Furnaces (or commonly referred to as heaters) are used as a major component of a central heating or HVAC system. Furnaces are permanently installed to provide heat to an interior space through intermediary fluid movement, which may be air, steam, or hot water. Heating appliances that use steam or hot water as the fluid are normally referred to as a boiler. The most common fuel source for furnaces in the US, and especially here in the Arkansas/Missouri region, use natural gas. Before we can understand why our furnace is not blowing warm air, it is important to understand the basic functionality of a furnace & how it works.

How a Gas Furnace Works

The heat capacity of a gas furnace is measured in British Thermal Units (BTUs). A BTU equals the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Essentially, a furnace creates a cycle of warming cooler air through a few simple steps.

• Burning a fuel such as natural gas, or in some cases propane, generates heat in the furnaces burner.
• The heat produced by this burning fuel is then passed through a heat exchanger, raising the temperature of the exchanger.
• Air from the home’s duct work is then blown over the heat exchanger by the air handler, which warms the cooler air.
• The furnaces blower then forces the now heated air back into the supply ductwork, which distributes the heated air throughout your home.

Furnace is Blowing Cold Air & Not Warm Air

When it dips below freezing, the last thing you would want is for your furnace to be blowing cold air out of your home’s vents. First, make sure that your gas bill is paid & not turned off. If there are no issues with your natural gas supply, the next step would be to check your thermostat. Make sure that it is set to “auto” and not “on” and that it is set to “heat.” If your thermostat is set to “70” but it is only “60” in your home or the temperature is dropping, then it’s time to take some action.

Check Air Filter

Next, it would be wise to check your air filter. This is one of the most common problems with HVAC systems failing to heat or cool properly. If your filter is dirty, then it is time to replace it! Turn off your unit while you replace your filter, then turn it back on & wait a while to see if this resolves your problem.

Check Furnace Pilot Light

Another common reason for your furnace to be blowing cold air instead of warm air is due to the pilot light being out. In older furnaces, this is a flame that stays lit, but newer systems use an electric ignition. A good way to diagnose this issue would be to locate the pilot light on your furnace and visually inspect it to ensure that you can see a small flame or flicker.

Call Your Local Heating & Air Professionals

If you have tried the above steps, and your furnace is still not working, then it might be time to call the professionals! Paschal Air, Plumbing & Electric is local, experienced, and ready to help you tackle your furnace problems. Contact us today or give us a call at 479-751-0195.