Heat Pump Backup Heat: Do You Need It, and Which Kind?

Cold-climate heat pumps handle most of a Canadian winter on their own. But on the coldest nights, during defrost cycles, or if the heat pump needs repair, a backup heat source keeps your home warm. Here's how backup heat works, the options, and what we recommend for Muskoka homes.

Do You Need a Backup Heat Source With a Heat Pump?

In Muskoka, almost always yes. Backup heat covers: - Extreme cold when heat pump capacity drops below your home's heat loss - Defrost cycles, so you don't feel cool air - Fast recovery after a thermostat setback - Equipment failure, so you're never without heat - Code and insurance requirements in some cases

Auxiliary Heat vs Emergency Heat

• Auxiliary (aux) heat comes on automatically alongside or instead of the heat pump when it can't keep up
• Emergency heat (EM heat) is a manual thermostat setting that runs only the backup, used if the heat pump fails

At What Temperature Does a Heat Pump Switch to Auxiliary Heat?

It depends on the system: - Standard heat pumps may call for aux heat around −5°C to −10°C - Cold-climate heat pumps can often carry the load well below −15°C - Dual-fuel systems switch at a set switchover temperature, chosen for cost and comfort, often somewhere around −5°C to −20°C

The right setting depends on your home's heat loss, your heat pump's cold-temperature capacity, and your fuel prices.

Backup Heat Options

1. Electric heat strips (air handler heat) Resistance heating elements inside the indoor air handler. - Simple, reliable, low installation cost - Expensive to run if used a lot, and needs electrical capacity

2. Gas or propane furnace (dual fuel) Your furnace provides backup and the heat pump sits on top of it. - Powerful heat on the coldest days, lower cost than strips in many homes, and keeps working if electrical capacity is limited - Requires a furnace and fuel supply

3. Electric boiler (hydronic systems) Used with air-to-water heat pumps and radiant or radiator systems.

4. Existing baseboards or wood/pellet stoves Common in cottages with ductless mini-splits. The existing baseboards stay as backup.

What Are Some Secondary Heat Sources for a Heat Pump?

Beyond the options above, many Muskoka homes keep a wood stove, gas fireplace, or pellet stove as supplemental heat and an off-grid comfort source during power outages. Note that a heat pump (and a furnace blower) needs electricity, so a backup generator is worth considering if outages are common.

Do Multi-Zone Heat Pumps Work in Canadian Winters?

Yes, with cold-climate multi-zone equipment sized properly for each room. Multi-zone systems often keep existing baseboard heat as backup in bedrooms and bathrooms.

What Is the Major Disadvantage of a Heat Pump System?

In cold climates, the main disadvantage is reduced capacity in extreme cold. That's exactly why backup heat is part of a well-designed system.

How We Design Backup Heat in Muskoka

We calculate your home's heat loss at the local design temperature, compare it with the heat pump's cold-weather capacity, and choose the most cost-effective backup: often your existing furnace, or right-sized heat strips for all-electric homes. We then set thermostat staging and switchover temperatures so backup runs only when it should. See Add a Heat Pump to Your Furnace and Cold-Climate Heat Pumps.

Book Your Free Quote

Call (705) 706-7622 or request a free quote online. Our team will get back to you quickly to book a visit.