Shedding light on the energy performance of today’s gas fuelled heating systems

Gas fuelled forced air space heating systems are market dominant in many areas of Canada. While gas fuelled furnaces are the most common option, combination systems have become increasingly more prevalent, and Integrated Mechanical systems (IMS) have become a third option.

How does the energy performance of these systems compare? This is a difficult question to answer. Efficiency ratings can not easily be compared as each product is tested to a different standard. These standards set different operating conditions, and may include tests on the overall system or only on its individual components.

Enbridge Gas Distributi on wanted to find out. They recognized that the CCHT was an ideal place to fairly compare diff erent systems. At the CCHT, systems could be tested under virtually identical space heating, hot water, and venti lation loads. Comparative data could be gathered during cold winter conditions, shoulder seasons, and the summer. These results could be extrapolated over a known year of load data to compare annual energy performance.

Enbridge Gas Distribution wanted to fi nd out how the performance of NY Thermal Inc.’s IMS (trade name: Matrix 100V) compared to that of traditional systems. They contracted Natural Resources Canada’s CanmetENERGY to conduct the analysis at the CCHT. This led to an Enbridge and NRCan (through the Program for Energy Research and Development) co-funded project that compared the performance of the following three systems:

  • Furnace+ consisting of: a 94% Annual Fuel Utilization Factor (AFUE) condensing natural gas furnace (CSA P.2), a powervented natural gas water heater with an energy factor (EF) of 0.60 (CSA P.3) ; and an HRV with a Sensible Recovery Efficiency (SRE) of 69% at 0°C (CSA C439)
  • Combination+ consisting of: a 90% Annual Fuel Utilization Factor (AFUE) boiler (CSA P.2); an air handler; a hot water storage tank; and a heat recovery ventilator with a Sensible Recovery Efficiency (SRE) of 69% at 0°C (CSA C439)
  • IMS with CSA P.10 ratings as follows: Overall Thermal Performance Factor (OTPF) 0.91, Annual Electrical rating (AE) 1826 kWh/year, 89% Composite Space Heating Efficiency (CSHE) , an 0.81 Water Heating Performance Factor (WHPF), and integrated heat recovery ventilation with a Sensible Recovery Efficiency (SRE) of 60% at 0°C


Over the course of a year at the CCHT, with all systems equipped with electronically commutated blower motors (ECM), the IMS would use the least energy: 7% less than the tested furnace based system, and 14% less than the tested combination based system. Looking at seasonal performance, the IMS would use the least energy for 310 days of the year, while the furnace based system would use the least energy on the coldest 55 days of the year, and the combination system would use the most energy on all days of the year. The diff erence between the Combination+ and IMS performance is partially a result of the intelligent IMS control varying the water loop temperature and fan speed to gain efficiencies at lower space heating loads. Results from this comparison therefore show that the IMS is an energy saving alternative to typical residential systems currently being installed in Canadian houses.

For more information on this project, see the Research Summary on Integrated Mechanicals Systems located at the bottom of this page:

Sample daily consumption data from the fireplace experiment.


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