The Best Air Source Heat Pumps 2021

The Grant Aerona³ R32 is the best air source heat pump overall

Hitachi’s top heat pump can save you £8,472 compared to a gas boiler

The LG Therma V R32 Monobloc still works when it’s -25°C outside


Air source heat pumps are the way forward. They use one of the most renewable sources of energy on the planet – air – and typically require four times less energy than a gas boiler to supply the same amount of heat.

That incredible level of efficiency could save you as much as £255 per year, cut your carbon footprint by 38%, and generally make you less dependent on gas – all for a reasonable price. You might also be able to keep the costs down with one of the UK government grants that are on offer.

We’ve analysed the best options the industry has to offer, comparing each machine’s price, efficiency, warranty, maximum power, and the minimum temperature at which it operates.

Here are the winners.

air source heat pump by a wall

The best air source heat pumps overall

Air source heat pump modelBest for
Grant Aerona³ R32Cost
Hitachi Yutaki M RASM-4VNEEfficiency
LG Therma V R32 MonoblocCold climates
HydroPro ECO 12Swimming pools
Vaillant flexoTHERM 400vMaximum power
NIBE F2040Warranty

Best for cost: Grant Aerona³ R32

CostEfficiencyWarranty (years)Max. power (kW)Min. temp (°C)
£5,394479%717-20

grant aerona3 air source heat pump

The best air source heat pump on the market right now is the Grant Aerona³ R32 – and luckily for all of us, it’s also the best value model around, at just £5,394.

Grant’s product is the cheapest high-quality heat pump around, yet its efficiency rating is still an astounding 479%, meaning it produces 4.79 units of heat for every unit of electricity it uses.

Most heat pumps’ efficiency ratings fall between 350% and 400%, making this a special machine – and it’s the lightest on our list too, weighing in at a svelte 120kg.

Best for efficiency: Hitachi Yutaki M RASM-4VNE

CostEfficiencyWarranty (years)Max. power (kW)Min. temp (°C)
£4,260500%511-25

Hitachi Yutaki M RASM-4VNE

If you have a medium-sized house, you should buy Hitachi’s heat pump as soon as you can, because you’ll start saving immediately.

With a table-topping efficiency rating of 500%, this machine will typically save you £8,472 over its lifetime, compared to heating your home with gas.

Its maximum output of 11kW is low compared to the other top heat pumps out there, but will still be more than enough for most homes.

Best for cold climates: LG Therma V R32 Monobloc

CostEfficiencyWarranty (years)Max. power (kW)Min. temp (°C)
£5,596400%7 (if approved install)16-25

LG Therma V R32 Monobloc

If you live in below-freezing conditions, it’s a massive relief not to have to go outside and fix the heating when it’s dangerously cold.

Fortunately, even though heat pumps work by absorbing warmth from the air outside, LG’s best model is still able to function happily at temperatures as low as -25°C.

So when the snow and icy winds sweep in at full power, you can wrap up with a hot drink, safe and comfortable in the knowledge that your heat pump will keep you warm.

Best for swimming pools: HydroPro ECO 12

CostEfficiencyWarranty (years)Max. power (kW)Min. temp (°C)
£1,495480%212+11

HydroPro ECO 12

With a maximum power of 12kW and a hugely impressive efficiency rating of 480%, this heat pump from the appropriately named HydroPro is the perfect way to keep your pool water nice and warm.

After all, heat pumps take warmth from the air to heat your water – so why not your pool water?

For less than £1,500, you can ensure that getting into your pool is always an enjoyable experience, rather than a chilly chore.

Best for maximum power: Vaillant flexoTHERM 400v

CostEfficiencyWarranty (years)Max. power (kW)Min. temp (°C)
£7,634467%7 (if approved install)19-10

Vaillant flexoTHERM 400v

This behemoth of a machine can provide you with heating and hot water in the blink of an eye, reaching temperatures of 65°C in no time.

Considering a hot shower comes in around 40°C to 45°C, that should be more than enough.

Vaillant’s model also has a high efficiency rate, meaning it’ll still save you plenty of money, despite using more energy than most heat pumps. If you have a particularly large house, this is the heat pump for you.

Best for warranty: NIBE F2040

CostEfficiencyWarranty (years)Max. power (kW)Min. temp (°C)
£5,500485%7 (if approved install)16-20

NIBE F2040

This Swedish firm was created in 1952, and has positioned itself excellently for the ongoing air source heat pump revolution, offering a model that’s five times as efficient as a typical gas boiler for an extremely reasonable price.

Throw in an unbeatable seven-year warranty and enough power to comfortably heat a three-bedroom house, and you’ve got an excellent machine you can rely on.

Next steps

In April 2022, the Boiler Upgrade Scheme is set to come into effect.

The grant could subsidise your air source heat pump installation by £5,000.

That means you’d be able to get one of these excellent heat pumps installed with no trouble.

And when you consider that heat pumps typically last 20 years – twice as long as the average gas boiler – you’ll be saving money for years to come.

Josh Jackman Senior Writer

Josh has written about eco-friendly home improvements and climate change for the past three years. His work has featured on the front page of the Financial Times; he’s been interviewed by BBC Radio; and he was the resident expert in BT’s smart home tech initiative.

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