Vaillant Heat Pump Review (2026): Is the aroTHERM plus Worth It?
Vaillant’s aroTHERM plus is the heat pump most UK installers would put on their own house. Here’s our honest verdict on efficiency, how quiet it really is, the warranty small print that catches people out, the price after the £7,500 grant, and how it compares to Octopus, Daikin and Mitsubishi.
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Who are Vaillant?
Vaillant was founded in Remscheid, Germany, in 1874 and is one of Europe’s largest heating manufacturers — a name most UK homeowners know from the ecoTEC boiler on their kitchen wall. It has been in the UK for decades, with a factory and headquarters in Belper, Derbyshire, and one of the biggest accredited installer networks in the country. That heritage shows in the heat pumps: they’re designed to slot into British wet heating systems, and there’s an installer within reach of almost every postcode who’s been trained on them. For how Vaillant sits against the other makers, see our best heat pumps guide.
The range: aroTHERM plus, split, flexoTHERM & hybrid
| Model | Type | Sizes | Best for |
|---|---|---|---|
| aroTHERM plus | Air-to-water monobloc, R290 | 3.5 / 5 / 7 / 10 / 12kW | Most homes — the one to buy |
| aroTHERM split | Air-to-water split | 3–12kW | Long pipe runs, frost-risk sites |
| flexoTHERM | Ground source | 5–19kW | Homes with land for a ground loop |
| aroTHERM + ecoTEC hybrid | Heat pump + gas boiler | Various | Hard-to-heat homes (no grant) |
This review focuses on the aroTHERM plus, because that’s what almost everyone means by “a Vaillant heat pump.” Note that Vaillant refreshed the range in 2025 with a new anthracite-finish generation and a “Flexible Space Function” that reduces the safety clearance R290 units need — so if you’re comparing quotes, make sure both are for the same model code. The hybrid is covered in our hybrid heat pumps guide, and remember it isn’t eligible for the Boiler Upgrade Scheme.
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Get My Vaillant Price After Grant →Our scores
Our rating
Vaillant aroTHERM plus
★★★★½ The premium all-rounder
The bottom line: top-tier efficiency, the quietest unit in its class and the widest installer network — held back only by a premium price and a warranty that depends on who fits it.
Get my Vaillant price →Sizes & which one you need
| Model | Output | Typical home |
|---|---|---|
| VWL 35/6 | 3.5kW | Flat or small, well-insulated new build |
| VWL 55/6 | 5kW | 2–3 bed modern semi or terrace |
| VWL 75/6 | 7kW | Typical 3-bed semi, 1930s–1990s |
| VWL 105/6 | 10kW | Larger 4-bed or older 3-bed |
| VWL 125/6 | 12kW | Big or poorly insulated detached |
The “7kW” and “12kW” models are the most searched for, and the 7kW is the one most 3-bed homes end up with. But the honest rule is that size comes from a room-by-room heat-loss survey, not from bedrooms or floor area. Oversizing is the single most common installer mistake with heat pumps — a unit that’s too big cycles on and off, runs less efficiently and wears faster. A good installer will show you the heat-loss figure that justified the size they’ve quoted. Vaillant also offers cascade setups (two units) for very large properties.
Efficiency & running costs
The aroTHERM plus uses R290 (propane) refrigerant, which is what lets it do two things older R32 units can’t: run at very high efficiency at normal flow temperatures (a SCOP of up to 5.0 at 35°C — five units of heat per unit of electricity) and push flow temperatures up to 75°C when it needs to. That second point matters enormously for older houses: it means the aroTHERM plus can heat existing radiators that were sized for a boiler, so you may not need to replace them — though efficiency drops to a SCOP nearer 3 at those temperatures, so a good installer will still aim to run it as cool as the house allows.
In real UK use, expect a SCOP of around 3.8–4.5 on a well-designed system with radiators at 45–50°C, and higher with underfloor heating. That puts running costs level with or below a gas boiler on a standard tariff, and clearly below with a heat-pump tariff (Octopus Cosy, OVO Heat Pump Plus) or solar panels. See heat pump running costs for numbers by house type.
Noise
This is where the aroTHERM plus quietly wins. Sound power is 51–58 dB(A) depending on size, and at three metres the sound pressure is under 30 dB(A) in normal operation — a quiet library. It carries Quiet Mark certification, has a night mode that drops fan speed further, and comfortably meets the 42 dB at the neighbour’s window limit that permitted development requires. If you’ve been put off heat pumps by noise, this is the unit that changes minds. For the wider picture see are heat pumps noisy?.
Worried about noise, radiators or an older house?
A free heat-loss survey answers all three for your home — and prices the right size unit.
Get My Vaillant Price After Grant →Warranty — the 2 vs 7 year catch
| Warranty | Length | Conditions |
|---|---|---|
| Standard | 2 years | Any MCS installer |
| Extended | Up to 7 years | Vaillant-accredited installer (Advance Platinum / Renewable Partner) + Vaillant uniSTOR cylinder + registered within 30 days + annual service |
This catches people out. The number you’ll see in adverts is 7 years, but that only applies if all the conditions are met — and the biggest one is who installs it. Fit an aroTHERM plus through a non-accredited installer and you get 2 years, which is thin for a £10,000+ system. So when you’re comparing quotes, the question isn’t just “is it a Vaillant?” but “is your firm Vaillant-accredited, and will the 7-year warranty apply?” — and get the answer in writing. Annual servicing (typically £150–£250) is also a condition, so factor it in. As with any heat pump, the unit warranty sits alongside the installer’s own workmanship guarantee; see how to choose an installer.
Price after the grant
| System | Installed (before grant) | After £7,500 BUS |
|---|---|---|
| 3.5–5kW + cylinder | £9,000 – £11,000 | £1,500 – £3,500 |
| 7kW + cylinder (typical 3-bed) | £10,000 – £12,500 | £2,500 – £5,000 |
| 10–12kW + cylinder | £12,000 – £15,000 | £4,500 – £7,500 |
| Radiator upgrades (if needed) | + £1,000 – £3,000 | — |
Vaillant sits at the premium end — typically £1,000–£2,500 more than a Samsung or Octopus system of the same size, and roughly level with Daikin and Mitsubishi. You’re paying for the R290 efficiency, the quietness, the 75°C capability and the installer network. With the grant applied, a 7kW aroTHERM plus system for a 3-bed semi lands around £2,500–£5,000 net, which is boiler money for a system that costs less to run. The air-to-water guide has the full cost picture across brands.
Controls, app & cylinder
The aroTHERM plus is controlled by the sensoCOMFORT wall unit, which handles weather compensation (adjusting flow temperature to the outside conditions — the key to high efficiency) and hot water scheduling. Add the internet gateway and the myVAILLANT app gives you remote control, energy monitoring and installer diagnostics; it’s decent, though not as slick as Octopus’s. Hot water comes from a matching uniSTOR cylinder (200, 250 or 300 litres, standard or slimline) — and using the Vaillant cylinder is one of the conditions of the 7-year warranty, so most installs include it. Legionella cycles are automated. If you want cooling, the aroTHERM plus can run in reverse through underfloor heating or fan coils, though few UK installs use it.
Vaillant vs Octopus, Daikin & Mitsubishi
| Brand | Best for | SCOP (approx.) | Max flow | Price |
|---|---|---|---|---|
| Vaillant aroTHERM plus | Premium all-rounder, old houses, quiet | Up to 5.0 | 75°C | Premium |
| Octopus Cosy 6 | Budget, Octopus customers | ~4.0–4.5 | ~60°C | Lowest |
| Daikin Altherma 3 | Efficiency, hybrid option | Up to 5.0 | 70°C | Premium |
| Mitsubishi Ecodan | Proven reliability, UK best-seller | ~4.0–4.5 | 60°C | Mid-premium |
The honest summary. Vaillant vs Octopus is the comparison people are making most: the Cosy 6 is a genuinely good unit at a lower price, but it’s only fitted by Octopus’s own installers and it doesn’t do 75°C — so for a modern home on an Octopus tariff it’s a real alternative, while for an older house or if you want choice of installer, Vaillant. Daikin matches Vaillant on efficiency and offers the best hybrid; Mitsubishi Ecodan is the UK’s best-seller, bulletproof, a touch louder and less efficient at high flow. Viessmann is the other German premium option; Samsung the value pick. For most homes it’s Vaillant or Mitsubishi; if budget rules, Octopus or Samsung.
Pros & cons
Pros
- SCOP up to 5.0 — among the most efficient units available
- 75°C flow temperature: works with existing radiators in older homes
- Exceptionally quiet — under 30 dB(A) at 3m, Quiet Mark
- R290 refrigerant: low-GWP and future-proof
- Biggest accredited installer network in the UK
- 150-year German brand, UK factory in Derbyshire
Cons
- Premium price — £1,000–£2,500 more than value brands
- Only 2-year warranty unless all the 7-year conditions are met
- 7-year cover requires annual paid servicing
- App is fine, not best-in-class
- R290 needs clearance from doors/windows (eased on the new range)
Our verdict
4.6 / 5 — the premium all-rounder, and the heat pump we’d choose for most UK homes. The aroTHERM plus combines top-tier efficiency, the quietest outdoor unit in its class, the ability to run old radiators at 75°C, and an installer network that means you’re never far from someone who knows it inside out. With the grant, a 3-bed system lands at boiler money.
The one thing to get right is the installer. The difference between a 2-year and a 7-year warranty — on a £10,000-plus system — comes down entirely to whether they’re Vaillant-accredited and you keep up the servicing. Choose the fitter as carefully as the unit, get the warranty in writing, and the aroTHERM plus is very hard to beat.
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Vaillant heat pumps: frequently asked questions
Are Vaillant heat pumps any good?
Yes — the aroTHERM plus is one of the best air source heat pumps you can buy in the UK and probably the most widely installed premium unit. It uses R290 refrigerant for a SCOP of up to 5, can run existing radiators at up to 75°C, and is exceptionally quiet. The main caveats are price — it sits at the premium end — and a warranty that’s only 2 years unless your installer is Vaillant-accredited and you meet the conditions for the 7-year version.
How much does a Vaillant heat pump cost installed?
Typically £9,000–£15,000 installed including the uniSTOR cylinder and controls, before the grant. After the £7,500 Boiler Upgrade Scheme that’s £1,500–£7,500 net; off-gas homes on oil or LPG can get £9,000 until March 2027. A 5–7kW unit for a typical 3-bed sits around £10,000–£12,000 before grant; radiator upgrades add £1,000–£3,000 if needed.
What sizes does the Vaillant aroTHERM plus come in?
Five sizes: 3.5kW, 5kW, 7kW, 10kW and 12kW. As a rough guide, 3.5–5kW suits a flat or small well-insulated house, 7kW a typical 3-bed semi, 10kW a larger 4-bed, and 12kW a big or older detached home. The right size comes from a room-by-room heat-loss survey, not the floor area — oversizing is the most common installer mistake.
What is the Vaillant heat pump warranty?
The standard warranty is 2 years. That extends to up to 7 years when the system is installed by a Vaillant-accredited installer (Advance Platinum or Renewable Partner), fitted with a Vaillant uniSTOR cylinder, registered within 30 days and serviced annually. Get the warranty length confirmed in writing on your quote — the difference between 2 and 7 years is entirely down to who fits it.
How noisy is a Vaillant heat pump?
Very quiet. The aroTHERM plus has a sound power rating of 51–58 dB(A) depending on size, and measures under 30 dB(A) at 3 metres in normal operation — roughly a quiet library. It comfortably meets the 42 dB permitted-development limit at a neighbour’s window, and it’s Quiet Mark certified. It’s one of the quietest units on the UK market.
Vaillant vs Octopus vs Daikin vs Mitsubishi — which heat pump is best?
Vaillant is the premium all-rounder: top efficiency, quietest, 75°C flow for old radiators, huge installer network. Octopus’s Cosy 6 is cheaper and well-designed but only comes through Octopus’s own installers. Daikin Altherma matches Vaillant on efficiency and offers a hybrid; Mitsubishi Ecodan is the UK’s best-seller and very robust but a little louder and less efficient at high flow temperatures. For most homes Vaillant or Mitsubishi; if budget rules, Octopus.
Figures are typical 2026 UK estimates for guidance only; efficiency, noise, warranty terms and prices vary by exact model, system design, installer accreditation and tariff — confirm the warranty length and model code in writing on your quote. Boiler Upgrade Scheme amounts (England and Wales) are as published by GOV.UK at the time of writing and can change. Always use an MCS-certified installer. Sources: Vaillant specifications and UK installer pricing.