The article focuses on retrofit applications and the importance of proper sizing, installation and commissioning to ensure a new high-efficiency replacement furnace will operate to its designed intent. Developed with content from FortisBC’s “High-Efficiency Furnace Installation Guide for Existing Homes”, the article offers helpful tips and solutions for contractors and consumers to consider when installing a new high-efficiency furnace.
The top seven list of installation practices recommended to optimize furnace performance are:
- Tapered Return Air Drop – Changing out poor ducting and installing new duct fittings, like a tapered transition at the top of the return air drop, can reduce turbulent air flow and result in lower static pressure within the ductwork.
- Sealed Ductwork Joints – All joints and connections that are visible on the existing ductwork and potential new fittings should be air sealed to ensure a furnace is delivering heated air to the design areas in order to maximize thermal comfort.
- Radius Elbow and/or Turning Vanes – The radius throat at the return drop elbow can reduce turbulence and lower pressure drop at the fitting, which may decrease the load on the furnace blower fan and lead to electricity savings. Additionally, turning vanes are designed to spread the return air more evenly across the filter so that particulates do not accumulate in one section, which can reduce the filter’s performance and potential service life.
- Proper Furnace Placement and Leveling – Ensuring that furnace placement meets manufacturers leveling requirements so that acidic condensate is draining away from the furnace to avoid potential premature equipment failure.
- Matching Thermostat and Compatible Wiring – Most manufacturers offer high-efficiency furnaces with a choice of two, three and/or variable stage gas valves with variable speed blower motors in their furnace offerings. To achieve the benefits of these features, high-efficiency furnaces require a matching thermostat that is wired correctly.
- Double-Pipe Combustion – Replacement furnace installations should incorporate a double pipe system with combustion air taken from the outside. Overall, a two-pipe system can reduce several common heating/ventilation issues, including air leakage, incidence of unwanted smells and equipment performance problems related to building depressurization.
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About Mechanical Business:
Mechanical Business is a Canadian-owned and operated magazine for HVAC/R, plumbing and hydronic professionals. It is distributed to 21,914 mechanical contractors, wholesalers and specifying engineers throughout Canada.
Ecolighten Energy Solutions is an environmentally-focused company dedicated to helping our clients find innovative solutions to using energy more wisely in our homes. Backed by real-world experience, Ecolighten has a broad and deep knowledge base in mechanical design, building science, house-as-a-system and energy services to help our clients meet the challenges of energy-efficiency.