The size of the air source heat pump is important. Choose one that is too small and when it is the most chilly outside, your house will be cold. Choose one that is too large and it will be switching on and off a lot of times, wasting power and affecting parts. Under this guide, you will be first introduced to the popular sizes of air source heat pumps in the UK. Then you will find straightforward instructions on how to select the right size for your house.
What should be the Size of Air Source Heat Pumps in the UK?
Air source heat pumps are available in various capacities, traditionally in kilowatts (kW). Usually the sizes of units used domestically are:
- Small Units
Approximately 4 – 6 kW – mostly in small flats or hugely insulated small homes.
- Medium Units
6 -12 kW approximately – most terraced homes and semi-detached homes are common.
- Large Units
12 -16 kW and larger – applied in larger detached buildings, where high heat demand is a factor or the requirement of the underfloor heating being more flow.
Important: There are also systems in which several smaller outdoors units are connected to a single indoor configuration.
Power supply is also important: Domestic systems use single phase power supplies, big ones might require three phase power supply.
Note: These dimensions are mere estimations. Your home will require the correct size which will depend on the amount of heat lost and not the rooms.
Get your £7,500 air source heat pump grant now and upgrade your home’s efficiency!
The importance of sizing is not the house size, but it is heat loss
The correct method of building the size of a heat pump is to take the calculation of your home’s heat loss in watts (W) at a given design temperature. Heat loss depends on:
- Reinforcement of insulation (walls, roof, floors)
- Quality of windows (assistance in the form of a double or triple glazing)
- Air tightness and draughts
- Layout of the house and bare walls.
- Desired indoor temperature
The amount of heat lost through two similarly sized houses may be very different. One of them may have solid walls and single glazing, and the other may contain cavity-wall insulation and new windows. The former will require a larger heating pump to warm.
Easy Actions to Select the Correct Size of Air Source Heat Pump
First get a Power Assessment or EPC
Your insulation, windows and heating system will be inspected by an installer. They end up giving you a competitive guess of the amount of heat needed or refer you to a qualified installer so that he can do a complete calculation of the amount of heat loss. Contact Home Energy Guide now for expert help.
Request them to Calculate Heat Loss
It is the most significant document which uses it to size the heat pump in kW by installers. The calculation is the maximum power your system requires on the coolest day and this is referred to as the peak heat demand.
Correlate the output of the match system to the design temperature heat loss
Select a heat pump which is able to satisfy the heat loss of your home at the selected exterior designing temperature. The installer will prescribe a unit with the correct output at a typical UK designed temperature (which is -1°C to -5°C in most regions).
If Possible, Use Low Flow Tempos
Heat pumps are efficient under low flow temperatures. When you have under floor heating or bigger radiators then a smaller unit can be used because the system will operate much better.
Avoid Oversizing
A heat pump that is oversized is switched on and off more frequently. A brief cycle gives less efficiency and causes more wear and can decrease life span. Installers usually go to larger units to ensure they are not always running flat in extreme cold conditions, but it is preferable to add a small backup or a hybrid backup.
Avoid Undersizing
A small sized unit will be running steadily and will fail to accomplish the desired temperature during cold days. This leads to increased consumption of electricity and inconvenience.
Note: In case you settle on a smaller unit, a hybrid system with either a boiler or an electric backup during peak times should be considered.
Additional Factors of Sizing
1. Hot Water Requirement
Debating between a cylinder size of hot water, those wishing to have hot water in the same system should add one with space heating and also have an electric booster such that the two can work together.
2. Controls and Zoning
Peak demands can be reduced by effective controls and room thermostats and a slightly smaller unit might be satisfactory.
3. Future Additions
In case you will insulate or further enlarge the work, you want to tell your installer about that, perhaps you want to build the system in the size you will need when the home is complete.
4. Identifying an Installer
Select a registered installer that is familiar with heat pumps. An installer should ensure that the temperature of flows is set appropriately and the system should be commissioned to guarantee efficient performance.
Learn more about air source heat pump installation in the UK
How Home Energy Guide can Assist You
Home Energy Guide will assist you throughout the process. We discuss the common size of the air source heat pumps and how they apply to various homes. We provide the way to obtain an appropriate calculation of heat loss, the way of comparing installer estimates, and what improvements (such as insulation, bigger radiators, etc.) will make a heat pump most effective. In case you are not sure where to begin, Home Energy Guide can provide you with the checklists and other helpful suggestions on preparing a survey, as well as how to make sure you avoid making typical mistakes. You can also check eligibility for the ASHP grant here.
Frequently Asked Questions (FAQs)
Ask a qualified installer of heat loss to do a calculation. They get the length of the walls, the windows and insulation provide you with a number in watts or kilowatts.
Rough rules of thumb may do, but they cannot be relied upon. Professional calculation of heat loss should be always observed to prevent over and undersizing.
Yes, insulated well will lower heat loss and this means that you have less to install. It is best to improve the insulation first to reduce the installation cost and running costs.
