Vaillant Arotherm Heat Pump Review: R290, COP, Price, UK Guide
Vaillant is a name that millions of UK homeowners already know from their gas boilers. The German manufacturer has been in the heating industry since 1874, and their transition into heat pumps has produced one of the most technically advanced domestic models on the market: the Arotherm Plus. What sets it apart is R290 (propane) refrigerant with a global warming potential of just 3 and the ability to deliver flow temperatures up to 75°C — meaning it can work with existing radiators in many older UK homes.
This review examines the Vaillant Arotherm Plus in detail, covering real-world performance, pricing, warranty, and whether it deserves its growing reputation as one of the best heat pumps available in Britain. For a broader perspective, see our complete UK brand comparison.
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The Arotherm Plus Range
The Arotherm Plus is Vaillant's flagship air-to-water heat pump for the UK domestic market. It is a monobloc design with all refrigerant components contained within the outdoor unit.
R290 Refrigerant: Why It Matters
The Arotherm Plus's most significant differentiator is R290 (propane) refrigerant. While most domestic heat pumps use R32 (GWP 675), Vaillant has moved to R290 (GWP 3) across their range. EU and UK regulations are progressively tightening restrictions on high-GWP refrigerants, so an R290 system is the most future-proof choice you can make today.
R290 is mildly flammable, requiring certain clearance distances from building openings — at least 750mm depending on charge size. This is rarely problematic in practice but needs confirmation during the site survey.
High Flow Temperature: 75°C Capability
The Arotherm Plus can deliver flow temperatures up to 75°C — one of the highest available in any domestic air source heat pump. This means older homes with standard radiators can often use the Arotherm Plus without replacing radiators. However, efficiency drops significantly at 75°C (COP around 2.0–2.3), so the system is most efficient at 35–45°C where COP reaches 3.5–4.0.
Real-World COP Performance
These figures are among the best in the industry. Weather compensation — where the system automatically reduces flow temperature as outdoor temperatures rise — should always be enabled for maximum efficiency. Understanding your running costs depends heavily on which flow temperature your system operates at.
Indoor Components and Controls
The Arotherm Plus integrates with Vaillant's uniTOWER Plus (integrated cylinder and hydraulic station in 190L or 290L), the sensoCOMFORT wall controller, and the myVAILLANT app for remote monitoring and control. The controls are intuitive and among the better interfaces on the market.
Noise Levels
The Arotherm Plus achieves 38 to 48dB at one metre depending on model size. The smaller 3.5kW and 5kW models are particularly quiet at 38–40dB. The inverter-driven compressor modulates output smoothly, keeping noise low during normal partial-load operation.
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Pricing
| Model Size | Unit Price | Total Installed | After BUS Grant |
|---|---|---|---|
| 3.5–5kW | £4,000–£5,000 | £9,000–£11,000 | £1,500–£3,500 |
| 7–10kW | £5,000–£6,000 | £11,000–£13,000 | £3,500–£5,500 |
| 12–15kW | £6,000–£7,000 | £13,000–£15,000 | £5,500–£7,500 |
Vaillant is positioned at the premium end — typically £500 to £1,500 more than a comparable Samsung or Mitsubishi installation. The Boiler Upgrade Scheme grant of up to £7,500 brings out-of-pocket costs down substantially. Pairing with solar panels can offset the electricity costs further.
Vaillant vs Competitors
Vaillant vs Daikin
Daikin Altherma 3 achieves similar SCOP and lower noise on some models. Vaillant wins on refrigerant (R290 vs R32), max flow temperature (75°C vs 55/70°C), and controller quality. Daikin has a longer heat pump track record.
Vaillant vs Mitsubishi Ecodan
Mitsubishi Ecodan has the largest UK installed base and the best reliability data. Vaillant offers higher flow temperatures, R290, and higher SCOP. Mitsubishi is typically cheaper.
Vaillant vs Bosch Compress 7400i
Bosch also uses R290 with similar high flow temperatures. Vaillant has slightly higher SCOP and a more established installer network. Both are strong environmental choices.
Pros and Cons
Pros
- R290 refrigerant — lowest environmental impact, most future-proof
- 75°C max flow temperature — works with existing radiators in older homes
- Excellent SCOP — up to 4.65 at 35°C
- Massive UK installer network from boiler heritage
- High-quality sensoCOMFORT controller and myVAILLANT app
- Wide capacity range from 3.5kW to 15kW
Cons
- Premium pricing — typically the most expensive mainstream option
- R290 clearance distances may restrict placement in tight spaces
- Heavier outdoor unit than some R32 alternatives (112–175kg)
- 7-year max extended warranty — shorter than Daikin's 10-year option
Frequently Asked Questions
Is the Vaillant Arotherm Plus a good heat pump?
Yes. It is one of the best domestic air source heat pumps available in the UK. The combination of R290 refrigerant, high flow temperatures, excellent SCOP, and Vaillant's UK support network makes it a strong choice for most UK homes.
How much does a Vaillant heat pump cost installed?
Total installed costs typically range from £9,000 to £15,000 before the BUS grant. After the grant, homeowners typically pay £2,500 to £8,000.
Is the R290 refrigerant safe?
Yes. R290 (propane) is mildly flammable but the small quantities used and outdoor installation mean the risk is negligible. The system has safety features to prevent leaks and the refrigerant is contained entirely within the outdoor unit.
Can the Vaillant Arotherm work with my existing radiators?
In many cases, yes. The 75°C maximum flow temperature means it can deliver enough heat through existing radiators in most homes. Running at lower flow temperatures is more efficient, so your installer should calculate whether existing radiators are large enough.
What is the warranty on a Vaillant Arotherm Plus?
5 years standard, extendable to 7 years through a Vaillant Advance installer. Regular annual servicing is required.
How does Vaillant compare to other brands?
Vaillant sits at the premium end. It matches or beats most competitors on efficiency and exceeds all on environmental credentials with R290 refrigerant. The main trade-off is price. See our full brand comparison guide for details.
Is Vaillant right for your home?
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Vaillant and the Transition to Renewable Heating
Vaillant's shift from gas boilers to R290 heat pumps represents the broader UK energy transition. The Arotherm Plus qualifies for the Boiler Upgrade Scheme, and when paired with solar PV systems, can deliver near-zero carbon home heating. Whether you are comparing against a gas boiler or weighing up brands, Vaillant's environmental credentials are unmatched in the mainstream market.