How much does a heat pump cost to run in New Zealand?

"Will it blow out my power bill?" is one of the first questions people ask us. For most homes the answer is the opposite: a correctly sized heat pump is one of the most efficient ways to heat with electricity. Here's why, and how to work out your own costs.

Why heat pumps are cheaper to run

A plain electric heater turns 1 kW of electricity into 1 kW of heat. A heat pump doesn't make heat; it moves it, pulling warmth from the outside air (even on a cold day) and bringing it inside. That's why it can deliver roughly three to four kilowatts of heat for every kilowatt of electricity it uses. The colder it gets outside, the harder it works, but it still stays well ahead of a resistive heater.

Estimate your own running cost

You only need three numbers:

1. Power used while running, in kW. This varies as the unit speeds up and slows down; once a room is warm it often runs well below its maximum.
2. Hours of use per day.
3. Your price per kWh, from your power bill.

Multiply them together. Example only: a living-room heat pump averaging 1.2 kW for 5 hours a day, on a plan charging 35 cents per kWh, works out at about $2.10 a day (1.2 × 5 × $0.35). Use your own plan's rate; prices vary between retailers and time of day.

Ten ways to keep the cost down

• Set it to 18–21°C. Every degree higher adds to the bill, and 30°C won't warm the room any faster.
• Use a timer. Have it start half an hour before you get up or get home, instead of running all day.
• Leave it on steady rather than blasting. On a cold evening, a steady setting is usually more efficient than repeatedly switching off and reheating a cold room.
• Close doors and curtains. Keep the heat in the space you're actually using.
• Clean the filters. Dusty filters restrict airflow and make the unit work harder. Every few weeks in winter is a good habit.
• Keep the outdoor unit clear. Plants, leaves or stored items around it reduce efficiency.
• Use heat mode, not auto, in winter. Auto can switch between heating and cooling and waste energy.
• Check your power plan. Some plans offer cheaper night or off-peak rates that suit pre-heating.
• Service it yearly. A clean coil and correct airflow keep efficiency where it should be.
• Make sure it's the right size. An undersized unit running flat out costs more than a correctly sized one ticking over.

Compared with other heating

Plain electric heaters (oil column, fan or panel) use roughly three times more electricity for the same heat. Gas and wood have their own fuel, flue and maintenance costs. For most Waikato homes already on electricity, a well-sized heat pump gives the lowest cost per unit of heat, plus cooling in summer.

Want to know what size suits your room? Try our free sizing calculator.