Forced Air Heating & Cooling
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Forced air systems use a furnace or heat pump to heat the air and then disperse it through the house via duct work and in-room vents. Once the temperature is set at the thermostat, cold air from the home is pulled onto the system where it passes through the air filter, removing allergens like pollen and dust. It then blows the air through the air handler where it is warmed via the furnace's heat source and spread to the home through the ducts via the blower motor. If a heat pump is your primary source for heat, it will immediately begin pulling heat out of the air at the outdoor unit, pass it through the refrigerant lines going into your home, and then through the air handler and into your ducts.
Benefits
A forced air system has a number of beneficial features to be noted:
Air quality and comfort. With regular maintenance, a forced air system can improve the air quality in your home. Filters located inside the system trap allergens and air particles that can be transferred into your home via the ductwork. Additionally, dehumidifer or humidifier units can be added to forced air systems to keep the air in your home at a comfortable humidity level without adding excess energy usage.
Energy efficiency. Most forced air heating systems run between 85-98% energy efficiency, ensuring that your fixed air system will heat your home efficiently, without wasting precious heat and hurting your bottom line.
Combined heating and cooling. Forced air systems are the only HVAC sytems that can combine heating and cooling. The ductwork used for the heating aspect of your forced air system can also distribute central air conditioning throughout your home.
Cost and Savings
The initial cost of installing a geothermal heat pump system can be two to three times that of a conventional heating system in most residential applications, new construction or existing. In retrofits, the cost of installation is affected by the size of living area, home's age, insulation characteristics, the geology of the area and location of the home/property.
For new construction, proper duct system design and mechanical air exchange should be considered an initial system cost. These systems can save the average family from $400-1400/year, reducing the average heating and cooling costs by 30-70% per installed system.
Types of forced air heating systems
Natural Gas - Propane - Oil - Coal
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Heat is produced via combustion of fuel
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A heat exchanger keeps the combustion byproducts from entering the air stream
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A ribbon style (long with holes), inshot (torch-like), or oil type burner is located in the heat exchanger
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Ignition is provided by an electric spark, standing pilot or hot surface ignitor
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Safety devices ensure that combustion gases and/or unburned fuel do not accumulate in the event of an ignition failure or venting failure
Electric
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A simple electric heating element warms the air
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When the thermostat calls for heat, blower and element come on at the same time
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When thermostat is "satisfied", blower and element shut off
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Requires very little maintenance
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Usually more expensive to operate than a natural gas furnace
Heat pump
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Extracts heat from outdoors, either from "ground source" or "air source" via the refrigeration cycle
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Requires less energy than electric resistance heating and possibly more efficient than fossil fuel fired furnaces (gas/oil/coal)
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Air source types may not be suitable for cold climates unless used with backup (secondary) heat. Newer models may still provide heat when coping with temperatures below 0°F
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A refrigerant coil is located in the air handler instead of a burner/heat exchanger. The system can also be used for cooling, just as any central air conditioning system
Hydronic coil
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Combines hydronic (hot water) heating with a forced air delivery
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Heat is produced via combustion of a fuel (gas/propane/oil) in a boiler
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A heat exchanger (hydronic coil) is placed in the air handler similar to the refrigerant coil in a heat pump system or central AC. Copper is often specified in supply and return manifolds and in tube coils
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Heated water is pumped through the heat exchanger then back to the boiler to be reheated
Environmental Impact
Consider the environmental impact of what you burn for heat. Natural gas is the cleanest burning fuel. In fact, it is far less harmful to the environment than oil, wood or electricity generated from fossil fuels.
Natural gas produces about 30 percent less carbon dioxide than oil and about half that of coal or wood. When properly burned, natural gas produces heat, carbon dioxide and water vapor. It produces almost no sulfur dioxide, carbon monoxide, dissolved solids, or particular matter.
Maintenance:
Most manufacturers recommend an annual cleaning and tuning of your forced air heating system annually, to prevent they are running at peak performance, and to clean and replace small parts that may go bad due to rust, corrosion or blockages.
Cleaning and tuning isn't just about safety; it's also about preventative maintenance. Catching a problem before your furnace quits in the middle of the night on a cold evening will prevent costly emergency service rates, and keep your family warm and safe.