A heat pump can be very efficient, but that doesn’t mean every home will see the same running costs. Two houses can have the same heat pump fitted and still perform differently depending on insulation, radiators, flow temperatures, controls and how the system has been set up.

That’s why I always think running costs need explaining properly. It’s not just “heat pumps are cheaper” or “heat pumps are expensive”. The real answer sits somewhere in the system design.

How heat pump running costs work

A heat pump uses electricity to move heat from outside into the home. The key point is that it can produce more heat than the electricity it uses.

For example, if a heat pump uses 1kWh of electricity and produces 3kWh of heat, that would be a COP of 3.

What affects running costs most?

1. Heat loss of the property

The more heat a house loses, the more heat the system has to put back in. This is why heat loss calculations matter. A larger or poorly insulated house will naturally need more energy than a smaller, well-insulated one.

2. Flow temperature

Flow temperature is one of the biggest factors. Heat pumps are most efficient when they can run at lower flow temperatures.

If the system needs to run at 55°C all the time, it will use more electricity than a system designed to run at 35–45°C.

3. Radiator sizing

Radiators need to be able to give off enough heat at lower temperatures. Sometimes existing radiators are fine. Sometimes a few need upgrading.

This is one of the main reasons proper design matters so much.

4. Controls and setup

A heat pump should usually run more steadily than a boiler. If controls are set badly, or the system is constantly stopping and starting, running costs can be worse than they should be.

5. Electricity tariff

Electricity tariffs can make a noticeable difference. A standard tariff is simple, but some homes may benefit from smart tariffs depending on how the system is used.

Typical running cost expectations

There isn’t one figure that works for every home, but a well-designed heat pump system should usually be competitive to run, especially when replacing oil, LPG or direct electric heating.

Compared with a modern gas boiler, the difference can be closer because electricity is currently much more expensive per unit than gas. Ofgem’s April to June 2026 average Direct Debit price-cap rates are 24.67p/kWh for electricity and 5.74p/kWh for gas, so efficiency is what helps a heat pump compete. [oai_citation:0‡Ofgem](https://www.ofgem.gov.uk/information-consumers/energy-advice-households/energy-price-cap-explained?utm_source=chatgpt.com)

Why heat pumps can still make sense

Even though electricity costs more per unit than gas, a heat pump can use far less energy to produce the same heat. Energy Saving Trust explains that heat pumps are generally cheaper to run than most other fuel types because they are highly efficient, although they may be slightly more expensive than a newer gas or oil boiler at current prices. [oai_citation:1‡Energy Saving Trust](https://energysavingtrust.org.uk/advice/in-depth-guide-to-heat-pumps/?utm_source=chatgpt.com)

That matches what I’d say in real life: if you’re replacing direct electric, LPG or older oil, the running cost argument can look strong. If you’re replacing a newer efficient gas boiler, the running cost saving may be smaller or not immediate.

Example calculation

Let’s keep it simple.

If a home needs 12,000kWh of heat per year:

• At COP 3, the heat pump would use around 4,000kWh of electricity
• At 24.67p/kWh, that would be roughly £987 per year for heating energy

That is only a rough example. It doesn’t include standing charges, hot water, tariff differences or exact property behaviour, but it shows how efficiency changes the calculation.

Why some heat pumps cost more to run than expected

When people have poor running costs, it’s usually not just “because heat pumps are expensive”. Often it comes down to one or more of these:

• system running at too high a flow temperature
• radiators not sized properly
• heat pump undersized or oversized
• controls not set up correctly
• poor insulation or high heat loss
• customer using it like an old boiler

Heating style makes a difference

A boiler often comes on hard, heats quickly, then switches off. A heat pump is usually better when it runs steadily and keeps the home at a more consistent temperature.

That’s why the radiators may not feel as hot as boiler radiators, but the house can still be comfortable.

What about hot water?

Hot water also affects running costs. Larger households using more hot water will naturally use more energy.

A well-set cylinder, sensible hot water temperatures and correct controls all help keep this under control.

How to keep running costs down

• get a proper heat loss calculation
• design for sensible flow temperatures
• upgrade radiators where needed
• set weather compensation correctly
• avoid unnecessary high temperature settings
• make sure the customer understands how to use the system

Are heat pumps cheap to run?

They can be, but the better answer is that they can be efficient to run.

For some homes, especially replacing oil, LPG or direct electric, they can make a lot of sense. For others, especially replacing a newer gas boiler, the running cost comparison needs to be looked at properly.

Final thoughts

Heat pump running costs in the UK depend on the property and the design. A good system should be sized properly, run at sensible flow temperatures and be set up so the homeowner understands how to use it.

That’s where the real difference is. Done properly, a heat pump can be comfortable, efficient and reliable. Done badly, the running costs can disappoint.