What Size Air Source Heat Pump Do I Need?

If you’ve been thinking about choosing an air source heat pump for your heating needs, one of the first questions you’ll likely have is ‘what size air source heat pump do I need?’  

When choosing the right system for your home, our installers will consider factors like the size and type of the property, quality of insulation and local climate. During a free site survey, we assess all of these factors to ensure you’re getting the right unit for your heating and hot water demands.

How Big is an Air Source Heat Pump? 

The most common size for an ASHP is 1 -1.5 metres high and 0.5–1 metre in width. Although, air source heat pumps can come in different sizes, depending on the property’s size and heating demands. ASHPs are usually comparable to the size of a dishwasher, but you also need to factor in having enough space around the unit for sufficient airflow. 

Domestic properties may require smaller units than commercial properties; a standard three-bedroom home will likely need an ASHP of around 5-7 kW. Commercial properties with multiple floors and rooms will require more kilowatts due to higher heating demands. 

The Importance of Getting the Right Size Heat Pump

Choosing the right size of heat pump is more important than just fitting it in your garden. If the pump is too small, it may not meet the heating and hot water demands for your property and could actually increase your energy bills if it needs to work harder. Similarly, if your ASHP is too large for your property, you could face a higher upfront cost. 

Having the right size heat pump enables: 

• Optimal efficiency as you’re using only the energy needed to heat your home/premises 
• Cost effectiveness when you balance installation cost with long-term running costs 
• Consistency and longevity as you’re keeping a steady indoor temperature, even on colder days 

A perfectly sized air source heat pump means your buildings stays sufficiently heated without wasting energy or money. If you’re wondering what size air source heat pump you need for your property, contact our expert team to have a chat about your options. 

Considerations of Air Source Heat Pump Size

When figuring out what size air source heat pump you need, there are a few factors to keep into account: 

Size of the Home and Property Type 

It goes without saying that a large family home with multiple floors will need a higher heat output to stay warm and cater to hot water demands. On the other hand, a single-person one-bed property with high quality insulation will need a much smaller model. 

The type of property also plays a part in the size of heat pump needed, as detached houses typically lose more heat than terraced houses. If your building has lots of external walls and windows, it may require a larger heat pump to compensate. 

Home Insulation & Efficiency 

Good insulation means your home can hold onto heat for longer, so your heat pump won’t have to work as hard. If your home has insulated walls, floors and lofts, as well as double or triple glazed windows, it’ll likely need a smaller system as it’ll retain heat better.  

On the other hand, airy homes with lots of windows or draughty doors may let heat escape, requiring a larger heat pump. If your home isn’t energy efficient, you’ll need a larger ASHP to make up for heat loss. Choosing the right sized heat pump for your needs will save you money on installation and ongoing energy bills.  

Home Ventilation

Good airflow is essential for comfort but too much ventilation like leaks or draughts can let heat escape. If this is the case, your system will have to work harder to keep up with heating and hot water demands.  

It’s also important to consider the outdoor temperature in your area, as external conditions can affect the system you’ll need; colder regions require more heat output than milder ones. 

Existing System

Your home’s existing heating system, including radiators and underfloor heating, may affect the size of the ASHP needed. If you have sufficient heating, with plenty of modern radiators, you may need a smaller heat pump, but older radiators can require more heat output from the ASHP.  Old radiators will most likely need replacing with newer or larger ones. 

Location  

ASHPs need to be installed in areas with enough airflow around the entire unit to ensure it operates smoothly. The system also needs to be in an accessible location so installers and engineers can carry out regular maintenance checks.  

Air source heat pumps need to be installed on solid, flat ground, as tilting or shifting could damage the unit or affect its performance. If you don’t have much space outside your building, it may not be the ideal location for an ASHP. 

Commercial Buildings  

For commercial properties, energy usage can vary significantly. Office buildings, warehouses and hospitality venues all have different heating needs depending on the type of service they provide and how many occupants are in the building. 

Larger spaces with high ceilings or frequent door openings may need higher-capacity ASHPs, whereas more energy-efficient commercial spaces could operate well with smaller units.  

Calculating Air Source Heat Pump Size 

So, how can you work out what size air source heat pump you need? The right size is often determined by calculating the heating demand of a building, looking at property size, insulation and climate.  

ASHPs are usually rated in kilowatts (kW) of heating output. Larger homes with poor efficiency often require higher kW units. When choosing the right air source heat pump size, your engineer will consider: 

• Property size and type 
• Insulation levels 
• Window quality 
• Number of rooms 
• Local climate  

A rough guide is 1kW per 10-25 square metres, but this can vary based on insulation and other factors. As an example, a well-insulated three-bedroom home may need an ASHP of 5–7 kW, while larger or less efficient properties could require 10-12 kW or more. The best way to be sure you’re getting the right system for your heating and hot water demands is to speak to a qualified ASHP engineer – contact our team to discuss more. 

How Rollings Renewables Help With Heat Pump Sizing 

At Rolling Renewables, we take the guesswork out of choosing the right size for your heat pump. Our experienced engineers have 20+ years of experience in installing ASHPs around the UK. With our team, you’ll get: 

• A free remote quote  
• Site survey to measure up the space available 
• Pre-installation paperwork such as your distribution network operator (DNO) application 
• Full installation followed by an MCS certificate 

If you’re unsure what size air source heat pump you need for your premises, contact us on sales@rollingrenewables.co.uk or call us on 01905 621777.