Are Heat Pumps Always Installed Outside?

The simple answer is yes air source heat pumps are always installed outside or externally to your property. This is because they wouldn’t work well if installed inside your property.

Air source heat pumps need access to external air to allow them to extract heat from it. They also need to expel cold air which has had heat extracted from it and fed into your heating system.

If an air source heat pump was installed inside it would need to work harder and harder to keep the temperature of your property because the cooled air expelled from the system would cool the temperature, meaning your property would cool down, rather than getting warmer.

Why do Air Source Heat Pumps Have to be Outside?

Efficiency and heating, is the main reason air source heat pumps are installed outside.

Similar to a fridge, if you were to put your fridge in a very tight space or an environment where ventilation is minimal, your fridge would have to work considerably harder to maintain the cooled temperature within the fridge, than one with efficient ventilation around it.

This is because a fridge takes air from around it, extracts the heat from the air and pushes cooled air into the insulated refrigeration compartment where you store your food. The heated air is blown away from the fridge.

Using sensors the fridge will be able to determine temperature fluctuations in the food storage compartment and power on when more cooling is required to keep your food cool.

The same is true of an air source heat pump, but in reverse. Air is collected from outside the property and heat energy is extracted from it. This is fed into your heating system and used to heat water in your radiators and heat water stored within your hot water tanks.

Cooled air is then blown back out of the heat pump into the atmosphere, so if your heat pump were installed inside, it would be counterintuitive to your heating goal because the room where your air source heat pump was installed would become a walk in fridge.

For this reason, air source heat pumps must been installed outside so they’re pushing cooled air back into the atmosphere, rather than into your home.

Why an outside wall?

Heat pumps don’t always have to be installed on an outside wall, some are freestanding, but they often are because of the following reasons:

  • stability – affixing a heat pump to an outside wall can help to make sure it is stable and secure, even in harsh or extreme weather conditions. Raising it off the ground can also help prevent snowfall impacting it’s performance.
  • closer to your heating system for efficient heat transfer
  • sheltered from the elements
  • power supply

These are the most common reasons why air source heat pumps are installed close to or attached to an external wall of your property.

What About Ground Source Heat Pumps?

However, the same isn’t true of ground source heat pumps, where installation of the heat pump can be within your property.

This is because ground source heat pumps differ in how they collect heat.

Rather than extracting heat from the air circulating around them and returning the cooled air to the atmosphere, ground source heat pumps collect heat energy stored in the ground and circulate this to your heat pump, usually installed inside your home, where the heat exchanger extracts the heat into the hot water and heating system of your property.

Once the heat has been extracted from the special cooling fluid running through the underground pipes, either installed within boreholes or as part of a ground loop system, the now cooled fluid is pushed around the pressurised pipe network once more to gather heat from underground.

The heating process is continuous with heat constantly being fed into your system ready for when you switch the heating on or take a hot shower.

Unlike air source heat pumps, which can be larger and much less attractive to look at, ground source heat pumps are much smaller and more conveniently sized, they’re usually approximately the same size as a conventional gas boiler, so can usually be hidden away in a cupboard, utility room or airing cupboard of most domestic homes.

Which is best? Ground Source Heat Pump vs Air Source Heat Pump?

The best type of heat pump for your needs depends on the property type where you are planning to install your heat pump and certain characteristics the property possesses.

You will also want to factor in things like;

  • what type of heating you want for the property
  • whether you want to use existing radiators and heating systems
  • how much money you want to spend
  • the weather conditions your property experiences
  • the terrain beneath your property
  • the land around your property, is it privately owned by you, shared with other homeowners or public land?
  • your electricity source
  • the type of property; flat, terraced house, detached house, large estate or suburban semi detached house.

Once you have an idea of the above, consider your budget carefully because this will likely have the largest bearing on the type of heat pump you will be able to install within your property.