"Should I just leave it running all day?"
It's one of the questions we're asked most often when installing or servicing heat pumps around Whangārei and Kerikeri. Some people swear that leaving the heat pump on 24/7 is cheaper. Others insist you should turn it off every time you leave the room.
So what's the honest answer?
The Short Answer
For most homes, no — you shouldn't leave your heat pump running all day when nobody is home.
A heat pump uses the most electricity when it's working hard to raise the temperature of a room. Once the room reaches the set temperature, modern inverter units throttle back and use far less power just maintaining it.
That leads some people to conclude that leaving it on all day must be cheaper than a big heat-up in the evening. In reality, a heat pump maintaining a warm room for eight empty hours almost always uses more electricity than one bringing the room up to temperature when you get home.
Heat constantly escapes through windows, walls and ceilings — and the colder it is outside, the faster it escapes. Keeping an empty house warm means paying to replace that lost heat all day long.
When Leaving It On Does Make Sense
There are some situations where running your heat pump for longer periods is the right call:
- Someone is home most of the day — if the house is occupied, you're paying for comfort you're actually using.
- Very well-insulated homes — a modern, airtight, double-glazed home holds its heat so well that maintaining temperature costs very little.
- Health reasons — for young children, elderly family members or anyone with respiratory conditions, a consistently warm, dry home is worth the modest extra cost.
- Damp-prone homes — in parts of Northland where winter dampness is a real problem, keeping the home gently warm helps prevent condensation and mould.
Use the Timer Instead
The best of both worlds is the built-in timer that almost every modern heat pump has — and that most people never use.
Set the heat pump to switch on 15–30 minutes before you get up in the morning or arrive home in the evening. You walk into a warm house without paying to heat an empty one.
If your unit supports Wi-Fi control (most current Mitsubishi, Fujitsu and Gree models do), you can switch it on from your phone before you leave work.
Set It and Leave It
Whichever way you run your heat pump, two settings make the biggest difference to your power bill:
- Temperature: set it between 20°C and 22°C for heating. Cranking it to 28°C or 30°C doesn't heat the room faster — the unit simply runs flat out for longer.
- Fan speed: leave it on Auto. The unit will choose the most efficient fan speed for the conditions.
Avoid constantly adjusting the temperature up and down. Pick a comfortable setting and let the heat pump do its job.
Overnight: On or Off?
For bedrooms, most people sleep better slightly cooler, so many households turn the heat pump off overnight or use a lower "sleep" setting around 16–18°C.
If your mornings are cold, use the timer to bring the living areas up to temperature before you get up rather than leaving the unit running all night.
An Inefficient Heat Pump Costs More Either Way
If your heat pump is struggling — weak airflow, longer heat-up times, or higher power bills than previous winters — no operating strategy will fix that.
Dirty filters, a clogged fan wheel, blocked outdoor coils or damaged pipe insulation all force the unit to work harder for the same result. A professional service restores efficiency and usually pays for itself in lower running costs.
We recommend cleaning your filters every 1–2 months over winter and having the system professionally serviced once a year.
Heat Pump Advice for Whangārei and Kerikeri
Gibson Electric installs, services and repairs heat pumps throughout Whangārei, Kerikeri and the wider Northland region.
If you're not sure whether your heat pump is running efficiently — or you'd like help setting up timers and getting the most out of your unit — get in touch with our team for friendly, honest advice.