Vaillant heat pumps review

A Vaillant heat pump for a UK house is usually an aroTHERM plus: a monobloc air source heat pump with propane (R290) as its refrigerant, in five sizes from 3.5 to 12 kW, every size listed in the MCS product directory. The 7 kW size, VWL 75/8.1, has an MCS SCOP of 4.90 at a 35 °C flow temperature and 3.55 at 55 °C, and a sound power of 46.8 dB(A).

Vaillant began in 1874 in Remscheid, Germany, and runs its UK business from Belper in Derbyshire, where it opened a heat pump production line in 2022. You buy a Vaillant heat pump through an installer, not from Vaillant. The brand suits you best if your installer is in Vaillant's myREWARDS scheme and you are happy to book an annual service, because the longer warranty depends on both: 3 or 5 years depending on the installer's tier, and 7 years only from its top tiers with a Vaillant cylinder.

The range

Vaillant's UK range lists the new and the previous aroTHERM plus and the aroTHERM split; the aroTHERM pro has its own UK page. Its ground source and hot-water-only heat pumps are outside this review.

aroTHERM plus: the new /8.1 and the older /6

The model code tells the two generations apart: VWL 75/8.1 is the new 7 kW unit, VWL 75/6 the previous one. The difference shows in the sound figures: Vaillant's UK fiche gives the VWL 75/6 a sound power of 55 dB(A); Vaillant's datasheet for the same /8.1 model, which has no UK edition, gives the VWL 75/8.1 46.8 dB(A). Installers may still offer the /6, so check the code on the quote.

Indoors, the aroTHERM plus works with either the uniTOWER or a hydraulic station plus a separate cylinder. The uniTOWER plus holds a 188-litre hot-water cylinder, the expansion vessel and the diverter valve in one cabinet, 1,880 mm high, 595 mm wide and 693 mm deep; Vaillant sells it only as a pack with the aroTHERM plus. With the hydraulic station, the installer adds a uniSTOR cylinder of 200 litres or 300 to 500 litres. If you are replacing a combi boiler, either option means finding floor space for a cylinder for the first time.

aroTHERM pro: 5, 7 and 11 kW

Vaillant describes the aroTHERM pro as its compact monobloc, suited to new builds and to replacing a boiler while keeping existing radiators. It reaches a 70 °C flow temperature. The myVAILLANT connect internet gateway doesn't come as standard with it.

aroTHERM split: refrigerant pipes into the house

In a monobloc such as the aroTHERM plus, the refrigerant circuit stays in the outdoor unit and only water pipes enter the house. In a split, refrigerant pipes connect it to an indoor unit, which helps where the outdoor unit stands some way from the house. The aroTHERM split comes pre-filled with refrigerant for pipes up to 15 m, allows 3 to 25 m, uses R410A and heats at up to 55 °C.

Efficiency and noise

SCOP, the seasonal coefficient of performance, is the heat a heat pump delivers over a heating season for each unit of electricity, measured on a standard test. The MCS product directory lists it for every certified model at each flow temperature, which gives one basis for comparing brands.

35 °C flow55 °C flow

MCS SCOP

Highest: plus 12 kW, 5.12 · Lowest: pro 7 kW, 4.74

0246

4.893.574.763.574.903.555.053.784.863.584.983.755.124.743.873.52

plus 3.5 kWplus 5 kWplus 7 kWplus 10 kWplus 12 kWpro 5 kWpro 7 kWpro 11 kW

Model	35 °C flow	55 °C flow
plus 3.5 kW	4.89	3.57
plus 5 kW	4.76	3.57
plus 7 kW	4.90	3.55
plus 10 kW	5.05	3.78
plus 12 kW	5.12	3.87
pro 5 kW	4.86	3.58
pro 7 kW	4.74	3.52
pro 11 kW	4.98	3.75

The gap between the columns matters more than the gap between sizes. For the VWL 75/8.1, 4.90 ÷ 3.55 = 1.38: on the test, the same heat at a 55 °C flow takes about 38% more electricity than at 35 °C. That is why your installer's design flow temperature, set by your radiators, does more for your bills than the choice between two sizes. The 75 °C is headroom for the coldest days, not a target.

A test SCOP is also not what a home achieves: the government-funded Electrification of Heat trial measured a median of 2.78 across 428 air source heat pumps. At about that level, our example home (a 1970s gas semi using 9,500 kWh of gas a year, 85% boiler efficiency assumed) would pay about the same for its heating units with a heat pump as with its boiler, on Ofgem price cap unit rates (GB average, direct debit, 1 October to 31 December 2026, no VAT on electricity in Great Britain until 31 March 2027) with standing charges left out; the result depends on the house, the installation and the tariff. The arithmetic is in heat pump running costs.

How loud is a Vaillant heat pump?

Sound power is a property of the unit; sound pressure is what reaches a window and falls with distance. Vaillant's UK page quotes 44 dB(A) for the 3.5 kW aroTHERM plus, which matches the 44.1 dB(A) sound power in its datasheet. In England and Wales, permitted development needs the MCS 020(a) calculation to show no more than 37 dB(A) at a neighbour's nearest window or door, and it uses sound power, never a low-noise-mode figure.

An example: a VWL 75/8.1 (46.8 dB(A)) on the ground against your house wall (two reflecting surfaces, factor 4), 3 m from a neighbour's bedroom window, with no fence in between. The MCS formula gives 46.8 + 10 × log(4 ÷ (4 × π × 3²)) = 46.8 − 14.5 = 32.3 dB(A), inside the limit. The older VWL 75/6 at 55 dB(A) in the same spot gives 40.5 dB(A); it would need about 4.5 m. Placement, barriers and other planning conditions are in heat pump noise; check with your local planning authority before you commit to a spot.

Boiler Upgrade Scheme

In England and Wales, the Boiler Upgrade Scheme takes £7,500 off an air source heat pump if your home qualifies; some off-gas-grid homes replacing oil or LPG may qualify for £9,000 instead, for applications properly made from 21 July 2026 to 31 March 2027. Your installer, who must be MCS-certified and in an approved consumer code such as RECC or HIES, applies to Ofgem and deducts the grant from your bill, so get the voucher before work starts. A heat pump supplied and installed in your home also carries 0% VAT until 31 March 2027, then 5%. Scotland and Northern Ireland differ: Scotland has its own grant and loan through Home Energy Scotland, and Northern Ireland has no grant open to every homeowner; the details are in heat pump grants.

The grant follows the installation, not the brand, but the model matters: the MCS design standard requires the heat pump to be listed on the MCS website. All five aroTHERM plus /8.1 sizes are listed with certificates running to 12 November 2029, and all three aroTHERM pro sizes to February or April 2036. Several aroTHERM plus /6 and aroTHERM split certificates end on or before 23 October 2027, so if you are offered one of those, ask the installer to confirm the certificate is current when your job is designed.

Vaillant also sells hybrid systems that pair a heat pump with a gas boiler. Under the Boiler Upgrade Scheme, a hybrid gets no grant, and your existing gas, oil or LPG heating must be fully replaced rather than kept as a back-up; the rules are written about heating, so if you want to keep gas for cooking, ask your installer.

Warranty

What Vaillant's warranty (its documents call it a guarantee) gives you depends on who installs the heat pump and what you register:

What the warranty terms require. A suitably qualified engineer (Vaillant gives MCS as an example) installs the heat pump and completes the Benchmark logbook. The heat pump must be serviced every year by Vaillant's own service organisation or another competent engineer; if it isn't, the warranty becomes invalid, and the service is never included. Parts replaced under warranty carry 12 months of cover but don't extend the original term. Moving the heat pump to another property without Vaillant's written consent ends the warranty. If a fault appears, the terms send you first to your original installer, or to Vaillant Group Service.

Where it applies. The terms cover domestic homes in the United Kingdom, but they exclude a list of postcodes in the Highlands and Islands. If you live there, ask Vaillant or your installer in writing what cover applies before you sign.

Cover & Care. These paid packages bundle the longer warranty with 4, 6 or 9 annual services, an Appliance Function Check in the first six months, and breakdown repairs with genuine parts, labour and call-out. Vaillant may change the fees. Compare a package with booking the annual service yourself.

Vaillant says spare parts stay available for at least 15 years after a model goes out of production. None of this replaces your statutory rights against the installer who sold and fitted the system. How servicing works and what it involves is in heat pump servicing and lifespan.

Controls, app and tariffs

The aroTHERM plus is run from the sensoCOMFORT control, which manages heating and hot water. With the myVAILLANT connect internet gateway, the myVaillant app shows the system's energy use and lets you set temperatures and fixed operating hours from your phone.

Solar panels. If you have solar panels, Vaillant's EnergyPLUS service uses local weather forecasts to suggest a time window for heating your hot-water cylinder when your own panels should produce the most. It needs a Vaillant heat pump, an internet gateway and solar panels of any make. Vaillant offers it at no extra charge to connected heat pump customers with solar panels, and says it may change that at any time. It doesn't work with a cascade of several heat pumps, and Vaillant says heating support for systems with a buffer cylinder is planned.

Tariffs. Vaillant says EnergyPLUS will later optimise on tariff prices too. On a time-of-use tariff, for now you set the schedules yourself in the app or the control.

Who Vaillant suits

A gas semi with radiators. The 7 and 10 kW aroTHERM plus sit either side of the 8 kW median size of heat pumps whose Boiler Upgrade Scheme grants were paid from July to September 2026; the survey decides the size. The 75 °C flow is headroom if a few radiators are small, but the lower your radiators let the flow temperature go, the better the SCOP.

Neighbours close by. The /8.1 generation's low sound power leaves more room in the 37 dB(A) calculation, especially in terraces and semis.

A smaller or well-insulated home. The 3.5 and 5 kW aroTHERM plus list an MCS SCOP of 4.89 and 4.76 at 35 °C; the heat-loss survey decides the size.

An outdoor unit far from the house. The aroTHERM split allows refrigerant pipes of 3 to 25 m, but it uses R410A and heats at up to 55 °C.

Less suited if you won't commit to an annual service, if you live in an excluded Highlands and Islands postcode, or if no myREWARDS installer near you fits the system, because then the 2-year warranty is what you can count on.

How Vaillant fares in our comparison. In our comparison of air source heat pumps we score the model nearest 8 kW from each brand on four published criteria: efficiency at 55 °C (40%), outdoor sound power (25%), the warranty you get at no extra charge (25%) and maximum flow temperature (10%). For the aroTHERM plus, the 46.8 dB(A) sound power and the 75 °C flow raise the score, as does the 7-year warranty, which we count because Vaillant names no fee for it; it needs a top-tier myREWARDS installer and a Vaillant cylinder, so ask your installer to confirm the cost. An MCS SCOP of 3.55 at 55 °C, below several rivals, lowers it. Manufacturers and installers don't pay for placement; how we score is in our editorial method.

Checklist for your quote

What a Vaillant quote should name

• The full model code with its generation, such as VWL 75/8.1 rather than "aroTHERM plus 7 kW", and its MCS certificate number.
• The indoor setup: uniTOWER, or hydraulic station with a uniSTOR cylinder and its size in litres.
• Whether the installer is in myREWARDS and at which tier, which warranty length you will get (2, 3, 5 or 7 years), and in writing whether it adds anything to the price.
• Who registers the heat pump with Vaillant within 30 days, and confirmation once it is done.
• Who carries out the annual service the warranty needs, and what it costs.
• The design flow temperature from the heat-loss survey, and the radiators that change to reach it.
• The sound power figure used and the MCS 020(a) result at your neighbours' nearest window.
• Whether the myVAILLANT connect gateway is included, which you need for the app and EnergyPLUS.

How to put two quotes side by side, and what consumer-code protection to ask about, is in choosing an MCS installer.

Frequently asked questions

How much does a Vaillant heat pump cost?

Vaillant doesn't publish homeowner prices; the installer sets the price for the whole job. Across all brands, the median installed price of an air source heat pump in England and Wales, for jobs whose Boiler Upgrade Scheme grants were paid from July to September 2026, was £12,826 before the grant, as reported by MCS installers, with VAT included. In England and Wales, if your home qualifies, the £7,500 Boiler Upgrade Scheme grant comes off that.

Is the Vaillant aroTHERM plus eligible for the Boiler Upgrade Scheme?

All five aroTHERM plus /8.1 sizes are listed in the MCS product directory, which the MCS design standard requires. Whether your installation gets the grant in England and Wales depends on your home, an MCS-certified installer and Ofgem's decision, not on the brand. A hybrid with a Vaillant boiler gets no grant.

What is the difference between the aroTHERM plus and the aroTHERM pro?

Both are propane monoblocs. The aroTHERM plus comes in five sizes from 3.5 to 12 kW and reaches 75 °C; the aroTHERM pro comes in 5, 7 and 11 kW and reaches 70 °C. At 7 kW the plus has the higher MCS SCOP at 55 °C (3.55 against 3.52) and the lower sound power (46.8 against 49.0 dB(A)).

How long is the Vaillant heat pump warranty?

Two years as standard, if the heat pump is registered within 30 days; otherwise 12 months. A myREWARDS installer can register 3 or 5 years, depending on its tier, and 7 years if it is a Platinum or Renewable Partner member and fits a Vaillant cylinder; a paid Cover & Care package gives 5, 7 or 10 years. Every option needs an annual service.

Where are Vaillant heat pumps made?

Vaillant opened a heat pump production line at its UK head office in Belper, Derbyshire, in 2022. It doesn't say which models or sizes come from Belper, and it describes the aroTHERM split as manufactured in Europe. Ask your installer if the origin matters to you.

How loud is the Vaillant aroTHERM plus?

The /8.1 generation has a sound power of 44.1 to 49.9 dB(A) at the energy-label test point, depending on size. In our example, a 7 kW unit 3 m from a neighbour's window against a wall gives 32.3 dB(A), inside the 37 dB(A) permitted development limit in England and Wales.