The air source heat pump market in the UK has matured rapidly since the Boiler Upgrade Scheme launched in 2022. Dozens of brands now hold MCS certification, but a handful consistently dominate installer recommendations and independent reviews. This guide compares the six strongest contenders for a UK residential install in 2026 — covering what the specs actually mean, what you will pay, and how each brand's smart controls stack up.
What to look for when choosing an ASHP brand
SCOP is the key efficiency figure. Seasonal Coefficient of Performance (SCOP), standardised under EN 14825, measures how many kilowatt-hours of heat a unit delivers per kWh of electricity consumed across the full heating season. A SCOP of 4.0 means four units of heat for every unit of electricity. Manufacturer figures are measured at the lab-standard A7/W35 condition (7 °C ambient, 35 °C flow temperature). Real-world UK field data — including the BEIS Electrification of Heat trial — shows a typical field median of around 2.8–3.1 SCOP, driven by legacy radiators and higher-than-optimal flow temperatures. At the UK's current electricity-to-gas price ratio of roughly 4–4.7:1, you generally need a real-world SCOP above 3.5 for the running costs to match a modern condensing gas boiler.
Noise levels matter more than many buyers expect. Sound power levels (dB(A)) quoted in specs are measured at source; sound pressure at 1 metre is roughly 10 dB lower. Most UK planning authorities and the updated MCS 020 standard (in force from 28 May 2026) require noise levels to stay below 42 dB(A) at the nearest neighbouring property. In practice, an outdoor unit below 50 dB(A) sound power is rarely a problem on a detached or semi-detached property.
Warranty tiers reward installer choice. Every brand listed below offers a base 2-year warranty, extended to 5–7 years if you use a brand-accredited installer. Choosing an accredited engineer is therefore doubly important: it qualifies you for the extended warranty and is required for the heat pump grants UK Boiler Upgrade Scheme grant of £7,500.
The UK's best air source heat pump brands compared
1. Vaillant aroTHERM Plus — best all-round SCOP
SCOP up to 5.03 (A7/W35); 48 dB(A) (Quiet Mark); installed £9,000–£20,000 before grant. The aroTHERM Plus is consistently cited as the most efficient domestic ASHP available in the UK. Its R290 (propane) refrigerant has a global warming potential of just 3 — the lowest of any mainstream UK heat pump — and the 3.5–12 kW models carry Quiet Mark accreditation at 48 dB(A) sound power. The 75 °C maximum flow temperature means it can run legacy radiator systems without upgrades in most mid-century properties, which distinguishes it from several rivals that top out at 55–65 °C on standard models.
Smart control is via the myVaillant app (iOS/Android), paired with the sensoCOMFORT wired controller. One known limitation: the app's live efficiency readout significantly underreports actual COP (field measurements often show ~3.5 COP while the app displays ~2.0). The active cooling feature requires a paid upgrade of around £500. Warranty is 2 years standard, rising to 7 years when installed by a MasterTEC-approved engineer and maintained with annual services.
2. Mitsubishi Ecodan — largest UK installer network
SCOP 4.49–4.62 (R290 PUZ-WZ range); from 42 dB(A) (Quiet Mark); installed £9,000–£15,000 before grant. Mitsubishi's Ecodan holds the largest installed base of any heat pump brand in the UK, which translates to the widest network of trained engineers and the easiest parts supply. The current R290 PUZ-WZ range is manufactured in Livingston, Scotland, making it the only major ASHP with UK domestic production. The Zubadan sub-range maintains 100% heating output down to -15 °C ambient — particularly useful in colder Scottish or northern English properties.
Ecodan also offers a hybrid configuration that pairs the heat pump with an existing gas or oil boiler, allowing a lower-cost entry point where full electrification is not yet practical. Control is via MELCloud (iOS/Android), which is functional and reliable, though considered basic compared to newer apps. Warranty runs to 7 years with Business Solutions Partner-tier installers plus annual service agreements.
3. Samsung EHS Gen 7 — best for smart home integration
SCOP 4.84 (ErP-certified, 5 kW R290); 35 dB(A) quiet mode; installed £7,000–£12,500 before grant. The Samsung EHS Generation 7 is typically the most affordable premium ASHP in the UK market and the quietest in active use — 35 dB(A) in quiet mode is lower than a refrigerator hum. The ErP-certified SCOP of 4.84 is verified by a third-party certification body, making it more comparable to the Vaillant figure than the manufacturer's own 5.10 headline. A High Temperature (HT) Quiet variant in R32 refrigerant delivers 70 °C flow for radiator retrofits, though its SCOP drops to around 3.0 at that flow temperature.
The headline differentiator for smart home users is SmartThings integration: the EHS Gen 7 connects natively to Samsung's ecosystem, enabling schedules, energy monitoring and automation alongside other SmartThings devices. The 7-year warranty with accredited installers covers parts only (not labour), which is a notable gap versus Stiebel Eltron's 5-year parts-and-labour offer.
4. Daikin Altherma 3 — best cold-weather performance
SCOP 4.6–4.7 typical (A7/W35); 44–50 dB(A), 38 dB(A) in quiet mode; installed £7,000–£14,000 before grant. Daikin's Altherma 3 is rated to operate down to -28 °C ambient — the widest operating range of any heat pump on this list and a genuine advantage for properties in the Scottish Highlands or elevated rural sites. The compact outdoor unit and 70 °C maximum flow temperature (at -15 °C ambient) make it one of the more retrofit-friendly options without needing to replace every radiator.
Control is via the Daikin Onecta app and the Madoka wired room controller. The main trade-off is refrigerant: the Altherma 3 uses R32 (GWP 675), which is significantly more impactful than the R290 used by Vaillant, Samsung and Stiebel Eltron. Warranty is extendable to 7 years with a Sustainable Home Expert (SHE) accredited installer.
5. NIBE S2125 — best smart controls
SCOP 5.00 (A7/W35); 49 dB(A) (Quiet Mark); installed £10,000–£16,300 before grant. NIBE's flagship S2125 matches the Vaillant SCOP headline at 5.0 and carries Quiet Mark certification at 49 dB(A). The standout feature is myUplink, NIBE's AI-driven cloud platform, which tracks real-time energy use, optimises schedules against electricity tariffs (including smart tariff integration) and delivers granular efficiency data the myVaillant app currently lacks. NIBE rates the S2125 A+++ at both 35 °C and 55 °C flow temperatures.
The S2125 replaces the older F2040 (now discontinued) and F2050. It commands a price premium over most rivals and requires NIBE-trained specialist installers, which can be harder to source outside major cities. The base warranty is 2 years, rising to 7 years with a certified installer and FlexiServ service plan.
6. Stiebel Eltron WPL-A — quietest on the market
SCOP 4.88 (WPL-A 07, EN 14825); 32 dB(A) — market-leading; installed £10,000–£18,000 before grant. The Stiebel Eltron WPL-A range claims the lowest noise output of any domestic ASHP available in the UK at 32 dB(A) sound power — roughly equivalent to a whisper at 1 metre. This makes it the most viable option for attached properties, noise-sensitive neighbours or installations close to boundary walls. The German manufacturer has over 50 years of heat pump production heritage and uses R290 refrigerant throughout the WPL-A range.
The 5-year parts-and-labour warranty (with a trained partner installer) is the best base warranty in this comparison — most rivals offer parts-only or require annual service contracts to hit the same level of coverage. The Internet Service Gateway (ISG) controller is functional but more basic than competitors' smartphone apps; however, the unit is Smart Grid Ready, enabling automatic load-shifting for solar PV self-consumption. The main constraints are a requirement for 2 m clearance in front of the fan, a smaller UK installer network, and premium pricing.
The Boiler Upgrade Scheme grant in 2026
All six brands above are MCS-certified and therefore eligible for the UK government's Boiler Upgrade Scheme (BUS), which provides a £7,500 grant off the cost of an air-to-water heat pump installation in England and Wales. The grant is applied directly by your MCS-certified installer — you do not claim it yourself. Scotland has a separate Home Energy Scotland scheme with equivalent support.
From 21 July 2026, properties currently heated by oil or LPG receive a temporary uplift to £9,000 (available until 31 March 2027). The previous insulation pre-requisite has been removed — cavity wall or loft insulation is no longer mandatory before claiming. The scheme is currently funded to approximately April 2028. ASHP installations also attract 0% VAT until 31 March 2027.
For a typical 3-bedroom semi-detached property, the installed cost before grant runs from around £10,000–£13,000; after the £7,500 grant, net outlay is typically £2,500–£5,500. See our full guide to heat pump installation cost for a detailed breakdown including radiator upgrades and hot water cylinder costs.
Which brand should you choose?
There is no single best brand — the right choice depends on your property, your priorities and your local installer network. As a starting point:
- Best SCOP / efficiency: Vaillant aroTHERM Plus or NIBE S2125
- Best for noise-sensitive sites: Stiebel Eltron WPL-A (32 dB) or Samsung EHS Gen 7 (35 dB quiet mode)
- Best smart home integration: Samsung EHS Gen 7 (SmartThings) or NIBE S2125 (myUplink)
- Lowest installed cost: Samsung EHS Gen 7 or Daikin Altherma 3
- Best cold-weather performance: Daikin Altherma 3 (-28 °C) or Mitsubishi Ecodan Zubadan (-25 °C at full output)
- Largest UK engineer network: Mitsubishi Ecodan
- Best warranty (base tier): Stiebel Eltron (5 years parts and labour)
Always get at least three quotes from MCS-certified installers and ask specifically whether each quote uses a brand-accredited tier engineer — this can be the difference between a 2-year and 7-year warranty at no extra cost. Our guide to the best heat pumps UK covers specific models in more detail, while the Vaillant aroTHERM Plus review gives a full deep-dive on the top-rated unit.
