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Heating · Dual-FuelHybrid (Dual-Fuel) Heat Pump Systems
A hybrid, or dual-fuel, system is a heat pump and a gas furnace sharing one set of ducts and one thermostat: the heat pump heats and cools the house through most of the year, and below a switchover temperature the furnace takes the load. It is the usual answer for a home with a furnace too young to scrap and an air conditioner that is finished.
Hybrid (dual-fuel) heat pump systems exist because the two pieces of equipment have opposite cost curves. A cold-climate heat pump is cheapest to run in October and April and gets steadily more expensive as the outdoor temperature falls, because it has to work harder for every unit of heat it delivers. A gas furnace costs the same per unit of heat at −22°C as it does at +6°C. Run each one only where it is the cheaper of the two and the season costs less than it would with either alone — that is the whole idea.
The switchover temperature is the number the system turns on, and it is arithmetic rather than preference. It sits where heat from the heat pump at your Burlington Hydro, Oakville Hydro or Alectra Utilities rate costs the same as heat from Enbridge Gas, and it moves whenever either rate moves. We work it out from your last year of bills at the quote stage, program it at commissioning, and show you how to change it yourself if you move to an ultra-low-overnight electricity plan. Left at the factory default, a dual-fuel system will happily burn gas at +5°C and cost you money all winter — heat pump thermostat settings covers what to look for.
Two things about the existing furnace decide whether a retrofit is straightforward. The blower has to move the airflow a heat pump needs — roughly 350 to 400 cubic feet per minute per ton, more than the same furnace pushes in heating — so a single-speed blower in a 1990s 80 per cent furnace often means a variable-speed replacement or duct changes. The other is control wiring: dual fuel needs a thermostat with an outdoor sensor and a proper compressor lockout, because if the burners light while the heat pump's indoor coil is running, that coil sits in the hot supply stream and the furnace trips its high limit.
The houses where this wins around here are the 1970s–90s two-storeys along the Orchard, up on the Hamilton Mountain and out in Binbrook, where the heat loss is big enough that going all-electric would mean a larger panel and a utility service upgrade behind it. Keeping the furnace as cold-weather backup avoids all of that. Ontario's Home Renovation Savings Program is the main rebate route for a heat pump added to a gas-heated home, and a smart thermostat included in the install qualifies for $75; rules and funding windows change, so we confirm eligibility in writing at the quote — see the program page. For a number on your house, book a free assessment.
Dual fuel is the right call when
- The air conditioner has failed but the furnace is under ten years old and still sound
- The electrical panel cannot carry a heat pump plus enough electric backup for a −20°C night
- You want a heat pump's shoulder-season economy without giving up gas heat in the coldest week
- The house is older brick with a large heat loss, where an all-electric system would be oversized and costly to run
- You heat with propane or oil, the furnace is recent, and you want to cut fuel use without scrapping it
How it works
We check the blower type, cabinet size, plenum and control board to see what the existing furnace can pair with, and pull your last twelve months of gas and hydro bills.
Outdoor unit, matched indoor coil and line set, a dual-fuel-capable thermostat with an outdoor sensor, and the furnace wired for lockout so the two never fire together.
We commission the heat pump, calculate the crossover from your actual rates, program it, and walk you through changing it if your rate plan changes.
Brands: We pair Daikin, Mitsubishi, Lennox and Carrier heat pumps with Lennox, Carrier, Goodman, Rheem, KeepRite and Napoleon furnaces, and can work with the furnace already in your basement.
Common questions
What should the switchover temperature be set at?
There is no single right answer, because it depends on your electricity rate, your gas rate and that specific unit's efficiency curve. We calculate it from your bills and set it, and if rates move you can adjust it in the thermostat — we show you where before we leave.
Can I keep the furnace I already have?
Usually, if the blower can move heat pump airflow and there is room in the cabinet for a matched coil. An 80 per cent single-speed unit from the 1990s often cannot, and then the honest answer is that the furnace should be replaced at the same time — can I keep my furnace and add a heat pump goes through the checks.
Does the furnace still need annual service?
Yes. It may only run a few weeks a year in a hybrid, which makes it more important, not less — the burners, venting and heat exchanger still need a combustion check before the one cold snap you are relying on it for. A furnace tune-up covers it.
Is hybrid better than a full cold-climate heat pump?
In a tight, well-insulated house with panel capacity, all-electric is simpler and there is no gas bill left to pay. In a leaky older house, or where the service is 100 amps and full, hybrid gets you most of the savings for far less money — do I need a backup furnace with a heat pump compares the two.
Does the heat pump replace my air conditioner?
Yes. A heat pump is an air conditioner that can also run backwards, so the old condenser comes out and the new outdoor unit does both jobs. Heat pump vs air conditioner explains what is actually different inside the box.