Heat pump tariffs: which ones work for air-to-air heat pumps and air conditioning

Yes, you can put an air-to-air heat pump on a heat pump tariff, and no supplier we checked turns one away. But the honest answer to "which heat pump tariff is best?" for a wall-mounted split you switch on at teatime is: possibly none of them. The cheap windows fall in the early hours and mid-afternoon, and several tariffs charge more than the price cap between 4pm and 7pm, exactly when most people want the living room warm.

Below: every current UK heat pump tariff, what each says about eligibility (none names air-to-air, so we read the small print), the sums for a 3.5kW unit heating a living room from 5pm to 11pm, the MCS certificate catch, smart meters, and solar and batteries. It is part of our air-to-air heat pumps guide; the rest of the winter series is in the heating hub.

Rates correct as of September 2026. Heat pump tariffs are regional and most suppliers change them with each quarterly price cap, so check your own postcode before switching.

What a heat pump tariff is, and why air-to-air is an awkward fit

A heat pump tariff is a smart time-of-use electricity tariff: one or more cheap windows (typically 4am to 7am and 1pm to 4pm), a standard rate the rest of the time, and on some tariffs a dearer peak rate from 4pm to 7pm. The cheap rate applies to everything in the house during those hours, not only the heat pump.

The design assumes an air-to-water heat pump running radiators and a hot water cylinder more or less continuously, so a big slice of its consumption lands in the cheap windows by itself. Nesta's modelling with Cornwall Insight (February 2025) found those households could save up to £600 a year without shifting anything. An air-to-air unit heats one room directly, with no water to store heat, so most owners run it when they are in the room. If that is the evening, the cheap hours pass you by and the peak hours land on you.

Which heat pump tariffs are available (September 2026)

OVO's Heat Pump Plus (heat pump electricity at 15p/kWh via a monthly rebate) closed to new customers in December 2025 and ended on 1 February 2026, so it is off the list. That leaves six supplier tariffs plus the two baselines everyone can get.

London figures are examples: Cosy Octopus from Octopus's London rates from 13 September 2026, EDF from its own regional table, and British Gas, E.ON and Good Energy from Sunsave's London comparison dated 19 June 2026 (treat those three as "about"). The Ofgem cap for 1 July to 30 September 2026 is 26.11p/kWh with a 57.19p daily standing charge. October's price cap moves electricity to 26.32p and 54.83p a day, with VAT removed, so it changes nothing in the sums below. Standing charges vary widely by region (EDF quotes 42.92p to 67.66p a day), so compare against the cap figure for your own region.

Do these tariffs accept an air-to-air heat pump?

No supplier page mentions air-to-air, reverse-cycle, or air conditioning either way. Here is what each says, checked on 15 September 2026.

Cosy Octopus. "If you have a heat pump (air or ground source), an electric boiler or electric radiators at your property, you can join Cosy Octopus." It "doesn't need to have been installed by us", and "if you have another system in your property, get in touch and we'll let you know if you're eligible". An air-to-air split is an air source heat pump in law (the Boiler Upgrade Scheme regulations call it exactly that), so this is the most open wording of the six.

British Gas Heat Power. Works with "any make of heat pump, electric heating system, EV and storage battery". Credit customers only, no prepayment meters.

EDF Heat Pump Tracker. "Have a heat pump installed in your home." EDF adds: "We may ask anyone who signs up for the tariff to provide evidence of their heat pump installation. This could be an MCS certificate or a photo." The photo route is the one air-to-air owners will need (see below).

E.ON Next Pumped. "Have a heat pump or an electric boiler in your home or be planning to have one installed." Direct debit and an online account are required.

ScottishPower Heat Pump Saver. For customers "who have a heat pump, of any make or model", and "all heat pump installs welcome, not just those installed by ScottishPower". It warns that if under 30% of your electricity falls in the 11am to 4pm window, the tariff may not suit you.

Good Energy Heat Pump. Sunsave's June 2026 review notes "you don't even need a heat pump"; the tariff is sold on smart-meter data alone.

Before you switch, email the supplier, say "I have a reverse-cycle air-to-air heat pump (a wall-mounted split system) that heats the house", and keep the reply. Wording changes, and a written yes protects you if the tariff is later reviewed.

The MCS certificate catch

Suppliers are used to seeing an MCS certificate, the document an installer issues for an air-to-water system under the Microgeneration Certification Scheme. EDF names it as acceptable proof, and Sunsave reports that Octopus "may check" for MCS certification.

Almost no existing air-to-air installation has one. MCS only began bringing air-to-air into its scheme in 2026; Daikin became the first manufacturer with air-to-air products on the MCS Product Directory on 1 September 2026, and installer certification was still catching up. Your split was fitted under the F-Gas regulations by a REFCOM-registered engineer, and the paperwork you hold is a commissioning record, not an MCS certificate.

That is not a barrier, but be ready for the question. EDF accepts a photo of the installation. For any supplier, have a photo of the outdoor unit, the installer's invoice and the F-Gas commissioning sheet ready. If a supplier insists on MCS, ask them to confirm in writing that air-to-air is excluded rather than accepting a vague no. What MCS means for the £2,500 grant is in our air-to-air heat pump grant guide.

Do you need a smart meter?

For every heat pump tariff, yes. Octopus needs a SMETS2 or Secure-branded SMETS1 meter it can read half-hourly; the other five require a working smart meter sending half-hourly readings, and E.ON will fit one as part of joining. Good Energy says three-phase and Economy 7 meters are not currently compatible.

There is no heat pump tariff without a smart meter. The only time-of-use option without one is Economy 7 on an existing dual-rate meter, worth a look only if around 40% of your electricity can go overnight. For an evening-run air-to-air unit that is unlikely, and Economy 7's 28p to 34p day rate is dearer than the cap.

The sums: a 3.5kW unit heating a living room, 5pm to 11pm

Take a 3.5kW-class wall split (for example a Daikin Perfera, which Daikin rates at SCOP 5.2; we use a conservative SCOP 4.5) delivering an average 2.5kW of heat for six hours on a cold evening. That is 15kWh of heat, which at SCOP 4.5 uses 15 ÷ 4.5 = 3.33kWh of electricity. A fan heater or panel heater giving the same warmth would use the full 15kWh.

Two things stand out. The air-to-air unit costs roughly a quarter of a resistive heater on any tariff, which is the saving that matters. And for an evening-only user every heat pump tariff is the same as or dearer than the price cap; on Cosy Octopus you pay about 10% more because two of your six hours fall in the peak. Over a 150-evening season the differences are small (a few pounds to about £35), but they run the wrong way.

Run the unit all day instead, 8am to 11pm at an average 2kW (30kWh of heat, 6.67kWh of electricity), and the cap costs £1.74 a day against £1.71 on Cosy, £1.65 on Next Pumped, £1.64 on EDF and £1.62 on ScottishPower. The tariffs now win, but only by 3p to 12p a day on the heating itself.

The heat pump tariff does not make the air-to-air unit much cheaper to run. What it does is make the rest of the house cheaper, if you can move it into the windows.

The real gains come from everything else the house uses. Washing, the dishwasher, the tumble dryer, an immersion heater or an EV all move easily into a 13p to 17p window. If your household can do that, a heat pump tariff can pay even with an evening-run split. If it cannot, and someone is home cooking and heating between 4pm and 7pm, a tariff with a peak rate will cost you more than doing nothing. The Energy Saving Trust's advice (August 2026) is blunt: without a battery, avoid a heat pump tariff that includes a peak rate.

Put your own room, hours and rate into the running cost calculator for your own figures.

How to shift an air-to-air unit into the cheap windows

A split cannot store heat the way a cylinder does, but a room holds some, and the unit's controls help.

• Pre-heat on the afternoon window. Use the unit's timer or app to bring the room up to 21°C or 22°C from about 2.30pm to 4pm on the cheap rate, then drop the setpoint to 18°C or 19°C for 4pm to 7pm. The unit ticks over at low output through the peak instead of working hard from cold at 5pm. It is worthwhile in an insulated room, not much use in a draughty one.

• Run steady, not in bursts. Inverter splits are at their most efficient running gently for long periods, so a lower setpoint held all evening beats blasting at 25°C for an hour. Our guide to the most efficient way to run an air-to-air heat pump goes through setpoints, fan speeds and the timer in detail.

• Use the late window. On Cosy Octopus and E.ON Next Pumped, 10pm onwards is cheap, so the last hour or two of the evening costs half as much.

• Match the tariff to your day. Home all day? E.ON Next Pumped's 6am to 4pm off-peak rate or ScottishPower's 11am to 4pm window suits you. Out until 6pm and unable to shift much? EDF's no-peak design means you cannot lose, and the 4am to 7am window gives a cheap morning warm-up.

How heating mode works, and why a split's output falls on the coldest nights, is in our guide to heating with air conditioning.

Heat pump tariffs with solar and a battery

A battery changes the answer. Charged at 13p in the afternoon window, it can run the split through the 4pm to 7pm peak, and the Energy Saving Trust suggests homes with batteries are the ones that should pick a tariff with a peak rate, because they get the deeper cheap rate without the exposure. British Gas explicitly includes storage batteries in Heat Power.

With solar only, pair the import tariff with an export tariff from the same supplier (Octopus's Outgoing tariffs sit alongside Cosy, for instance). A UK roof produces almost nothing at 5pm in January, so the export side is a summer bonus, not a winter heating strategy.