Forced Air vs. Other Heating Methods

Friday, 07 May 2010 11:21

There are 3 primary methods to transfer or conduct heat.

Conduction

This is easiest to explain by grasping something that is cold with your hand. Heat flows from a warmer substance to a cooler substance. After a short time your skin temperature drops and your hand feels cold. Although this happens all the time in heating your home conduction would be too slow to transfer enough heat quickly enough.

Convection

This is the transfer of heat through some medium. It can be forced air, hydronics through water and other methods. It is via convection that most heating appliances work and use this type of heat transfer.

Radiation

This is the transfer of heat through heat waves or the electro magnetic spectrum. It is best explained by the feeling of driving in your car with the sun shining through the side window. Via radiation the heat rays of the sun strike your face while the other side stays cool. Ever walk on a bitterly cold sunny day and yet if there is little wind and the winter sun is shining brightly your face can actually feel comfortable. Once the sun goes down the radiation is gone and the earth radiates heat back out to space. In the heating business there are appliances that use this effect.

As mentioned before convection is the most popular means of heat distribution. In southern Ontario forced air has been and will continue to be the most popular method of heating and cooling your house. It is popular because of the demand for central air conditioning which needs forced air to transfer heat and it still remains the least expensive method to install in a home incorporating heating and cooling. Duct work usually made of galvanized metal is used to move and contain the forced air as it moves down and away from the furnace. Many fittings can be fabricated and there is extensive knowledge required to properly design, make and install duct work.

Proper sizing is critical to ensure that every room in the house is comfortable. Many people call to ask me to correct a family room above a garage that feels cold. In designing the heat needed for that area extensive info has to be calculated regarding the heat loss, and therefore the amount of heat required to be delivered. Generally more outlets may be required as well as the main trunk duct may need to be sized larger.

It is important to balance your duct work by adjusting the metal round dampers located usually below your floor register.

Hydronic or hot water heating uses hot water pumped via a circulator or hot water source through a series of heat emitters or rads. Old homes have the so called Old Fashion Cast Iron Radiators which can be large and a bit obstructive. They are one of the best methods to emit heat and many a person coming in from the cold has snuggled up to one of these to warm up! Newer designs are smaller slimmer but require more linear footage of material to give off the same heat. Hydronic heating is more efficient and a superior way to heat your home. It is silent, dustless, and very even for temperature distribution. Its big disadvantage is higher cost and difficult integration with cooling systems. ie.: you would need a separate cooling system installed if you wanted air conditioning.

Appliances using radiation use some substance that when heat emits infrared radiation. Radiant tube heating and radiant floor heating are examples. Radiant floor heating is by far the absolute best way to heat especially in the basement areas. The extreme uniformity in heat distribution plus the gentle emitting of heat at floor level means you will never need slippers or get cold feet again! Call me if you would like more information. Again the downside is cost and lack of integrating central air easily.