Furnace type
Condensing furnaces
A condensing furnace extracts latent heat by cooling flue gas below its dew point, which is how it reaches 95%+ AFUE. It produces acidic condensate, vents through plastic pipe, and is the only type of gas furnace you can buy new in Canada for standard residential installations.
Short answer
Since July 3, 2019, residential gas furnaces manufactured for Canada must be at least 95% AFUE, which means every new furnace condenses: it cools flue gas until water vapour condenses in a stainless secondary heat exchanger, drains the mildly acidic condensate, and vents through sealed plastic pipe. The practical consequences for the home are a condensate drain, plastic venting to an approved termination, and installation per the manufacturer's venting rules.
The regulation behind it
NRCan's Energy Efficiency Regulations set the 95% minimum for residential gas furnaces manufactured on or after July 3, 2019, with narrow exceptions for through-the-wall units and manufactured-home furnaces. The guide on this site cites the regulation and its exceptions in the buying context.
What condensing requires
Condensing furnaces need a condensate drain or pump, plastic venting sized per the manufacturer's tables, and combustion air handled per the installation type (direct vent, ventilated combustion air or single-pipe). Retrofits from 80% furnaces almost always mean new venting and a drain route.
Efficiency by the numbers
Condensing furnaces on this site certify from 95.0% to 98.5% AFUE depending on family, size and position (for example, downflow and horizontal installations often certify lower than upflow). The rating plate states the certified figure for the installed position.
Related
- ServiceGas Furnace InstallationNew furnace installation sized from a heat-loss calculation, not from the old furnace
- ServiceGas Furnace ReplacementReplace an aging or failed furnace with the right high-efficiency furnace for your house
- ServiceFurnace RetrofitReplacing an old furnace into an existing house: the work that comes with it
- SymptomWater around a condensing furnace
- ComponentCondensate trap, drain and pump
Questions people ask
Can I still buy an 80% furnace in Canada?
Not for a standard residential installation: the 95% AFUE minimum applies to furnaces manufactured on or after July 3, 2019, with narrow exceptions.
Why does my high-efficiency furnace make water?
Condensing is how it reaches 95%+. The water is mildly acidic condensate that must drain continuously; see the condensate component page for what happens when it does not.
Can a condensing furnace vent into my old chimney?
No. Condensing furnaces need plastic venting to an approved sidewall termination. If a water heater shared the chimney, that chimney may need attention once the furnace leaves it.
Need this looked at?
Call BC Wide with the brand, model number and anything on the display. Or
Request service online with this page attached.