How much does it cost to install ductwork for a Toronto home with hydronic heating conversion?

Installing a complete duct system when converting a Toronto home from hydronic (hot water baseboard or radiator) heating to forced-air costs $8,000 to $20,000 for the ductwork alone, with the total conversion project — including a new furnace, air conditioning, and ductwork — ranging from $15,000 to $35,000. This is one of the most involved residential HVAC projects because hydronic homes have no existing ductwork whatsoever, so every supply run, return duct, trunk line, and plenum must be designed and built from scratch.

Hydronic-to-forced-air conversions are extremely common in Toronto, particularly in older neighbourhoods like the Annex, Roncesvalles, High Park, Leslieville, the Danforth, and Leaside, where post-war homes and century homes were built with hot water boilers and cast iron radiators or baseboard convectors. Homeowners convert for two primary reasons: they want central air conditioning, which requires ductwork, and modern high-efficiency furnaces combined with ductwork offer better energy efficiency than aging boilers. The challenge is finding space for ducts in homes that were never designed to have them.

The duct layout in a conversion project is the biggest cost driver. In a typical two-storey Toronto home with a basement, the trunk line runs through the basement ceiling, supply branches rise through interior walls or purpose-built chases to reach upper floors, and return air ducts run parallel routes back down. The basement is relatively straightforward — trunk duct along the ceiling joists with supply boots dropping down to floor registers. But getting ducts to the second floor requires cutting into walls, building closet chases, or creating soffits in first-floor ceilings, each adding $500 to $2,000 per vertical run in carpentry and finishing costs on top of the duct installation. A two-storey home typically needs 6 to 10 supply runs to the second floor, so the structural and finishing work alone can add $3,000 to $10,000.

Many Toronto contractors offer a high-velocity small-duct system as an alternative for hydronic conversions. Systems like Unico or SpacePak use 2-inch flexible supply tubes instead of standard 6- to 8-inch ducts, making them far easier to snake through existing walls and ceilings without major renovation. High-velocity systems cost $12,000 to $25,000 for the complete installation including the air handler, but they avoid the extensive drywall work and bulkheads that standard ductwork requires. The trade-off is slightly higher operating noise and the need for a compatible air handler rather than a standard furnace.

Ontario Building Code requirements add to the project scope. A new forced-air system requires a building permit from the City of Toronto, typically $300 to $800 in permit fees. The duct system must be designed using Manual D calculations based on Manual J heating and cooling load analysis. Any gas furnace installation or gas line work requires a TSSA-registered contractor. Electrical work for the thermostat, air handler, and air conditioning condenser requires an ESA-Licensed Electrical Contractor. The old boiler must be properly decommissioned, which includes capping gas and water lines — budget $500 to $1,500 for boiler removal and disposal.

Get at least three quotes from contractors experienced specifically in hydronic-to-forced-air conversions, as this is a specialty project that not every HVAC installer handles regularly. Toronto Ductwork can connect you with experienced local professionals through the Toronto Construction Network.