Heat pump running costs · Ontario
Why Is My Hydro Bill So High With a Heat Pump?
Most often because the heating moved onto it. If the house was heated by Enbridge gas, the cost of heat now arrives on the hydro bill instead. A higher bill can also mean electric backup heat is running in cold snaps or during defrost, the heat pump is the wrong size, the thermostat is turned down too far at night, or your price plan charges more for the hours the heat pump works hardest. Each one can be checked.
Did your heating move from the Enbridge bill to the hydro bill?
If the house used to be heated by gas, yes, and that is the biggest reason a hydro bill jumps. The heat now comes from electricity, so last winter's heating cost on the Enbridge bill has become this winter's hydro cost. The fair comparison is both bills added together, this winter against last.
Even added together, the total can be higher. At Ontario prices from November 1, 2026, 1,000 kWh of heat costs about $48–$66 from a cold-climate heat pump and $31 from an Enbridge gas furnace. For a home whose furnace burned 2,000 m³ of gas a year, that is about $950–$1,310 of electricity for a year of heat, against $610 of gas. If the furnace stays as backup, Enbridge's customer charge of $27.69 a month before HST stays too.
Against electric baseboards or an oil furnace, it runs the other way: the same heat costs about $140–$159 from baseboards and $277–$288 from oil. The Ontario running-cost comparison sets out each input.
Is backup electric heat running in cold snaps?
Probably, on the coldest days. Natural Resources Canada says an air-source heat pump loses heating capacity as the temperature falls and has a minimum operating temperature somewhere between −15°C and −25°C. Below the point where it can no longer keep up, a backup heat source covers the rest.
When that backup is electric, in duct heaters or baseboards, it turns 1 kWh of electricity into 1 kWh of heat. A cold-climate heat pump delivers about 2.4 to 2.9 units of heat per unit of electricity over a season. So the hours on backup heat are the expensive ones, and a cold snap shows up on the next bill.
NRCan suggests setting electric backup 2°C to 3°C below the heat pump's set point, so the heat pump does as much of the work as it can. Your installer sets the temperature at which the backup takes over, or at which the heat pump shuts off, and can tell you what yours is. The cold-climate heat pump guide explains how output changes with temperature.
Does defrost add to the bill?
A little, and more on damp days near freezing. When the outdoor coil frosts over, the heat pump switches briefly into cooling mode to melt it, and NRCan notes supplementary heat may run during defrost. Units with demand defrost only defrost when frost is actually there; time-temperature controls start one every 30, 60 or 90 minutes whether it is needed or not.
Two settings help, and an installer can make both: demand defrost where the unit offers it, and turning the indoor fan off during defrost, which NRCan says saves energy though defrost takes a little longer.
Is the heat pump the right size for the house?
If it is too small, backup heat runs more often; if it is too big, it cycles on and off. NRCan says an undersized unit still runs efficiently but leans on the supplementary heat, so the expected savings do not arrive, while an oversized one cycles in mild weather, which wastes energy and wears the heat pump. NRCan recommends having a heating and cooling professional size the system with a recognized method such as CSA F280-12. The sizing guide explains what one looks like.
Are thermostat setbacks costing you?
They can. A heat pump warms a house slowly, so after a deep setback overnight or during the day, the backup heat runs until the heat pump catches up, and that is the expensive heat. NRCan recommends setbacks of no more than 2°C, or a smart thermostat that starts warming the house early. Home Renovation Savings pays $125 toward an eligible smart thermostat; see the Home Renovation Savings guide.
Two smaller habits matter too. NRCan advises changing or cleaning the air filter every three months, since a clogged filter cuts airflow and efficiency, and keeping vents and registers clear of furniture and rugs.
Which price plan suits a heat pump: Time-of-Use, Ultra-Low Overnight or Tiered?
It depends on when your house uses power, and the OEB says you can switch between the three plans. The Ontario Energy Board sets the prices every November 1. These are the prices from November 1, 2026, before delivery, regulatory charges and HST:
| Plan and period | When | ¢ per kWh |
|---|---|---|
| Time-of-Use: off-peak | weekdays 7 p.m. to 7 a.m., and all day on weekends and holidays | 9.1 |
| Time-of-Use: mid-peak | weekdays 11 a.m. to 5 p.m. | 14.6 |
| Time-of-Use: on-peak | weekdays 7 to 11 a.m. and 5 to 7 p.m. | 18.9 |
| Ultra-Low Overnight: overnight | every day 11 p.m. to 7 a.m. | 3.7 |
| Ultra-Low Overnight: weekend off-peak | weekends and holidays 7 a.m. to 11 p.m. | 9.1 |
| Ultra-Low Overnight: mid-peak | weekdays 7 a.m. to 4 p.m. and 9 to 11 p.m. | 14.6 |
| Ultra-Low Overnight: on-peak | weekdays 4 to 9 p.m. | 37.7 |
| Tiered: first 1,000 kWh a month | any time, November to April | 11.2 |
| Tiered: above 1,000 kWh a month | any time, November to April | 13.2 |
- Tiered charges one price at any hour, so a heat pump running through cold weekday mornings and evenings pays 13.2¢ for use above the winter threshold, rather than Time-of-Use's 18.9¢ on-peak.
- Time-of-Use rewards use on weekday nights and weekends, when the price is 9.1¢. The OEB says Ontario households already use nearly two thirds of their electricity off-peak.
- Ultra-Low Overnight has the cheapest hours, 3.7¢ from 11 p.m. to 7 a.m., and the dearest, 37.7¢ on weekdays from 4 to 9 p.m. It pays off only when a lot of use can move to between 11 p.m. and 7 a.m., and a heat pump keeps heating through the weekday evening peak in January.
Delivery, regulatory charges and HST come on top of every kilowatt-hour. With them, and the Ontario Electricity Rebate taken off, one more kilowatt-hour in winter cost about 14¢ to 15.9¢ at the five utilities we checked. The OEB's bill calculator compares the three plans for your own monthly use.
What to check first
- Add up both bills. This winter's hydro plus any Enbridge bill, against the same months last winter.
- Compare kilowatt-hours, not dollars. Your hydro bill shows the kWh used; a big jump in a cold month points to backup heat.
- Ask the installer two numbers: the outdoor temperature at which backup heat takes over, and the set point gap between the heat pump and the backup.
- Check the thermostat schedule. Setbacks of more than 2°C, or a thermostat not set up for a heat pump, bring the backup on.
- Clean or change the filter if it has been more than three months.
- Run your use through the OEB bill calculator on all three price plans.
If the heat pump replaced baseboards or oil, the yearly total should come down even if a cold month spikes. If it replaced Enbridge gas, the heat pump vs furnace running costs in Ontario show what to expect.