What is a condensing furnace?

A condensing furnace is a high-efficiency gas furnace that captures and uses heat from water vapor in the exhaust gases, achieving efficiency ratings of 90% or higher. Unlike conventional furnaces that vent hot exhaust gases directly outside, condensing furnaces have a second heat exchanger that extracts additional heat by cooling the exhaust gases until water vapor condenses back into liquid.

This condensation process is what makes these furnaces so efficient. The primary heat exchanger works like a traditional furnace, while the secondary heat exchanger captures heat that would otherwise be wasted up the chimney. As the exhaust gases cool and water vapor condenses, this releases additional heat energy that gets transferred to your home's air. The condensed water (condensate) is drained away through a small plastic pipe, usually to a floor drain or condensate pump.

In Ottawa's climate, condensing furnaces are particularly valuable because they can achieve Annual Fuel Utilization Efficiency (AFUE) ratings of 90-98%, compared to older furnaces that typically operate at 60-80% efficiency. This means more of your natural gas dollar goes toward heating your home rather than being lost through the exhaust. You'll recognize a condensing furnace by its white PVC exhaust pipe rather than a traditional metal chimney - the exhaust is cool enough that it doesn't require a heat-resistant vent.

Installation considerations in Ottawa include proper condensate drainage (important during our cold winters to prevent freezing) and ensuring adequate combustion air supply. TSSA permits are required for installation, and the work must be performed by licensed G2 technicians. The upfront cost is higher than conventional furnaces, but the energy savings typically pay for the difference within 5-7 years.

For homeowners considering an upgrade from an older furnace, a condensing furnace represents excellent value in Ottawa's heating climate. Want to discuss whether a high-efficiency condensing furnace makes sense for your home? We offer free consultations to assess your current system and heating needs.