Quick answer
Not necessarily. A correctly sized cold-climate heat pump can heat a Burlington-area home on its own, with electric resistance strips covering the few nights below its balance point. If you already own a working gas furnace, keeping it as a hybrid usually makes sense: on the coldest nights gas is the cheaper heat at current Ontario rates, and the furnace as backup avoids an electrical panel upgrade.
Whether you need a backup furnace with a heat pump depends on which problem you are solving: the physics of the coldest night, the cost of that night, or the wiring in your basement. A heat pump does need some form of backup for the nights below its balance point. That backup does not have to be a gas furnace — but in most Burlington, Oakville and Hamilton houses that already have one, keeping it is the sensible choice.
Every heat pump needs some backup; not every one needs gas
Below the balance point — the outdoor temperature at which the heat pump's output no longer matches the house's heat loss — something has to make up the difference. Your options are electric resistance strips inside the air handler, an existing gas furnace as the second stage, or, rarely, a heat pump sized so large that it never reaches its balance point on the lakeshore. Electric strips are the standard all-electric answer and they work; they are the most expensive heat to run, which is why the heat pump should be doing the work above that point.
Reason to keep the furnace: the coldest nights cost less on gas
At -20°C a cold-climate heat pump is still producing heat, but its efficiency has dropped from around three units of heat per unit of electricity in mild weather to closer to one and a half or two. At that point, at current Ontario rates, an Enbridge gas furnace generally makes heat for less than the heat pump does, and far less than electric strips. A dual-fuel thermostat handles this with a switchover temperature below which the furnace takes over. Where that lands — often somewhere between about -5°C and -15°C — depends on your electricity plan, the gas price and the equipment's cold-weather efficiency, so it is a setting to calculate, not a default to accept. Our post on Burlington Hydro rates and heat pumps shows how that switchover moves if you are on time-of-use or ultra-low overnight pricing.
Reason to keep the furnace: your electrical panel
Electric backup strips draw a lot of current. A 10 kW strip package needs roughly a 50–60 amp circuit on its own, and larger packages need more. That is easy on a 200-amp service in a 2000s Alton Village build and a real problem on the 100-amp panels still common in 1950s–60s Aldershot bungalows and pre-war Kerr Village homes, where the strips plus the heat pump plus an electric range can exceed what the service can carry. A hybrid keeps the furnace as backup, so the only new load is the outdoor unit — often on a circuit much like the one the old air conditioner used. Electrical panel upgrades for heat pumps covers when an upgrade is unavoidable.
Reasons to go without a furnace
- You heat with oil, propane or electric baseboards today, so there is no gas furnace to keep. Oil-heated homes — and only oil-heated homes — may also qualify for the federal Oil to Heat Pump Affordability program.
- You want off gas entirely, whether for the carbon or to stop paying Enbridge's fixed monthly charge on a bill that would otherwise be near nothing from May to October.
- The furnace is 15+ years old regardless, so strips plus a properly sized cold-climate unit can cost less than a new furnace plus a heat pump.
- You already have a 200-amp service, or are upgrading anyway for an EV charger or a hot tub.
A hybrid can still earn a rebate. The current Ontario program is the Home Renovation Savings Program, run by Enbridge and Save on Energy since January 2025; it returns up to $7,500 on a heat pump depending on the system, and it replaced the Canada Greener Homes Grant and Enbridge HER+, both of which are closed. The amount and the order of the paperwork are set by the program, not by the installer, so check the Home Renovation Savings Program page before you sign anything; we file the application as part of the job.
What a backup furnace does not give you
Heat during a power outage. A gas furnace needs electricity for its blower, igniter and control board, so it is as dead as the heat pump when an ice storm takes the lines down along the escarpment. If outage resilience is the worry, the answer is a generator or a battery, not the choice of backup fuel.
The honest recommendation for most local homes
If you have a gas furnace under 12 years old and a 100-amp panel: hybrid, without much debate. If you have a 200-amp panel and a furnace at end of life: a cold-climate heat pump with strips deserves a serious look, provided the sizing is done from a real heat-loss calculation rather than the old furnace's rating. Either way the heat pump should carry the vast majority of heating hours; the backup is insurance, not the plan.
ZK Mechanical installs both hybrid heat pump systems and all-electric cold-climate systems from our Burlington shop, and we will tell you plainly which one your panel and your house call for. Request a free assessment or call (647) 801-1252 to talk it through.