Plenty to Consider When Upgrading Your Furnace - October 17th 2011


Plenty to Consider When Upgrading Your Furnace


Last week my column was written to help you in selecting the proper fireplace for your home, now I will give you the tools you need, so you are able to make an informed decision when you decide upgrade your furnace. On December 31st 2009, a new national minimum energy performance standard for residential gas furnaces was introduced.

This standard applies to virtually all gas furnaces sold in Canada and requires a minimum fuel efficiency level of 90%. This level of efficiency is achieved by using well-established "condensing technology", where the products of combustion are vented through a plastic pipe, most commonly routed through a sidewall. It should be noted that there may be a small existing stock of mid-efficient (80% with respect to fuel efficiency) available, some heating contractors brought in additional stock prior to the standard update, and may still have some available. I would highly recommend using and adapting a high efficient furnace in all cases when possible.

The implementation of this standard is part of Canadas ongoing efforts to address climate change and improve the environment. Energy efficient furnaces are also cost-effective for consumers. The installation of a condensing gas furnace (minimum 90% efficiency) will result in a fuel consumption and cost reduction of about 12% when compared to furnaces at the current standard. The dollar amount will depend on the house size and heat loss.

The first-time installation of a high efficiency gas furnace typically requires changes to the venting system. In some cases, hot water heater venting alterations may be necessary as well.

There may be some situations, however, where through-wall venting can be more complex. Examples include narrow, attached houses with front and rear obstructions, closely spaced doorways and large windows or full-width porches and/or decks.

If your house is narrow and attached to neighbouring dwellings (on both sides), and your current gas furnace is more than 15 years old, you should consider consulting with a licensed heating, ventilating and air conditioning (HVAC) professional who will assess your specific situation and recommend solutions for your home.

Choose the Right Size of Air Conditioner, Furnace, Heat Pump or Boiler to Fit Your Home

In addition to the savings on your gas bill, you may be eligible for an ecoENERGY Retrofit grant from the federal government and complementary LiveSmart BC provincial program when upgrading your furnace.

When considering adding or replacing air conditioning or heating to your home, insist that the installing contractor "sizes" the system properly. A qualified contractor will not recommend equipment size based solely on the size of your home or assume that your existing equipment was sized properly in the first place. Be sure to also tell your contractor if you plan to renovate in the near future. Changing windows, upgrading insulation levels, finishing the basement, air-sealing or a new addition will impact the sizing calculation for any new system.

To complete the design load calculation, the contractor will need to take measurements during the initial visit to your home and ask some questions. They also take into account:

- Local climate conditions
- Size and number of windows that let in heat from the sun
- Existing insulation levels of the home
- Number and lifestyle of your home's occupants
- Predicted or known air exchange rate of home

There is only one correct size of equipment for your home. Not only will a unit that is too big turn on and off more often, which is annoying but over-sizing equipment can result in increased fuel consumption and higher operating costs which is inefficient and can contribute to premature part failure, higher noise levels and reduced comfort (hot or cold spots within the home). You need just the right size! Under-sizing of equipment will also cause severe comfort problems. Ideally, the equipment should be designed within plus or minus 10% of the required size.

So hire a contractor that has the appropriate skills to perform a "heat loss and heat gain calculation" based on professional guidelines, to calculate the proper size of heating and cooling equipment that your home requires. A good estimate will take several hours. Do not agree to a simple "rule of thumb" calculation (e.g., an amount of BTUs based simply on the square foot size of the home). Be sure to request a "heat loss and heat gain calculation" as part of your purchase process.

When a contractor completes the heat loss and heat-gain calculation and determines your needs, be sure to purchase the right equipment, and not stock that the contractor happens to have sitting on the truck or back at the shop. High efficient furnaces, with an efficiency rating of 90% and above, are my preferred option.