The Vaillant aroTHERM Plus is an R290 air-to-water heat pump for heating and hot water. It is worth considering for a retrofit, but the exact model and system design matter more than the brand name. This review checks manufacturer documentation and buying conditions; it is not a hands-on performance test. Our heat-pump comparison covers alternatives.
Check the generation on your quote. The technical table below covers the VWL /6 aroTHERM Plus range. Vaillant also markets a new aroTHERM Plus in anthracite. Its headline noise figure must not be applied to older /6 units. Ask for the full product code, matching data sheet and included indoor equipment before comparing offers.
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- Check the full model code - older VWL /6 specifications and the new anthracite range are not interchangeable
- High-temperature capability does not guarantee a radiator-free retrofit - each room still needs a heat-loss and emitter check
- Compare noise on the same basis - sound power and sound pressure at a stated distance are different measurements
- Up to 7 years of guarantee cover is conditional - confirm the installer tier, cylinder package, registration and annual servicing
- Grant eligibility changes the net cost - the usual £7,500 BUS award can rise to £9,000 for qualifying oil/LPG homes without mains gas until March 2027
Key Specifications
The VWL /6 aroTHERM Plus range has five nominal outputs from 3.5kW to 12kW. Vaillant lists R290 refrigerant, flow temperatures up to 75°C and operation down to -25°C for this generation.
The dimensions below come from Vaillant’s VWL /6 specification table. Dimensions are the outdoor unit only, before the access and safety space required by its installation manual. Similar dimensions do not prove that two models have identical hardware or that one can be converted to another through software.
| VWL /6 model | Nominal output | Height × width × depth |
|---|---|---|
| VWL 35/6 | 3.5kW | 765 × 1,100 × 449mm |
| VWL 55/6 | 5kW | 765 × 1,100 × 449mm |
| VWL 75/6 | 7kW | 965 × 1,100 × 449mm |
| VWL 105/6 | 10kW | 1,565 × 1,100 × 449mm |
| VWL 125/6 | 12kW | 1,565 × 1,100 × 449mm |
Pricing
The installed price is quote-based. Compare the complete heating-system specification and the confirmed grant deduction, rather than treating a supply-only heat pump price as the final cost.
The official pages checked for this review do not provide a retail price list for each output. The previous trade-price and installed-price tables could not be substantiated from those sources, so they are not used as current Vaillant prices. Obtain itemised quotes for the same heat-loss requirement, cylinder size and installation scope.
What your quote should include
| Quote item | What to confirm |
|---|---|
| Outdoor unit | Full product code, generation, electrical supply and delivery |
| Controls and connectivity | Controller, sensors and compatible internet gateway for app use |
| Indoor equipment | Cylinder, hydraulic module, valves, pumps and any buffer or volumiser required by the design |
| Installation work | Base, pipework, insulation, drainage, electrical work and radiator changes |
| Handover | Commissioning, controls demonstration, certification and registration |
| Aftercare | Guarantee term, annual service cost and who handles faults |
Compare complete installed quotes
| Cost comparison | Ask the installer |
|---|---|
| Before-grant total | Does this cover every required component and all labour? |
| Grant deduction | Which scheme and amount have been confirmed for this property? |
| Amount you pay | Are optional extras, finance charges and any exclusions clear? |
| Radiator or cylinder changes | Which changes are required by the heat-loss calculation, rather than optional? |
BUS grant: the government lists £7,500 towards an eligible air-to-water heat pump. Until March 2027, an extra £1,500 is available where the property is heated by oil or LPG and has no mains-gas connection. This makes £9,000 in total for qualifying homes. An oil boiler alone does not establish eligibility for the uplift. Have the installer confirm the current property and system conditions.
For broader budgeting, see our heat-pump installation cost guide. A national estimate is a starting point for a survey, not a Vaillant price promise. Ask whether each quote includes the same heating design, controls, cylinder and aftercare.
Which aroTHERM Plus Size is Right for Your Home?
A search for a 7kW review or a 12kW price cannot establish which unit your home needs. The installer should calculate heat loss room by room and check the unit’s available output at the design outdoor temperature and chosen water temperature. Bedroom count and your existing boiler’s rating are not sufficient sizing methods.
| Sizing decision | Evidence to request |
|---|---|
| Heat demand | Room-by-room heat-loss calculation and design outdoor temperature |
| Available output | Capacity at the intended flow temperature during design winter conditions |
| Radiator suitability | Output of each emitter at the proposed water temperature |
| Mild-weather operation | Minimum output and control strategy when heat demand is low |
| Hot water | Cylinder capacity, recovery time and the household usage assumptions |
Ask the installer to explain the trade-off if two sizes are proposed. A higher nominal output is not automatically more efficient, quieter or better value. Compare the relevant data for each exact unit and include the indoor components in the decision. For more detail, see our heat-pump sizing guide.
Key Features
The aroTHERM Plus combines R290 refrigerant with weather-compensated heating controls and optional connected-app access. Existing radiators may be usable, but the installer must check their output at the proposed flow temperature.
R290 Natural Refrigerant
R290 is propane, a refrigerant with a low global warming potential. That is a useful feature, but it is not unique to Vaillant and does not prove that one complete heating system has the lowest lifetime emissions. Refrigerant choice, electricity use and installation quality all matter. Several competing ranges now use R290 too.
The refrigerant is flammable, so siting and service work must follow the model’s installation manual. Use a suitably qualified heat-pump installer. An F-gas credential alone does not establish competence with R290, and Vaillant’s guarantee terms do not say every installation must be carried out by a MasterTEC engineer.
75°C Flow Temperature for Retrofit
A higher maximum flow temperature gives the designer more options when assessing existing radiators. It does not remove the need to check each room. If an emitter cannot meet that room’s heat loss at the intended operating temperature, the design may need a larger radiator, a different emitter or improvements to the building fabric.
The published maximum is a capability limit, not a recommended everyday setting. Ask which flow temperature the design needs on the coldest day and how the controller reduces it in milder weather. The efficiency figure used for the running-cost estimate should match the proposed system, rather than a lower-temperature headline result.
Quiet Mark Certification
For VWL /6 units, Vaillant lists A7/W35 sound-power levels of 51, 51, 53, 58 and 58 dB(A) for the 3.5, 5, 7, 10 and 12kW models respectively. Its page identifies Quiet Mark accreditation for all except the 10kW model. Certification does not replace the installation’s planning noise assessment. The new generation has a different headline noise claim; use the data sheet for the quoted unit.
sensoCOMFORT Weather Compensation
Weather compensation adjusts the target water temperature as the outdoor temperature changes. The sensoCOMFORT controller provides heating and hot-water management, with remote access through compatible connected equipment. Ask the installer to demonstrate the weather-compensation settings and explain which adjustments you can make. This review does not promise a fixed percentage saving from the controller.
myVaillant App and Internet Gateway
The myVaillant user guide shows temperature adjustments, time programmes and energy-consumption graphs. These are useful for everyday control. They should not be treated as independent proof of whole-system efficiency without checking what the displayed figures include. The previous claim of a universal app calculation error was not supported by the primary documentation checked for this review.
App access needs compatible controls and an internet gateway. Have these listed explicitly in the quotation, including setup and the connection requirements. Do not assume every installer package contains the same accessories, and ask what happens to heating control if the internet connection is unavailable.
uniTOWER Integration
Vaillant describes the uniTOWER as an indoor package with a 190-litre cylinder and hydraulic components. Alternatively, the outdoor unit can be paired with a hydraulic station and a suitable cylinder. The right arrangement depends on hot-water demand and the available space. The product choice alone does not establish how many days an installation will take.
Cooling Mode
Vaillant says cooling requires an additional cooling module and advice from the installer. Ask whether the proposed model, controls and emitters support it, and have the complete cost itemised. This is not evidence of a universal software activation fee. The previous promise of compressor-free passive cooling has also been removed.
Installer responsibility and grant paperwork
Ask which MCS-certified business will be responsible for the installation, commissioning and BUS application. If another business provides certification or design support, get the arrangement in writing. Manufacturer training, warranty eligibility and MCS certification answer different questions; a training badge is not a substitute for confirming who is responsible for the completed system.
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Pros and Cons
The strengths are the range of system configurations, connected controls and suitability for a properly designed retrofit. The buying checks are the exact generation, emitter changes, total installed scope and conditions attached to the guarantee.
Efficiency and Running Costs
Running costs depend on heat demand, achieved seasonal efficiency and the electricity tariff. The examples below are calculations using stated assumptions, not measured Vaillant performance or a guaranteed annual bill.
A laboratory rating and an owner’s measured seasonal result describe different things. Compare published SCOP figures only when the climate, flow temperature and system combination match. For an operating installation, use heat output and electricity input measured over the same period and be clear about which pumps, controls and backup heaters are included.
Reading efficiency figures correctly
| Measure | Meaning | Comparison limit |
|---|---|---|
| COP | Efficiency at a stated operating point | Match the air and water temperatures; it is not a seasonal result |
| SCOP | Seasonal rating under specified test conditions | Match the climate, flow temperature and model combination |
| Measured seasonal performance | Heat delivered divided by electricity used over a season | Check the measurement boundary and include the relevant system inputs |
Estimated Annual Running Costs
The examples use Ofgem’s 26.32p/kWh average Direct Debit electricity rate for October to December 2026, which carries no VAT until 31 March 2027. The three efficiency assumptions are illustrative scenarios, not measured results or performance limits. Calculation: annual heat demand divided by seasonal efficiency, multiplied by £0.2632. Figures exclude standing charges, servicing, repairs and any electricity outside the stated measurement boundary. Use your actual tariff for a personal estimate.
| Illustrative demand | Annual Heat Demand | Efficiency assumption 4.0 | Efficiency assumption 3.6 | Efficiency assumption 3.0 |
|---|---|---|---|---|
| Lower demand | 8,000 kWh | £526/yr | £585/yr | £702/yr |
| Middle example | 12,000 kWh | £790/yr | £877/yr | £1,053/yr |
| Higher demand | 18,000 kWh | £1,184/yr | £1,316/yr | £1,579/yr |
App graphs help you spot changes in operation. For a measured efficiency assessment, ask the installer how heat and electrical consumption are recorded and which components are included. Do not infer a fixed app error from a mismatch between figures using different measurement boundaries.
How It Compares
Compare complete system proposals and exact product generations. A lower sound-pressure figure at a distance cannot be ranked against another unit’s sound-power rating, and a COP value cannot be substituted for SCOP.
The comparison below keeps the product distinctions that can be supported by current manufacturer pages. It does not rank brands by unverified trade prices, mixed noise measurements or assumed reliability. Follow the source links and ask each installer for the same design conditions so the quotations can be assessed fairly.
| Range | Verified distinction | What to check |
|---|---|---|
| Vaillant aroTHERM Plus | VWL /6 and new anthracite generation have separate specifications | Exact model code, sound-power data and cylinder package |
| Daikin Altherma 3 H HT F | High-temperature heating system with an integrated hot-water tank option | The published 65°C figure on this page is domestic hot water, not a heating-flow comparison |
| Mitsubishi Ecodan | Current range includes R290 models with flow temperatures up to 75°C | Do not treat older R32 Ecodan specifications as the whole range |
| Samsung EHS Mono HT Quiet | Manufacturer’s 35 dB(A) claim was measured 3m away in an anechoic room at 7°C | Not directly comparable with a sound-power rating |
| Grant Aerona³ R32 | Four nominal outputs: 6, 10, 13 and 17kW | Grant lists 5.40 SCOP at 35°C for the 13kW unit; match test conditions before comparing |
| NIBE F2050 | A current inverter-controlled air-source range | Ask for the model-specific data sheet; do not carry forward the old F2040 row |
There is no defensible quietest-brand or cheapest-brand winner in these mixed product pages. Siting, output, controls and the installer’s design can change the decision. For a shortlist, compare a written heat-loss calculation, the proposed flow temperature, the acoustic assessment and a complete installed quote for each option.
aroTHERM Plus vs the Rest of Vaillant’s Heat Pump Range
Vaillant’s UK site currently lists aroTHERM Plus, aroTHERM Split, flexoTHERM and aroSTOR among its heat-pump products. It also has a dedicated page for the new aroTHERM Plus. Use the product code to distinguish generations. A supplier’s informal name such as “Pro” is not enough to identify the unit or establish which specifications apply.
- aroTHERM Plus: monobloc air-to-water heating, with generation-specific specifications.
- aroTHERM Split: a split-system alternative; ask the designer how its installation requirements differ.
- flexoTHERM: a ground- or water-source option, requiring an appropriate heat-source design.
- aroSTOR: a heat-pump hot-water cylinder, rather than a direct substitute for a whole-home space-heating system.
Choose the system architecture before comparing accessories. Outdoor siting, indoor cylinder space and the available heat source determine which options are practical. A monobloc installation and a ground-source installation have different works and costs, so they should not be compared using outdoor-unit prices alone.
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Warranty
Vaillant advertises a two-year standard guarantee and up to seven years of extended cover. The longer term is conditional; the installer, cylinder package, registration and servicing requirements must all be checked.
The established aroTHERM Plus page limits the extended offer to Platinum and Renewable Partner installers registering the appliance with a Vaillant cylinder. Lower installer tiers or no qualifying cylinder can mean upgrade charges. The new-generation page describes a myREWARDS installer and Vaillant-cylinder condition. Get the exact term for your package confirmed before accepting a quote.
- Register the heat pump within 30 days under Vaillant’s guarantee terms.
- Keep the completed Benchmark logbook and proof of purchase.
- Arrange annual servicing by Vaillant or another suitably competent, qualified engineer.
- Confirm which cylinder and ancillary components have separate cover.
Vaillant’s terms say the guarantee becomes invalid if the heat pump is not serviced annually. They do not promise a fallback to two-year cover after a missed service. Late registration has a separate consequence: cover can revert to 12 months, with the start date depending on the paperwork. Annual servicing is not included in the guarantee price.
| Manufacturer | Published cover | Conditions to compare |
|---|---|---|
| Vaillant | 2 years standard; up to 7 years extended | Installer/cylinder eligibility, registration and annual servicing |
| Daikin | 2 years standard; 5 years after eligible registration; 7-year paid option | Stand By Me registration; qualifying installer for paid extension; annual maintenance |
| Grant Aerona³ | 7-year offer through eligible G1 installers | Installer must have completed Grant heat-pump training; terms apply |
| NIBE | 24 months standard, subject to manufacture-date limit; 7 years through eligible Pro installers | Registration within 28 days, trained installation, annual servicing and Benchmark records |
Compare the guarantee included in your actual quote, not the longest term advertised by the brand. Ask who pays for annual servicing, who attends a fault and whether a charge applies to the extension. Keep the registration confirmation and service records.
Who Should Buy the Vaillant aroTHERM Plus?
The aroTHERM Plus belongs on a retrofit shortlist where a survey confirms suitable heat loss, emitters and outdoor siting. Its higher flow-temperature capability gives the designer options, but does not guarantee lower bills or eliminate radiator work.
The most useful buying question is whether the proposed system meets your home’s requirements at an acceptable total cost. Our guide to whether heat pumps are worth it explains the wider financial decision. Consider installation quality and aftercare alongside the product specification.
Best For
- Retrofit projects with a completed survey. Existing radiators may be suitable where their output meets the room heat losses.
- Buyers who want connected heating controls. Confirm the compatible controller and internet gateway are included.
- Homes with suitable outdoor and cylinder space. Review the installation layout before ordering.
- Eligible oil/LPG homes without mains gas. The temporary BUS uplift can change the net installation cost, but running-cost savings still need a separate calculation.
Not Ideal For
- Buying solely on a headline noise number. The correct model and acoustic assessment matter more than a brand ranking.
- Choosing from bedroom count alone. Ask for heat-loss and emitter calculations before agreeing the output.
- Assuming seven years of cover is automatic. Confirm all package and servicing conditions in writing.
- Expecting cooling without additional design work. Check the required module, emitters and controls with the installer.
Our Verdict
The aroTHERM Plus is worth shortlisting for a retrofit, but the system design matters as much as the heat pump. Ask for a heat-loss survey, a model-specific quote and confirmation of the controls and warranty included. The myVaillant app needs compatible connected controls.
Our editorial rating remains 8.5/10. The case for the aroTHERM Plus is its range of heating-system options and controls, provided the installer produces a sound design. The rating is an editorial judgement, not a measured efficiency result or a guarantee that it will beat every alternative on cost or noise.
Use our free Heat Pump Running Cost Calculator to get a personalised cost estimate based on your specific requirements.
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