Worked Quotes and Choosing a System
Hybrid dual-fuel heating: pairing a heat pump with a gas furnace in Canada
How hybrid heat pump and furnace systems work in Canada, what they cost to add, how to pick the switchover temperature with your own rates, and when they make sense.
A hybrid or dual-fuel system adds an air-source heat pump to a gas (or propane) furnace and lets a control decide which one heats the house: the heat pump in mild and moderately cold weather, the furnace below a chosen switchover temperature. It is often the cheapest way for a Canadian gas-heated home to cut gas use substantially without paying for a cold-climate system sized for the coldest night, and it replaces a central air conditioner at the same time. Its weak points are that you keep two systems, keep paying the gas fixed charge, and need the switchover set with your actual energy prices rather than a factory default.
This guide is part of how to compare HVAC quotes. Figures are illustrative.
How the switchover works
The heat pump's outdoor unit and an indoor coil sit on top of the furnace, sharing the furnace blower and ducts. A compatible thermostat or control with an outdoor sensor chooses the heat source. Two temperatures matter:
- Capacity balance point: the outdoor temperature where the heat pump's output equals the house's heat loss. Below it, the heat pump alone cannot keep up.
- Economic balance point: the outdoor temperature where heat from the heat pump costs the same as heat from gas. Below it, gas is cheaper per unit of heat.
The switchover should be set at whichever is warmer, unless you choose a colder setting on purpose to cut emissions further and accept a higher bill.
Worked example: finding your economic switchover
Illustrative prices only.
- Cost of gas heat per kWh. Gas at $0.50 per m³ (all variable charges), 10.3 kWh per m³, furnace 95%: $0.50 ÷ (10.3 × 0.95) ≈ $0.051 per kWh of heat.
- Cost of heat pump heat per kWh = electricity price ÷ COP. With electricity at $0.15 per kWh, heat pump heat is cheaper than gas whenever COP > 0.15 ÷ 0.051 ≈ 2.9.
- Read the manufacturer's table. Suppose the unit's COP is 3.4 at 5 °C, 2.9 at −5 °C and 2.3 at −15 °C. The economic switchover is about −5 °C.
- Check capacity. If the heat pump still meets the house's heat loss down to −10 °C, capacity is not the constraint, so the economic point (−5 °C) governs.
If electricity were $0.10 per kWh, the COP threshold falls to about 2.0 and the switchover could move much colder. Where time-of-use electricity rates apply, the right switchover can even differ between day and night.
What it costs to add a heat pump to a furnace
| Scenario | Illustrative cost before tax | Notes |
|---|---|---|
| Heat pump instead of a new central AC, furnace kept | 2.5 tons × $3,500–$5,500 + $800 = $9,550–$14,550 | Replaces the AC; furnace must have a compatible blower and control |
| Heat pump plus new two-stage furnace together | add $6,000–$8,500 for the furnace | One visit, matched equipment |
| Cold-climate heat pump with electric backup (full conversion) | see the cold-climate guide | Gas disconnected if other appliances switch |
A new central air conditioner is itself a cost, so the fair comparison for many homes is heat pump minus the AC you would otherwise buy. If an AC replacement would cost, say, $6,500, then a $12,000 hybrid heat pump is really a $5,500 decision. Put that figure into the heating system cost estimator or the payback calculator.
How much gas does a hybrid save?
It depends on how many heating hours fall above your switchover. In much of southern Ontario and coastal regions, a large share of heating hours sit above −5 °C, so a hybrid can shift a large share of the annual heat to the heat pump while gas covers the coldest stretches. Colder regions shift less. Ask the contractor for an estimate built on hourly or bin temperature data for your location, and check it against your bills after the first winter.
Hybrid arrangements in Quebec
In Quebec, where many homes heat with electricity, "dual energy" (biénergie) has long meant an electric system backed by a fuel system for the coldest periods. Hydro-Québec offers a dual-energy rate (rate DT), and the Government of Quebec describes these systems as running on electricity about 70% of the time, with natural gas taking over at about −12 °C and colder. A program to convert natural gas central heating to dual energy, run by the Government of Quebec, Hydro-Québec and the gas distributors, was still listed on quebec.ca in 2026; you apply through Énergir or Enbridge Gaz Québec. Conditions and the rate's switchover temperature are set by Hydro-Québec; check them before designing a system around them.
Pros and cons
| Pros | Cons |
|---|---|
| Lower upfront cost than a full cold-climate conversion | Two systems to maintain |
| Furnace provides reliable heat in extreme cold or power-sensitive situations (furnaces still need electricity for the blower) | Gas fixed charges continue |
| Replaces central AC with heating-capable equipment | Savings depend on correct control setup |
| Smaller electrical load than electric backup strips | May not qualify for programs that target full electrification |
Setup mistakes that erase the savings
- Factory default switchover left in place regardless of your rates.
- Incompatible thermostat that runs the furnace and heat pump together or locks out the heat pump too early.
- Undersized coil airflow because the furnace blower was not adjusted for the heat pump.
- Deep night setbacks that make the system call on the furnace every morning. Steadier settings let the heat pump do more.
For problems after installation, see heat pump installation failures. To check that the heat pump is sized sensibly for the hours it will carry, use the heat loss sizing guide, and to compare the hybrid against a full electric conversion or gas only, run the running-cost comparison with your own rates.
FAQ
Can I add a heat pump to an old furnace?
Often yes, if the furnace blower can deliver the airflow and the control is compatible. If the furnace is near the end of its life, replacing both at once is usually cleaner.
Does a hybrid system qualify for rebates?
It depends on the program. Some focus on cold-climate units or on homes leaving fossil fuels. Read the eligibility rules in the 2026 program guide.
Is a hybrid worth it if I already have a new AC?
The payback is longer because you are not replacing the AC anyway. Many owners wait until the AC fails.
Sources
- Natural Resources Canada — air-source heat pump guide and add-on systems
- Hydro-Québec — dual-energy rates and conversion offers
- Énergir — dual-energy conversion for natural gas customers
- Enbridge Gas — gas bill structure and energy programs
- Ontario Energy Board — electricity price plans in Ontario
