The short answer
Daikin (Altherma range) and Vaillant (aroTHERM range) are both widely fitted, reputable air source heat pump brands in the UK. Both offer monobloc units across the output range most homes need, both reach a SCOP of around 3 to 4, and both have recent ranges using R290 refrigerant, which supports higher flow temperatures useful for retrofits. Daikin is one of the world's largest manufacturers with a very broad range and large installer network; Vaillant is a long-established heating brand with strong UK support and a well-regarded aroTHERM line. Neither is objectively 'better' — the differences are in specific model specs, warranty terms, noise figures and your installer's familiarity with the brand. As with any heat pump, correct sizing and installation quality by an MCS-certified installer affect real-world performance far more than the choice between these two brands.
Daikin and Vaillant come up constantly in heat pump quotes. Both are solid choices, so the useful question is how they differ in practice and what should actually drive your decision.
Daikin vs Vaillant
- Daikin rangeAltherma (monobloc and split)
- Vaillant rangearoTHERM (monobloc)
- Typical SCOPAround 3.0 to 4.0 (both)
- R290 modelsAvailable in recent ranges (both)
- Decisive factorSizing and installer quality
What each brand offers
Daikin is one of the largest HVAC manufacturers in the world. Its Altherma air source range covers monobloc and split configurations across a wide span of outputs, with a large UK installer base and well-developed support. The breadth of the range means there is usually a Daikin model to match most domestic heat losses.
Vaillant is a long-standing European heating manufacturer with a strong UK presence. Its aroTHERM air source range is widely installed, with recent generations using R290 refrigerant to reach higher flow temperatures — helpful when retaining existing radiators. Vaillant's heating heritage means good integration with its own cylinders and controls.
Both brands are mainstream, well-supported choices. The meaningful comparison is not 'which brand wins' but how a specific model from each fits your property and system design.
How they compare on the practical specs
On the headline measures the two are close. The differences worth checking are model-specific rather than brand-wide, so always compare the exact units being quoted.
| Factor | Daikin (Altherma) | Vaillant (aroTHERM) |
|---|---|---|
| Configurations | Monobloc and split | Monobloc |
| Typical SCOP | ~3.0–4.0 | ~3.0–4.0 |
| R290 refrigerant | Available in recent models | Available in recent models |
| Output range | Very broad | Broad |
| UK support/network | Large | Strong |
| What to verify | Exact model spec, warranty, noise | Exact model spec, warranty, noise |
Indicative comparison for guidance, not a ranking. Sources: manufacturer data; MCS; Which?.
Flow temperature, noise and hot water
Three model-level details are worth digging into when comparing a Daikin and a Vaillant quote, because they affect comfort and efficiency more than the brand name does.
Flow temperature determines how well the unit suits your radiators. R290 models from both brands can reach higher flow temperatures, which helps when retaining existing radiators in a retrofit; lower flow temperatures give higher efficiency where the emitters are sized for it. Check the maximum and the efficiency at the temperature your system is designed around.
Noise matters where the outdoor unit sits near a boundary or below a bedroom window. Both brands publish a sound power level for each model — compare those figures directly rather than assuming one brand is quieter. Correct siting by the installer also makes a large difference, and planning rules in England include noise conditions for permitted development.
Hot water performance depends on the cylinder and how the heat pump reheats it. Both Daikin and Vaillant offer matched cylinders and controls; using the manufacturer's own cylinder and controls can simplify commissioning and warranty. Ask how each system handles hot water recovery and whether a legionella cycle is included.
What should actually decide it
Because both brands are reliable and similarly efficient, the decision should follow the system design, not lead it. Start with an MCS-certified installer's heat loss survey, which defines the output you need and narrows each brand to a suitable model.
From there, weigh the factors that vary in real life: warranty length and terms, published noise figures (important near boundaries or bedrooms), UK parts availability, and whether your installer regularly fits and commissions that brand. An installer who knows a brand well will design, set up and commission it more effectively, which has a bigger effect on efficiency and reliability than the badge. In short, either Daikin or Vaillant can give an excellent system — the quality of the sizing and installation is what determines the outcome.
Frequently asked questions
Is Daikin or Vaillant better for a heat pump?
Neither is objectively better. Daikin's Altherma and Vaillant's aroTHERM ranges are both reputable, widely fitted, and reach a similar SCOP of around 3 to 4, with R290 models in their recent ranges. The right choice depends on the specific model that suits your heat loss, the warranty and noise figures, and your installer's familiarity with the brand.
Do both use R290 refrigerant?
Recent ranges from both brands include R290 models. R290 has a very low global warming potential and supports higher flow temperatures, which helps when keeping existing radiators in a retrofit. Older units may use other refrigerants, so check the exact model being quoted if R290 matters to you.
Does the brand or the installer matter more?
The installer. A correctly sized, well-designed and properly commissioned system from either Daikin or Vaillant will outperform a poorly designed install of either brand. Choose an MCS-certified installer who carries out a proper heat loss survey first, and let the brand and model follow from that design.
Sources & further reading
- MCS — find a certified installer
- Which? — heat pump brands and reviews
- Energy Saving Trust — air source heat pumps
Figures on this page are typical UK ranges drawn from published sources and depend on your specific home. They are guidance, not a quotation or guaranteed saving.