2. What size air source heat pump do I need?
Air Source Heat Pumps

What size air source heat pump do I need?

In order for your heat pump to deliver the results you expect, it needs to be installed correctly, which also means it needs to be the right size. This is where the expertise and support from a qualified installer comes in.

Read on to learn about: 

 

•    The importance of correct air source heat pump sizing 
•    The different air source heat pump size options
•    Calculating the right air source heat pump size
•    Other considerations affecting air source heat pump size 

What size air source heat pump do I need - ASHP sizing guide

The importance of correct air source heat pump sizing

 

When talking about the size of an air source heat pump, we’re actually referring to the power output, measured in kilowatts (kW) rather than its physical size. The output your heat pump will need to deliver depends on unique aspects of your home, such as:

 

•    The size and layout of your property
•    Occupancy and average heating usage
•    How old your property is
•    Quality of insulation 
•    Type of windows 
•    Your desired indoor temperature
 

These, naturally, will be different for everyone, so be sure that you assess all of these carefully with your installer.

Exploring air source heat pump size options

A general rule of thumb is that larger properties will need a larger output, but remember, the factors we mentioned in the last section will also have an impact. At Baxi, our heat pumps have an output of between 4kWs and 13kWs.

 

An undersized unit may not have enough power to heat your home. Not only will this affect your comfort, but having the system running at a higher level than is needed could make your energy bills more expensive. Going the other way, oversized heat pumps will short cycle, which can lead to greater wear on key components, and even higher energy bills than an undersized heat pump.

An undersized air source heat pump may not have enough power to heat your home. Oversized heat pumps will short cycle, which can lead to greater wear on key components and higher energy bills.

Calculating the right air source heat pump size for your home - Baxi ASHP sizing guide

Calculating the right air source heat pump size for your home

To ensure the heat pump will be the right size for your needs, a heat loss calculation will be carried out by your installer. This will look at various attributes of your home, taking into account everything from the size of the property, the building materials used, and how airtight the property is.


This calculation ensures your heat pump is the right size for your needs and that the unit works to its full potential. Most importantly, you’ll have the consistent performance that you expect. 

Other aspects that should be considered in a heat pump system design

 

You’ll also need to consider your current heating systems, such as how many radiators you have and if these will need upsizing so that they are compatible with the lower flow temperatures that your heat pump will operate at when compared to a traditional boiler. If you have underfloor heating, these systems also tend to work well with heat pumps. Finally, there needs to be enough clearance around the heat pump to allow for clear airflow and to help with maintenance.

 

We've outlined some other important factors for you in our air source heat pump comprehensive guide, which you can read here. 

Ask us about air source heat pump sizing

 

At Baxi, our air source heat pumps are engineered for efficiency and reliability, ensuring consistent heating while helping you to achieve your energy goals.

 
Learn more about our heat pumps here.

Baxi Heat Pumps

Our air source heat pumps will deliver reliable, energy-efficient performance. Suitable for a wide range of properties.

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