Considerations When Installing a Condensing Furnace

November 22, 2013
Ross and Witmer

When you’re considering installing a condensing furnace, it’s helpful to know what’s involved. This type of heating system offers very high efficiency, but it’s not as straightforward to install as a non-condensing system.

Besides its remarkable efficiency, the condensing furnace could be one of the safest furnaces on the market, because it has a sealed combustion burner. It pulls air into the chamber from the outdoors, and once the heat is almost completely removed from the two heat exchangers, the remaining air and vent gases go outdoors.

Because it draws fresh air into the combustion chamber, this type of system minimizes the risk of carbon monoxide entering your home’s air, which is a hazard associated with other kinds of combustion systems. To get the longest life, safety and efficiency from the combustion furnace, make sure your HVAC contractor takes these factors into account when he’s installing a condensing furnace:

  • Vent placement: Keep the vents away from your clothes dryer. Gases from any laundry bleach or fabric softener can enter the combustion chamber and cause it to corrode. Some manufacturers will void the warranty if the air intake and outlet vents are close to laundry equipment or even a water softener. The vent pipes must be on the same side of the home, as well, so that the air pressure is the same for both.
  • Slope of the exhaust vent: The angle at which the exhaust vent leaves the furnace matters a great deal, along with proper sizing. For each foot of pipe, there should be a slope of 0.25 inches toward the furnace. This slope prevents any combustion gases from pooling in the exhaust pipe and sends the condensation into the plumbing. The pipe also needs adequate support so no sagging can occur.
  • Size of the furnace: Be certain the HVAC contractor sizes the furnace properly, using Manual J software to avoid short cycling, which causes water to more readily pool throughout the unit.

For more information about installing a condensing furnace, contact the pros at Ross & Witmer. We serve homeowners throughout the Charlotte area.

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