Heat pump electrical·Toronto and the GTA

Is 100 amp service enough for a heat pump?
Toronto answer, with real numbers (2026)

Short answer

Usually, yes. A cold-climate heat pump sized to the house, not to the old furnace, draws less than most people expect. 100 A gets tight when backup heat, an EV charger and induction cooking all land at once, and a load check on your meter data sorts that out before you buy anything.

By Energable, engineering-led electrical, Toronto. Updated November 2026.

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What actually uses the amps

Most of the amps in an electric heating system come from a few parts. Getting these right is what keeps a heat pump on a 100 A service.

Size the heat pump to the house. Old furnaces are often far bigger than the house needs. In one 1960s Toronto home the furnace put out about 80,000 Btu/h, while the home's own meter data showed it needed about 23,000 on the coldest day.
Keep backup heat small and staged. Backup strips are the big draw: 8 kW is about 33 A at 240 V. Set up in stages, and locked out above about -15 °C, they only run in the coldest hours.
Check the service by the Code method. Take the highest demand from 12 months of meter data, multiply by 1.25, then add each new load at its rating. That shows whether 100 A holds, before anything is installed.
Plan the next loads now. An EV charger or induction range later changes the answer. Counting them now tells you whether you need a load manager or an upgrade, and when.

Real Toronto homes

Two Toronto homes, heating with electricity

One on 100 A with a heat pump and backup coil, one fully electric on 200 A.

East York: heat pump on 100 A

Heat pump with a 10 kW backup coil

Highest demand in 12 monthsJanuary, heat pump and backup coil running

67 A

x 1.25, by the CodeESA Bulletin 8-3-15

84 A

The service100 A

100 A

The heat pump fits on 100 A. Adding a 48 A EV charger later needed a certified load manager, still no upgrade.

1960s home: everything electric

Heat pump, backup heat, heat pump water heater, induction, ERV

Busiest 15 minutes before the switchFrom the home's own meter

53 A

Calculated, every load electricCode method, all new loads counted

141 A

The service200 A

200 A

Fully electric at 141 A calculated. The first month on the heat pump peaked at just 40 A.

Why the old furnace size misleads

Furnaces were often sized generously decades ago, and since then windows, insulation and air sealing have cut the heat a house needs. Sizing a heat pump to the old furnace makes it oversized: it short-cycles, swings the temperature and costs more to run.

Measured against outdoor temperature, a year of meter data shows the real heating load. That number sizes the heat pump and the backup heat, and it feeds the service check.

Backup heat is the part to watch

The compressor in a right-sized heat pump is a modest load. The backup heater is what can push a 100 A service. Left at factory default, many systems bring the whole heater on at once. Staged, and locked out above the temperature where the heat pump carries the house, it supplies about 1% of the season's heat in a typical Toronto home.

When 100 A is not enough

If the house already peaks high, or you are adding a heat pump, an EV charger and induction cooking together, the calculation may land over 100 A. Then the choice is a certified load manager for the charger or a service upgrade, and the numbers show which one is cheaper for your home.

Case studies

See it on real jobs

Electrification

A 1960s home, fully off gas

Heat pump sized on meter data, 141 A calculated on 200 A.

Read the case study →100 A service

Heat pump plus a 48 A charger on 100 A

East York. Load manager instead of an upgrade.

Read the case study →Room to spare

29.5 A left on a full 100 A panel

East Danforth. Space for a heat pump later.

Read the case study →

Load assessment first

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Straight Answers

Common Questions

The kind we would give before you commit a dollar of capital. Tap a question.

Can I run a heat pump on a 100 amp service in Toronto?

In most cases, yes. A home in East York runs a heat pump with a 10 kW backup coil on 100 A, with a highest demand of 67 A in January, 84 A after the Code's 1.25 margin. A load check on your own meter data confirms it for your home.

How many amps does a heat pump use?

It depends on the size and model. The compressor of a right-sized 2 to 3 ton cold-climate unit is a modest load; the backup heater is the big one, about 33 A for 8 kW and 42 A for 10 kW at 240 V.

Do I need backup heat with a cold-climate heat pump?

Usually a small electric heater, set up to stage in steps and locked out above the temperature where the heat pump carries the house. In a typical Toronto home it covers about 1% of the season's heat.

Can I add an EV charger after a heat pump on 100 A?

Often, with a certified load manager that pauses the charger during the few peak hours. That is how the East York home added a 48 A charger without a service upgrade.

Is there a rebate for heat pumps in Ontario?

Programs change, so we check what applies to your home when we quote. Ask us and we include the current rebate steps with the proposal.

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