Forced-air

src: i.ytimg.com

The forced-air central heating system is one that uses air as its heat transfer medium. The system relies on ducts, ventilation, and plenum as a means of air distribution, separate from actual heating and air conditioning systems. The plenum again brings air from some large back grill (ventilation) to the central air controller for reheating. Plenary supplies direct air from the central unit to the room designed for heat. Regardless of its type, all air handlers consist of air filters, blowers, heat exchangers/elements/coils, and various controls. Like other central heating systems, thermostats are used to control forced air heating systems.

Forced air warming is probably the most common type of central heating installed in North America. It is less common in Europe, where hydronic heating predominates, especially in the form of hot water radiators.

Video Forced-air

Type

Natural gas/propane/oil/coal

• Heat is generated through fuel combustion.
• The heat exchanger maintains the by-product of the combustion product so as not to enter the airflow.
• Band style (length with hole), inshot (like-torch), or oil type burner located in heat exchanger.
• Ignition is provided by electric sparks, standing pilots, or hot surface ignition.
• The security device ensures that unburned combustion gases and/or fuels do not accumulate in the event of a failure of ignition or ventilation failure.

Electricity

• Simple electric heating elements warm the air.
• When the thermostat calls for heat, blowers and elements to flash at the same time.
• When the thermostat is "satisfied", blowers and elements die.
• Needs very little maintenance.
• Usually more expensive to operate than natural gas furnaces.

Heat Pump

• Extracts heat from the outside, whether it is difficult to install a cheaper "ground source" or "air source" through the cooling cycle
• Needs less energy than heating electrical resistance and may be more efficient than fossil fuel burning furnaces (gas/oil/coal).
• The type of air source may not be suitable for cold climates unless used with a reserve (secondary) heat source. Newer models may still provide heat when overcoming temperatures below 0 Â ° C (32 Â ° F).
• A cooling coil is located in the air handler in place of a heat exchanger/burner. This system can also be used for cooling, as do central air conditioning systems.
• View heat pump

Hydronic coil

• Combine hydronic heating with forced air delivery
• Heat is generated through fuel combustion (gas/propane/oil) in the boiler
• The heat exchanger (hydraulic reel) is placed in an air handler similar to the cooling coil in the Heat Pump or Central air-conditioning system. Copper is often specified in the supply manifold and back and in the tube rolls.
• Hot water is pumped through a heat exchanger then returned to the boiler for reheat

Order of operation

1. The thermostat calls for heat
2. Flame source provided in boiler
3. The circulator initiates the flow of water into the hydronic coil (heat exchanger)
4. After the heat exchanger heats up, the main blower is activated
5. When the call for heat stops, boiler and circulator turn off
6. The blower will die after a certain period of time (depending on the particular equipment involved, this may be a fixed amount of time or it can be programmed)

Maps Forced-air

See also

• Forced air gas
• Copper in heat exchanger

src: cdn7.bigcommerce.com

References

Source of the article : Wikipedia