Vaillant’s flagship heat pump is quiet, efficient and unusually comfortable around older radiators. But is it worth the premium price?
The Vaillant aroTHERM plus is one of the best-known air source heat pumps in the UK.
That is partly because Vaillant has been keeping British homes warm for donkey’s years, and partly because the aroTHERM plus has some genuinely impressive numbers attached to it.
A SCOP of up to 5.03. Flow temperatures up to 75°C. Quiet Mark certification. Natural R290 refrigerant. Outputs ranging from a dainty 3.5kW to a considerably less dainty 12kW.
Lovely collection of numbers.
But specifications alone do not heat your home efficiently. The system still needs to be correctly sized, properly installed and paired with suitable radiators or underfloor heating.
So, is the aroTHERM plus worth buying, or is it just an expensive grey box with a very confident marketing team?
Let’s get into it.
Ready to make your home more energy-efficient and cut down on your heating bills? Get a heat pump quote today.
Vaillant aroTHERM plus review: the quick verdict
The Vaillant aroTHERM plus is a premium air source heat pump that is particularly well suited to UK retrofit projects.
Its ability to produce higher flow temperatures gives installers more flexibility when working with existing radiator systems, while its low noise output makes it a sensible option for terraces, semis and homes with nearby neighbours.
It is not the cheapest heat pump available, and its standard two-year guarantee looks a little underwhelming until extended-cover conditions are met.
However, its efficiency, controls and established UK support network make it a very strong all-rounder.
Our scores:
Category | Heatable score |
Reliability | 4.5/5 |
Performance and efficiency | 5/5 |
Warranty | 4/5 |
Price and value | 4/5 |
Overall | 4.5/5 |
In short: it is the German estate car of heat pumps. Sensible, refined and unlikely to start demanding attention halfway up the M6.
Key Vaillant aroTHERM plus specifications
Feature | Vaillant aroTHERM plus |
Heat pump type | Air-to-water monobloc |
Avaialble outputs | 3.5kW, 5kW, 7kW, 10kW and 12kW |
Maximum flow temperature | Up to 75°C |
Maximum advertised SCOP | Up to 5.03 |
Energy rating | Up to A+++ at 35°C |
Refrigerant | R290 |
Refrigerant GWP | 3 under the manufacturer’s published specification |
Controls | sensoCOMFORT and optional myVAILLANT app connectivity |
Standard guarantee | 2 years |
Extended guarantee | Up to 7 years, subject to installer, cylinder and registration conditions |
Typical fitted price | Approximately £9,000–£15,000 before grants |
Government grant | £7,500 for eligible homes, or up to £9,000 for certain off-grid oil and LPG properties |
What is the Vaillant aroTHERM plus?
The aroTHERM plus is an air-to-water heat pump.
It absorbs heat from the outside air and uses a compressor to raise its temperature before transferring that energy into your central heating and hot-water system.
Yes, it still works when it is cold outside. There does not need to be a small Mediterranean climate taking place behind your bins.
It is a monobloc system, meaning the refrigerant circuit is sealed inside the outdoor unit. Water pipes then connect the heat pump to the equipment inside your home.
In most installations, that indoor equipment will include:
A hot-water cylinder
Heating controls
Pumps and valves
Potentially a buffer vessel or volumiser
Any upgraded radiators required by the system design
This is important if you currently have a combi boiler. A heat pump normally needs stored hot water, so you will need to find room for a cylinder indoors.
Vaillant aroTHERM plus sizes
The aroTHERM plus is available in five nominal outputs:
Model size | Likely application |
3.5kW | Very efficient small homes, flats or low-energy new builds |
5kW | Smaller houses and well-insulated two or three-bedroom properties |
7kW | Medium-sized family homes |
10kW | Larger properties or homes with greater heat loss |
12kW | Large houses and properties with substantial heating demand |
These are only rough examples.
Heat pumps should be selected using a room-by-room heat-loss calculation - not the number of bedrooms, the output of your old boiler or an installer standing in the driveway and squinting thoughtfully at the roof.
A well-insulated four-bedroom home could need less output than a draughty three-bedroom property. Oversizing can also cause cycling, reduce efficiency and shorten component life.
For more detail, read our guide to choosing the right heat pump size.
Reliability: 4.5/5
Vaillant is an established heating manufacturer with a substantial UK installer, service and spare-parts network.
That matters.
A heat pump could be capable of warming Buckingham Palace using the breath of a field mouse, but it is not much use if nobody within 200 miles knows how to service it.
The aroTHERM plus is also a mature product rather than a newly launched experiment.
Its monobloc design keeps the complete refrigerant circuit inside the factory-sealed outdoor unit, reducing the amount of refrigerant work required inside the property.
Vaillant’s product-specific Feefo page displayed almost 200 verified aroTHERM plus reviews when checked in July 2026.
Feedback highlighted by Vaillant includes positive reports about ease of use, quiet operation and maintaining a warm home during sub-zero weather.
As always, reviews should be treated with some perspective. The system’s reliability and comfort will depend heavily on the quality of its design and installation.
A brilliant heat pump installed badly is still a badly installed heat pump.
Performance and efficiency: 5/5
Performance is where the aroTHERM plus earns its premium badge.
Vaillant publishes a maximum SCOP of 5.03 under specific test conditions.
In simple terms, that means the system can produce just over five units of heat for every unit of electricity consumed.
That does not mean every aroTHERM plus will achieve a SCOP of 5.03 in every home.
Real-world efficiency depends on:
Outdoor temperatures
Required flow temperature
Radiator or underfloor-heating design
Heat loss
Hot-water use
Controls and weather compensation
Installation and commissioning quality
The lower the required flow temperature, the more efficiently a heat pump will generally operate.
A well-designed system running at 35°C to 45°C could produce excellent seasonal results. A system constantly being asked to fire out 65°C or 70°C water will consume more electricity.
The 75°C flow temperature
One of the aroTHERM plus’s headline features is its ability to reach a flow temperature of up to 75°C.
That makes it more flexible than many conventional low-temperature heat pumps, particularly when retrofitting an older property with existing radiators.
However, 75°C should be viewed as extra capability - not the everyday target.
It is a bit like the top speed on your car. Reassuring to know it is there, but you probably should not use it to collect a prescription.
A professional installer should still design the system to operate at the lowest practical flow temperature. Some radiators may need replacing or upsizing to achieve this.
What does it cost to run?
Using the average July–September 2026 Direct Debit rates quoted in Heatable’s energy price-cap guide:
Electricity costs approximately 26.11p per kWh.
Gas costs approximately 7.33p per kWh.
A heat pump achieving a SCOP of 3.5 produces useful heat for roughly 7.5p per kWh.
At a SCOP of 4, that falls to approximately 6.5p per kWh.
A 90%-efficient gas boiler produces useful heat for approximately 8.1p per kWh.
These are simplified comparisons and exclude standing charges. Energy rates also change every three months.
The point is not that an aroTHERM plus is guaranteed to slash every gas-heated home’s bills.
It is that a well-designed system can be highly competitive, while a poorly designed system running at unnecessarily high temperatures can quickly ruin the maths.
Find more examples in our guide to heat pump costs and running expenses.
How quiet is the Vaillant aroTHERM plus?
Very quiet, provided the model is correctly selected and positioned.
Vaillant’s current technical information lists sound power figures from approximately 48dB(A), depending on the model and operating condition.
It also states that sound pressure can fall below 30dB(A) at a distance of three metres under specified conditions.
Several aroTHERM plus outputs have received Quiet Mark certification, although certification and sound levels vary across the range.
In normal-person language, the smaller models should not sound like someone permanently drying their hair behind your fence.
You will hear the fan and compressor when standing close to the outdoor unit, particularly during colder weather or hot-water heating. Correct placement, anti-vibration measures and the installer’s acoustic assessment remain important.
Controls and smart features
The aroTHERM plus can be paired with Vaillant’s sensoCOMFORT controller.
This provides weather compensation, adjusting the system’s flow temperature as outdoor conditions change.
Rather than blasting out the same temperature all day, the heat pump supplies only as much heat as the property needs.
It is a small difference with a potentially large effect on efficiency.
With the myVAILLANT connect internet gateway, homeowners can also use the myVAILLANT app to:
Adjust temperatures
Set heating and hot-water schedules
Monitor the system
Make changes remotely
The gateway and associated controls may not be included in every quotation, so check exactly what your installer has specified.
R290 refrigerant: why it matters
The aroTHERM plus uses R290, better known as propane, as its refrigerant.
Before you picture a camping stove cable-tied to the patio, relax.
The refrigerant is contained within a sealed outdoor circuit, and the installation must follow the manufacturer’s siting and safety requirements.
R290 has a very low global-warming impact compared with many older refrigerants. It also performs well at higher temperatures, helping the aroTHERM plus achieve its maximum 75°C flow temperature.
This makes the refrigerant one of the product’s biggest technical advantages, particularly for future-proofing and retrofit work.
Warranty: 4/5
The Vaillant aroTHERM plus comes with a two-year standard guarantee.
That is adequate, although hardly an excuse to release balloons from the ceiling.
The guarantee can be extended to as much as seven years when the system meets Vaillant’s conditions.
These include installation and registration through an eligible Vaillant partner and, for certain offers, installation with a qualifying Vaillant cylinder. Annual servicing and other terms may also apply.
Always ask your installer to confirm:
The exact guarantee period included
Which components are covered
Whether labour is included
The servicing requirements
Who will register the system
Whether the cylinder and controls have separate cover
“Up to seven years” and “seven years included with this quotation” are not automatically the same thing.
Vaillant aroTHERM plus cost: 4/5
A complete aroTHERM plus installation will typically cost around £9,000 to £15,000 before grants.
The final price depends on far more than the outdoor unit. It can include:
A suitable hot-water cylinder
New or upgraded radiators
Larger pipework
Electrical work
Heating controls
System cleaning
Groundwork and mounting
Design, commissioning and certification
A straightforward installation in a reasonably heat-pump-ready home may sit near the lower end.
A larger property requiring several radiator and pipework upgrades can comfortably exceed it.
The aroTHERM plus is not a budget heat pump, but its higher-temperature capability, strong efficiency and UK support network help justify the premium.
Boiler Upgrade Scheme grants
Eligible homeowners in England and Wales can currently receive £7,500 towards an air-to-water heat pump through the Boiler Upgrade Scheme.
Until March 2027, an additional £1,500 is available where both of the following apply:
The property is heated by oil or LPG.
The property does not have a mains-gas connection.
That brings the grant to £9,000 for qualifying off-grid properties.
The grant is installer-led, so an MCS-certified installer applies and deducts the approved amount from the price.
You do not receive £9,000 in your bank account to spend on a heat pump, a hot tub and an unnecessarily large ornamental gong.
Hybrid heat-pump systems are not eligible for the BUS.
Check the latest rules on the official Boiler Upgrade Scheme website.
Installation and space requirements
The smaller aroTHERM plus units measure approximately 1,100mm wide, 765mm high and 450mm deep.
The 10kW and 12kW models are taller, at roughly 1,565mm high, 965mm wide and 450mm deep.
You will also need suitable clearance around the unit for airflow and maintenance. Its location must satisfy noise, drainage, planning and R290 safety requirements.
Inside, most homes will need a hot-water cylinder. Vaillant offers matching uniSTOR cylinders, although the precise cylinder size should reflect the household’s hot-water demand.
Installation commonly takes between two and five days, depending on how much work the existing heating system needs.
Expect a proper installation process to include:
A room-by-room heat-loss calculation.
Radiator and pipework assessment.
Outdoor-unit siting and noise calculations.
Hot-water-cylinder sizing.
Electrical assessment.
Installation and system cleaning.
Commissioning and control setup.
MCS, warranty and grant paperwork.
If the entire survey consists of somebody asking how many bedrooms you have, it is not a survey. It is small talk.
Vaillant aroTHERM plus pros and cons
Pros:
Excellent maximum SCOP of up to 5.03.
Flow temperatures up to 75°C provide added retrofit flexibility.
Broad 3.5kW to 12kW range.
Quiet Mark certification on eligible models.
Low-GWP R290 refrigerant.
Suitable for radiators and underfloor heating.
Strong UK installer and support network.
Smart controls and weather compensation available.
Up to seven years of guarantee cover when the relevant conditions are met.
Eligible installations can access the Boiler Upgrade Scheme.
Cons:
More expensive than several entry-level heat pumps.
Only a two-year standard guarantee.
The full seven-year guarantee is conditional.
A hot-water cylinder will usually be required.
Some homes will still need radiator or pipework upgrades.
Higher flow temperatures reduce efficiency when used regularly.
Controls, gateway and cylinder packages can make quotations difficult to compare.
Larger 10kW and 12kW units need considerably more outdoor space.
Vaillant aroTHERM plus vs the competition
Heat pump | Main advantage | Potential drawback | Best suited to |
Vaillant aroTHERM plus | High-temperature capability and strong retrofit credentials | Premium price and conditional extended guarantee | Older homes, radiator systems and premium retrofits |
Mitsubishi Ecodan | Proven UK track record and very quiet models | Cylinder space and model choice can be confusing | Homeowners prioritising reliability and low noise |
Daikin Altherma | Broad product range and polished controls | Some systems can be expensive | New builds and carefully designed premium systems |
Samsung EHS | Competitive pricing and smart technology | Support experience can depend more heavily on the installer | Buyers seeking modern features at a lower price |
Grant Aerona | Competitive package and extended guarantee options | Less sophisticated control ecosystem | Value-focused rural and off-grid installations |
There is no universal best heat pump.
The Vaillant’s special talent is combining premium efficiency with a maximum temperature that gives installers more options in existing homes.
Read our best heat pump brands guide for a wider comparison.
Who is the aroTHERM plus best for?
The Vaillant aroTHERM plus should make your shortlist if:
You own an existing property with radiators.
You want a premium heat pump from an established manufacturer.
Noise is an important consideration.
You want app-based controls and weather compensation.
Your home needs more retrofit flexibility than a basic low-temperature model provides.
You are replacing oil, LPG or direct electric heating.
You have room for an outdoor unit and hot-water cylinder.
You value long-term efficiency more than finding the cheapest initial quotation.
Who might want to look elsewhere?
Another model could be a better fit if:
Your main priority is the lowest possible upfront price.
You cannot accommodate a hot-water cylinder.
Outdoor space is extremely restricted.
Your home needs extensive fabric, pipework and radiator upgrades that you do not want to undertake.
You want a longer unconditional standard warranty.
You are expecting boiler-style bursts of heat rather than steady, lower-temperature heating.
Not sure whether your property makes sense? Read our guide: Is my home suitable for a heat pump?.
The Heatable verdict
The Vaillant aroTHERM plus is one of the strongest premium retrofit heat pumps on the UK market.
It is quiet, highly efficient and backed by a manufacturer with an established UK presence. Its 75°C maximum flow temperature provides useful flexibility in older homes, although the system should still be designed to run cooler whenever possible.
The downsides are mostly financial. It carries a premium price, its standard guarantee is only two years, and the cost can grow if your home needs a cylinder, larger radiators or pipework upgrades.
But with the right design?
It is an excellent bit of kit.
The aroTHERM plus is not a miracle box that makes every draughty Victorian terrace cost 14p a year to heat. It is, however, a sophisticated and dependable heat pump that can produce very good results in new and existing homes.
Our final score: 4.5 out of 5.
Get the specification and installer right, and the Vaillant aroTHERM plus should keep quietly extracting heat from the British weather while you remain indoors, refusing to make eye contact with February.
Very sensible.
Next Steps For Your Heat Pump Journey:
When planning to install a heat pump for your home, there are several important factors to consider. Make sure to refer to the following guides to help you make informed decisions:
To dive deeper into these topics, head over to our advice section or check out our YouTube channel to learn more.
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