Mid-efficiency furnaces get the boot

Is your furnace on the fritz? Pretty soon your options for buying a replacement will be limited: as of January 1, 2010, Canadian homeowners will only be able to install high-efficiency gas-fired furnaces–those with an annual fuel utilization efficiency (AFUE) of 90 per cent or higher. This federally legislated efficiency boost, up from the current minimum of 78 per cent AFUE, is expected to conserve about 650 million cubic metres of natural gas every year. That’s great news for the environment, but there are a couple of potential drawbacks for homeowners.

High-efficiency–also known as condensing gas–furnaces include a secondary heat exchanger that extracts some of the energy from the exhaust gases that are normally lost up the chimney with a mid-efficiency model. Rather than venting out the chimney, condensing furnaces vent horizontally through the wall. In some cases, it can be difficult to find sufficient clearance from windows, doors and gas meters on adjacent exterior walls, forcing installers to cut through floors and interior walls to run the PVC piping to the outside.

There are also concerns about maintenance of the more complex equipment. “The cost of repair can be a little bit higher; there are more parts, most notably, the secondary heat exchanger,” says Bill Wood, president of Appleby Systems, an HVAC retailer in Oakville, Ont. And clogged condensation drains can lead to furnace shutdowns, so annual maintenance is even more crucial. (While high-efficiency furnaces retail for about $1,000–more than comparable mid-range models–current rebate programs, including the federal ecoENERGY Retrofit for Houses, in most cases, will offset the additional upfront cost).

Still, Natural Resources Canada estimates that, depending on usage and the efficiency of the equipment being replaced (older conventional furnaces may have AFUEs as low as 60), households will save anywhere from $40 to $260 on annual gas bills. The prudent thing just might be to sock away some of those savings for future repairs.