What is an Air Source Air Pump?

With the world changing and fossil fuels becoming more and more scarce, we need to look at different ways to heat our homes.

One of those ways is by using an air source heat pump to convert the outside air into hot water.

‘What?!’ I hear you cry ‘That sounds like magic!’

But it’s not, it’s physics.

What is an Air Source Heat Pump?

Often referred to with acronym ASHP, these are systems designed to take air from the outside and use it to heat water in a tank.

While the name air source heat pump may conjure up an image of a single item, it’s actually a collection of different components that make up the whole system.

There is a fan to draw air in from the surrounding area … a series of pipes that carry a coolant solution … a water tank … and a return system.

How does an Air Source Heat Pump work?

Fan:

This draws air in from the outside world. There is heat in that air even if you’re wrapping up in gloves and scarves to go do the shopping.

It’s a surprising thing to hear, but modern air source heat pumps can still heat your home when the outside temperature drops to -15°C … some models can even work below -22°C.

The air is transferred to a heat exchange that’s filled with a refrigerant - the same liquid that’s in the pipes on the back of your fridge.

The heat is enough to turn the liquid into a low-pressure gas.

This process is called Evaporation.

Compression:

The refrigerant gas is then fed into a high-powered compressor that ‘crushes’ the gas down, causing friction and raising the temperature even more.

This hot gas is then fed into a condenser.

Condensation

Inside the condenser are pipes filled with water.

The refrigerant gas hits the pipes and starts to condense, this allows the heat every to be transfer form the gas into the water, heating the water up and return the refrigerant to its liquid form.

But we’re not done with our refrigerant just yet.

Expansion

The cooled refrigerant is passed through an expansion valve, which lowers the pressure, allowing it to absorb more heat energy. When it’s good and warm, it’s pumped back into the heat exchanger to repeat the cycle.

How does an Air Source Heat Pump heat your home?

Radiators – it’s that simple.

Basically, the air source heat pump would replace the boiler in your home.

Your current gas boiler heats the water in your radiator circuit, and an air source heat pump does the very same thing.

Most modern central heating systems will easily convert to an ASHP, but you may need to replace one or two radiators to make sure the are big enough to heat a room.

If you have underfloor heating, you have just about the perfect system for an air source heat pump.

Busting those Air Source Heat Pump Myths

They don’t keep homes warm enough

This one seems to have come from the UK’s own media with a journalist from the Daily Telegraph when he said “you can’t find an engineer prepared to install one of the devices in your home because, in all honesty, they know it wouldn’t actually keep you warm.”

Unfortunately for that chap, the data just doesn’t support that assertion.

A recent survey by Nesta found that 81% of ASHP owners were more than happy with the performance of their heat pump – a similar survey returned more or less the same results for gas boiler users.

Plus, ASHPs are way more sustainable, and that’s always a good feeling.

They make a right row!

This one isn’t a myth, but it’s certainly not true in all cases, as ASHPs have a fan in them so they will make a little noise.

But, like all technology, ASHP tech is changing week by week and newer models are built to be super quiet.

Recent surveys have shown that only 100 in every 3000 people who fit an air source heat pump complain about the noise.

That’s not to say they don’t make a little bit of noise; they emit a low hum at about 40 decibels - about the same as a fridge freezer.

They take ages to install

Of the ‘Heat Pumps’ the Air Source is by far the easiest to fit – there is no need to dig the garden up like you’d have to if you were fitting a ground source heat pump … and you don’t need planning permission.

That are slightly more com0plicated than a gas boiler as you will need to replace your water heater with one compatible with the system.

You may also need to replace a few radiators – but that’s par for the course if you’re upgrading your heating system anyway.

They are only good enough for a new house

While heat pumps are often fitted to new homes as part of government initiatives, they can be fitted to most properties.

The criteria for getting the most of an ASHP is that your home must be very well insulated – which is a goal we should all be striving for whether we are fitting heat pumps or not!

In fact, if you want to take advantage of the UK’s Boiler Upgrade Scheme, you have to live in an existing home rather than a new build.

If you need any proof that air source heat pumps work in older building, check out the 11th Century Church in Lympne, Kent – the parishioners there are kept warm with their very own ASHP.

So long at the heat pump you install is suitable for the size of your home, and your house is well insulated, an ASHP will keep you snug and cosy all year round.

They won’t work during a power cut

While this is true, neither will anything else in the home that requires electricity – including your gas boiler!

But, if you have a gateway fitted on your solat system, they absolutely will.

Although, it’s not the 70s and we don’t have power cuts very often.

They’re more expensive to run than gas boilers

While ASHP can be less efficient than gas boilers, if they are fitted and used correctly, they are about the same.

Statistically, an ASHP is 4 times more efficient than a gas boiler but, as they are designed to stay at a constant temperature when they are cranked up that can use a little more energy.

Think of it like cruise control on your car – if you flip that switch you car will be incredibly economical, but if you are speeding up and breaking all the time you’re going to burn a fair bit of fuel.

However, ASHPs are a LOT more economical than electric heating, especially if you have fitted solar as well.

They don’twork in flats

They do you know.

The only problem with fitting in flats is access to fit them as heat pumps are typically installed outside of a building or home, which can make fitting them for apartment buildings or flats difficult.

So, if you can get permission to hang the fan on the side of your flat, you can have an air source heat pump.

You need a backup system for when it’s cold.

Again, while there is some truth in that, it’s not something we have to worry about here in the UK.

ASHPs will work even when it’s minus 20 outside, which is an unusually low temperature for the UK. In fact, the last time England recorded a temperature that low was 1982.

Air SourceHeat Pumps are a nightmare to maintain and repair

This is just simply untrue.

Gas boilers contain a baffling amount of complicated bits and bobs, gas can be very dangerous so boilers have to be incredible well made and locked down.

ASHP aren’t dangerous at all and only contain a few essential parts – making maintaining them an absolute doddle.

They only work in warm countries

This sems to be a uniquely British myth, as Nordic countries have the highest sales of heat pumps in Europe.

The is still a huge amount of profit to be made in gas boiler sales so many manufacturers and salespeople will cling to the idea they are best for years to come.

Truth is, we are slap bang in the middle of a transition away from fossil fuels and into renewables – so it’s always best top do a little research yourself to see what’s real and what’s not.