Guides · Backup heat
Electric vs Propane Backup: The Deep-Cold Question
Your heat pump does most of the winter's work. What backs it up on the coldest nights decides what you pay — and what you can stop paying for.
Why does a heat pump need backup heat at all?
A cold-climate heat pump keeps heating down to −25°C or colder, but as it gets colder outside, moving heat costs more electricity. At some point — the balance point, often around −10°C to −18°C depending on the home — a backup source becomes the cheaper way to heat. Below that point, the backup carries the house. It's automatic, and it covers a small share of the winter's hours, but it's the share everyone asks about.
| Electric backup | Propane furnace backup | |
|---|---|---|
| How it works | Heating elements in the air handler, like a giant toaster coil | A high-efficiency propane furnace that fires when called |
| Running cost in deep cold | Highest per hour — electric resistance heat is the priciest way to make heat | Usually cheaper per hour than electric elements in a cold snap |
| What you give up | The propane tank, its rental and its deliveries — gone entirely | Nothing leaves: you keep a tank and a fuel account |
| Electrical panel | Needs capacity for the elements — many older rural panels need an upgrade | Far smaller electrical load; panels usually fine as-is |
| Tank question | No tank at all | Owned tank: no rental. Rented tank: the monthly rental stays as long as the tank does |
So which one should you choose?
If your electrical panel can carry it (or is due for an upgrade anyway), electric backup is the clean exit: no tank, no rental, no deliveries, ever again — and since backup only runs on the coldest nights, the higher hourly cost touches a small slice of the season. If your panel is small and upgrading it is expensive, a propane furnace you own the tank for is the pragmatic pick — but price the tank rental into the comparison if yours is rented. There is no universal answer; it's a per-house calculation, done at the in-home visit with your panel and your tank contract in front of you.
What if I heat with natural gas?
Then this decision is already made, and it's a good one: a modern gas furnace is the cheapest deep-cold backup in Ontario. Dual-fuel (heat pump + gas furnace) is the most common setup in gas country for a reason.
Backup heat — common questions
How many nights a year does backup heat actually run?
In most of eastern Ontario, temperatures sit below a typical balance point for a few dozen nights a year — and only part of most of those nights. The heat pump still does the large majority of the season's heating.
Will my hydro bill explode with electric backup?
Your hydro bill goes up in winter — you're heating with electricity now — but your total heating cost goes down, because the heat pump delivers two to three units of heat per unit of electricity for most of the season. Backup elements are the exception hours, not the rule.
Can I decide after the heat pump is installed?
The backup is part of the system design, not an add-on — it has to be chosen before install, and it's part of what the rebate pre-approval describes. Decide it at the quote stage.
Run your numbers first
Your rebate doesn't change with your backup choice — but your running costs do. Start with the rebate estimate.
See your rebate AND your monthly number