Furnaces or Heaters

Unit “configuration” refers to how units are positioned in the home. Furnaces can be located in a basement, crawl space, closet or attic. They can be units that blow the air up (upflow) normally in a basement or closet application, blow the air down (downflow), usually in a closet application where the supply ducts are in the floor, or horizontally (horizontal), usually where the unit is in the crawl space or attic.
Furnaces can use a variety of heat sources.

Gas Furnaces

Gas Furnaces have been very popular where gas utility lines are available, due one of the lowest costs of operation and heating temperatures that are higher than you would typically find with a Heat Pump. Newer Gas Furnaces have greatly improved safety controls and efficiencies, and the manufacturers suggest annual maintenance as a minimum on the heating portion of the system. Any fossil fuel type furnace (gas, oil) has a potential for creating deadly carbon monoxide so it is wise to have an annual check that includes testing for this

Gas furnaces can be identified in a variety of ways. First, you will have a chimney or exhaust pipe leading to the outdoors. Lower efficiency systems use a metal chimney or “flue” pipe – possibly leading into a brick chimney that goes up and out the roof. Higher efficiency systems use plastic pipe, either running up and out the roof or through the side wall.

To determine if you currently have a gas furnace, you will probably be paying for natural gas or propane either independently or on a utility bill. Gas furnaces are among the most cost effective source of heat available today, depending on the current cost of fuel.

Electric Furnaces

Electric Furnaces are commonly used where no gas is available, or as a backup heat source to Heat Pumps. They usually require a large electrical circuit to the indoor unit, and they typically cost more to operate than most of the other types of systems. These systems use an electric coil to produce heat, similar to a toaster but on a much larger scale. In many cases an electric furnace is also an “Air Handler” a term usually used when the electric furnace comes pre-installed with an air conditioning evaporator coil. If you don’t pay for natural gas, propane gas or oil as a heat source, you might have an electric furnace or a heat pump that uses the electric furnace as a back up source of heat. Maintenance on this type of system is recommended to reduce dust buildup on the coils while it is not in use, and to insure all electrical connections are tight.

Oil Furnaces

Oil Furnaces have been in use for many years and have been most popular in rural areas where natural gas utility lines were not available. Typically the oil is stored in an above ground or below ground tank, or sometimes even a tank located in a basement or cellar. Oil furnaces are sensitive to moisture and debris in the fuel oil.

Identifying an oil furnace. As with a gas furnace, you will have a chimney – normally metal connecting to a brick chimney. If you have an oil furnace you probably know it, because they typically can have a diesel oil smell, usually when the system is being serviced. Oil furnaces must have a tank that is filled on a regular basis, usually at least once a year or more. The tank could be in a basement or buried underground.

Heat Pumps

To explain a Heat Pump it’s important that you first read the section on Air Conditioners and How an Air Conditioner Works.

From the outside a heat pump looks just like an air conditioner – and works just like an air conditioner in the “cooling” mode. When it needs to produce heat, it reverses its cycle. Yes, even if it is 0 degrees Fahrenheit outside, the outdoor unit “absorbs” heat from the outside air that passes through the outdoor coil. By pressurizing the refrigerant with a compressor, it actually raises the temperature of the refrigerant to the point it can give off heat as it passes through the indoor coil.

Obviously a heat pump works better the warmer it is outside, so in most cases it needs a “back up” heat source, typically electric – but sometimes gas or oil. You might wonder why it makes sense to have a heat pump when you need a back up source. Heat pumps have the ability to produce as much as 3 times more heat for the money than an electric furnace, and they are becoming more efficient as technology improves. Heat pumps come in window units, PTACs, split systems, package units and ductless split systems.

One of the easiest ways to identify a heat pump is to look at your thermostat. If you have a “back up” or “secondary” heat switch, it’s a good chance that your system is a heat pump.

Geothermal Heat Pumps

A Geothermal Heat Pump uses the same principle as a standard heat pump or air conditioner, except it does not have an outdoor unit with a fan. The most common type of geothermal unit uses water that passes over a coil. The water either adds or removes heat from the coil depending on if it is heating or cooling. The reason geothermal units are some of the most efficient systems available are due to the relatively constant temperature of water, compared to the extremes of a heat pump that uses the outside temperature of the air. Geothermal units are among the most expensive systems to install, due to the cost of the burying a water coil underground.
A good way to identify a geothermal system is to first identify it as a heat pump, but without the outdoor unit.

Air Handlers

The Air Handler is the indoor portion of an air conditioning system or heat pump when a standard furnace is not being used in the system.