Why Is My Furnace Not Keeping Up With Cold Weather?

A cold snap is moving in and your furnace can't handle it. No matter how high you crank the thermostat, your furnace is just not keeping up with the cold. When the temps drop into the teens or single digits, it can be challenging for even the best heating systems to keep a home warm. 

Sometimes, though, a furnace can't keep up because of a larger issue, such as a faulty fan or toasted thermostat. Occasionally, the furnace may not be the right size for the house, making it work harder than it should. If you're struggling to keep warm, pull on another layer, wrap yourself in a blanket, and get to the bottom of what's happening.

1. It's Just Too Cold

Assuming there are no major problems with the heating system, your furnace does its best to keep your home at a comfortable temperature throughout the winter. But during an extended cold snap, when temperatures are way colder than average for several days, your furnace can struggle to keep up. 

It's just the nature of things. Instead of pushing your furnace to its limit, straining it and your local utility providers, find creative ways to warm up (presuming your home is just chilly, not absolutely freezing). 

Next Steps

Here are some tips to keep warm in a cold house:

• Wear an extra sweater and thick socks.

• Use a personal space heater.

• Cozy up with blankets.

• Drink warm beverages. 

• Cook and bake in your kitchen to utilize the oven’s heat.

2. Your Furnace Needs Some Attention

What about times when it's not particularly cold outside, but your furnace still isn't doing a good enough job? In those cases, it could be that there's something wrong with the furnace itself. It may be a quick fix, such as replacing a dirty and clogged air filter. Or, your furnace may need more extensive repairs, such as a fan replacement or duct repair.

Next Steps

If you suspect that your furnace is having problems, contact a local furnace repair company and schedule an inspection. During the inspection, the technician will check your furnace to ensure it's operational and will let you know their recommendations for correcting any problems.

3. Your Furnace Is Tired

Furnaces don't last forever. Depending on the age of your system and how well you've cared for it over the years, your furnace could be near the end of its life. (For reference, furnaces last between 15 and 20 years.) If it's struggling to heat the home and makes loud and frightening noises every time it kicks on, that could be a sign that it's time to replace your furnace.

Next Steps

Schedule an inspection with a furnace technician, who can explain if it's more cost-effective to repair your particular furnace problem (or problems) or replace the system entirely. 

4. The Thermostat Is Fried

Like furnaces, thermostats don't last forever. Often, at the end of their lives, thermostats start to act weird. Your thermostat may think it's registering the correct temperature when it's actually a few degrees cooler. 

In some cases, the position of a thermostat makes it difficult for it to do its job. For example, if you put the thermostat right over a vent, it will read a warmer temperature before the rest of the room can heat up. The furnace will shut off even though the room is still chilly. Other factors that can make your thermostat act up include dust inside the cover and dying batteries. 

Next Steps

The process for fixing a faulty thermostat will depend on its cause. For example, if your thermostat is too close to a vent, then moving it will solve your problem. Otherwise, you might need to change the batteries, check the settings, or remove dust that’s gathered on it. If none of that works, bring in an HVAC pro to figure out what’s going on.

5. You Shut the Furnace Off

If you live in an area where the temperature fluctuates throughout the winter, you may turn the furnace off on warmer days to save energy. But, if a warm spell is followed quickly by a cold spell, your furnace will need to work extra hard to heat up your home—and, unfortunately, it may not be able to keep up.

Next Steps

Instead of turning the furnace on and off, the best thing to do is leave the furnace on throughout the winter. When it's warmer, turn the thermostat up so the furnace isn't making the house too hot. That way, when the inevitable cold snap comes along, your furnace will be primed and ready for action.

6. Your Furnace Is Too Big (or Too Small)

Size matters for furnaces, and bigger isn't better, especially if you live in a smaller house. 

It may be pretty easy to see why an undersized furnace will struggle to keep a larger home warm. The system will run and run and the temperature on the thermostat won't budge. You'll be shivering and your furnace will be working itself into an early grave.

On the flip side, an oversized furnace will blast heat through a smaller home quickly. The furnace will then shut off. Since the furnace doesn't run for long, the warm air never has a chance to blend with the cooler air, making some areas or rooms feel chilly. The temperature reading on the thermostat drops quickly, turning the furnace back on again, and the cycle repeats.

Next Steps

If your furnace can't keep up with the cold because of a size problem, the best option is to replace it. Before replacing the heating system, the technician you hired should perform a Manual J Load calculation to determine what size furnace is right for your home.