Octopus Cosy vs Viessmann Vitocal: Which Air Source Heat Pump Is Better? (2026)
Quick Verdict
Viessmann Vitocal is the more efficient choice with a higher SCOP, meaning lower running costs over time, while Octopus Cosy is more budget-friendly with pre-grant pricing from £8,000 (the £7,500 grant applies equally to both in England and Wales).
Side-by-Side Comparison
| Feature | Octopus Cosy | Viessmann Vitocal |
|---|---|---|
| Installed price (before grant) | £8,000 - £12,000Lower | £10,000 - £16,000 |
| After £7,500 grant (illustrative, England and Wales) | £500 - £4,500 | £2,500 - £8,500 |
| SCOP (seasonal efficiency) | 4.1 | 4.4Higher |
| Max heat output | 9kWLarger homes | 8kW |
| Unit warranty | 5 years | 7 yearsLonger |
| Compressor warranty | 5 years | 7 yearsLonger |
| Noise level | 45dB | 43dBQuieter |
| Annual running cost (est.) | ~£610/yr | ~£570/yrLower |
| Refrigerant | Varies by model | R290High flow temps |
| Country | UK | Germany |
| UK brand | Yes | No |
| Best for | Price-led switchers happy to go with one vertically integrated provider | Period-property owners who want premium hardware without a full radiator re-pipe |
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 25p/kWh (Ofgem cap average; changes quarterly). Confirm current models and exact pricing with your MCS-certified installer.
Price Comparison
Octopus Cosy starts from £8,000 installed before any support (indicative, June 2026), while Viessmann Vitocal starts from £10,000. That is a difference of roughly £2,000 at the entry level. Octopus Cosy is the more budget-friendly option upfront, though Viessmann Vitocal 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 £500 - £4,500 for Octopus Cosy and £2,500 - £8,500 for Viessmann Vitocal out of pocket. Your MCS-certified installer claims the grant for you.
Efficiency Comparison
SCOP (seasonal coefficient of performance) is the key efficiency metric for a heating heat pump: it measures how many kilowatt-hours of heat you get per kilowatt-hour of electricity across a whole heating season. Octopus Cosy reaches a SCOP of 4.1, while Viessmann Vitocal reaches 4.4. The Viessmann Vitocal is roughly 7% more efficient on this measure, which on our estimates is worth about £40 a year at Ofgem cap electricity prices, or approximately £400 over ten years. Real-world SCOP depends heavily on system design and flow temperature, which is what the MCS heat-loss survey is for.
Warranty Comparison
Octopus Cosy offers a 5-year unit warranty and 5-year compressor warranty. Viessmann Vitocal offers a 7-year unit warranty and 7-year compressor warranty. The Viessmann Vitocal has the stronger coverage with 7 years on the unit, 2 more than the Octopus Cosy. Note that accredited-installer schemes often extend manufacturer warranties, so ask each installer what they can register for you. Workmanship cover for the installation itself comes separately from your installer and should be at least 12 months, 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, and siting is part of the installation assessment. Octopus Cosy operates from 45dB, while Viessmann Vitocal runs from 43dB. The Viessmann Vitocal is quieter at 43dB. At this level it is among the quieter units on the market, comparable to a quiet office, and sensible siting makes it unobtrusive even in terraced streets.
Cold-Weather and Retrofit Suitability
Two things decide how well a unit suits an older UK home: cold-weather output and flow temperature. Octopus Cosy uses a refrigerant that varies by model, while Viessmann Vitocal uses R290. Viessmann Vitocal's R290 (propane) range reaches high flow temperatures, which helps existing radiators carry the load without a full re-pipe, a real advantage in period properties and quick retrofits. Modern units from both brands 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
Octopus Cosy
Pros
- Cheapest mainstream route to a heat pump (avg ~£4,460 post-grant via Octopus)
- UK-designed, end-to-end install by one company
- Tariff pairing cuts running costs
- Grant handled entirely for you
Cons
- Install only through Octopus (no independent quotes on the hardware)
- Newer hardware with a shorter track record
- Standard 5-year warranty
Viessmann Vitocal
Pros
- Top-tier German build quality
- High flow temperature (radiator-friendly)
- Excellent SCOP
- Quiet operation
Cons
- Among the priciest options
- Smaller UK installer pool than Mitsubishi/Daikin
Which Should You Choose?
Choose Octopus Cosy if...
- You want a lower upfront cost (from £8,000 vs £10,000 before the grant)
- You want a UK brand with local manufacturing or headquarters behind it
Choose Viessmann Vitocal if...
- You want the best efficiency and lowest running costs (SCOP 4.4 vs 4.1)
- You want a longer unit warranty (7 years vs 5 years)
- Quiet operation matters to you (43dB vs 45dB)
- You want lower estimated annual running costs (~£570/yr vs ~£610/yr)
- You want R290 refrigerant with high flow temperatures, which helps existing radiators carry the load without a full re-pipe
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 from 21 July 2026) 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 June 2026.
Where are you?
See indicative costs and local installers for your area