperature. If you have a programmable thermostat, make sure it has fresh batteries.
- Is the circuit breaker tripped? Your furnace can’t operate if it doesn’t have electricity. Reset the switch if it’s facing the outside of the electrical panel.
- Is the furnace switch off? Your furnace has a power switch located on or close to it. Since this switch looks like a light switch, it’s easy to unintentionally turn it off. If it was off, it might take your furnace a few minutes to start.
- Is the air filter clean? A dirty air filter can cause a lot of issues for your furnace. Get a new one if you can’t see light through it.
Estimated Repair Cost
This problem can be complex, so the estimated cost to repair it varies according to what’s wrong.
2. Furnace Won’t Stay Lit
Your furnace follows a certain sequence when it begins heating your home.
- Your thermostat notices the temperature has dropped and tells your furnace to start running.
- The draft inducer fan activates to pull in fresh air for combustion.
- The gas valve unlocks for the burners, which are ignited electronically.
- The flame sensor signals to your furnace the burners have been ignited.
If something is wrong during the sequence, your furnace will shut off as a safety precaution.
A couple of potential causes for this issue include:
- Dirty or malfunctioning flame sensor. If the sensor doesn’t detect a flame, it will shut off your furnace to prevent natural gas from spilling into your home. The ignition process corrodes flame sensors as time passes. While cleaning during annual furnace maintenance can help, yours may ultimately need to be taken out and changed.
- Bad limit switch. This safety feature will shut off your furnace if it detects backdrafting. Backdrafting is dangerous, since carbon monoxide and natural gas can seep into your home. These switches can fail due to age, damage or dust accumulation.
- Old thermostat. If your thermostat isn’t working properly, your furnace won’t be able to operate.
- Dirty air filter. A dirty air filter can limit airflow and force your furnace to shut down to prevent overheating. Make sure to change yours every 30 to 90 days, or whenever you can’t see light through it.
Estimated Repair Cost
These costs are estimates, so it’s important to note yours may fluctuate based on your furnace’s brand and model.
- Flame sensor: $350–$500
- Limit switch: $150–$300
- Thermostat: $150–$350
- Furnace filter: $10-$30
3. Furnace Won’t Blow Hot Air
In many instances, this problem is tied to a wrong thermostat setting or a dusty air filter that’s limiting airflow. Follow the steps above to fix the problem.
4. Furnace Won’t Turn Off
If it’s very cold outside or you like your home to be toasty, your furnace may be working for a long time.
If this isn’t what's happening, make sure your thermostat is set correctly and running properly. If your fan setting is at “on,” the blower motor will be going even when the furnace isn’t, so it’ll sound like your furnace is on all the time.
Alternatively, there might be a problem with the blower motor or your ductwork may be losing air, forcing your furnace to run constantly to make up for the lost air.
Estimated Repair Cost
These costs are approximations, so it’s necessary to note yours may vary based on your furnace’s brand and model.
- New blower motor: $250–$800
- Seal ductwork: varies based on square footage
House of Heating Incorporated Can Resolve Your Furnace Problems Quickly and Affordably
Furnace issues can be an expensive headache, but not when you call House of Heating Incorporated. We’ve been providing the quality, affordable furnace repair Marshfield homeowners have relied on since 1962. Contact us at 715-384-3163 to receive your free estimate today.