Can air conditioning heat my home in winter?
It heats, it works in a cold snap, and it is several times cheaper to run than an electric heater. Here is what the manufacturers publish, and where the honest limits are.
- REFCOM certified, REF1025662
- Daikin registered installer
The short answer
Yes. Every system we install is a reversible heat pump, so the same unit that cools in August heats in January, and it keeps working well below freezing. Daikin publishes heating output down to minus ten degrees for these units: a 2.5kW unit still delivers around 2kW of heat at that temperature. Because a heat pump moves heat rather than generating it, seasonal efficiencies run between about 4.0 and 5.2, which means four to five units of heat for every unit of electricity, and a cost of roughly 5.7p to 5.1p per kWh of heat at the current price cap. What it will not do is heat rooms it is not installed in, and it does not produce hot water.
It is a heat pump, and it always was
A wall mounted split system does not make cold. It moves heat from one side of a wall to the other. Running it the other way round moves heat from outside into the room, and that is all heating mode is: the same refrigerant cycle with a reversing valve.
There is genuinely no meaningful difference between the box marketed as air conditioning and the box marketed as an air source heat pump. This is the same technology, in the air to air form, and it is why these units are subject to the same permitted development rules as any other air source heat pump.
The reason this matters is efficiency. A fan heater or an electric radiator turns one unit of electricity into one unit of heat, and it cannot do better, because that is the physical ceiling for resistive heating. A heat pump is not bound by that ceiling, because it is not making the heat. It is fetching it.
What the published seasonal figures say
SCOP is the seasonal coefficient of performance: heat delivered across a heating season divided by the electricity used to deliver it. Manufacturers publish it for every size under the ecodesign rules, so it is comparable between makes.
| Range and size | Published SCOP | Energy class | Cost per kWh of heat |
|---|---|---|---|
| Daikin Perfera 2.5kW | 5.20 | A+++ | 5.1p |
| Daikin Stylish 2.5kW | 5.15 | A+++ | 5.1p |
| Daikin Comfora 2.5kW | 4.61 | A++ | 5.7p |
| Daikin Comfora 5.0kW | 4.40 | A++ | 6.0p |
| Daikin Comfora 7.1kW | 4.01 | A+ | 6.6p |
Manufacturer published seasonal figures for average climate. Cost per kWh of delivered heat at the Ofgem price cap of 26.32p per kWh for 1 October to 31 December 2026. Estimates, not quotes.
The comparison that needs no assumptions
An electric heater costs you the full unit rate for every kWh of heat it produces, which is 26.32p at the current cap. It cannot do better than that. A heat pump with a seasonal efficiency of 5.15 delivers the same kWh of heat for about 5.1p. That is not a marketing figure, it is arithmetic on a number the manufacturer is legally required to publish.
What it delivers when it is actually cold
The usual objection is that heat pumps stop working in the cold. They do not, but their output does fall as the outside temperature drops, so the honest way to settle it is the figure the manufacturer publishes for minus ten degrees.
| Range and size | Heating output at minus ten degrees |
|---|---|
| Daikin Stylish 2.5kW | 2.09kW |
| Daikin Comfora 2.5kW | 2.09kW |
| Daikin Comfora 5.0kW | 3.15kW |
| Daikin Perfera 5.0kW | 4.50kW |
| Daikin Comfora 7.1kW | 4.24kW |
Daikin published Pdh heating capacity at minus ten degrees outdoor temperature. For context, temperatures that low are uncommon in London and are well outside a typical winter night.
Why it heats a room faster than you expect
A radiator warms a room by warming the air touching it and waiting for that to circulate. A wall mounted unit blows heated air directly into the room at a controlled temperature, so the room reaches a comfortable temperature in minutes rather than the best part of an hour.
That difference matters most in a room you use intermittently. A spare room, a home office or a loft conversion can be brought up to temperature on demand rather than kept warm all day on the off chance, and that is often where the real saving sits, rather than in the efficiency figure itself.
What it will not do
Every range has a limit and a page that does not name it is a brochure. These are the honest ones.
It does not heat rooms it is not in
A single wall mounted unit heats the room it is installed in. It will take the edge off an adjoining space through an open door and it will not warm the rest of the house. Heating a whole home this way means a unit in each room you want heated, which is a different job and a different budget from one unit in the living room.
It does not do hot water
An air to air heat pump heats air, not water. Your hot water still comes from whatever produces it now. This is the single biggest difference between these systems and the air to water heat pumps people usually mean when they talk about replacing a boiler.
Output falls as it gets colder
The figures above are real and so is the decline behind them. A unit sized for the room on a mild day has margin in hand; a unit sized with no margin will struggle on the coldest nights of the year. This is a sizing question, and it is why the survey looks at the room rather than at a price list.
It will defrost, and you will notice
In cold damp weather the outdoor unit periodically melts frost off its coil, which pauses heating for a few minutes and can produce steam outside. It is normal operation, not a fault, and it is worth knowing about in advance so it does not read as one.
It is not a boiler replacement on its own
If your aim is to take a gas boiler out of a whole house, this is not the system for that, and we will say so. What it is very good at is heating specific rooms efficiently and on demand, alongside whatever heats the rest.
Where it makes the most sense
The rooms where this stacks up best are the ones your existing heating serves worst. Loft conversions, which are the hottest room in summer and often the coldest in winter. Home offices used for eight hours a day while the rest of the house sits empty. Extensions where extending the existing heating would mean disturbing the floor.
In each of those the alternative is usually an electric heater, and against an electric heater the running cost argument is not close.
The ranges this applies to
Every price is fully installed and includes the unit, the installation, the electrical work and VAT.
Instant estimate
Thinking about it for a cold room?
Tell us the room and we will size it for heating as well as cooling, because the two are not always the same answer. The estimate takes about a minute.