What Does Martin Lewis Think About Heat Pumps?
Martin Lewis and MoneySavingExpert do not simply say that every household should install a heat pump.
Their guidance is more cautious. Heat pumps can reduce carbon emissions and may work very well, but the financial result depends on the property, installation quality, system efficiency, electricity prices and the type of heating being replaced.
A heat pump is not automatically cheaper to run than a gas boiler.
It can still be a good choice, particularly where:
- The home is suitable for low-temperature heating
- The system is properly designed
- The installer calculates the heat loss correctly
- Radiators or underfloor heating are adequately sized
- The heat pump achieves good seasonal efficiency
- The household can access a suitable electricity tariff
- A grant reduces the installation cost
- The alternative is oil, LPG, direct electric or an old inefficient boiler
I have run a heat pump in my own 1930s home since 2022 and publish detailed performance and cost data on Energy Stats UK.
If you are considering an installation, you can also use my hand-picked installer directory:
Find a Trusted Heat Pump Installer
What does Martin Lewis think about heat pump running costs?
MoneySavingExpert warns that a heat pump does not guarantee lower energy bills.
A heat pump uses electricity, which usually costs more per unit than gas. It compensates for this by producing several units of heat from each unit of electricity consumed.
The result depends on the heat pump’s efficiency.
For example, a heat pump with a seasonal performance factor of 4 produces around four units of heat for every unit of electricity it uses.
Whether that heat is cheaper than gas depends on:
- The electricity unit rate
- The gas unit rate
- Boiler efficiency
- Heat pump efficiency
- Standing charges
- The tariff used
- Whether the gas supply can be removed completely
This is why broad claims that heat pumps are always cheaper or always more expensive are not reliable.
You need to compare the cost of useful heat in your own home.
I have created a calculator for this:
Use the heat pump break-even SPF calculator
Does Martin Lewis recommend heat pumps?
It would be inaccurate to say that Martin Lewis gives heat pumps a blanket recommendation.
MoneySavingExpert explains the possible benefits, available grants and key risks. It encourages homeowners to check whether a heat pump is suitable before committing.
The main concerns are reasonable:
- High upfront cost
- Poorly designed systems
- Homes that need radiator or insulation work
- Electricity costing more per unit than gas
- Savings that depend on achieving good efficiency
- Installations being sold using unrealistic claims
The underlying message is not that heat pumps are bad.
It is that homeowners should understand the numbers and avoid treating a heat pump as a simple boiler replacement.
Can a heat pump save money?
Yes, but not in every home and not under every tariff.
A heat pump is more likely to reduce running costs when:
- It replaces direct electric heating, oil or LPG
- It operates at a high seasonal efficiency
- The flow temperature remains low
- The home is heated steadily
- The electricity tariff has useful cheaper periods
- The gas meter can be removed, avoiding the gas standing charge
- The household has solar panels or other flexible electricity use
Savings against a modern gas boiler can be harder to achieve because electricity remains relatively expensive compared with gas.
A well-performing heat pump may still offer other benefits:
- Lower carbon emissions
- More stable indoor temperatures
- No combustion inside the home
- No gas boiler or flue
- Potential cooling with some systems
- Better use of solar generation
- Access to heat-pump-specific tariffs
The right comparison is not simply electricity price versus gas price. It is the cost of each usable unit of heat delivered into the home.
What does MoneySavingExpert say about heat pump grants?
The main national grant in England and Wales is the Boiler Upgrade Scheme.
It currently provides £7,500 towards an eligible air source or ground source heat pump installation.
The installer normally applies for the grant and deducts it from the amount paid by the homeowner.
The scheme is mainly aimed at replacing fossil-fuel heating systems.
Eligibility conditions apply, and the grant may not cover every part of the installation. Additional costs could include:
- New radiators
- A hot-water cylinder
- Electrical work
- Pipework changes
- Groundworks
- Planning requirements
- Insulation improvements
- Removal of the existing heating system
A grant makes the initial cost more attractive, but it does not make a poor design into a good installation.
The installer and system design still matter.
Are heat pumps suitable for older homes?
Older homes are not automatically unsuitable for heat pumps.
My own home is a 1930s semi-detached house heated entirely by a 5 kW air source heat pump.
The important question is not the age of the building. It is how much heat the property loses and whether the heating system can deliver that heat efficiently.
An older property may need:
- Loft or wall insulation
- Draught reduction
- Larger radiators
- Better heating controls
- Careful room-by-room heat-loss calculations
- Lower-temperature system design
Some older homes can work well without major fabric changes. Others may need more work before a heat pump makes sense.
A competent installer should assess the actual building rather than rejecting or approving it based only on age.
Why heat pump installation quality matters
The same heat pump can perform very differently in two homes.
The result depends heavily on design and commissioning.
A good installation should include:
- A room-by-room heat-loss calculation
- Correct heat pump sizing
- Suitable radiators or underfloor heating
- Sensible pipe sizing
- Low design flow temperatures
- Proper control settings
- Weather compensation
- Hydraulic balancing
- Clear handover information
- Monitoring of actual performance
Oversizing can cause short cycling and poor efficiency.
Undersizing can lead to comfort problems or excessive use of direct electric backup heating.
High flow temperatures can also reduce efficiency.
This is why choosing the installer is at least as important as choosing the heat pump brand.
Finding a suitable heat pump installer
Martin Lewis’s caution about heat pumps is largely a warning against making an expensive decision without checking the property, figures and installer.
I created Trusted Heat Pump Installers to give homeowners a more focused place to start.
The site includes a hand-picked selection of national and independent installers.
It is not a guarantee that every installation will be perfect. You should still compare quotes, ask questions and check the proposed design.
However, it helps narrow the search to companies I believe are worth considering.
Find a Trusted Heat Pump Installer
When comparing installers, ask each one for:
- The calculated design heat loss
- The proposed heat pump size
- The design outdoor temperature
- The design flow temperature
- Any planned radiator changes
- The expected seasonal efficiency
- Details of monitoring and warranties
- The final price after grants
- What is included in the quote
- Examples of similar completed installations
Do not compare quotes using price alone.
Two companies may be quoting very different systems, design temperatures and levels of work.
My own heat pump performance
My Vaillant air source heat pump was installed in October 2022.
It heats a 1930s semi-detached home using radiators and also provides our hot water.
In 2024, the system delivered:
- 11,559 kWh of heat
- Using 2,735 kWh of electricity
- Combined seasonal performance of 4.23
- Space-heating performance of 4.45
- Hot-water performance of 3.84
Those figures are based on monitored heat output and electricity use rather than manufacturer estimates.
My result shows that a heat pump can work well in an ordinary older UK property.
It does not prove that every home will achieve the same performance.
The result depends on design, weather, household temperatures, hot-water use and system settings.
You can read the full data here:
My heat pump running costs and performance
Are heat pumps cheaper on a special tariff?
A suitable electricity tariff can reduce heat pump running costs, but it does not replace good system efficiency.
Some tariffs offer several cheaper periods during the day. Others have a low overnight rate but a much higher daytime price.
The best option depends on how the heat pump is operated.
A heat pump normally works most efficiently when it runs steadily rather than being switched off for long periods and then forced to recover quickly.
You should compare:
- The cheap-rate windows
- The peak rate
- The standing charge
- How much heating can realistically be moved
- Whether a battery is available
- Hot-water timing
- Comfort during expensive periods
- The effect of colder weather
A tariff that looks cheap for an EV may not be the best tariff for a heat pump running throughout the day.
Compare heat pump electricity tariffs
What should I check before buying a heat pump?
Before accepting a quote, check:
- Whether the installer has completed a proper heat-loss calculation
- What flow temperature the system is designed around
- Whether the proposed heat pump is correctly sized
- Which radiators need changing
- Whether a new hot-water cylinder is required
- The expected seasonal efficiency
- The full price after grants
- Whether planning permission is needed
- What electrical work is included
- What happens if the home does not reach the promised temperature
- How performance will be measured after installation
Be cautious if an installer:
- Sizes the heat pump from the existing boiler
- Does not measure every room
- Cannot explain the flow temperature
- Promises a fixed percentage saving
- Gives no performance estimate
- Avoids discussing radiator sizes
- Pushes for an immediate decision
Should I get a heat pump?
A heat pump can be a good choice when the property is suitable, the system is properly designed and the financial case works for the homeowner.
It may be less attractive where:
- A relatively new gas boiler is working well
- The installation needs extensive additional work
- The home has severe unresolved heat-loss problems
- The proposed system requires high flow temperatures
- The installer cannot explain the design
- The homeowner expects guaranteed savings against gas
The decision should be based on the whole installation, not simply the heat pump unit or the available grant.
Martin Lewis and MoneySavingExpert are right to urge caution.
But caution should mean checking the design and figures, not assuming heat pumps cannot work.
Find a Trusted Heat Pump Installer
A good heat pump starts with a sensible design and a capable installer.
You can view my hand-picked installer options here:
Find a Trusted Heat Pump Installer
The directory includes national and independent installers, along with information about areas covered, customer offers and relevant interviews.
Some installer links are referral links. I may receive a commission if an installation goes ahead.
You will not pay more for using those links.
The income helps support Energy Stats UK, my independent monitoring work and the Energy Unwrapped podcast.
