It's not pleasant to come home to a cold house on a winter evening. Fortunately, you can usually find an HVAC contractor to make emergency calls when your furnace breaks down, but there are a few simple things you can check first. Here are some possible reasons your furnace isn't heating your home.
The Thermostat Is Malfunctioning
Programmable thermostats are useful, but they also increase the risk of potential problems. Make sure the thermostat is not programmed to keep your house cooler than you want. This might happen if the batteries fail or are low and the thermostat resets itself. Try changing the batteries and reprogramming the thermostat. While you're at it, set the thermostat for a few degrees warmer than the temperature of your house. Then, wait a few minutes. If the furnace kicks on, you know the power and blower are okay. If nothing happens, the next thing to check is the power supply. The furnace may have tripped a breaker. If you restore the power by flipping the breaker back on and the circuit trips again, leave your furnace off and call an HVAC contractor for repairs.
The Safety Switch Is Activating
Your furnace probably has a safety switch that shuts it down in certain situations. One reason might be because the panel is open slightly. Maybe someone opened the panel to check the furnace or clean it and then didn't close it tightly. Make sure the panel is closed all the way, and that might fix the problem. Another safety feature that shuts down the furnace is when it overheats. Your furnace might overheat because the filter is clogged and blocking airflow. Check the filter and clean or replace it if needed. Hold it to the light to look for dust buildup. Unless you just recently put in a new filter, you may want to go ahead and change it to see if your furnace will operate again.
The Ducts Are Leaking
If your furnace seems to be running and blowing air, but little air is coming out of the registers, then you might suspect the ducts. A hole in a duct allows air to leak into the attic instead of flowing through the registers like it should. You might be able to repair a hole with duct tape you have around the house, but a more permanent solution could be to repair the hole with mastic duct sealer.
The Furnace Has Worn Or Broken Parts
Several parts can affect the functioning of your furnace. The limit control switch or blower fan might be bad. A belt or motor bearings might be worn. An HVAC repair person can narrow down the problem by checking whether the furnace runs at all and if it blows hot or cold air. Noises coming from the furnace offer a clue as well. You may need a new thermostat or internal parts to get your furnace working again. If simple tricks like changing the filter and resetting the circuit breaker don't help, call for professional repairs rather than run a furnace that isn't working properly.
For more information, contact a heating repair service near you.