subject: Replacing Your Furnace [print this page] There are usually two major reasons why you are choosing another forced-air furnace. The first is that your furnace does not function. It has just broken down, irrevocably, or it has been red-tagged or condemned by gas inspectors. If it is winter, and your house is getting colder quickly, you may not have the luxury of making a reasoned choice on what to buy next. The other situation is that your furnace is getting old, or your fuel bills are becoming too excessive to tolerate. In this case, you have the time to shop around and get the best furnace and fuel for your situation.
This About Your House is written to address both situations. If you have a dead furnace and a chilly house, you will probably take some shortcuts in your selection process.
Choice of Fuels
For many years, CMHC and others could offer sound advice on what fuel choice would be the most economical. During that period, heating systems based on electricity or propane cost the most to operate. Heating oil was somewhat more economical, and natural gas (if available in your community) was the least expensive choice.
Since 2000, the prices of these commodities have been fluctuating, and it is difficult to offer reliable advice on pricing. At one point in 2001 2002, heating with electricity in Manitoba was as economical as heating with natural gas. Predicting these prices over the next two decades (a common life span for a furnace) is nearly impossible. The best advice is to make a calculation based on the current prices quoted to you in your locality.
Furnace Sizing
You probably do not need a furnace with the output of your current furnace. Most furnaces in Canadian houses can provide far more heat than the house requires. A properly sized furnace will be running almost continuously during the coldest day of the winter. Having a furnace of a correct size will result in efficient operation during the whole heating season. A grossly oversized furnace will run only for a short period, never coming up to peak efficiency. Note, however, that sizing may not be a big issue with high-efficiency, condensing gas furnaces. Due to the design of condensing appliances, they are efficient even when oversized.
So, how do you size your furnace? You can have the contractor use a home heat loss calculation that is available from Canadian Standards Association (CAN/CSA F280) or a sizing procedure from the Heating, Refrigeration and Air Conditioning Institute of Canada (HRAI). Having a proper sizing will cost you $150 $300 from a qualified contractor.
Those who keep their heating bills, and who are mathematically inclined, can try the calculation of house heat loss from utility bills.
