Should I Leave My Heat Pump On All Day?
A practical guide for homeowners wondering whether it is cheaper to leave a heat pump running all day, or turn it on only when heating or cooling is needed.
Should I leave my heat pump on all day? Quick Answer
In most homes, no — you do not need to leave your heat pump running all day. Modern inverter heat pumps are designed to ramp up, heat or cool the room efficiently, then slow down and maintain the temperature.
If you are not home, or the room does not need heating or cooling, leaving the heat pump running is usually just paying to replace heat that your house is losing.
What you’ll learn
- Where the “leave it on all day” idea came from
- How inverter heat pumps work
- When leaving it on can make sense
- Why older homes lose more heat
- How power peak rates can affect cost
- What temperature to set for heating
- What temperature to set for cooling
- Simple running-cost tips
The simple answer
For general day-to-day use, the best approach is to turn your heat pump on when you need heating or cooling, run it at a sensible temperature, and turn it off when the room is no longer being used.
There are exceptions, especially for people who are home for long periods, sensitive to cold, or need consistent warmth. But for most households, leaving a heat pump on all day is not automatically cheaper.
Quick Guide
| Do you need to leave it on all day? | Usually no. Modern inverter heat pumps are efficient and can be turned on when heating or cooling is needed. |
| Is it ever worth leaving on? | It can make sense if someone is home all day, needs steady warmth, or the home is very well insulated. |
| What about older homes? | Drafty, single-glazed or poorly insulated homes lose heat quickly, so leaving the heat pump running can waste power. |
| Best heating temperature? | Around 21–22°C is a sensible heating range for comfort and efficiency. Avoid setting unit extremely high. |
| Best cooling temperature? | Around 19–21°C is usually a sensible cooling range. Avoid setting the unit extremely low. |
| Peak power times? | Many Energy Provider plans have higher rates around Peak Times. This is usually 7–9am and 5:30–9pm, but check your own Energy Provider plan. |
Where Did the “Leave It On All Day” Idea Come From?
For years, many people were told that it was cheaper to leave a heat pump running all day rather than turning it on and off. This advice has stuck around, especially with homeowners who have been using heat pumps for a long time.
The idea came from older ways of thinking about heating, and from older systems that were less flexible than modern inverter heat pumps. People often believed that because a heat pump worked harder when first turned on, it must be cheaper to leave it running constantly.
That is not always true with modern heat pumps. Today’s inverter units are designed to ramp up, bring the room to temperature, then slow down and maintain that temperature efficiently. You do not need to treat them like an old fixed-speed heater that has to run flat out every time it starts.
How Modern Inverter Heat Pumps Work
Most modern heat pumps use inverter technology. This means the heat pump can vary its output instead of simply switching fully on or fully off.
When you first turn the heat pump on, it may ramp up and work harder to bring the room up to the set temperature. Once the room is comfortable, the unit can slow down and run at a lower speed to maintain the temperature.
This is one of the reasons heat pumps are so efficient. They do not need to run at full power all the time. Once the room, furniture, carpet, walls and ceiling have warmed up, less energy is usually needed to keep the room comfortable.
But that does not mean the heat pump should always be left on. If no one is home, or the room is not being used, the heat pump is still using electricity to replace the heat your home is losing.
Your Home Makes a Big Difference
The efficiency of leaving a heat pump running depends heavily on the home it is installed in.
In an older home with single-glazed windows, poor insulation, open underfloor areas, gaps, drafts or high heat loss, leaving the heat pump on all day can be expensive. The unit may be constantly trying to replace heat that is escaping through the building.
In that situation, it often makes more sense to heat the room when you are actually using it, rather than heating an empty or leaky space all day.
In a modern, well-insulated home with double glazing and good sealing, the room will generally hold heat much better. In those homes, maintaining temperature can use less energy once the space is warm. Even then, it still does not mean you must leave the heat pump on all day. It simply means the cost difference may be smaller.
When Might You Leave a Heat Pump Running?
There are times when leaving a heat pump running for longer periods can make sense. The main reason is comfort, not always cost.
If someone is home all day, sensitive to cold, unwell, elderly, has young children at home, or needs a consistent indoor temperature, then keeping the room warm can be the right choice. Once the room is warmed through, the heat pump may only need to run gently to maintain the temperature.
This can also help because the whole room absorbs warmth over time. The carpet, furniture, wall linings, ceiling and surfaces all slowly warm up. Once the building fabric is warm, the room can feel more comfortable and stable.
But for normal everyday use, especially if everyone leaves for work or school, there is usually no need to heat an empty room all day.
Watch Out for Peak Power Rates
Another thing to consider is your electricity plan. Some power companies charge different rates at different times of the day. These are often called peak, off-peak and night rates.
Peak rates often line up with the times most households are using the most power. A simple way to remember it is morning and evening: around 7am to 9am, and around 5:30pm to 9pm. These times can vary depending on your provider and your exact plan, so it is worth checking your bill.
If your plan has expensive peak rates, you may save money by warming the room before peak time, then turning the heat pump down or off during the most expensive period if the home stays comfortable enough.
This will not suit every household, but it is a smart thing to understand. The same heat pump can cost more or less to run depending on when you use it.
Do Not Run the Heat Pump at Extreme Temperatures
One of the biggest running-cost mistakes is setting the heat pump to an extreme temperature. For heating, some people set the unit to 28°C or 29°C thinking it will heat the room faster. In most cases, this does not help. It just makes the heat pump work harder for longer and can cost more to run.
For heating, a sensible target is usually around 21–22°C. This is warm enough for most homes while still allowing the heat pump to operate efficiently.
The same idea applies in summer. Setting the unit to the lowest possible cooling temperature does not usually cool the room in a sensible or efficient way. A cooling setting around 20–21°C is usually a better starting point.
Your heat pump will generally run more efficiently when it is asked to maintain a realistic indoor temperature, rather than being pushed to its maximum heating or minimum cooling setting.
Best Way to Run Your Heat Pump
For most homeowners, the best approach is simple: use the heat pump when you need it, set it to a sensible temperature, and turn it off when the room is no longer being used.
If you are coming home to a cold house, it is fine to turn the heat pump on and let it bring the room up to temperature. A modern inverter unit is designed to do this efficiently.
If you are home for the day, you may choose to leave it running at a moderate set temperature so the room stays comfortable. If you are leaving the house for several hours, it usually makes sense to turn it off rather than heat an empty space.
Frequently Asked Questions
Is it cheaper to leave my heat pump on all day?
In most homes, not usually. If the room is not being used, the heat pump is still using power to replace heat that is being lost through the house. Modern inverter heat pumps are efficient enough to turn on when needed.
Should I leave my heat pump on overnight?
Only if you need the room kept at a stable temperature overnight. Otherwise, use a timer, sleep mode, or a sensible lower setting to reduce running cost.
What temperature should I set my heat pump to in winter?
Around 21–22°C is a good starting point for heating. Setting the unit to 28°C or 29°C usually does not heat the room faster and can cost more to run.
What temperature should I set my heat pump to in summer?
Around 20–21°C is a sensible cooling range for many homes. Avoid setting the unit to its lowest possible temperature unless there is a specific reason.
Do peak power rates matter?
Yes, they can. Some power plans charge more during busy household periods, often around 7–9am and 5:30–9pm. Check your own power plan to see when your expensive periods are.
So, Should You Leave Your Heat Pump On All Day?
For most households, no — you do not need to leave your heat pump running all day. Modern inverter heat pumps are designed to heat or cool efficiently when needed, then slow down once the room reaches temperature.
Leaving it on can make sense if someone is home all day, needs steady warmth, or the home is very well insulated. But if the house is older, drafty or poorly insulated, leaving the heat pump on while no one is home can simply waste power.
The best approach is to use the heat pump when you need it, set a sensible temperature, understand your power plan, and avoid running the unit at extreme settings.
Related Guides
To keep this guide focused, these related questions are best covered in their own articles.
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