Quick answer
Yes. Adding a heat pump to an existing furnace — a hybrid or dual-fuel system — is the most common route into a heat pump for a Burlington or Oakville house with ducts and gas. The outdoor unit replaces your air conditioner, its coil sits where the AC coil was, and the furnace becomes the backup stage. It suits a furnace under about 12 years old with a variable-speed blower.
Keeping your furnace and adding a heat pump is called a hybrid or dual-fuel system, and for a house that already has ducts, a working furnace and a central air conditioner nearing the end of its life, it is usually the lowest-cost route into a heat pump. Here is what changes, what has to be true of your furnace, and what the installation involves.
What gets replaced and what stays
- Replaced: the outdoor AC condenser becomes a heat pump outdoor unit, and the evaporator coil on top of the furnace is swapped for a coil matched to the new unit.
- Almost always replaced: the thermostat, which must be able to run two fuels. Sometimes replaced: the copper line set, if it is the wrong diameter, too long for the new unit, or came from an old R-22 system and cannot be flushed clean.
- Stays: the furnace, the gas line, the venting, the ductwork, and in most cases the electrical circuit the air conditioner used.
- New: an outdoor temperature sensor, or a thermostat that reads outdoor temperature online, so the system knows when to hand off to the furnace.
What your furnace needs to be
The heat pump's indoor coil needs airflow, and the furnace blower supplies it. A furnace with a variable-speed ECM blower, which many high-efficiency units sold in the last 15 years have, can be set to the airflow the heat pump wants in each stage. A 1990s furnace with a single-speed PSC blower can be made to work, but the airflow compromise costs efficiency and there is no gentle low speed for the heat pump's lighter stages.
Age is the other test. A furnace over 12–15 years old will likely need replacing within the heat pump's life, and doing the two together saves the second labour visit and the second round of sheet metal — the same logic as replacing furnace and AC together. Once a heat pump is in, the furnace runs a fraction of its former hours, so a furnace with a few years left tends to get many more.
The thermostat is the brain of a hybrid
A hybrid needs a thermostat that can run the heat pump as first stage and the furnace as second, and switch between them on outdoor temperature rather than calling for more heat. Ecobee and Honeywell models do this with the right wiring; many builder-grade thermostats cannot. The switchover point is set at commissioning and tuned over the first winter, and the thermostat needs either a wired outdoor sensor or a reliable online weather feed to know when to switch.
What an add-on heat pump costs, and what the rebate covers
A cold-climate heat pump in Ontario runs $6,000–$16,000 installed before rebates, and an add-on to an existing furnace sits toward the lower part of that range because the furnace, ducts and venting are already paid for. Replacing the furnace at the same time adds a furnace-tier price ($3,500–$7,500) on top. Current Ontario rebates ($500–$7,500 depending on system) come through the Home Renovation Savings Program, and a hybrid can qualify; the Greener Homes Grant and Enbridge HER+ that older quotes still cite are closed. The figure for your setup is on the Home Renovation Savings Program page, and we file the paperwork with the install.
Which houses this suits best
- 1980s–90s two-storeys in Millcroft, Glen Abbey and River Oaks with a high-efficiency furnace installed in the last decade and an air conditioner that is due.
- 2000s+ builds in Alton Village, the Orchard, Joshua Creek and Waterdown where the original builder-grade AC is failing and the furnace still has years left.
- Any house on a 100-amp panel, since the hybrid keeps the gas furnace as backup and usually needs no electrical panel work.
- Less suited: houses with undersized or leaky ductwork. A heat pump moves more air for longer, so restrictions show up as noise and short-cycling, and a duct assessment belongs in any proper quote.
What the install day looks like
An add-on to a compatible furnace is typically a one-day job: remove the old condenser and coil, set the new outdoor unit on a stand or bracket, fit the new coil and line set, evacuate and charge, wire the thermostat, and commission both stages. Replacing the furnace at the same time usually makes it two days. The installer pulls whatever mechanical permit the municipality requires, and how long does heat pump installation take breaks the day down hour by hour.
ZK Mechanical quotes hybrid heat pump systems after looking at your furnace's blower, your ducts and your panel, not from a phone call. For heat pump installation in Burlington, Oakville or Hamilton, book a free assessment and we will tell you whether your furnace is worth keeping.