Comparison · 3 picks
Aira vs BOXT vs Octopus Heat Pump UK 2026 (3-Way)
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UK heat-pump installs have consolidated around three high-volume routes: Aira, BOXT, and Octopus Energy. They've taken different commercial routes - a cover-led purchase, a fixed-price install and a tariff-led install - and the right answer depends entirely on what trade-off you're willing to make. This guide walks through where each pulls ahead.
The commercial models in one line each
What you actually pay - and how.
Aira: Purchase install, quoted individually after a free home energy assessment, with the £7,500 BUS grant deducted. Pay up front or on zero-deposit finance - Aira's representative example is £8,200, or £158.15/month over 5 years at 5.9% APR and £107.91/month over 10 years at 9.9% APR. You own the heat pump. The optional 15-Year Aira Guarantee covers servicing and repairs for £19.90/month after a free first year (Aira, October 2026).
BOXT: Fixed-price purchase install. Photo-based quotes, post-BUS-grant price shown upfront (typically GBP 3,500-7,000 net of grant for standard properties). You own the heat pump outright. 7-year warranty.
Octopus Cosy 6: Survey-based purchase install with Cosy Octopus tariff integration. Survey + design + install, typically GBP 4,500-8,000 net of grant. You own the heat pump. 10-year warranty on the unit. The Cosy Octopus electricity tariff has preferential rates for Cosy 6 owners.
At a glance
All 3 options side by side.
 | Octopus Cosy 6 |  | |
|---|---|---|---|
| Price | - | £4,460 | - |
| Commercial model | Purchase (cash or finance) | Fixed-price purchase | Survey-based purchase |
| Upfront cost | Quote-only; £8,200 representative example, £0 deposit on finance (Oct 2026) | GBP 3,500-7,000 post-grant | GBP 4,500-8,000 post-grant |
| Monthly cost | Finance if used (£107.91–£158.15 on the example) + £19.90 guarantee from year 2 | GBP 0 (or finance) | GBP 0 (or Cosy Octopus tariff) |
| BUS grant | Deducted from your quote | Passed to customer (price shown post-grant) | Passed to customer (post-survey quote) |
| Ownership | Customer-owned outright | Customer-owned outright | Customer-owned outright |
| Equipment | Aira Indoor + Outdoor units (Daikin-derived) | Vaillant aroTHERM plus + Daikin | Cosy 6 (R290, in-house design) |
| Warranty | 15 years with the optional Aira Guarantee; 5 years without | 7 years | 10 years on unit |
| Install timeline | 6-8 weeks | 4-6 weeks | 8-12 weeks |
| Review | Read review → | Read review → | Read review → |
| Buy |
The picks in detail
BOXT (× Vaillant) BOXT
Pros
- Fastest install timeline of the three (4-6 weeks)
- Fixed-price photo-based quote - no survey commitment before pricing
- Customer-owned heat pump with 7-year warranty
- Established Vaillant aroTHERM plus equipment with long UK track record
Cons
- Photo-based quotes occasionally miss edge cases that catch you later
- 7-year warranty is shorter than Octopus's 10
- No supplier-tariff integration vs Octopus's Cosy Octopus advantage
- Less suited to complex/period properties than survey-based routes
Octopus Energy Octopus Cosy 6
Pros
- All-in installed cost typically around £3,818 (July 2026) after the £7,500 Boiler Upgrade Scheme grant - among the most price-transparent UK heat pump packages
- R290 natural refrigerant (GWP of 3) - future-proof against the F-gas regulation tightening that will hit R32-based competitors
- Generous warranty: 8-year product cover plus 5-year labour, both backed by Octopus directly rather than a third-party installer
- Compact 855mm × 1125mm outdoor unit - fits awkward UK side returns where larger units would not pass clearance rules
- Single point of contact: survey, install, monitoring, repair, and tariff all handled by Octopus - no installer / manufacturer / energy-supplier coordination loop
Cons
- SCOP 3.4 at 50°C flow / 2.8 at 65°C flow - mid-range efficiency; older homes that can't run at low flow temperatures will see noticeably higher running costs than published headline figures imply
- Cosy 6 caps at properties with measured heat loss below 5.6kW. Many UK semis and detached homes (especially pre-1990s with limited insulation upgrades) need the Cosy 9 or Cosy 12 instead
- Hardware can only be bought through Octopus's install service - you cannot have an independent installer fit a Cosy 6 if you prefer your own tradesperson
- Annual service plan is an extra £9/month - adds £108/year on top of the headline price
- Cosy Pods are basic temperature/humidity sensors, not a full smart-thermostat replacement; integrators wanting Honeywell / tado° / Hive controls will need additional kit
Aira
Pros
- Zero-deposit finance over 5 or 10 years from 5.9% APR (Aira, October 2026)
- Maintenance + repairs included while the optional 15-Year Aira Guarantee runs
- Performance Guarantee: at least 4x a gas boiler's efficiency over a year
- Aira's in-house Indoor + Outdoor units engineered together
Cons
- Quote-only pricing - no published price to benchmark
- Finance costs 5.9–9.9% APR in Aira's representative examples - more than a 0% offer
- Guarantee costs £19.90/month from year two (Aira, October 2026)
- Locked into Aira's own hardware and installer network
When Aira wins
When long-term cover from one provider matters more than the lowest price.
Aira is right for:
- Buyers who want to spread the cost with no deposit - Aira's finance runs 5 or 10 years from 5.9% APR, with payments starting once the system is running (Aira, October 2026).
- Buyers who prefer 'fix it for me' service over the 'own it + arrange repairs' model. With the 15-Year Aira Guarantee active, Aira handles servicing and repairs - free for year one, then £19.90/month.
- Risk-averse first-time heat-pump buyers who want Aira's Comfort and Performance Guarantees (18-22°C indoors; at least 4x a gas boiler's efficiency).
Trade-off: on Aira's own £8,200 example, 10-year finance plus the guarantee comes to about GBP 15,100 over 10 years, or about GBP 10,350 paid up front, against GBP 4-8k + ~GBP 1-2k cumulative servicing for buying outright from BOXT or Octopus.
When BOXT wins
When you want predictable fixed-price install and fastest timeline.
BOXT is the right pick for:
- Standard properties (3-4 bed detached/semi, conventional wet-radiator heating, replacing gas combi) where a photo-based quote is sufficient.
- Buyers who value price certainty upfront over survey-based engineering rigour.
- End-of-life boiler scenarios where you need a fast timeline (4-6 weeks vs 8-12 for Octopus or 6-8 for Aira).
- Buyers happy with Vaillant aroTHERM plus as the heat-pump unit (long UK track record, reliable parts supply).
Trade-off: 7-year warranty (vs Octopus's 10), no tariff integration (vs Octopus + Aira), occasional friction from the photo-quote model on edge-case properties.
When Octopus Cosy 6 wins
When engineering rigour + run-cost economics matter most.
Octopus is the right pick for:
- Complex properties (period homes, extensions, mixed insulation, awkward heating loads) where survey-based design catches issues.
- Cosy Octopus tariff users - the bundled heat-pump tariff has the most attractive UK run-cost economics when paired with the Cosy 6.
- Buyers wanting low-GWP refrigerant - the Cosy 6 uses R290 (GWP 3) by default.
- 10-year warranty preference - 3 years longer than BOXT.
- Long-term Octopus Energy customers who'll benefit from the supplier-integrated service experience.
Trade-off: longer timeline (8-12 weeks), survey commitment before price is known, locked to Octopus as supplier for the Cosy tariff benefit.
Total cost over 10 years
Subscription vs purchase economics on a realistic timeline.
For a typical 3-bed semi-detached property over 10 years (including run cost at off-peak EV-style tariff):
- Aira (representative example, 10-year finance at 9.9% APR): GBP 0 deposit + ~GBP 12,950 in repayments + ~GBP 2,150 for the guarantee in years 2-10 + ~GBP 4,000 in electricity. Total: ~GBP 19,100. Paid up front instead: GBP 8,200 + ~GBP 2,150 guarantee + ~GBP 4,000 electricity = ~GBP 14,350 (Aira figures, October 2026).
- BOXT: ~GBP 5,000 upfront install + ~GBP 4,500 in electricity (no preferential tariff) + ~GBP 600 in cumulative servicing. Total: ~GBP 10,100.
- Octopus Cosy 6 (with Cosy Octopus tariff): ~GBP 6,000 upfront install + ~GBP 3,500 in electricity (cheaper via tariff) + ~GBP 500 in cumulative servicing. Total: ~GBP 10,000.
BOXT + Octopus are roughly equivalent over 10 years. Aira costs ~GBP 4k more paid up front and ~GBP 9k more on 10-year finance, in exchange for servicing and repairs bundled under its guarantee. Aira's example is a 2-bed terrace, so a 3-bed quote would likely be higher.
Bottom line
Three different right answers for three different buyer profiles.
The three routes target genuinely different buyer profiles:
- Aira for buyers who want long-term cover from one provider and a zero-deposit way to spread the cost. Pay more in total; get servicing and repairs bundled while the guarantee runs.
- BOXT for standard properties wanting the fastest, most predictable fixed-price purchase install. The default choice for the modal UK buyer.
- Octopus Cosy 6 for complex properties wanting engineering-led design + the best run-cost economics via the Cosy Octopus tariff integration.
All three handle BUS grant + warranty + ongoing service. Pick by the trade-off axis that matters most for your situation.