Seven Reasons Why I Don’t Like Forced-air Furnaces

Most houses in the U.S. have forced-air furnaces. The only advantage to a furnace is it can deliver even heat to every room in your house. They have way more disadvantages than advantages. Electric furnaces are even worse than gas ones because of the cost of using electricity to produce heat.  If you can build or adapt a house to use single-point interior heat sources like free-standing wood or gas heaters you will be much better off. Here is why I don’t like forced air furnaces:

Furnace in unheated basement with uninsulated ducts

1.       Inefficient. Although gas furnaces have a high efficiency rating, as high as 90%, this refers to the efficiency of combustion plus the efficiency of the heat exchangers inside the unit. The delivered efficiency, which is the amount of heat delivered into your house through the duct system is much lower. How much lower depends on how well the duct system is constructed. The heat is delivered to the rooms via ducts in the attic, crawlspaces and inside walls. These ducts leak heat, air, and are usually outside the insulated areas of your house. If you already have a house with a forced air furnace, check the ducts. Where are they? Are all the joints completely sealed with tape? Are the ducts wrapped with insulation? If not, you are losing a lot of heat. 

      Another source of inefficiency is how a furnace cycles on and off. Before the blower turns on, the gas burner runs until the heat exchangers get hot. Once the blower is on, the ducts need to get heated up before maximum heat is delivered to your rooms. Then the thermostat turns off, the whole system cools down and the cycle starts all over again. This results in wasted heat as the system heats itself up over and over again.

dirty and clean air duct

2.       Unhealthy air. Old duct systems, particularly leaky ones, eventually get dirty. Mold grows in them, dust accumulates, rodents and insects get in your ducts through larger leaks and poop and pee, make nests, and die and rot in there. Whenever your furnace fan is on, all that junk gets blown into your house. Yuck! Some chronic allergies and health issues are causes solely by having dirty ducts in your home. If you have an older forced air system you should have your air ducts cleaned. There are services that do this. Furnaces have filters that help to mitigate this problem but you have to remember to change them often and check that they are installed correctly. A dirty filter can seriously block the air flow causing even more of the hot air to leak out.

3.       No power, no heat. The furnace delivers heat to your house via an electric blower, which needs power to work. If your power is out, not only will your furnace not light (electric ignition circuits and relays turn your furnace on and off), it can’t deliver any heat to your house. None at all.

4.       Blowing air is less comfortable. When air blows against a moist surface like your skin, it cools your skin. Even the warm air from your furnace will do this. You feel warmth but this is in spite of the heat it delivers. You will feel much warmer if the same amount if heat is delivered via direct radiation (like from a wood stove) or radiant floor heating rather than from blowing hot air.

5.       Furnaces are noisy. Your thermostat turns your furnace on and off many times during cold days and nights. Every time it turns on, the fan motor and the flow of air makes noise. This cycling on and off is not only noisy, it is intermittent noise which is harder to get used to.

6.       Heating unused rooms. Unless you close the heat registers in rooms you don’t spend much time in, you will be heating areas of your house that don’t need to be heated much. It is a waste of energy. Since the registers are either up by the ceiling or on the floor, it is not easy or convenient to close and open them all the time so people mostly don't do it.

7.       Expensive. Buying and installing a furnace with all the ducting and air vents costs a lot of money. Installing a gas stove or wood stove costs a lot less. Unless you put a stove in every room of your house, the furnace will probably be more expensive.

Instead of buying a furnace, design your house with a fairly open floor plan and get one or more single point interior heating appliances like free-standing gas stoves and/or wood stoves. The gas stoves are only slightly less efficient than a furnace in the combustion and heat exchanger departments but all that heat gets into your house because the whole thing is inside your house. No heat loss or dirty air blowing through ducts or leaks because – no ducts!

They can run without external electricity. They have thermostats that run on the tiny voltage created by a thermopile which uses the heat of a pilot light to generate the electricity. You can get them with fans to circulate air, but they will run just fine without a fan. If you want to circulate air, get a ceiling fan or two. On low, a ceiling fan uses very little power. It isn’t necessary, though, and you will still have heat if there is a power outage.

Gas stoves are a lot quieter than furnaces. The only sound you hear is the flame burning. The radiant heat coming from a gas stove is more comfortable and you can always go stand right next to the stove to get toasty warm.

You will need either natural gas or propane to run a gas heater and there are costs for that. There is also the possibility that the gas grid goes down or propane becomes unavailable for a time due to a disaster. If you are worried about that, get a wood stove, at least as a backup heater.

Wood stoves have many of the advantages of a gas stove and none of the problems that furnaces have. They are more work to use, do not have thermostats, and need to be attended and cleaned regularly but you can still have heat in some part of your house if you are unfortunate enough to lose both electricity and gas supplies.

If you already have a house with a forced air furnace get a wood or gas stove as a backup heater in case of a power outage. You may find you like the backup heater so much that you will turn off your furnace for good.