Slashing Heating Bills With a High-Efficiency Furnace

When Ken Stengler replaced the two 35-year-old furnaces in his Calgary home, he had to choose between a medium-efficiency and a high-efficiency model. He decided to spend about $800 more for a high-efficiency furnace, and he's glad he did.

Stengler recently bought a 96.6-per-cent high efficiency furnace instead of an 80-per-cent mid-efficiency model, primarily for the 17-per-cent difference in natural gas consumption. He also opted for a variable-speed motor, which uses much less electricity to drive the furnace fan than conventional direct-drive motors. The combined savings on his utility bills should pay for the $800 difference in purchase price in a couple of years. With his single new furnace, Stengler has replaced two aging furnaces that were far less efficient than their original 60-per-cent rating and were increasingly a fire hazard. He also equipped his new furnace with an electronic air filter, which captures all the dust that used to blow through his old furnaces.

"We're hoping to cut our gas bill nearly in half," says Stengler. "Since we had the furnace installed, the house is already safer and the air is noticeably cleaner. It's no longer open season on the dust bunnies."

About a decade ago, Canadians could still buy furnaces with an efficiency rating as low as 55 per cent. Now, all new furnaces must have an AFUE (annual fuel utilization efficiency) of at least 78 per cent. In this case, 78 per cent of the fuel is being turned into useful heat and the rest is vented up the chimney as combustion byproducts.

Like Stengler, today's homeowners can choose to buy a medium-efficiency furnace - 78-82 per cent AFUE - or a high-efficiency furnace - 89-97 per cent AFUE. Besides wringing considerably more usable heat out of every gas dollar, high-efficiency furnaces deliver even, comfortable heat and send considerably less greenhouse gas emissions into the environment.

Most high-efficiency furnaces are condensing furnaces, which use additional heat exchangers to draw enough heat from combustion gases so that moisture in the gas condenses, releasing additional usable heat. The condensate is piped to a floor drain and exhaust gases are cool enough to be vented out a sidewall with a four-inch piece of plastic pipe, thus eliminating the need for a chimney. Because the combustion in these furnaces is sealed, there is also no risk of carbon monoxide leaks.

In the early days of their development, high-efficiency furnaces had a reputation of being expensive to buy, difficult to install and costly to maintain. While some of these misconceptions still linger, they are not true. Indeed, these units are generally easily installed, highly reliable and likely to pay for their extra cost in a few years (see chart).

Tips When Buying a New Furnace:

• Draft-proof and insulate your house first. It's counterproductive to buy an efficient furnace only to see much of the heat escape from a leaky house. By contrast, a too tightly-sealed house can affect air quality. Installing a fresh air intake or mechanical ventilation system will bring in and circulate fresh air, without causing drafts or heat loss.
• Look for the EnerGuide label, which lists the energy efficiency of the furnace on the page of manufacturers' brochures.
• Get estimates from at least two reliable furnace installation contractors. The Heating, Refrigeration and Air Conditioning Contractors of Canada has a listing and location of qualified contractors on its website.