Octopus Energy Heat Pumps — Costs, Savings & the £7,500 Grant

An air source heat pump works like a fridge in reverse. It extracts warmth from the outside air — even on cold days — compresses it to raise the temperature, and uses it to heat your radiators and hot water. Because it moves heat rather than creating it, it's remarkably efficient: a modern heat pump delivers roughly 3–4 kWh of heat for every 1 kWh of electricity it uses.

Compare that to a gas boiler, which at best converts around 90% of the energy in the gas it burns into useful heat. A heat pump running at 300–400% efficiency is in a different league — the question is simply whether cheap-enough electricity makes the running costs stack up. That's exactly what the Cosy Octopus tariff is designed to do.

Heat pumps run at lower flow temperatures than boilers, so they heat your home gently and steadily rather than in short, hot blasts. Well-set-up systems keep homes at a comfortable, even temperature all day — many owners say their house has never felt warmer.

Octopus isn't just an energy supplier — it's one of the UK's biggest heat pump installers, with its own training centres and an in-house R&D operation. The flagship product is the Cosy 6, a 6kW air source heat pump Octopus designed itself to bring installation costs down. It uses R290 refrigerant (very low global warming potential) and is built specifically for the lower flow temperatures that suit UK homes and radiators.

The process is deliberately simple: you complete a short online assessment, Octopus carries out a home survey, and you get a fixed-price quote with the government grant already deducted. Installation is handled by Octopus's own MCS-certified engineers, usually in two to three days, and the system connects to the same Octopus app that 7.3 million customers already use. It's the same approach that earned Octopus a 4.8/5 Trustpilot rating from over 779,000 reviews — see our 10 benefits of switching for the full picture.

If your home isn't suitable for a Cosy 6, Octopus also installs heat pumps from other manufacturers — the survey determines the right fit, not a sales target.

The Boiler Upgrade Scheme (BUS) is a government grant of £7,500 towards the cost of an air source heat pump in England and Wales. It's available to homeowners replacing a fossil fuel heating system (gas, oil, or LPG), and it's paid per property — you don't need to be on benefits or means-tested to qualify. Scotland has its own separate funding via Home Energy Scotland.

The best part: you never touch the paperwork. The grant is claimed by the installer, not the homeowner, so Octopus applies on your behalf and simply deducts £7,500 from your quote. There's no waiting for a rebate and no forms to fill in — the price you're quoted is already the post-grant price.

With the grant applied, Octopus advertises installations from around £500 for the most straightforward homes. Bigger or more complex properties pay more, but for context, a like-for-like gas boiler replacement typically costs £2,000–£4,000 anyway — so for many households the upfront gap between a new boiler and a heat pump has effectively disappeared. Want to fund it from your bills? Our guide to saving money with Octopus covers every trick.

Exact figures depend on your home's insulation, your heat pump's efficiency, and how well the system is scheduled around the cheap windows — but the pattern is consistent: heat pump + smart tariff beats gas, and the gap widens further if you add solar panels or a home battery. Switching tariff itself takes about five minutes.

Heating is the single biggest source of carbon emissions for most UK homes. Swapping a gas boiler for a heat pump cuts your heating emissions by around 80% — and if your electricity comes from Octopus's 100% renewable supply, the heat you use is effectively zero-carbon at the point of generation.

Heat pumps are also a long-term investment. A well-maintained unit lasts 15–20 years — comfortably longer than the 10–15 years you'd expect from a gas boiler — with fewer moving parts exposed to combustion, no flue, and no annual gas safety risk. Over its lifetime, a single heat pump avoids many tonnes of CO₂ compared to sticking with gas.

For households trying to decarbonise step by step, the typical order is: switch to a renewable supplier, get a smart meter, then electrify heating and transport. A heat pump is the biggest single step most homes can take.