Two-thirds of all Canadian homes are heated with forced-air furnaces; of those, two-thirds are fired by natural gas, and the remainder by oil or propane or heated electrically. These systems are popular for a number of reasons, primarily their ability to heat a house quickly: just turn up the temperature on your thermostat, and seconds later warm air comes blowing out of the registers. The ductwork can also be used for air-conditioned cooling in summer, and a forced-air furnace can easily be equipped to multi-task as an air filter, humidifier and/or fresh-air ventilator. On the fuel side, the gas line required for a gas-fired furnace will also provide fuel for your stove, dryer, and barbecue, heat your hot water, and even supply a warm, soothing fireplace with the flick of a switch.
On the downside, the air blowing out of your vents can feel drafty, and may circulate dust. The ducts can also carry noise from the furnace and blower throughout the house.
If your current furnace is older than your VHS collection, then it’s probably a “conventional” model that has an annual fuel utilization efficiency (AFUE) of only 60 to 65 per cent. What that means is that for every $1 you spend on fuel, 35¢ to 40¢ goes up the chimney as waste exhaust gases. Since 1995, the minimum efficiency level for furnaces sold in Canada has been 78 per cent.
Today, there are two furnace types on the market. The first are the “mid-efficiency” models that are about 80 per cent efficient. Simply put, these have a combustion chamber below a heat exchanger that warms the air the blower circulates through your heating ducts. The lighter-than-air combustion gases vent through your chimney.
As a result of their market dominance, more research and development goes into forced-air furnaces than other heating systems, and so they benefit from the most technological advancements. Some innovations, such as the electric ignition furnace, which have long since replaced pilot lights, are now standard. Other refinements get bundled in as you move up the price list of new furnaces.
A standard furnace has a single-stage gas valve. “When there’s a call for heat, the whole valve opens and you get full capacity going into the furnace,” says Ted Patterson, technical standards manager for Direct Energy in Toronto. In other words, every time your furnace turns on, it’s running at high gear.
The alternative is to upgrade to a two-stage valve. Two-stage furnaces run in low gear the majority of the time. They only kick in to the second stage on the coldest days. “It allows the system to run longer heating cycles at, typically, half the total capacity of that furnace. This allows it to have a constant stage of heating so you don’t have temperature swings. It equals better comfort and better efficiency for the system,” explains Chad Johnson, senior product manager with U.S.-based manufacturer Carrier.
A second upgrade is a variable-speed fan blower. These fans usually run at a lower speed almost continuously, and thereby reduce energy consumption and noise. Another advantage of a variable-speed fan is that it will do the same job for your central air conditioner.
Finally, not unlike cars, as furnaces incorporate more complex technology, diagnosing problems becomes increasingly difficult. Higher-end furnaces now come equipped with self-diagnostic systems that point technicians in the right direction, because it’s not easy for homeowners to isolate problems themselves.
Call the Club now to clean and safety-check your forced-air furnace and save $10.