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An air source heat pump is an energy-efficient method of heating a home and its hot water. It uses a small amount of electricity to create a large amount of heat. In fact, the energy output is many times more than the input. One of the main challenges of installing heat pumps is choosing where to locate the outdoor unit. It can be tempting to place it inside a garage or similar structure, but this is not usually advisable, for several reasons.
To understand why location is so important for air source heat pumps, and why garages are not usually a good idea, we need to first think about how they work. They are electric-powered but still reduce carbon emissions and energy use due to their efficiency. An air source heat pump is 300-400% efficient. In comparison, the efficiency of even an A-rated condensing gas boiler is 90-98.4%.
An air source heat pump is designed to extract heat from the outside air and pump it into the home. It works exactly like a fridge but in reverse.
Find out more: How Does An Air Source Heat Pump Work
The heat from the outside air is blown or pumped over the heat exchange surface. Inside, there is a refrigerant liquid. This liquid heats up and starts to evaporate and turn into a gas.
The refrigerant gas is then compressed, increasing the heat even more. The heated gas then moves through a heat exchanger, which transfers the heat to the home's heating and/or domestic hot water system. This could be through vents and fans, a hot water cylinder, underfloor heating, or a central heating system.
Once the heat has been released into the property, the refrigerant gas cools down and condenses back into a liquid. Then it cycles back through the air pump system to begin the cycle again.
An air source heat pump is also an air conditioner. The cycle can be reversed by extracting heat from inside the property and pumping it outside.
Dig deeper: Can Air Source Heat Pumps Cool
The basic process is the same for all types of heat pumps. The differences come from where they extract the heat. Air source heat pumps take it from ambient air outside, ground source heat pumps take it from underneath the ground, and water source heat pumps take it from nearby bodies of water.
Take a look: How Much Does It Cost To Install Ground Source Heat Pump
There are two main types of air-source heat pumps. A monoblock heat pump contains all of the components in its outdoor unit. It connects directly to the wet heating system of the house, and it heats the water to go into that outside.
A split system, on the other hand, has both an outdoor and an indoor unit. The outdoor unit houses only the compressor, while the indoor unit houses the heat exchanger. Split air source heat pumps can be both air-to-water (transfers the heat to the property's heating and hot water system) and air-to-air (transfers the heat directly to the air inside through the use of fans or ducts).
Generally speaking, no. An air source heat pump should not be placed in a garage and there are a few reasons for this.
Air source heat pumps require a constant supply of fresh air to work as they should. An ambient air source is a poor conductor of heat energy, so the air source heat pump needs to take in a large amount of air to be able to extract enough heat to evaporate the refrigerant liquid.
Inside a garage, there is a limited amount of air and, even if the garage is quite draughty, the air isn't replaced quickly enough for there to be enough for the heat pump to work efficiently.
It will end up using a high level of electricity attempting to extract enough heat from the limited air supply and may become as inefficient, or even less efficient, than a gas boiler.
For a heat pump to be placed indoors and still work well, the room it is placed in would need to be much larger than the space you are trying to heat.
After the air source heat pump extracts heat from the surrounding air, it blows out cold air. This is a constant process while the heat pump is operating. When it is outside, this isn't an issue. But if the heat pump is placed in an enclosed space, the cold air will remain inside for a longer time.
The result of this is that a) the garage would become very cold, and b) the heat pump would have to work harder and harder to extract heat from air that is becoming progressively colder. This would again result in it becoming much less energy efficient.
Garages are often multi-use. They are a space where cars and other vehicles are parked and they may also house flammable materials and substances. This can throw up a range of safety issues concerning an air-source heat pump.
The air-source heat pump could become damaged through vehicle use near to it, or through corrosive substances. Having a heat pump next to flammable liquids creates a potential fire risk.
There are fewer issues with placing the indoor unit of an air source heat pump in a garage. Ventilation, cooling, and safety issues are not a concern because the heat extraction is still taking place in the outdoor unit.
The only potential problem with garage placement for the indoor unit is the distance from the heating system. The more pipe or ductwork you need to lay to heat the house or its hot water, the more inefficient the system will be. There will always be some heat loss as the water or air moves through pipes, and the further it has to move, the more heat loss there will be.
It is better to place the indoor unit in a more central location, if possible. This will help the air source heat pump system to work at maximum efficiency.
If you are dead set on placing the outdoor unit of your air source heat pump in your garage, the only way of doing this is by using a ducted system so you can exhaust air elsewhere. The unit itself would be inside but the cold air output would be ducted through the wall to the outside.
This will eliminate the problem of the garage becoming excessively cool because the cold air will be taken outside.
It doesn't, however, help with the ventilation issues. The air source heat pump would still be extracting heat from a much, much smaller volume of air than it needs to to be at full efficiency.
The only other solution would be to use a garage-like structure that is more like a pole barn. This has completely open sides, or at least two open sides. This would increase the air flow to the air source heat pump, but it would no longer be usable as a normal garage because it would be open to the elements.
So what can you do instead? It can be a good idea to think about the problems that housing the unit in a garage might solve and address these with different solutions.
Air source heat pumps are functional pieces of equipment that aren't designed to be necessarily attractive. For this reason, it is tempting to think about hiding it away in a garage, but there are other solutions.
An imperfect solution is to create a structure to surround the air source heat pump, with an open roof but sides that shield it from view. This would have more air flow than a closed structure, but it would still restrict some of the air and reduce the efficiency of the unit.
A better solution would be the careful placement of the heat pump so that it either blends in with the surroundings or is in a location that naturally isn't very visible. Even a single fence that blocks the view of the heat pump, but remains far away, would work well. This wouldn't hide it from all angles but it would be a good balance.
It is a common misconception that air source heat pumps need to be kept in the shade. Heat is transferred via convection, not radiation, so the radiating heat from the sun won't affect the operation very much at all.
The outdoor unit is specifically designed for use outdoors in all weather, including bright sunlight, and any components that have the potential to be affected by it will already be housed in parts of the units that shield them.
Noise reduction is an important consideration with air source heat pumps. It is a major focus of the Microgeneration Certification Scheme planning regulations, to reduce noise disruption as much as possible.
While air source heat pumps do make noise, however, the more modern units make much less of it than the older ones.
Storing the outdoor heat pump in a garage would lessen the noise heard outside, but the trade-off with efficiency is not worth it.
Instead, choosing a space for the heat pump that will prevent it from causing everyday noise disturbance is a better option. Anyone who installs an air source heat pump must be MCS certified, and as part of that training will conduct a thorough noise disturbance survey before identifying the best placement for the outdoor unit.
Is noise pollution as much of a problem as it first appears? Not really. Air source heat pumps don't make all that much noise. On average, it is between 40 and 60 decibels. This is the equivalent of a dishwasher or a microwave.
Yes, there will be noise, but once the heat pump is outside with all of the ambient noise already present, it won't be too noticeable. The key consideration is to not place it near anywhere that level of noise could create a disturbance. For example, outside a downstairs bedroom window or too close to a neighbour's property.
In most cases, air-source heat pumps (and other types like ground-source heat pumps and water-source heat pumps) do not require planning permission. This is because they fall under permitted development rules. These rules allow for certain types of modifications to properties without needing to seek permission from the local authority.
As always, there are regulations about how a heat pump can be installed to keep it within permitted development. If these regulations aren't followed, then it would need planning permission or it would have been installed illegally.
There are special regulations around properties that are a listed building, or located in World Heritage Sites, Conservation Areas, or Scheduled Monument sites.
The possibility of placing the outdoor unit of an air source heat pump inside a garage is not explicitly mentioned in the planning permission regulations. They do, however, say that the heat pump must be installed according to MCS regulations.
The MCS states that the heat pump is to be placed outside, either fitted to a wall or on ground level, and that it must have plenty of space around it so it can have a good flow of air.
This suggests that placing an air source heat pump in a garage would go against MCS building regulations, and would therefore also not be in line with planning permission regulations.
The outdoor unit of an air source heat pump should be placed outside, against a wall of the property. It is best to place it at ground level, but it can also be directly attached to the wall at a greater height.
To allow for sufficient air flow, there should be a minimum of one-metre clearance at the front and sides, and 30cm of clearance at the back.
To increase energy efficiency, it can help to place the outdoor unit of the heat pump as close as possible to the indoor unit. Limiting the amount of pipework the liquid needs to flow through helps to retain as much heat as possible.
Air source heat pumps do sometimes freeze. They have an automatic defrost cycle to deal with this, which reverses the system temporarily, drawing heat outside to warm the heat pump. If you live in an area that gets a lot of snow, you should avoid placing the heat pump anywhere that snow tends to create a bank.
Place the air source heat away from anywhere that could cause a noise disturbance, and make sure it is at least one metre away from any neighbouring properties.
Uncover more: Where To Install An Air Source Heat Pump
If you need to have your heat pump in a garage, you could opt for a ground-source heat pump or water-source heat pump instead. These can both be placed inside.
Neither of these will create any of the issues that an air source heat pump would when placed inside. They don't require any air flow and they won't make the garage cold.
This is because, rather than extracting heat from the air, they draw it from beneath the ground through a network of pipes. The warmth in the ground will heat water in the pipes, which is then taken to the heat pump to heat the refrigerant liquid. The rest of the process is identical to an air source heat pump.
Ground-source heat pumps or water-source heat pumps aren't as reliant on air temperatures because the water underneath the ground stays very stable, so they won't get less efficient over the winter.
They are more costly and more complicated to install, however, because they require the pipes to be placed in trenches or boreholes. And they will require the use of more land.
Our engineers understand air source heat pumps inside and out. And they have the knowledge that comes with hands-on experience and dedicated training. Because of this, they are perfectly placed to assist you with determining the best placement for your air source heat pump.
When you contact us, our team will visit your property to conduct an assessment. Based on all of the available criteria, plus your personal preferences, they will find the best location. They will also look at your current heating system and other key elements to help you decide what type of air source heat pump is right for you, and whether or not your internal heating system needs any modifications.
After that, they will take care of the installation process and will keep you informed of their progress every step of the way. If any problems arise, they will be discussed with you as soon as possible. You will also receive a clear and detailed quote before work begins, so you will know beforehand how much the work will cost.
Contact us today to find out how we can help you with your air source heat pump installation.
Air source heat pumps should not be placed in a garage. They require open space and sufficient air flow for them to work efficiently and extract as much heat as possible from the air. Their cold air output would also make a garage very cold. Instead, you should place the heat pump outside, in a well-ventilated spot.
