Why Isn’t My Furnace Making the House Warm Enough?

We recently wrote about the major emergency that homeowners hope they don’t run into during the deeps of a Minnesota winter: a furnace that breaks down and won’t work at all. But a furnace doesn’t need to break completely in order to fail to heat your home adequately. You may notice that your house feels colder than it should be, even with the furnace running. What’s wrong—and what can you do about it?

Check the air filter first

The first thing you should do is see if the furnace has a clean air filter. If the filter is heavily clogged with dust and debris, it cuts down on airflow, which in turn means less heated air is getting around the house. Change the filter for a clean one if it’s clogged, and continue to change it every 1 to 3 months while the furnace is running.

Blocked air vents

If only one or two rooms are cold, the issue may be that the room vents are obstructed or closed. Furniture might be blocking the vents, or someone could’ve closed them thinking it would save energy. (It doesn’t, by the way).

Malfunctioning thermostat

A common cause for a furnace that isn’t living up to its potential is that the thermostat isn’t working. It might be sensing incorrect temperatures and forcing the furnace to shut down earlier than it should. Or maybe its programming isn’t working correctly. You’ll need a professional to diagnose such troubles.

The furnace is short-cycling

Short-cycling is when a furnace starts its heating cycle only to cut it off before its finished. The furnace will soon turn back on—and then shut off again. This makes it difficult for the furnace to distribute heated air around the house. There are many reasons for short-cycling in a furnace, and you’ll need an HVAC technician to get to the bottom of the problem.