Add a Heat Pump to Your Existing Furnace

You don't have to rip out a good furnace to get the benefits of a heat pump. Many Ontario homeowners are adding a heat pump to their existing furnace, creating a dual-fuel (hybrid) system that uses the heat pump for most of the year and the furnace only when it's very cold. Bridlewood Mechanical designs and installs dual-fuel systems across Gravenhurst, Bracebridge, and Muskoka for homes heated by natural gas, propane, and oil.

How a Hybrid Heat Pump System Works

A hybrid heat pump system pairs an air-source heat pump (the outdoor unit plus an indoor coil on your furnace) with your gas or propane furnace, sharing the same ductwork:

• Spring, summer, and fall: the heat pump handles heating and air conditioning
• Moderate winter days: the heat pump keeps heating efficiently
• Very cold days: below a set switchover (balance point) temperature, the system switches to the furnace
• Defrost cycles: the furnace can supply heat so you don't feel cool air

The thermostat or control board decides which runs, based on outdoor temperature and, in smarter systems, fuel and electricity costs.

Can I Add a Heat Pump to My Existing Gas Furnace?

In most cases, yes, if: - Your furnace is in good condition with plenty of life left (typically under 10–12 years old) - It has a variable-speed or multi-speed blower that suits the heat pump's airflow needs - Your existing ducts are sized for the airflow - There's space for the indoor coil on top of or beside the furnace - Your electrical panel can support the outdoor unit

If your furnace is old, it's often better to replace both together with a matched dual-fuel system. See Furnace Replacement.

Will a Heat Pump Work With Your Existing Ducts?

Usually. Heat pumps deliver air at lower temperatures than furnaces, so they move more air to deliver the same heat. Undersized ducts can cause noise and poor comfort. We check static pressure and duct sizing during our assessment, and because we fabricate custom sheet metal in-house, we can make targeted modifications (larger returns, resized trunks, new plenums) without a full duct replacement. See Ductwork Installation.

What Is the Switchover Temperature?

The switchover or cut-off temperature is the outdoor temperature at which the system changes from heat pump to furnace. Two approaches:

• Economic balance point: switch when the furnace becomes cheaper to run than the heat pump, based on your local gas or propane and electricity prices
• Thermal balance point: switch when the heat pump can no longer keep up with your home's heat loss

With a cold-climate heat pump, the switchover can be set quite low, around −10°C to −20°C, so the furnace runs only on the coldest days. We set it for your home, fuel, and comfort preferences. Some systems also run the heat pump and furnace in sequence (bivalent parallel operation) during transitions.

What Is the "20 Degree Rule" for Heat Pumps?

In cooling mode, it refers to the typical 15–20°F (about 8–11°C) difference between return air and supply air. In heating, homeowners may notice heat pump supply air feels cooler than furnace air even though it's heating effectively. That's normal and one reason proper airflow design matters.

Why Dual Fuel Makes Sense in Muskoka

• Lower operating costs for homes on propane or oil, where heat pump heat is much cheaper most of the season
• Reliable backup for Muskoka's coldest nights
• Central air conditioning included
• Lower installed cost than replacing the furnace when it still has life left
• Rebate eligibility for qualifying cold-climate heat pumps
• Reduced emissions

How Much Does It Cost to Add a Heat Pump to an Existing Furnace?

Cost depends on heat pump size and model, cold-climate rating, indoor coil installation, line set length, electrical work, thermostat or controls, and any duct modifications. It's typically less than a full system replacement because the furnace and ductwork stay. We give free written quotes with rebate guidance. See Heat Pump Installation Cost.

Hybrid Heat Pumps vs a Conventional Propane Furnace

For propane-heated homes, the difference can be large. A heat pump typically delivers heat for a fraction of propane's cost per unit of heat over much of the season, while the propane furnace remains for deep cold. Many of our Muskoka customers see propane deliveries drop sharply after adding a heat pump.

Can a Heat Pump Replace a Furnace Entirely?

In some homes, yes, especially well-insulated homes with a cold-climate heat pump and electric backup heat. In older or larger homes in Muskoka's climate, keeping a furnace for backup usually gives the best combination of comfort, reliability, and cost. See Cold-Climate Heat Pumps.

What Is the Major Disadvantage of a Heat Pump System?

Upfront cost, and the need for careful design and installation. A poorly configured dual-fuel system can run the wrong heat source at the wrong time. We set up controls, switchover temperatures, and airflow properly and explain how it all works.

Our Dual-Fuel Installation Process

1. Assess your furnace, ductwork, and electrical panel
2. Calculate heat loss and select a cold-climate heat pump
3. Install the outdoor unit on a snow-safe bracket or stand
4. Install the indoor coil, line set, and drainage
5. Make any duct modifications with custom sheet metal
6. Configure dual-fuel controls and the switchover temperature
7. Commission, test, and walk you through operation

Book Your Free Quote

Call (705) 706-7622 or request a free quote online. Our team will get back to you quickly to book a visit.