Best air source heat pumps in the UK: seven models compared by our criteria

Of seven air source heat pumps around 8 kW, the Daikin Altherma 4 H scores highest by our criteria, with 73.9 of 100 points, ahead of the NIBE S2060-10 (66.2) and the Vaillant aroTHERM plus 7 kW (62.7). We score each model on its MCS-certified efficiency at 55 °C flow, its outdoor sound power, the warranty at no extra charge and its maximum flow temperature, weighted 40, 25, 25 and 10%. We don't test heat pumps ourselves, and manufacturers and installers don't pay for placement.

At a glance

• Result. Daikin 73.9 points, NIBE 66.2, Vaillant 62.7, Viessmann 59.1, Grant 58.2, Mitsubishi Electric 52.4, Panasonic 29.3.
• Criteria. Efficiency at 55 °C counts 40%, outdoor noise 25%, warranty at no extra charge 25%, flow temperature 10%. One model per maker, the size nearest 8 kW.
• Your home counts more. In our example semi, at October to December 2026 cap rates, a seasonal efficiency (SCOP) of 2.5 rather than 3.1 costs about £164 more electricity a year; the widest efficiency gap between two ranked models is worth roughly £83.
• Not ranked. Samsung, because its UK homeowner pages give no warranty length or terms for its heat pumps.

Air source heat pumps compared: the ranking around 8 kW

1. Daikin Altherma 4 H 8 kW, 73.9 points: efficient at 55 °C, the lowest sound power here at its rating point, and five years at no extra charge once registered and activated.
2. NIBE S2060-10, 66.2 points: the highest MCS efficiency at 55 °C here and seven years through a NIBE Pro Partner or Pro Exclusive installer, but a louder outdoor unit.
3. Vaillant aroTHERM plus 7 kW, 62.7 points: quiet at its rating point and up to seven years with a Vaillant cylinder and a myREWARDS Platinum or Renewable Partner installer, but less efficient at 55 °C.
4. Viessmann Vitocal 200-A ie size 10, 59.1 points: five years once an installer in Viessmann's VPlus partner programme registers it, with yearly servicing and an internet connection.
5. Grant Aerona 290 9 kW, 58.2 points: seven years when a G1 installer registers it.
6. Mitsubishi Electric Ecodan R290 8.5 kW, 52.4 points: five or seven years by installer status, the lowest MCS efficiency at 55 °C of the ranked models.
7. Panasonic Aquarea L 9 kW, 29.3 points: Panasonic's warranty is granted to the installer, not to you.

All eight use R290 (propane) as refrigerant and hold a current MCS product certificate.

Manufacturer photos of the ranked models, in ranking order (none of the NIBE S2060):

Our criteria and their weights

We turn each criterion into 0 to 100 points from published values, then apply its weight:

How a score is built. The Daikin Altherma 4 H 8 kW has an MCS SCOP of 3.83 at 55 °C: 80 × 3.83 − 256 = 50.4 points. Its 45 dB(A) gives (60 − 45) × 5 = 75 points, five years at no extra charge 100 and 75 °C flow 100. Weighted: 0.40 × 50.4 + 0.25 × 75 + 0.25 × 100 + 0.10 × 100 = 73.9 points.

Why these weights. Efficiency at 55 °C sets the electricity a heat pump needs in a home that keeps its radiators, and noise decides where the outdoor unit can go. How long a heat pump lasts can't be compared from published data, so the written warranty stands in for it. Flow temperature counts least: every ranked model reaches 75 °C. Paid warranty extensions are named, not scored.

Which model per maker. From each maker's current UK range we take the single-phase size whose output at −7 °C outside and 35 °C flow is nearest 8 kW (see the Output column) and, where a maker has several ranges, the one that scores highest. Why 8 kW: it was the median size of air source heat pump in Boiler Upgrade Scheme grants paid in England and Wales from July to September 2026 (middle half 6 to 10.2 kW).

Air source heat pump reviews: what this ranking is and isn't

This ranking is not a hands-on review: we don't test heat pumps, publish review scores or quote other people's tests. We compare values anyone can check in the MCS product directory, makers' datasheets and UK warranty terms.

SCOP, the seasonal coefficient of performance, is a year's heat divided by the electricity used. An MCS SCOP comes from a standard calculation, not a home, and homes vary more: across 428 air source heat pumps in the government-funded Electrification of Heat trial the median measured result was 2.78; more on heat pump efficiency.

Sound power is shown as each manufacturer publishes it. Where no UK document gives another value, we say so: Vaillant's 75 °C and output come from its German documents, Daikin's output and Panasonic's values from European catalogues.

What efficiency is worth in our example home

Our example home is a 1970s gas-heated semi in England with radiators: 97 m², 9,500 kWh of gas a year. With 85% boiler efficiency (our assumption) it needs about 8,075 kWh of heat (9,500 × 0.85). Electricity = heat ÷ SCOP, charged at 26.32p/kWh (price cap, GB average, direct debit, 1 October to 31 December 2026, no VAT on electricity in Great Britain until 31 March 2027):

The same home's gas costs £757 a year in unit charges (9,500 × 7.97p, same cap period, 5% VAT included), so the heat pump breaks even at a SCOP of about 2.81. Standing charges and servicing are left out; full figures are on heat pump running costs.

A SCOP of 3.1 rather than 2.5 is worth £164 a year in electricity. The gap between models is smaller: with MCS SCOPs at 55 °C of 3.94 and 3.51, the widest gap among the ranked models, the NIBE needs about 11% less electricity than the Mitsubishi Electric in the standard calculation (1 − 3.51 ÷ 3.94 = 0.109). If that gap held in a home running at SCOP 2.8, it would be worth about £83 a year (£759 × 0.109).

Quietest air source heat pumps: rating point and the 37 dB(A) test

The ranking uses each unit's sound power at its rating point, the figure on its energy label. An MCS installer must use that value, not a "low noise mode" one, for the permitted-development noise test in England and Wales, MCS 020(a): at most 37 dB(A) at 1 m outside the centre of a neighbour's habitable-room window or door. Scotland and Northern Ireland set their own conditions.

Take an outdoor unit on the ground against your house wall (two reflecting surfaces, Q = 4), 3 m from your neighbour's window with nothing in between. Under MCS 020(a), sound pressure = sound power + 10 × log(4 ÷ (4 × π × 3²)) = sound power − 14.5 dB:

• Daikin, 45 dB(A): 30.5 dB(A), within the limit.
• Vaillant, 46.8 dB(A): 32.3 dB(A), within the limit.
• NIBE, Viessmann, Grant, Mitsubishi Electric and Panasonic, 54 dB(A): 39.5 dB(A), over the limit at this spot; at 4 m the result is 37.0 dB(A).

At this spot a 54 dB(A) unit needs about a metre more distance or a solid barrier.

At full output each unit is louder than its rating-point figure: up to 57 dB(A) for the Daikin (preliminary data), 57.4 dB(A) for the Vaillant, 60 dB(A) for the NIBE and 61 dB(A) for the Viessmann.

Your installer runs the noise check for the real spot; permitted development has other conditions too, so check with your local planning authority. More on how loud a heat pump is.

Warranty: what you get at no extra charge

For most makers here, the longer warranty depends on your installer's status in the maker's scheme. Daikin, Viessmann and Grant say their cover costs nothing extra once registered; NIBE, Vaillant and Mitsubishi Electric name no fee, so we count their longer cover, with Vaillant's "up to seven years" as five or more. Ask your installer to confirm in writing that it costs you nothing extra:

Most makers tie the warranty to an annual service, which you pay for; see heat pump servicing.

Counting only the warranty you get without an installer tier or scheme membership narrows the gaps but keeps the order:

Our weightsBase warranty only

Points out of 100

• Daikin Altherma 4 H
  73.9
• NIBE S2060-10
  66.2
• Vaillant aroTHERM plus
  62.7
• Viessmann Vitocal 200-A ie
  59.1
• Grant Aerona 290
  58.2
• Mitsubishi Electric Ecodan R290
  52.4
• Panasonic Aquarea L
  29.3

Model	Our weights	Base warranty only
Daikin Altherma 4 H	73.9	73.9
NIBE S2060-10	66.2	53.7
Vaillant aroTHERM plus	62.7	50.2
Viessmann Vitocal 200-A ie	59.1	46.6
Grant Aerona 290	58.2	45.7
Mitsubishi Electric Ecodan R290	52.4	39.9
Panasonic Aquarea L	29.3	29.3

Boiler Upgrade Scheme: the model is rarely the obstacle

In England and Wales the Boiler Upgrade Scheme needs an installer who is MCS-certified and belongs to an approved consumer code such as RECC or HIES, and an air-to-water heat pump with a SCOP of at least 2.8. Every model here has an MCS SCOP above 3.4 at 55 °C; your installer checks whether your installation qualifies. The grant, £7,500 in England and Wales if your home qualifies (more for some off-gas homes), doesn't depend on the brand; Scotland and Northern Ireland differ (see heat pump grants).

Not in the ranking: Samsung

The Samsung EHS Mono R290 8 kW is MCS-certified, with a SCOP of 3.41 at 55 °C, 59 dB(A) on its UK energy label and 75 °C flow. Samsung's UK homeowner pages give no warranty length or terms for its heat pumps, only that an annual service helps keep the warranty valid. Without terms we can't score the warranty; scored at zero, Samsung would reach 18.0 points. If a quote offers Samsung, ask for its warranty terms in writing.

Heat pump brands ranked

We also sum up the same values for each brand as scores out of 5, with our estimate of the brand's usual price level as a third part; the same ranking appears on our home page and brand reviews. How we convert the points is in our editorial method.

Which heat pump suits your home?

An older home keeping its radiators. Efficiency at 55 °C matters most: NIBE 3.94, Daikin 3.83, Viessmann 3.72. Your installer's room-by-room survey shows whether your radiators manage at 55 °C or less.

Underfloor heating or a well-insulated home. At 35 °C flow the order changes: Viessmann 5.00, NIBE 4.99, Vaillant 4.90, Daikin 4.89.

35 °C flow55 °C flow

MCS SCOP

BUS grant minimum in England and Wales: SCOP 2.8

• Above the line7 options
• NIBE S2060-10
  3.941.14 above
• Daikin Altherma 4 H
  3.831.03 above
• Viessmann Vitocal 200-A ie
  3.720.92 above
• Grant Aerona 290
  3.690.89 above
• Panasonic Aquarea L
  3.570.77 above
• Vaillant aroTHERM plus
  3.550.75 above
• Mitsubishi Electric Ecodan R290
  3.510.71 above

Model	35 °C flow	55 °C flow
Daikin Altherma 4 H	4.89	3.83
NIBE S2060-10	4.99	3.94
Vaillant aroTHERM plus	4.90	3.55
Viessmann Vitocal 200-A ie	5.00	3.72
Grant Aerona 290	4.74	3.69
Mitsubishi Electric Ecodan R290	4.47	3.51
Panasonic Aquarea L	4.71	3.57

A terrace or a small garden. At the rating point, Daikin (45 dB(A)) and Vaillant (46.8 dB(A)) sit well below the others' 54 dB(A).

Other inputs, another order. Counting only the base warranty lowers five scores but keeps the order (chart in the Warranty section). NIBE's product fiche gives a lower operating limit, 60 °C for the S2060-10, and its UK datasheet publishes no output above 55 °C flow, beside the 75 °C NIBE states for continuous running; we score each maker's stated maximum, and at 60 °C the NIBE would have 58.7 points and drop to fourth, behind the Viessmann. The ranking is a starting point, not a recommendation for every home.

Checklist before you buy: the model on your quote

• Model. The full model number of the outdoor and indoor unit, and its MCS certificate number.
• Size. The output at your design outdoor temperature from the heat-loss survey, not the number in the name.
• Efficiency. The MCS SCOP at your planned design flow temperature.
• Noise. The sound power used in the MCS 020(a) calculation and the result at your neighbour's window.
• Warranty. Length, who registers by when, the installer's scheme status, any fee and the service condition, in writing.
• Grant. In England and Wales, the Boiler Upgrade Scheme voucher issued before work starts; in Scotland, Home Energy Scotland's written offer before any work.

How to compare the rest of the quote line by line is covered in choosing an MCS installer and comparing quotes; installed prices are in what a heat pump costs.

Figures that change

How we compared

Values come from the MCS product directory, makers' datasheets and UK warranty terms (other-market documents only where named), re-checked at every revision. The example home and its 85% boiler efficiency are our assumptions; manufacturers and installers don't pay for placement. The full method is in our editorial method.

Frequently asked questions

Which is the best air source heat pump in the UK?

Of the seven air source heat pumps around 8 kW we rank, the Daikin Altherma 4 H scores highest by our criteria, with 73.9 of 100 points, ahead of the NIBE S2060-10 and the Vaillant aroTHERM plus 7 kW. No model comes first in every home: the design flow temperature, where the unit goes and a careful installer matter as much.

What are the best heat pump brands in the UK?

Our comparison ranks models, one per maker at the size nearest 8 kW, and Daikin, NIBE and Vaillant lead it. Our brand ranking turns the same values, with our estimate of each brand's price level, into scores out of 5. Another size or range from the same maker can score differently, so compare the exact model on your quote.

Are air source heat pumps tested independently?

For MCS certification, normally yes: the scheme generally accepts independent testing by a UKAS-accredited (or equivalent) laboratory as evidence, and the MCS SCOP we compare is worked out with MCS's own calculator. We don't run tests or quote other people's results; we add the makers' sound power and flow figures and their written UK warranty terms, and say where a value comes from a non-UK document.

Which air source heat pump is the quietest?

At the rating point, the Daikin Altherma 4 H 8 kW has the lowest sound power in our comparison, 45 dB(A), then the Vaillant aroTHERM plus 7 kW at 46.8 dB(A), both as the manufacturers publish them. Running hard, a unit is louder, and what decides permitted development in England and Wales is the MCS 020(a) result at your neighbour's window.

Which air source heat pump is the most reliable?

Reliability can't be compared from makers' published data, so we don't rank it. The nearest written commitment is the warranty: Grant gives seven years through its G1 installers at no additional cost, NIBE seven through its top installer tiers with no fee stated, Vaillant up to seven, and Mitsubishi Electric five or seven depending on the installer, and most require an annual service. Ask which warranty applies to the exact model on your quote, and who registers it by when.

Does the installer matter more than the brand?

In our example home it does: a SCOP of 2.5 rather than 3.1 costs about £164 more electricity a year at October to December 2026 cap rates, while the widest efficiency gap between two ranked models, the NIBE and the Mitsubishi Electric, is worth roughly £83. Sizing, flow temperature and set-up decide where your heat pump lands.