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Vaillant aroTHERM plus vs Aira: Which Air Source Heat Pump Is Better? (2026)

Quick Verdict

Vaillant aroTHERM plus is the more efficient choice on its MCS-certified figures, with lower estimated running costs, while Aira has the longer standard warranty (5 yr (up to 15)).

Side-by-Side Comparison

FeatureVaillant aroTHERM plusAira
Installed price (before grant)£10,000 - £16,000Lower£14,229 - £19,500
After £7,500 grant (illustrative, England and Wales)£2,500 - £8,500£6,729 - £12,000
SCOP at 35°C (MCS)4.88Higher4.62
SCOP at 55°C (MCS)3.63Higher3.52
Largest size12kWLarger homes8kW
Standard warranty2 years5 yearsLonger
Longest warranty (conditions apply)7 years15 yearsLonger
Sound power (declared)55 dB(A)Lower56 dB(A)
Annual running cost (est., 45°C flow)~£620/yrLower~£645/yr
Refrigerant and max flowR290, up to 75°C flowHotter flow for radiatorsR290, up to 70°C flow
CountryGermanySweden
UK brandNoNo
Best forEfficiency-first buyers who want a proven, widely monitored unitHomeowners who want one company to handle design, installation and upkeep, and are happy to pay a monthly plan for 15-year cover

Specifications and pricing are indicative for the UK market as at June 2026. Post-grant figures illustrate the £7,500 Boiler Upgrade Scheme in England and Wales (Scotland uses the Home Energy Scotland grant and loan; Northern Ireland has no equivalent). Running costs assume ~10,000 kWh of heat a year at 26.32p/kWh (Ofgem cap average, October to December 2026; changes quarterly). Confirm current models and exact pricing with your MCS-certified installer.

Price Comparison

Vaillant aroTHERM plus starts from £10,000 installed before any support (indicative, June 2026), while Aira starts from £14,229. That is a difference of roughly £4,229 at the entry level. Vaillant aroTHERM plus is the more budget-friendly option upfront, though Aira may claw some of that back through running costs over time. Both are installed prices in GBP with 0% VAT (until 31 March 2027) already applied. In England and Wales the £7,500 Boiler Upgrade Scheme grant comes off both equally, so the pre-grant difference carries straight through: illustratively £2,500 - £8,500 for Vaillant aroTHERM plus and £6,729 - £12,000 for Aira out of pocket. Your MCS-certified installer claims the grant for you.

Efficiency Comparison

SCOP (seasonal coefficient of performance) is the key efficiency measure for a heating heat pump: the kilowatt-hours of heat you get per kilowatt-hour of electricity across a whole heating season. The figures here are MCS-certified, at 35°C flow (underfloor heating or large radiators) and 55°C (hotter radiators). Vaillant aroTHERM plus is certified at 4.88 at 35°C and 3.63 at 55°C, while Aira is certified at 4.62 and 3.52. On our estimates at a 45°C design flow temperature, the Vaillant aroTHERM plus costs about £25 a year less to run at Ofgem cap electricity prices, or approximately £250 over ten years. Real-world efficiency depends heavily on system design and flow temperature, which is what the MCS heat loss survey is for.

Warranty Comparison

Vaillant aroTHERM plus: 2 years as standard; up to 7 years with a Vaillant cylinder through a Platinum, Renewable Partner or myREWARDS installer. Register within 30 days and service annually. Aira: 5 years product warranty as standard (repair or replacement of the defective product only, no labour, conditional on servicing per Aira's handbook), plus a separate 6-year design and installation warranty. The 15-year Aira Guarantee (all parts, labour and maintenance) applies only with the All Inclusive Plan: free for the first year, then £19.90 a month. On standard terms, the Aira has the longer cover; the longer terms on either side depend on registration, servicing and the installer. Workmanship cover for the installation itself comes separately from your installer and should be in writing.

Noise Comparison

Noise matters in UK homes because the outdoor unit often sits close to a neighbour's boundary or a bedroom window. The like-for-like figure is the maker's declared sound power: the noise the unit itself emits. Vaillant aroTHERM plus: 55 dB(A). Aira: 56 dB(A). On paper the Vaillant aroTHERM plus is quieter by 1 dB(A). What a neighbour hears is much lower and falls with distance, and permitted development rules require the installation to meet the MCS noise standard at their window, so siting matters as much as the unit.

Cold-Weather and Retrofit Suitability

Two things decide how well a unit suits an older UK home: cold-weather output and flow temperature. Vaillant aroTHERM plus uses R290 refrigerant (up to 75°C flow), while Aira uses R290 (up to 70°C flow). The Vaillant aroTHERM plus's higher flow temperature helps existing radiators carry the load without a full re-pipe. Modern units hold useful output well below freezing. In the colder parts of the UK (Scotland and northern England in particular), frosty mornings trigger short defrost cycles that trim efficiency, so ask each installer for low-temperature output figures and take the MCS heat loss survey seriously; radiator upsizing is more commonly recommended there so the system can run at efficient flow temperatures.

Pros and Cons

Vaillant aroTHERM plus

Pros

  • Natural R290 refrigerant, up to 75°C flow
  • Quiet Mark certified (except the 10 kW)
  • Among the best measured real-world efficiency on heatpumpmonitor.org (median 4.06)

Cons

  • Standard warranty is 2 years; 7 needs a Vaillant cylinder and a partner installer
  • The /6 range is being replaced by a new model launched in June 2026
  • The 12kW outdoor unit is tall (1,565 mm) and heavy (194 kg)

Aira

Pros

  • Designed, sold, installed and maintained by Aira itself
  • R290 refrigerant, rated A+++ at 35°C
  • 15 years of parts, labour and maintenance cover on the All Inclusive Plan (first year free)
  • Publishes real-world UK performance data: average SPF 3.79 for November to March
  • Published pricing: £7,150 to £12,000 after the grant, per Aira

Cons

  • Only available through Aira, so there are no competing quotes on the same hardware
  • Without the paid plan, the product warranty is 5 years, parts only, with no labour
  • Aira's headline SCOP of 4.7 is above its MCS-listed figures (4.40 to 4.62)
  • Declared sound power of 56 dB(A) (8 kW), higher than the LG and NIBE models here (49 to 50 dB(A))

Which Should You Choose?

Choose Vaillant aroTHERM plus if...

  • You want a lower upfront cost (from £10,000 vs £14,229 before the grant)
  • You want the higher certified efficiency (SCOP 4.88 vs 4.62 at 35°C, MCS)
  • A lower declared sound power matters to you (55 vs 56 dB(A))
  • You want lower estimated annual running costs (~£620/yr vs ~£645/yr)
  • You are keeping existing radiators and want a higher maximum flow temperature (75°C vs 70°C)

Choose Aira if...

  • You want a longer standard warranty (5 yr (up to 15) vs 2 yr (up to 7))

The grant is the same, whichever brand you pick

Every air-to-water unit on this page qualifies for the £7,500 Boiler Upgrade Scheme grant in England and Wales (£9,000 for oil and LPG heated homes until March 2027) when fitted by an MCS-certified installer, who claims it on your behalf so it comes straight off the quote. Scotland uses the Home Energy Scotland grant of up to £7,500 (£9,000 rural and island) plus an optional interest-free loan; Northern Ireland currently has no equivalent scheme. 0% VAT on residential installations applies UK-wide until 31 March 2027. Accurate as at July 2026.

Boiler Upgrade Scheme guide →Gas boiler vs heat pump calculator →

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