Vaillant vs Daikin: Which Heat Pump Is Better?
Vaillant’s aroTHERM plus and Daikin’s Altherma 4 H are two of the best-known R290 heat pump ranges in the UK. Both reach 75°C for radiators. Daikin’s newer range leads on published efficiency and noise; Vaillant offers very small sizes and a familiar name among heating engineers.
- Manufacturer datasheets checked 25 October 2026
- Published data, not paid placement
- Independent UK research
Quick verdict
See the specificationsOn published data, Daikin’s Altherma 4 H is ahead on efficiency and noise for the sizes we compared. Vaillant’s aroTHERM plus is still a strong choice, especially for small homes that need as little as 3.5kW, and many UK heating engineers already know Vaillant from its boilers.
Choose Vaillant aroTHERM plus if…
- Your home needs a very small output: aroTHERM plus starts at 3.5kW
- Your installer is experienced with Vaillant and its uniTOWER
- You like the idea of a Cover & Care plan that bundles servicing and repairs
- You already use myVAILLANT or Vaillant controls
Choose Daikin Altherma 4 H if…
- You want the higher published efficiency at both 35°C and 55°C
- Noise is a concern: 45 dB(A) sound power at 8kW
- You want 5 years’ cover free through Stand By Me
- You want to link a large tank to solar thermal panels
Vaillant aroTHERM plus vs Daikin Altherma 4 H side by side
Both are monobloc-style heat pumps: the R290 refrigerant stays sealed in the outdoor unit and water pipes run into the house.
Vaillant
Vaillant aroTHERM plus (R290)
- 3.5, 5, 7, 10 and 12kW models
- Up to 75°C flow temperature
- Heats down to -25°C outside
- Pairs with Vaillant’s uniTOWER indoor unit or a separate cylinder
Best suited to: flats and small, well-insulated homes, and households who want servicing and repairs bundled into one yearly fee.
Daikin
Daikin Altherma 4 H (R290)
- 8, 10, 12 and 14kW, plus 4, 6 and 7kW versions added in 2026
- 70–75°C leaving water down to -15°C outside
- Runs down to -28°C
- Wall-mounted unit, integrated cylinder or ECH2O tank options
Best suited to: older homes keeping their radiators, tight plots near neighbours, and homes that want the highest published efficiency.
Product photos are for illustration and may not show the exact model compared.
Specifications compared
We compared the closest sizes each brand makes: Vaillant’s 7kW (VWL 75/6) and Daikin’s 8kW (EPSK08). Vaillant’s figures are from its aroTHERM plus installer’s quick guide; Daikin’s are from its EPSK08 technical data. Checked 25 October 2026. We have not tested these heat pumps ourselves.
| Specification | Vaillant aroTHERM plus | Daikin Altherma 4 H |
|---|---|---|
| Model compared | 7kW (VWL 75/6) | 8kW (EPSK08) |
| Refrigerant | R290 (propane) | R290 (propane) |
| Range of sizes | 3.5, 5, 7, 10 and 12kW | 4kW to 14kW |
| SCOP at 35°C (underfloor) | 4.36 (A+++) | 5.14 (A+++) |
| SCOP at 55°C (radiators) | 3.39 (A++) | 3.94 (A+++) |
| Maximum flow temperature | 75°C | 70–75°C (down to -15°C outside) |
| Lowest outdoor temperature | -25°C | -28°C |
| Sound power (heating) | 55 dB(A) | 45 dB(A) |
| App | myVAILLANT | Onecta |
| Longest manufacturer warranty | 2 years as standard; 5, 7 or 10 years through a paid Cover & Care plan that includes servicing (details) | 5 years free through Stand By Me; up to 7 with a Sustainable Home Expert, last 2 paid; 2 as standard (details) |
Ask installers which of these brands they fit, and get both quoted if you can. A good installer will size the heat pump from a room-by-room heat loss calculation, not from the size of your old boiler.
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Efficiency and winter performance
Daikin’s 8kW Altherma 4 H is rated at a SCOP of 3.94 at 55°C, against 3.39 for Vaillant’s 7kW aroTHERM plus. That is the largest gap of any pairing we have compared, and it is at the temperature most radiator systems need on cold days.
At 35°C Daikin is rated at 5.14 against 4.36 for Vaillant. The aroTHERM plus has been on sale for longer, and the Altherma 4 H is a newer design. Vaillant heats down to -25°C and Daikin to -28°C, so both handle UK winters.
These are lab ratings for an average European climate, on slightly different sizes. In a real home, good design matters far more: a heat pump running at a low flow temperature with weather compensation will beat a better-rated one that is set up badly. Our guide to heat pumps in winter explains what happens on the coldest days.
Noise
Daikin’s 8kW unit is rated at 45 dB(A) sound power, against 55 dB(A) for Vaillant’s 7kW (measured at A7/W55). A 10 dB difference is large and can make siting easier on a tight plot.
Vaillant offers a quiet mode for night-time running. Daikin’s larger 12 and 14kW units are rated at 52 dB(A), so the gap narrows at bigger sizes.
Sound power is measured at the unit itself. What you and your neighbours hear depends on distance, walls, fences and how hard the heat pump is working. Your installer must check the position against the MCS noise assessment for permitted development, so ask to see that calculation.
Hot water and indoor units
Both offer an indoor unit with the cylinder built in: Vaillant’s uniTOWER and Daikin’s integrated floor-standing unit. Daikin’s has a 180 or 230-litre stainless steel cylinder on a 595 × 625mm footprint.
Vaillant also pairs the aroTHERM plus with separate cylinders and a wall-hung hydraulic module. Daikin offers a wall-mounted unit with a separate cylinder and ECH2O tanks of 300 or 500 litres that can link to solar thermal panels.
Either way you will normally need a hot water cylinder. If you are coming from a combi boiler, our combi to heat pump guide explains how to find the space. Your installer will also set a regular legionella cycle.
Controls and apps
Vaillant uses the myVAILLANT app; Daikin uses Onecta, with voice control through Google Assistant and Amazon Alexa.
Both let you change temperatures and schedules remotely and see energy use. Daikin’s indoor unit has a 5-inch colour touchscreen with block-based scheduling.
We compare the apps in more depth in our best heat pump apps guide.
Warranty and installer network
Both start at 2 years. Daikin extends to 5 years free through Stand By Me, and up to 7 with a Sustainable Home Expert (last 2 paid). Vaillant extends to 5, 7 or 10 years through a paid Cover & Care plan.
Vaillant’s Cover & Care plans cost £295–£312 a year when we checked and include annual servicing, which you would pay for anyway. The heat pump must be under 18 months old to join.
Registration deadlines and servicing conditions apply. Our heat pump warranties guide sets them out brand by brand. In practice, the cover you get depends on the installer, so ask about their accreditation before comparing quotes.
Cost: what changes the price
Neither brand publishes UK installed prices, and the brand is rarely the biggest factor in what you pay. The Energy Saving Trust puts a typical air source heat pump installation at around £12,000 before grants, and the Boiler Upgrade Scheme takes £7,500 off for most eligible homes in England and Wales.
What actually moves the quote is the heat pump size your heat loss survey calls for, the cylinder, how many radiators need upgrading, pipework and electrical work. Installers also get different trade prices from different brands, so the same home can be quoted very differently for Vaillant and Daikin. The only reliable way to compare is to get quotes for both from MCS-certified installers, using the same heat loss figures. Our air source heat pump cost guide and grants guide cover the detail.
Which suits your home?
Older home keeping radiators
Daikin has the clearly higher published SCOP at 55°C, which matters most for radiator systems.
Flat or small home
Vaillant’s 3.5kW aroTHERM plus suits very low heat loss. Daikin now starts at 4kW.
Terrace or tight plot
Daikin’s 8kW is quieter on paper. Check the noise assessment for your exact spot.
Read what size heat pump do I need and get a proper heat loss survey. An oversized heat pump costs more and can short-cycle, which hurts efficiency.
Questions to ask installers
- Which of these two brands do you fit, and are you accredited with either one?
- What output does my heat loss calculation call for, and which model size would you fit?
- What is the SCOP at the flow temperature you are designing for, not just at 35°C?
- Where will the outdoor unit go, and does it pass the MCS noise assessment for that spot?
- Which cylinder or indoor unit would you use, and how much floor space does it need?
- How many years of manufacturer warranty will I actually get, and who registers it?
- Will you set up weather compensation and show me how to use the app before you leave?
Frequently asked questions
Is Vaillant or Daikin better?
On published data, Daikin’s Altherma 4 H is more efficient and quieter than the aroTHERM plus at the sizes we compared. Vaillant offers smaller sizes and is familiar to many UK installers. The best choice depends on your home and installer.
Which is quieter, Vaillant or Daikin?
Daikin’s 8kW Altherma 4 H is rated at 45 dB(A) sound power, against 55 dB(A) for Vaillant’s 7kW aroTHERM plus. Siting and quiet modes also make a big difference.
Is Vaillant’s Cover & Care worth it?
It can be if you value a fixed yearly cost. The plans include annual servicing, which most warranties require anyway. Compare the total over the full term with paying for services separately.
Do both work with existing radiators?
Yes. Both can reach 75°C, though they run more efficiently at lower temperatures, so your installer may suggest upgrading some radiators.
Can I get the Boiler Upgrade Scheme grant with either brand?
Yes, as long as an MCS-certified installer fits it and your home meets the scheme rules. The grant does not depend on the brand. See our grants guide for eligibility.
Sources and further reading
All sources checked on 25 October 2026. Specifications can change between model updates, so ask your installer for the datasheet of the exact model they quote.
- Vaillant: aroTHERM plus installer’s quick guide (technical data)
- Vaillant: aroTHERM plus installation and operating manual
- Vaillant: Heat pump Cover & Care packages
- Daikin: Daikin Altherma 4 H product page
- Daikin: EPSK08-10AW1 technical data
- Daikin: Daikin Altherma 4 EPSKS smaller models (January 2026)
- Daikin UK: Warranty
- Energy Saving Trust: Air source heat pumps
- GOV.UK: Apply for the Boiler Upgrade Scheme