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Reasons Your Furnace Won’t Heat the House

gas-furnaceGas furnaces are built for reliable, powerful performance. Few home heating systems are more dependable.

But no natural gas furnace is immune to malfunctions and user error. You may discover the furnace falling behind on its job this winter. The blower is running, warm air flows from the vents, but the house isn’t warming up to the levels you expect.

Don’t raise the thermostat to make up the difference. The furnace has a problem somewhere that needs to be addressed. It may be simple and you can correct it on your own. Or you may need to call our technicians for furnace services in Garner, NC. We have 24/7 emergency repairs available so you can always get the help you need for home comfort.

Incorrectly set thermostat

In our age of Wi-Fi and smart thermostats, it’s easy for someone in your home to accidentally alter the thermostat settings, or alter them without telling you. In fact, you may be the culprit! Check the programming on the thermostat to ensure it’s turning the furnace on and off at the right time. If the thermostat isn’t responding at all, you may need our technicians to repair it.

Thermostat miscalibration

The temperature sensor in the thermostat may start to pick up readings that are a few degrees off. For example, you set the thermostat for 68°F, but because the thermostat falsely reads the temperature as 4°F warmer, it will heat the home to only 64°F and then shut off. Our technician can recalibrate the thermostat or install a new one.

Clogged filter

One of the basic checks to make when a furnace acts up is to see if the filter is clogged. If not replaced regularly (every one to three months) the filter will become so congested that it will block airflow into the furnace. This means less air is heated, and less heated air reaches the rooms.

Leaky ductwork

The problem may not be inside the furnace itself, but in the ventilation system. Leaks along the ducts allow heated air to escape, lowering how much reaches the room. If certain rooms in the house are cold, it may be the fault of leaky ductwork. You can’t repair this on your own—call our team to locate the leaks and seal them with caulking, metallic tapes, or replacing duct sections.


When the furnace shuts off before completing its full heating cycle, only to turn back on again soon after, it’s called short-cycling. It not only wastes power, it puts more stress on the furnace and doesn’t allow enough time for all the rooms to warm up. There are many possible sources for short-cycling, so let our technicians diagnose the problem and solve it.

The furnace is too old

Loss of heating capacity can mean the furnace is too worn down with age. Repairs may manage to restore it for a short time, but it’s better to replace a furnace more than 15 years old rather than let it limp on with inferior performance and high bills. We’ll offer an honest assessment about your furnace and if it’s time to replace it.

Comfort Master Heating & Air Conditioning, Inc. provides service throughout the Triangle Area of North Carolina. Call us for furnace repair when you need it.

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