Air source heat pumps are heating, cooling and hot water systems that require both internal and external components to provide these functionalities for a home.
The type of air source heat pump can affect what internal apparatus is used with a heat pump system. Air to water head pumps work with an indoor central heating system, while air to air heat pumps work with a space heating system
Air handling units can be the internal components of an air to air heat pump system, and can either be part of a ductless or ducted setup. Air handlers provide heating by blowing heated air into a room or across a home, and can also typically be used to provide cooling.
Our own source heat pump is the air to water type and so works with a central heating system that consists of radiators and underfloor heating.
As such there aren’t any air handling units within our heat pump system, but for air to air setups, indoor air handlers would be used to provide heating or cooling.
While the above external heat pump unit can be similar to the one found with an air to air heat pump system, one or more air handling units will be needed with an air to air setup, and would be located indoors as part of the internal heating and cooling apparatus.
We discuss in more detail below how air source heat pumps work, what air handling units are and how they work as part of an air to air heat pump system.
What Are Air Source Heat Pumps?
An air source heat pump system can provide heating and cooling or hot water for a home, depending on the type of heat pump used.
Both internal and external components will be required with an air source heat pump (ASHP) setup. An external air source heat pump unit will always be required located outside of a home, alongside an internal setup such as radiators, underfloor heating or air handlers.
For a deeper explanation on air source heat pumps see our other article.
How Air Source Heat Pumps Work
In heating mode, air source heat pumps work by using fans to force air over refrigerant flowing through coils to capture heat.
A compressor helps to increase temperature and heat is delivered inside a home for use in a heating system.
Depending on the type of system used (either air to air or air to water – explained in more detail here), heat will either be released into a home through a water-based system or air-based system.
For air to water heat pump systems (like ours), a water-based central heating system is used where apparatus such a radiators and underfloor heating deliver the heat.
Air to water setups can also be used to provide domestic hot water when using a hot water tank.
For air to air heat pump systems, space heating apparatus such as air handling units will be used. An air to air system can also be used for effective cooling, in a similar way to how an air conditioning unit would work.
For more information see our article on how air source heat pumps work.
What Are Air Handling Units (AHUs)?
Air handling units can often resemble typical domestic air conditioning units and are the internal components of an air to air heat pump system.
With a ducted system, a central air handling unit can work with ducts and vents to move heated or cooled air around a home.
The video below explains more about how an internal air handling unit works with an air source heat pump ducted system.
With a ductless system, mini-split arrangement, one or more air handling units can be used across a home.
These can come in a variety of options to suit the indoor space such as wall mounted, floor mounted, and ceiling mounted.
Parts Of An ASHP Air Handling Unit
Parts of an air handling unit for an air source heat pump system can include:
- Air Inlet and Outlet. The air inlet is responsible for collecting air from outside for conditioning and distribution, while the outlet releases the air after operation completion.
- Dampers. Dampers are present at the inlet and outlet. They help to regulate the amount of air entering or going out of the unit.
- Filter. Filters can help increase the air’s purity by preventing dust, bacteria, viruses, and other pollutants from passing through. They ensure that the circulating air is clean and healthy and doesn’t contaminate the interior. It also prevents debris from building up in the components and damaging them.
Cleaning the filter in an air handling unit should be part of the maintenance regime of an air source heat pump system.
- Fan. The fan is an electromechanical system that pulls air from the outside into the AHU and moves it through the dampers and filters for conditioning before getting into the duct system for distribution.
- Heat Exchanger. The heat exchanger transfers heat between the air and the refrigerant flowing through as part of the ASHP system. The heat exchanger either releases or extracts heat depending on whether the ASHP system is in heating or cooling mode.
Advantages And Disadvantages Of ASHP Air Handling Units
Pros Of ASHP Air Handling Units
- They can be considered eco-friendly. Air source heat pump systems, including air handling units, run solely on electricity and so don’t directly burn any fossil fuels to heat or cool a home.
- Versatile. Air handling units can come in a range of types to allow them to be mounted in many different places around a home, such as in cupboards, attics, on walls, on floors and on ceilings.
- They have cooling capabilities as well. Air handling unit work with an air to air heat pump system that can also be used to provide cooling for a home as well as heating, by working in reverse and extracting heat from the inside air and expelling it outside at the outdoor heat pump.
- Can be used with both ductless and ducted systems.
Cons Of ASHP Air Handling Units
- Efficiency can reduce if any air filters aren’t cleaned or replaced.
- Can only work with air to air heat pump systems and not air to water heat pump setups.
- Dust can be an issue when used with ducts to move air around a home.
- If using air handling units with an air to air heat pump system, the heat pump system can’t be used to provide domestic hot water and another system to deliver hot water must be used.
Further Reading
Parts Of An Air Source Heat Pump Explained
Where To Install An Air Source Heat Pump