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Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun Counties and the
surrounding area

Monday - Friday 7:30am - 5:30pm | Saturday 8:00am - 1:00pm. CALL FOR EMERGENCIES


Serving Maryland, Virginia,
and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun
Counties and the surrounding area

24 Hour Emergency Services, 7 Days a Week

Home of Mr. Heat Pump

B&B Air Conditioning & Heating Service Blog

Why Your Furnace Is Running But Not Keeping the House Warm Enough


At the start of spring, the weather is often still cold, and that means you’ll need to keep your furnace running to keep everyone warm. But maybe you’ve noticed your furnace isn’t doing its job as well as it was at the start of winter. What’s happening? We’ll examine some of the possible causes below.

You’ve left the same air filter in place for too long

Dirty air filters are perhaps the most common reason that furnaces fail to provide enough heat to a home. (They’re behind plenty of other problems as well.) Over time, this air filter will become clogged with dust, dirt, and other debris. This restricts the airflow and causes the furnace to work harder to circulate warm air throughout a house. Fortunately, all you have to do to fix this problem is to change the air filter. This is definitely something you should do if you’ve had the same air filter in place since the start of winter!

The furnace is short cycling

Short cycling describes when a furnace turns on and off frequently, running for only short periods of time. Instead of completing a full heating cycle, the furnace turns off before it has a chance to distribute enough heat to reach the desired temperature in the house, and then turns back on again shortly after. Along with not giving the furnace enough time to heat the house, short cycling also wastes power.

A variety of factors can cause short cycling: a clogged air filter, a malfunctioning thermostat, a faulty limit switch, overheating, or a problem with the furnace’s heat exchanger. Since short cycling is both a symptom of another problem and a problem in itself, have technicians look into it ASAP.

Ductwork problems

Here’s a problem that doesn’t lurk in the furnace itself but in the air ducts that transport heated air around the house. If your ductwork has air leaks, you’ll lose the warm air blowing from the furnace before it can reach some of the areas in your house.

This will also force the furnace to work harder to compensate for the lost heat, resulting in higher energy bills on top of the poorly heated home. If you suspect your home has leaky ducts, call for professionals to test the ducts and handle repairs.

Faulty thermostat

The thermostat is the control panel where you send instructions to the HVAC system about how to heat and cool the house. If it isn’t working properly, the heating system won’t function properly either, leading to a potentially chillier home.

The issue could be as simple as an incorrectly set thermostat, so always double check the settings. A more serious problem is a miscalibrated thermostat (it’s sensing the wrong temperatures and shutting the furnace off early) or one that has a bad connection to the control board in the HVAC system. Call for a professional to repair, recalibrate, or in some cases replace the thermostat. 

When you need furnace repair in Fairfax, VA, you can rely on the B&B team. We’ve been in business for over 60 years, and we take pride in delivering efficiency, honesty, and integrity at a fair price.

Reach out to B&B Air Conditioning & Heating Service. We are always there when you need us.

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