The worldwide growth in sustainable building over the last several decades has led to a search for more environmentally-friendly heating and air conditioning options. In Canada, the result of this search has been a turn towards condensing high-efficiency boilers, which are often the first choice for designers, contractors, and owners looking to build green. While old and mid-efficiency boilers typically offer an efficiency below 75% and 85% respectively, condensing boilers can reach efficiency levels as high as 96%, making them one of the most eco-friendly and cost-effective heating options on the market.
What Sets High-Efficiency Boilers Apart?
In traditional boilers the hot gasses, including water vapor, that are released from combusted fuel are captured and used to provide heat. High-efficiency boilers work in much the same way, except that condensers are used to recapture the heat in water vapor that is lost in traditional systems. This added efficiency makes condensing boilers cost-effective, but also means that these boilers have different requirements than their mid-efficiency counterparts:
- Condensing boilers require low-temperature return water (ideally < 57 degrees C) in order to run at peak efficiency.
- Because the condensate is slightly acidic, more expensive aluminum alloys or stainless steel is often required, although in low-temperature areas plastics can be used.
- Condensing boilers have a lower flow rate, meaning pipes, valves, and pumps are smaller than those used in other systems.
- A higher rate of heat transfers and lower supply water temperature means that radiators and heating coils must be sized appropriately.
These unique attributes make condensing boilers ideal for functions such as in-floor heating and snow melting, both of which involve a high temperature drop and low-temperature return water. However, the systems can be adapted to a wide variety of other applications.
High-Efficiency Boilers by the Numbers
Because condensing boilers are high-tech systems that require more precise controls and higher-quality materials than conventional boilers, the initial cost is usually higher. Natural Resources Canada estimates that the cost for a 1000-MBtu/hr condensing boiler ranges from $25,000 – $35,000, which similarly rated mid-efficiency units sell for only $10,000 – $20,000. However, because high-efficiency systems use less energy, the cost can be recouped in a matter of years.
Design-build projects in particular can make the most of the benefits that high-efficiency boilers provide. When incorporated into the early planning stages of a project, a condensing boiler can provide owners with an integrated heating plan that minimizes upfront costs and promises reliable, low-cost temperature control. For those looking to build green in Vancouver, condensing boilers offer a cost-effective, environmentally-friendly means of heating.
*The content of this article has been derived from an official work that is published by the Government of Canada and that the reproduction has not been produced in affiliation with, or with the endorsement of, the Government of Canada. The Original Copy has been published by the office of energy efficiency of Natural Resource Canada.