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High Efficiency Furnaces and HVAC Systems

Posted on September 21, 2009 by HSC

The average Canadian household devotes 60 per cent of its total energy use solely to space heating. Therefore making smart decisions about your home’s heating, ventilating, and air conditioning (HVAC) system can have a big effect on your utility bills and comfort. If you are experiencing excessive noise, discomfort or high utility bills it may be time to invest in a new furnace.


Highly Efficient Furnaces

Currently the minimum standards require that a furnace have efficiency rating of 78% but as of December 31, 2009, Natural Resources Canada is proposing to increase the minimum annual fuel utilization efficiency (AFUE) of furnaces to 90%. A gas furnace with an AFUE rating of 95% means that 95 cents of every $1.00 of heating energy expense warms your home.

High efficiency furnaces also known as condensing gas furnaces are the main component used for space heating they not only use less fuel but run much quieter and possess the ability to maintain a more constant temperature. Look for the ENERGY STAR® symbols: their furnaces must have (AFUE) ratings of 90% or higher. Older furnaces can have efficiency levels as low as 60% while mid efficiency models average around 80%.

High-efficiency models only cost about $500 to $1000 more in material costs than mid-efficiency units. Most of the time utilities offer rebates that will cover much of the difference. Replacing an old furnace with a high efficiency one can save you over $300 a year and reduce your house’s greenhouse gas emissions by one tonne. In addition to the natural gas savings, a reduction of 20 to 30 per cent of the electricity used by the furnace fan can be obtained by selecting a furnace with a variable speed brushless Direct Current motor. The payback period depends on local energy costs, the price of the system, the difference in efficiency between the new and old furnaces and climate. Overall on average high-efficiency furnaces will take less than six years to pay for it self.

A furnace of the correct size will operate more efficiently, last longer and thus save you money. A high-efficiency model can generally be somewhat smaller than an older or a mid-efficiency furnace. To find out how many BTU’s your furnace should be (the size), have a qualified heating contractor do a building heat loss calculation.

Highly Efficient Boilers

The cost of a high-efficiency boiler can be up to twice that of a conventional boiler. Most of the time utilities offer rebates that will cover reasonable amounts of the difference. High efficiency boilers pay for themselves in about five years or less when you consider the rising fuel prices and the life of the boiler, which is guaranteed at 25 years. ENERGY STAR® qualified boilers have (AFUE) ratings of 85% or greater, while most old boilers are typically in the 55-65% range.

The gases coming out of the flue in a high efficiency condensing boiler have a temperature of approximately 50-60° F as compared to 120° or more in a non-condensing boiler. The more efficient your boiler, the less fuel you use, which results in lower bills. However, this does not necessarily mean that you should buy the most efficient boiler on the market. That decision depends on many factors — for example: the cost of the system, whether you use gas or oil, how well your building is insulated, and your climate. The size of the boiler is extremely important a highly efficient boiler will most likely be much smaller in size. A large oversized boiler will reduce efficiency and result in unnecessary amounts of wasted fuel.


Before purchasing a furnace or boiler you should ensure that all ductwork is properly sealed, in good condition and well insulated. You should also consider installing a programmable thermostat that will allow you to preset temperatures for specific times of the day and night. Inquire about zoned heating devices that allows for a better application of heat, similar to non-central heating systems. Zones are controlled by multiple thermostats which either allow or block air through the system as desired.

Do not forget about the building envelope or the “skin” of the building and be sure the roof and walls are properly insulated and sealed in order to minimize air leakage. Before any major purchase visualize the house as a system: your building is only as strong as its weakest link.

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