Heating and Heat Distribution

The basic requirements for an effective forced air heating system

Design

One of the most important but most over looked components of any heating system is the design. Before the contract is signed for the supply and installation of the forced air gas heating system, a homeowner is best served by having a proper design completed.

If all system components and details are clearly laid out to all subcontractors to tender on because they were designed beforehand, chances are better that a high quality furnace and ductwork distribution system will be priced out and installed. If, as is the industry norm, an architectural set of floor plans is given out to mechanical subtrades for them to select components and design the heating system for pricing, a "lowest price mentality" may drive the process. Components, materials, and workmanship may be reduced to meet General Contractor and consumer demands for a low price and you may not end up with a heating system that meets your expectations.

Selection of a gas furnace

There are currently three basic types of gas fired furnaces to select from within the Manitoba market.

1. Mid-efficiency furnaces burn gas at about 80% efficiency. This furnace type is generally vented up a chimney and uses room air for the combustion process. The gas burner is usually a conventional, naturally aspirating type but does not have a continuous pilot light.
   
2. High-efficiency condensing furnaces burn gas at about 90% - 92% efficiency. This furnace type is vented out the sidewall of the home through piping that both brings in combustion air and exhausts the products of combustion. Because the combustion efficiency of this furnace goes beyond 80%, the additional heat removed from the combustion gas cools it to a point where water vapour condenses out within the system. Because the condensate is corrosive, most of the heat exchangers are made out of higher-grade stainless steel.
3. The most recent addition to the market is the high-efficiency condensing furnace with a two-stage gas burner, which takes the seasonal efficiency rating up to around 94%. The burner initially comes on at about 40% - 60% of its capacity, which suits cooler temperature spring and fall conditions. If the initial stage cannot warm the house, the burner upgrades to 100% capacity to meet colder winter conditions. This furnace is generally associated with an energy efficient DC blower motor to save on electrical consumption.