Why you should consider a condensing boiler

November 6, 2014

Condensing boilers continue to grow in popularity across Canada, due in large part to their high energy efficiency. Many models offer about 90 per cent thermal efficiency, although some are rated as high as 98 per cent. The efficiency with which these boilers burn gas or oil compares very favourably to the 70-80 per cent ratings offered by traditional, non-condensing boilers. System design and installation are key to maximizing energy savings, so a comparison of what local contractors can offer is advisable.

Why you should consider a condensing boiler

How does a condensing boiler work?

A condensing boiler takes advantage of the fact that when natural gas or oil burns, hydrogen atoms are released and the hydrogen combines with oxygen to generate steam. Steam contains approximately 8 per cent of the energy originally contained in the natural gas. A condensing boiler is able to "condense" the water vapour in order to capture much of the energy that would otherwise be released into the air.

The relatively complex technology employed in a condensing boiler makes it more expensive than a standard boiler of comparable capabilities. However, the extra cost is easily recovered over time in the form of energy savings. Plus, the environmental advantages of more energy-efficient boilers are another bonus.

Myths addressed

Certain myths that have been associated with condensing boilers in the past have been addressed by researchers. For example, the U.K.'s Building Research Establishment draws upon its experience with condensing boilers that dates back to the 1980s. The BRE asserts that:

  • Condensing boilers are not challenging to install.
  • Condensing boilers are equal to standard boilers in terms of reliability.
  • Condensing boilers don't need more servicing, nor are they more difficult to work on.
  • Servicing is not overly expensive despite the need to periodically check the condensate drain.
  • Compared to standard boilers, condensing-type models are always more energy efficient.


Because condensing boilers are highly energy efficient, government agencies and power companies have encouraged their use in new homes and in retrofits. Because of the advantageous reduction in fossil fuel use and accompanying environmental benefits, there are rebate programs in place to encourage the installation of condensing boilers.

For example, the Alberta government has made rebates available to homeowners that install high-efficiency boilers. A variety of rebate programs are available to Ontario residents as well. Wherever you live, a call to a local heating and plumbing contractor is often all that it takes to learn about current rebates that are available in your area.

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