High-Efficiency Furnace

The furnace accounts for up to 60 per cent of all the energy consumed in the average Alberta house. Switching to a high-efficiency furnace will cost about $5,000 to install and should cut your heating bills by at least 25 per cent.	It's a significant investment, requiring a fair bit of planning.	Replacing an old furnace with an energy-efficient model can reduce your household's greenhouse gas emissions by at least 1.4 tonnes per year.

What is a high-efficiency furnace?

A high-efficiency furnace has an annual fuel utilization efficiency (AFUE) rating of 90 to 97 per cent. In other words, a furnace at the high end of this range will convert 97 per cent of the combusted natural gas to usable energy, with the remaining three per cent going up the chimney. By comparison, many older furnaces have an AFUE of only about 60 per cent, meaning 40 per cent of the fuel is wasted.

How do they work?

Most high-efficiency furnaces use a condensing process. Two heat exchangers draw enough heat from combustion gases 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.

If I'm replacing my old, inefficient furnace, do I have to buy a high-efficiency model?

No.  You can buy a mid-efficiency model, with a 78-84-per-cent AFUE rating (less efficient furnaces can no longer be sold).  But mid-efficiency furnaces are up to 19 per cent less efficient than a high-efficiency model and thus will increase your operating costs and greenhouse gas emissions. 

Is it difficult to install a high-efficiency furnace?

Because of the increasingly popularity of high-efficiency furnaces in Alberta, a sizable number of contractors now have considerable experience installing them. The layout and space considerations of your house will dictate what ductwork is required. For example, most high-efficiency furnaces are vented, by a four-inch pipe, to an outside wall and combustion air is drawn in through plastic pipes.

Will I notice any difference in the heating of my house?

A high-efficiency furnace runs quieter than a mid-efficiency furnace and should make your house more comfortable with its ability to maintain a more constant temperature. You may notice it cycles on and off more often, but for shorter time periods, than your old furnace.

What size should my high-efficiency furnace be?

An experienced contractor can properly size your new furnace. A high-efficiency model can generally be somewhat smaller, in BTU input, than an older or a mid-efficiency furnace.

The size of furnace you'll need will be affected by the level of insulation and air tightness of your house. So it makes sense to plug those heat leaks and perhaps upgrade your insulation (especially under the roof, where you can get the most bang for your buck) before investing in a new furnace. 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.

How do I know the furnaces I'm looking at are high-efficiency models?

Check the EnerGuide label - on the back page of furnace manufacturers' brochures - for the efficiency rating. Any furnace with an efficiency rating of 90 or higher will carry an Energy Star® label.

Should I consider getting a variable-speed motor to run the fan of my new furnace?

Yes. Although the cost of a direct-current, variable-speed motors is higher, the electricity consumption will be at least 30 per cent less than with a conventional motor. Considering the furnace fan is often the second-largest consumer of electricity in Alberta homes, the energy savings of a variable-speed motor can be significant.

Can I get a rebate if I install a high-efficiency furnace in my house?

Yes, you are eligible for an ecoENERGY Retrofit grant of $300 from National Resources Canada (NRCan) if you replace an existing furnace with an Energy Star-qualified model with an AFUE rating of 90 per cent or higher. The rebate increases to $500 for furnaces that have an AFUE rating of 92 per cent or better and a variable-speed motor. Note: Rebates are available until March 2011 and require an energy audit by an NRCan-licensed advisor.

How can I find a qualified installer for a high-efficiency furnace?

Check the Heating, Refrigeration and Air Conditioning Contractors of Canada website for a listing of local contractors qualified to install high-efficiency furnaces. Get estimates and references from at least two experienced installers and ask for a heat loss calculation, used to determine the size of furnace needed.

How much maintenance does a high-efficiency furnace require?

A high-efficiency furnace should require no more maintenance than any other type of furnace. An annual maintenance check will help ensure your furnace is operating safely and at peak efficiency.