Cosy 6 Heat Pump Review 2026: Pricing, Features, Pros & Cons
Octopus Energy shook up the heat pump market when it launched its own British designed heat pump, the Cosy 6, with eye catching prices and a heat pump tariff to match. Since then, Octopus has become one of the biggest heat pump installers in the country.
In this Octopus Cosy 6 heat pump review, we look at how the unit performs, what it really costs, how it compares with brands like Mitsubishi, Daikin, Vaillant and Aira, and which homes it suits.
As an independent installer working across London, the South East, the South West and South Wales, we regularly meet homeowners weighing up an Octopus quote against a locally designed system. This guide gives you the honest, practical information you need to compare both routes and choose with confidence.
Octopus Cosy 6 heat pump review: At a Glance
The Octopus Cosy 6 is a compact air source heat pump designed to provide efficient, quiet heating for smaller and medium-sized UK homes. It uses R290 refrigerant and offers competitive pricing, making it an appealing option for homeowners looking to switch to low-carbon heating.
However, the system is only available through Octopus Energy, which also handles installation. The table below summarises its key features, benefits and potential drawbacks.
| What you need to know | Octopus Cosy 6 |
|---|---|
| Company | Octopus Energy, UK |
| Who makes it | Designed and built by Octopus Energy’s own heat pump business in the UK |
| Cosy range | Cosy 6, Cosy 9 and Cosy 12 |
| Output | Around 6kW (Cosy 6) |
| Refrigerant | R290 (natural propane, very low global warming impact) |
| Maximum flow temperature | Up to around 70°C (approximate) |
| Efficiency (SCOP) | Around 4 to 4.5 at 35°C, around 3.2 to 3.6 at 55°C (approximate) |
| Works down to | Around minus 20°C outdoors (approximate) |
| Noise | Very quiet, one of the main selling points |
| How you buy | Direct from Octopus Energy only |
| Typical installed cost | Roughly £8,500 to £11,500 before grant |
| Cost after £7,500 grant | Roughly £1,000 to £4,000, sometimes less |
| Typical running costs | Around £650 to £1,000 a year for a smaller 2 to 3 bed home on the Cosy Octopus tariff |
| Warranty | Octopus manufacturer and installation warranty, check current terms |
| Servicing | Annual service recommended, offered by Octopus |
| Smart controls | Cosy Hub, room sensors and the Octopus app |
| Best for | Flats with outdoor space, terraces, bungalows and smaller semis |
| Grant eligible | Yes, MCS certified and covered by the Boiler Upgrade Scheme |
Compare Octopus with a free quote from a local specialist. Before you commit to any heat pump, it pays to get more than one price. EE Renewables provides expert air source heat pump installation across Southern England, Greater London, South West England and South Wales, including London, Brighton, Oxford, Southampton, Bristol and Cardiff.
We will design a system around your home and give you a clear, itemised quote to compare. Get in touch today for a free air source heat pump quote tailored to your location.
Are Octopus Cosy 6 heat pumps worth it?
Octopus Cosy 6 heat pumps are worth it for smaller, reasonably well insulated homes where low upfront cost matters most, especially if you are happy to switch your electricity to Octopus’s heat pump tariff. For larger homes, older properties with high heat loss, or anyone who wants to choose their own installer and brand, another system may be a better fit.
The Cosy 6 was designed in the UK specifically for British homes, with a focus on low noise, small size and low cost.
Unlike brands such as Mitsubishi, Daikin, Samsung or Worcester Bosch, which sell through independent installers, Octopus sells the Cosy direct and installs it with its own engineers. That keeps prices low, but it also means you cannot shop around for the same unit.
Pros & Cons of Octopus Cosy 6 heat pumps
| Pros | Cons |
|---|---|
| Among the lowest upfront prices on the market after the grant | Only sold and installed by Octopus, so no installer choice |
| Very quiet and compact, ideal for small gardens and terraces | 6kW output is too small for many larger or older homes |
| Low carbon R290 refrigerant | Short track record compared with Vaillant, Daikin or Mitsubishi |
| Designed in the UK for British homes | Best value relies on switching to the Cosy Octopus tariff |
| Smart Cosy Hub and room sensors included | Warranty and aftercare tied to Octopus |
| Octopus has a strong reputation for customer service | Installation lead times can vary by region and demand |
| Easy online quote process | Less flexibility on system design than a specialist installer |
Is an Octopus Cosy 6 Heat Pump Right For Your Property?
Choose the Cosy 6 if…
- Your home is a flat with outdoor space, a terrace, a bungalow or a small semi
- Low upfront cost is your top priority
- You are already an Octopus customer, or happy to switch to the Cosy Octopus tariff
- You want a quiet unit for a small garden or tight space
- Your home is reasonably well insulated
Do Not Choose the Cosy 6 If…
- Your home is large, draughty or needs more than 6kW, where the Cosy 9, Cosy 12 or a larger Daikin, Vaillant or Viessmann may be better
- You want to compare several installers for the same heat pump
- You prefer a long established brand with decades of heat pump data
- You want to stay with a different energy supplier
- You want a bespoke system design, such as a split system or hybrid set up
How much does an Octopus Cosy 6 cost?
An Octopus Cosy 6 costs roughly £8,500 to £11,500 installed before the grant, or around £1,000 to £4,000 after the £7,500 Boiler Upgrade Scheme grant. Octopus has advertised some installations for very low prices, and occasionally close to nothing, after the grant for simple jobs in smaller homes, but most real quotes include extras that push the price up.
| Octopus Cosy model | Output | Typical property | Installed before grant (approx) | After £7,500 grant (approx) |
|---|---|---|---|---|
| Cosy 6 | 6kW | Flats with outdoor space, bungalows, terraces, small semis | £8,500 to £11,500 | £1,000 to £4,000 |
| Cosy 9 | 9kW | 3 bed semis and medium sized homes | £9,500 to £12,500 | £2,000 to £5,000 |
| Cosy 12 | 12kW | Larger 4 bed homes | £10,500 to £14,000 | £3,000 to £6,500 |
These are approximate 2026 prices. Octopus prices each home after a survey, and offers and promotions change regularly, so always check your actual quote.
Government Boiler Upgrade Scheme data puts the average installed air source heat pump at around £12,000 to £13,000 before the grant, so the Cosy 6 sits comfortably below the market average.
Aira, LG and Samsung systems typically cost more, while premium brands such as Vaillant, Viessmann and Stiebel Eltron sit higher again. Budget friendly brands like Midea and Gree can come close on unit price, but the total depends heavily on the installer.
Other costs to budget for with an Octopus Cosy 6
Other costs to budget for with an Octopus Cosy 6 are mainly about your existing heating system rather than the heat pump. Common extras include:
- Hot water cylinder: often needed if you currently have a combi boiler
- Radiator upgrades: some rooms may need larger radiators
- Pipework changes: older microbore pipes can limit heat pump performance
- Electrical work: occasionally a consumer unit upgrade is needed
- Insulation: may be needed first to meet grant rules or make a 6kW unit big enough
Heat pump installations also benefit from 0% VAT in Great Britain until 31 March 2027.
Which Octopus Cosy heat pump models are available in the UK?
The Octopus Cosy heat pump models available in the UK are the Cosy 6, Cosy 9 and Cosy 12, with the number showing roughly how many kilowatts of heat each can produce. All three are R290 monobloc units designed by Octopus in the UK.
Octopus Cosy 6
The Cosy 6 is the original and smallest model, designed for smaller homes with lower heat demand. It is compact enough to fit on a small patio, balcony or narrow side return, which makes it popular in London terraces and Brighton flats. Its R290 refrigerant has a global warming potential of just 3, compared with 675 for the R32 used in many older heat pumps.
Octopus Cosy 9 and Cosy 12
The Cosy 9 and Cosy 12 extend the range to medium and larger homes. They follow the same design approach, with a focus on low noise and simple installation. Even so, for very large, older or poorly insulated homes, higher output units from Mitsubishi, Nibe or Hitachi may still be needed.
How efficient is the Octopus Cosy 6?
The Octopus Cosy 6 is efficient, with seasonal efficiency (SCOP) figures of around 4 to 4.5 when running at 35°C, which suits underfloor heating or generously sized radiators. In everyday terms, every 1kWh of electricity you use produces around 4 to 4.5kWh of heat. A modern gas boiler, by comparison, turns 1kWh of gas into about 0.9kWh of heat.
At the 45°C to 50°C most UK radiator systems run at, a well designed Cosy 6 system typically achieves a SCOP of around 3.3 to 3.8. That is respectable, though premium brands such as Vaillant, Daikin and Panasonic often post slightly higher lab figures. In practice, good system design affects your bills far more than small differences between brands.
SCOP and COP explained
SCOP and COP are the two main ways to measure heat pump efficiency. COP (coefficient of performance) is a snapshot at a single moment. SCOP (seasonal coefficient of performance) averages performance across a full year, including the coldest days, so it is the better guide to your running costs.
Why system design matters
System design matters because a heat pump that is too small, or paired with undersized radiators, has to run hotter and works less efficiently. Real world data from the Heat Pump Monitor project shows that well designed systems from many brands achieve SCOPs above 3.5. With only 6kW available, accurate heat loss calculations are especially important for the Cosy 6.
How much does an Octopus Cosy 6 cost to run?
An Octopus Cosy 6 costs around £650 to £1,000 a year to run in a typical smaller 2 to 3 bed home on the Cosy Octopus tariff, depending on insulation and how warm you like your home. Running costs on a standard flat rate tariff are usually higher.
Here is a simple example. A smaller home might need around 9,000kWh of heat a year. A Cosy 6 running at a SCOP of 3.6 would use about 2,500kWh of electricity. At a standard rate of around 26p per kWh, that is roughly £650 a year. Shifting much of that use into cheaper tariff windows can reduce it further.
How the Cosy Octopus tariff works
The Cosy Octopus tariff works by offering cheaper electricity during several set windows each day, typically in the early morning, early afternoon and late evening, and more expensive electricity during the late afternoon peak. The Cosy Hub can pre heat your home and hot water in the cheap periods so the heat pump does less work at peak times. Exact times and rates change, so check Octopus’s current tariff details.
You do not have to have an Octopus heat pump to use this tariff, and other suppliers offer similar heat pump tariffs too. Any well designed heat pump, whether a Grant, Samsung or Daikin, can benefit from time of use pricing.
Compared with a gas boiler, running costs are usually similar or lower, and the savings can be significant if you are replacing oil, LPG or electric storage heaters. You also save the gas standing charge, roughly £100 to £130 a year, if you remove your gas connection.
Running cost figures are estimates. Energy prices change every quarter under the Ofgem price cap, so check your current tariff.
How noisy is the Octopus Cosy 6?
The Octopus Cosy 6 is one of the quietest heat pumps on the UK market, and low noise was one of Octopus’s main design goals. From a few metres away, it produces little more than a soft hum, often quieter than a typical fridge. This makes it a strong option for terraced streets and small gardens in London, Brighton and Bristol, where the unit may sit close to a neighbour.
To install a heat pump under permitted development in England, it must meet the MCS noise limit of 42 dB(A) at the nearest neighbour’s habitable room. England relaxed its rules in 2025, so the unit no longer has to sit a full metre from your boundary, but the noise test still applies.
A quiet unit like the Cosy 6 makes passing this test easier. Wales has its own rules, so homeowners in Cardiff, Swansea and Newport should check before installing.
How well does the Octopus Cosy 6 work in cold weather?
The Octopus Cosy 6 works well in typical British winters and is designed to keep running in outdoor temperatures well below freezing, down to around minus 20°C. That is far colder than the South of England or South Wales usually experiences.
All heat pumps lose some efficiency as temperatures drop. On a frosty morning, a Cosy 6 might run at a COP of around 2.5, still producing two and a half times more heat than the electricity it uses.
The key risk with a 6kW unit is not the cold itself but undersizing: if your home needs more heat than the unit can produce on the coldest days, rooms may not reach temperature. That is why accurate sizing matters so much. You may also see steam rising during short defrost cycles, which is perfectly normal.
What does an Octopus Cosy 6 installation involve?
An Octopus Cosy 6 installation involves an online questionnaire, a home survey, a system design and usually two to four days of fitting work by Octopus’s own engineers. The process typically runs like this:
- Online quote: you answer questions about your home and receive an initial estimate.
- Home survey: an Octopus surveyor checks your home, radiators and where the unit will go.
- Final quote and grant: Octopus confirms the price and applies for the Boiler Upgrade Scheme grant.
- Installation: engineers fit the Cosy 6, cylinder, any new radiators and the Cosy Hub and sensors.
- Handover: you are shown how to use the app, and you may be offered the Cosy Octopus tariff.
This direct model is similar to Aira, but very different from brands such as Grant, Ideal, Baxi and Vaillant, which sell through independent installers. With those brands, you can collect several quotes for the same unit and choose the installer you trust most.
What grants can you get for an Octopus Cosy 6?
The main grant you can get for an Octopus Cosy 6 is the Boiler Upgrade Scheme, which takes £7,500 off the cost of an air source heat pump in England and Wales. Octopus applies on your behalf and deducts it from your price.
To qualify, you must own the property, including rental homes, have a valid EPC with no outstanding loft or cavity wall insulation recommendations, and be replacing a fossil fuel or older electric heating system. Since 2022, the scheme has funded well over 100,000 heat pump installations.
Other support may include:
- 0% VAT on heat pump installations until 31 March 2027
- ECO4 and the Great British Insulation Scheme for eligible lower income households
- Warm Homes: Local Grant through some local councils
- Nest in Wales for eligible Welsh households
Landlords can use the grant on rental properties, and a heat pump can help lift a property’s EPC rating as minimum standards for rented homes tighten.
What smart controls come with the Octopus Cosy 6?
The smart controls that come with the Octopus Cosy 6 are the Cosy Hub, wireless room sensors and the Octopus app. The Hub acts as a smart thermostat and controller, while the sensors measure temperature in different rooms so the system can respond to how your home actually feels.
The real strength is how the controls link to the Cosy Octopus tariff, heating your home and water during cheaper periods. That kind of tariff integration is something most traditional brands, including Haier, Hisense and Dimplex, do not offer out of the box. Landlords can also check on a system remotely through the app.
How often does an Octopus Cosy 6 need servicing?
An Octopus Cosy 6 needs servicing once a year to stay efficient and keep its warranty valid. Octopus offers servicing for its heat pumps, so check your agreement for what is included and how much it costs.
A service typically covers the refrigerant circuit, filters and strainers, water pressure and inhibitor levels, the outdoor unit and the controls. Between services, keep leaves, snow and clutter away from the unit. There is no combustion, so no gas safety check is needed.
Octopus Cosy 6 Warranty: What cover do you get?
The Octopus Cosy 6 warranty is provided by Octopus Energy, covering both the heat pump and the installation because Octopus makes and fits the system itself. The length and terms of cover have changed over time and may depend on servicing, so always check the exact warranty in your quote before signing.
Here is how typical manufacturer warranties compare across popular brands. Most of these “up to” figures depend on using an approved installer, registering the product and keeping up with annual servicing.
| Brand | Typical warranty (up to) |
|---|---|
| Octopus Cosy 6 | Octopus warranty covering unit and installation, check current terms |
| Aira | Up to 15 years with its own packages |
| Vaillant aroTHERM plus | Up to 10 years |
| Viessmann Vitocal | 7 to 10 years on selected models |
| Mitsubishi Ecodan | Up to 7 years |
| Daikin Altherma | Up to 7 years |
| Grant Aerona | Up to 7 years |
| LG Therma V | 5 years standard, longer through approved installers |
If a long warranty is your top priority, compare Octopus’s current offer carefully against Aira, Vaillant and Viessmann, which lead on headline cover.
What to check in an Octopus Cosy 6 warranty
The things to check in an Octopus Cosy 6 warranty are how long it lasts, what it covers and what you need to do to keep it. Check:
- Length of cover for the heat pump, cylinder and controls
- Parts and labour: whether engineer visits are included
- Servicing conditions: whether annual servicing is required and what it costs
- Transfer on sale: whether the warranty passes to a new owner
- Consumer protection: MCS installers must belong to a consumer code such as RECC or HIES
Which property types is the Octopus Cosy 6 best suited for?
The Octopus Cosy 6 is best suited for smaller, reasonably well insulated homes, such as flats with outdoor space, bungalows, mid terraces and smaller semis. These homes typically need 6kW of heat or less on the coldest days, which plays to the Cosy 6’s strengths.
| Property type | Is the Cosy 6 a good fit? | Notes |
|---|---|---|
| Ground floor flats with outdoor space | Yes | Compact size and low noise help, freeholder consent may be needed |
| Bungalows | Yes, often ideal | Many bungalows need 6kW or less |
| Mid terraces | Yes | Shared walls keep heat loss low |
| Small 2 to 3 bed semis | Often | Depends on insulation and heat loss survey |
| Modern, well insulated homes | Yes | Low heat demand suits a 6kW unit |
| Larger semis and detached homes | Usually not | Consider Cosy 9, Cosy 12 or another brand |
| Older, draughty period homes | Often not | High heat loss may need a larger unit |
| Upper floor flats with no outdoor space | No | Consider other options |
Octopus Cosy 6 for landlords
The Octopus Cosy 6 for landlords can be a cost effective way to upgrade smaller rental flats and terraces, especially where low upfront cost matters. Bear in mind that the cheapest running costs depend on the tenant choosing the Cosy Octopus tariff, which you cannot always control.
Landlords with mixed portfolios often prefer one independent installer who can fit a range of brands, such as Mitsubishi, Ideal or Baxi, across different property types.
Homes where another brand might suit you better
Homes where another brand might suit you better include larger family homes, older properties with high heat loss and homes that need split, hybrid or cascade systems. Larger units from Daikin, Nibe, Hitachi or York, or premium options from Vaillant and Viessmann, may be more suitable.
An independent heat loss survey will show you exactly what size and type of system your home needs.
Why Compare the Octopus Cosy 6 With a Free Quote From EE Renewables?
Considering the Octopus Cosy 6 for your home? Getting a second quote from EE Renewables Ltd can help you compare installation costs, heat pump performance and long-term value before making a decision. We offer free, no-obligation air source heat pump quotes, giving you the opportunity to explore alternative brands and find a system that suits your property’s heating requirements and budget.
Our experienced team can assess your home’s heating needs, recommend suitable heat pump models and help you compare important factors such as system design, energy efficiency, warranty cover and ongoing aftercare. This gives you a clearer understanding of your options beyond the Octopus Cosy 6.
Request your free air source heat pump quote today and see how alternative heat pump systems compare with the Octopus Cosy 6.
We provide expert air source heat pump installation across Southern England, Greater London, South West England and South Wales, including London, Brighton, Oxford, Southampton, Bristol, Cardiff and surrounding areas.
Whether you are a homeowner replacing an ageing gas or oil boiler or a landlord looking to improve your rental property’s energy efficiency, comparing quotes can help you make a more informed investment.
Frequently Asked Questions
Do you need to be an Octopus Energy customer to get a Cosy 6?
You do not always need to be an Octopus Energy customer to get a Cosy 6, but Octopus’s best prices and running costs are designed around its own electricity tariffs. Check the terms of any offer, as some deals require you to switch supply to Octopus.
How long does an Octopus Cosy 6 last?
An Octopus Cosy 6 should last around 15 to 20 years with good installation and annual servicing, in line with other modern air source heat pumps. That compares with a typical lifespan of 10 to 15 years for a gas boiler.
Can the Octopus Cosy 6 work with solar panels and a home battery?
Yes, the Octopus Cosy 6 can work alongside solar panels and a home battery. Using solar power during the day and stored or off peak electricity at night can cut your heating costs considerably. Any modern heat pump can be paired with solar and battery storage in the same way.
Can I keep my gas hob if I get an Octopus Cosy 6?
Yes, you can keep a gas hob or gas fire after installing an Octopus Cosy 6, and you can still claim the Boiler Upgrade Scheme grant, as long as the heat pump replaces your main heating system. However, keeping a gas connection means you will still pay the gas standing charge.
Does a heat pump like the Cosy 6 add value to your home?
A heat pump like the Cosy 6 can add value to your home by improving its EPC rating and lowering running costs, both of which matter more to buyers and tenants every year. Research by Rightmove has found that improving a home’s EPC rating can be linked to a higher sale price, although the exact effect varies by area and property.
