Choosing a New Furnace


In Canada, most homes are heated with either oil or natural gas and there are three major reasons why homeowners change their furnaces:

  1. The Furnace Does Not Function. If the furnace has quit working or condemned by gas inspectors then the unit has to be replaced in a minimum of time. Unfortunately, winter is time when most furnaces tend to quite. With the home getting cold very quickly the homeowner may not have the time to make a reasonably choice for the next heating unit.
  2. The Furnace is Old. Old furnaces mean that the fuel bill is high compared to the amount of heating efficiency. Even though the bills may be high there is still time to shop and compare furnaces. In the spring many home heating stores put on some very impressive sales.
  3. Type of Fuel: Whether the homeowner is worried about his or "carbon footprint" or just wants to dump the oil tank in favour of the gas line running up the street fuel is a valid reason for some people to change their furnace.

Furnace Sizing

The Canada Mortgage and Housing Corporation has produced studies that state that most homes have a furnace that is too large for their home. In other words, most furnaces in Canadian homes produce more heat than the house needs. A properly-sized furnace, one that is picked for the home based on squared footage and other needs, will run continuously during the coldest days of the year leaving no cycles of being too hot or too cold. One the other hand, an oversized furnace runs only for a short period of time until it overwhelms the thermostat. Then the house cools down until the next cycle but it never comes up to the peak efficiency required for comfort.

Furnace Efficiency

1. Electric Furnaces

The technology behind electric heat is based on simple, electric resistance. This means that 100 % of the electricity used goes towards heat. It is clean, cheaper to install than other heating systems and no ductwork or hydronic piping is needed. For the purse, however, electricity is the most expensive of all the heat unless it is used in compunction with an Off-Peal Power package with the local power company. Although this can mean a 60% decrease in the cost of power this still puts it around the same price as the other fuels and the start-up costs an be as much as $12,000.

2. Oil Furnaces

Once the standard of home heating in Canada (after the decline of coal) oils was pushed aside in many parts of the country because natural gas was so plentiful, cheap and clean. Houses with oil furnaces always had an oily smell in the basement and oil tanks were subject to leaking. However, in recent years oil furnaces have become more efficient, going from roughly 60% to well over 80% because of new technologies. New flame-retention head burners and high-static pressure burners allow oil to burn cleanly and more efficiently. If changing to an oil system a stainless-steel flue-liner will have to be installed in the chimney.

3. Condensing Gas Furnaces

Like the oil furnace, new technologies in gas furnace have increased the efficiency of 97 AFUE, or Annual Fuel Utilization Efficiency, while the old ones were as low as.

The Secondary Heat Exchanger: In old gas furnaces one heat exchanger transferred the heat from the burning gas to the plenum and upwards into the home. Any heat not absorbed went up the chimney. Condensing gas furnaces have a primary exchanger that draws off heat from the newly-burned gas but then the air is moved across a secondary heat exchanger. Here the exhausting gases cool and then the added time in a second heat exchanger draws more heat from the exhaust gases that can be ducted into the home.

The Modulating Gas Valve: In a condensing gas furnace the modulating gas valve regulates the gas flow to the furnace when the thermostat wants it. Unlike the old-style valves the new technology allows the furnaces to automatically adjust fuel consumption from 40% to 100% of capacity. This saves energy during warm fluctuation as the furnace adjusts to the temperature fluctuations.

The Variable-Speed Fan Blower: With most forced-air furnaces heat is moved through the home ductwork with a blower that works in tandem with the modulating gas valve. This dual-control system eliminates the cycles of hot-and-cold that happens with most conventional furnaces.

ECM (Electronically-Commutated Motor): The standard furnace fan motor used to be the SPC, or split-capacitor, motor. Although extremely reliable they consume power in a year as much electricity as a refrigerator, 800 kilowatts per year. The new Electrically-Commutated Motors are lightweight and are powered by direct-current. These are similar to the motors in laptops computers

For more information on replacing or upgrading your present furnace consult our Contractor Directory for a heating contractor or simply post your project online.

Posted by: Kim Kinrade
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