How to Buy a Heat Pump: A Homeowner’s Guide
Buying a heat pump is a major decision, but it does not need to be confusing. The most important thing to know is that a heat pump is not simply a replacement boiler. It is part of a complete heating and hot water system that should be designed around your home, your household and the way you live.
A good installation begins long before the outdoor unit arrives. It starts with understanding how your property loses heat, whether your radiators can deliver enough warmth at lower water temperatures, how much hot water your household needs and where the equipment will sit.
This guide explains how to buy a heat pump, what to expect from the process and the questions worth asking before you commit.
Start with your home, not a heat pump catalogue
It can be tempting to begin by comparing brands, outputs and prices. These are important later, but they are not the first decision.
The first question is whether a heat pump can be designed to work well in your home.
Air source heat pumps can be suitable for many types of property, including older homes, newer builds, terraces, detached houses, cottages and homes currently heated by gas, oil or LPG. What differs from home to home is the system design.
A property does not need to be perfectly insulated before you consider a heat pump. However, better insulation, fewer draughts and suitable radiators or underfloor heating can help it run at lower water temperatures. This can improve efficiency while maintaining a comfortable temperature indoors.
Before moving ahead, it is useful to think about:
Your existing heating fuel, such as gas, oil, LPG or direct electric heating
The age, layout and construction of your property
Any extensions, loft conversions or rooms built to a different standard
Your existing radiators, underfloor heating and heating controls
Your insulation, glazing and known draughts
How much hot water your household uses
Whether you have room for a hot water cylinder
The available outdoor space for a heat pump
Access for installation, servicing and deliveries
Your plans for the property in the years ahead
A heat pump should be designed around these details. It should not be selected simply because it is a popular model or because it appears in a standard package.
Understand how a heat pump heats your home
An air source heat pump collects heat from the outside air and uses electricity to raise that heat to a useful temperature. It then transfers warmth into the water that circulates through your radiators or underfloor heating. In most homes, it also heats water stored in a hot water cylinder.
Heat pumps work differently from traditional boilers.
A gas, oil or LPG boiler often produces high temperature water and switches on in relatively short bursts. A heat pump usually works best by running for longer periods at a lower water temperature, maintaining a steady, comfortable indoor temperature.
This means your radiators may feel warm rather than extremely hot. That is normal. The purpose is not for the radiator surface to feel very hot. The purpose is for each room to receive enough heat to remain comfortable.
Energy Saving Trust explains that a heat pump installation should be approached as a step by step process, including deciding whether a heat pump is right for the home, checking potential funding, finding an installer, choosing the system and preparing for installation. Energy Saving Trustenergysavingtrust.org
Speak to an installer before making assumptions
A discovery call is a useful first step if you are unsure where to start.
At this stage, a good installer should want to understand the basics of your home and your priorities. That might include your current heating system, property type, household size, hot water use, available space and any concerns you have about radiators, installation disruption or running costs.
It is also a chance to ask practical questions such as:
Is a heat pump likely to suit my home?
Will I need a hot water cylinder?
Could my existing radiators be suitable?
What could installation involve?
Is there likely to be any funding available?
How long could the process take?
Where could the outdoor unit be installed?
Can the system be designed to work alongside solar panels or a battery?
At Your Energy Your Way, the purpose of this conversation is to help you understand the likely next step. It is not a substitute for a full survey. No responsible installer should offer a final heat pump size or complete system design before gathering detailed information about the property.
Arrange a proper heat pump survey
A heat pump survey is one of the most important stages in the buying process.
This is where an installer moves beyond general assumptions and looks closely at how your particular home works. The survey should cover the property fabric, the existing heating system, hot water needs, electrical supply, access and the practical details of installation.
A thorough survey may include:
Measuring rooms and recording ceiling heights
Reviewing walls, floors, roofs, windows and external doors
Looking at insulation, glazing and potential draughts
Assessing different parts of the home separately, including extensions and converted spaces
Measuring and checking existing radiators
Reviewing underfloor heating, if present
Inspecting pipework, valves, controls and water quality
Checking hot water arrangements and possible cylinder space
Reviewing the electrical supply and cable routes
Considering outdoor unit position, airflow, drainage, noise, access and future servicing
Discussing your preferred room temperatures and hot water routine
The outdoor unit needs a sensible location with good airflow and access for future maintenance. It also needs a suitable pipe route back into the property and a safe way to manage condensate water.
Careful surveying helps avoid surprises later. It also gives the installer the information needed to provide a proposal based on the home, rather than a rough estimate based on floor area or the rating of the existing boiler.
Why heat loss calculations matter
Before choosing the heat pump, the installer should calculate how much heat your home loses on a cold day.
Heat loss occurs in two main ways. Some heat travels through the building fabric, including walls, windows, roofs, floors and doors. Heat is also lost through planned ventilation and uncontrolled air leakage, such as draughts.
A heat loss calculation should be completed room by room. This matters because every room is different. A large room with several external walls and older windows may need more heat than a small internal room, even if they are close together.
The calculation tells the installer:
The total heating demand of the home
The heating requirement for each room
Whether each existing radiator can provide enough heat
Which radiators may need changing or adding to
Whether underfloor heating can provide sufficient output
The heating water temperature that the system can use
The capacity the heat pump needs to provide in cold weather
MCS explains that its Heat Load Calculator supports installers in completing calculations aligned with BS EN 12831 1: 2017, the recognised method used to establish a building’s heat load for heat pump design.
A homeowner does not need to understand every part of the calculation. However, you should be able to ask your installer whether they have completed a room by room heat loss assessment and how that information has shaped the proposed design.
Choose the right heat pump size
Heat pump sizing is not about buying the biggest unit available.
The right heat pump is one that can meet your home’s heating demand during cold weather while running smoothly and efficiently throughout the rest of the year.
Many older boilers are larger than a property needs for space heating. This is often because they were selected to provide rapid hot water or because they were installed with a large margin. Matching a heat pump to the output of the old boiler can therefore lead to the wrong result.
A heat pump that is too large may cost more than necessary and can start and stop repeatedly when demand is low. This can reduce efficiency and may create more wear on components over time.
A heat pump that is too small may struggle to keep the home warm during extended cold weather. It may also take longer to heat hot water or require more help from supplementary electric heating.
There is another important detail. A heat pump’s output changes according to the temperature outside and the temperature of the heating water it is required to produce. A model described as an 8 kW heat pump, for example, will not necessarily provide 8 kW in every operating condition.
This is why an installer should use the manufacturer’s performance information alongside your calculated heat loss. The aim is to choose a unit that works well in your actual home, rather than selecting by headline rating alone.
Check the radiators, underfloor heating and pipework
The outdoor unit is only one part of a heat pump installation. The rest of the heating system needs to be able to deliver the heat it produces.
Radiators
Heat pumps generally work efficiently at lower water temperatures than conventional boilers. Lower temperature water gives off less heat from a radiator, so some radiators may need to be larger or higher output models.
This does not automatically mean every radiator needs to be changed.
A proper room by room design will show whether each radiator can provide the heat that room needs at the planned flow temperature. Some may be suitable as they are. Others may need to be upgraded, repositioned or supplemented.
Energy Saving Trust notes that radiators sized for traditional higher temperature boiler systems may not provide enough heat when a heat pump runs at around 45°C.
Underfloor heating
Underfloor heating can work well with a heat pump because it spreads warmth across a large area and can often operate at lower water temperatures.
However, it should still be assessed carefully. Pipe spacing, loop lengths, insulation beneath the floor, floor coverings, manifold controls and the room heat loss all influence how much heat it can deliver.
Pipework
Existing pipework should also be checked. The system needs enough water flow to move heat from the heat pump to the radiators or underfloor heating.
Small pipe sections, long runs, hidden restrictions and poorly balanced circuits can affect performance. A good installer will assess what can be retained, what may need to change and whether the system needs cleaning, flushing, treatment and filtration before commissioning.
Understand flow temperature
Flow temperature is the temperature of the water leaving the heat pump and travelling to your radiators or underfloor heating.
The lower the flow temperature, the less work the heat pump generally has to do. This can improve efficiency. However, the lower the water temperature, the more radiator or underfloor heating area you need to provide the same level of comfort.
The goal is not to make the heating water as hot as possible. The goal is to find the lowest practical flow temperature that keeps every room warm when outdoor temperatures are low.
For many homes, this may involve flow temperatures around 45°C to 55°C, but there is no universal setting. The right temperature depends on the heat loss of the home, the radiator output, the underfloor heating design and the household’s comfort expectations.
Weather compensation can help the system operate efficiently. It adjusts the flow temperature according to the outdoor temperature. When it is mild outside, the system can use cooler water. When the weather gets colder, it can raise the heating water temperature as needed.
This is one reason why heat pumps are best managed through steady operation, rather than frequent switching on and off or large daily temperature changes.
Plan for hot water
Most air source heat pump systems use a hot water cylinder.
This is because heat pumps usually heat water more gradually than a high output combi boiler. A cylinder stores enough hot water for baths, showers and household use, then the heat pump reheats it on a planned schedule.
The right cylinder depends on your household.
Your installer should consider:
The number of people in the home
Bath and shower routines
Whether two or more showers may run at once
Larger baths or high flow shower systems
Space available for a cylinder
The cylinder coil size and compatibility with a heat pump
Expected hot water recovery times
Heat losses from any hot water circulation pipework
Hygiene cycles and higher temperature requirements
It is important to have realistic expectations. A heat pump hot water system is not identical to unlimited instant hot water from a combi boiler. However, with the right cylinder size and controls, it can provide reliable hot water for the household.
What to check before you buy a heat pump
After the survey and design process, you should receive a clear proposal explaining what has been recommended and why.
A good proposal should be understandable. It does not need to hide every technical detail, but it should give you confidence that the installer has designed the system for your home.
It should normally set out:
Your calculated heat loss
The proposed heat pump and the reason for its selection
The intended flow temperature
Proposed radiator, underfloor heating or pipework work
Hot water cylinder details
Controls and operating approach
Outdoor unit location
Electrical work and condensate drainage
Any building work, base or mounting work required
Installation timescale
Warranty information
The total cost, assumptions and exclusions
Information about aftercare and maintenance
This is a good stage to compare quotes. Do not compare only the final price. Compare the quality of the survey, the detail of the design, the equipment included, the scope of work, the commissioning plan and the support offered after installation.
The least expensive quote may not include radiator upgrades, hot water cylinder work, electrical upgrades, system protection, commissioning or aftercare. These are not small extras. They can make a significant difference to comfort, reliability and long term performance.
Check funding and grants
Eligible homeowners in England and Wales may be able to access financial support through the Boiler Upgrade Scheme.
At the time of writing, the scheme offers £7,500 towards eligible air to water and ground source heat pump installations. Eligible off gas grid properties replacing oil or LPG heating can qualify for an increased £9,000 grant for qualifying air to water or ground source installations. The £9,000 uplift is time limited and is currently available for eligible applications made by 31 March 2027.
The grant is typically applied for by the installer and deducted from the cost of the installation. Eligibility requirements, funding values and deadlines can change, so it is important to check the latest official guidance before relying on a grant in your budget.
A properly certified installer can explain how the grant process works and whether your project is likely to meet the relevant requirements. Ofgem’s official homeowner guidance is a helpful starting point.
Prepare for installation
Once you have chosen an installer and accepted the proposal, careful preparation helps installation run smoothly.
Before work begins, the installer should confirm the outdoor unit position, pipework routes, cylinder location, electrical work, access arrangements, delivery plans and any radiator changes.
Your installer should also explain:
How long the work is likely to take
Which rooms or areas will be affected
Whether there will be temporary interruptions to heating or hot water
How floors, furnishings and work areas will be protected
Where equipment and materials will be stored
What access is needed during the work
What will happen to old equipment, where removal is included
At Your Energy Your Way, we plan the practical details carefully before arriving on site. That allows us to manage disruption properly, protect your home and keep time without hot water to a minimum wherever possible.
What happens during heat pump installation?
Every installation is different, but the work typically includes fitting the outdoor unit, installing or changing the hot water cylinder, connecting new pipework, upgrading radiators where required, carrying out electrical work and setting up the controls.
The installation may also include cleaning and flushing the existing heating system, fitting filters, installing safety components, insulating external pipework and arranging condensate drainage.
The visible finish matters. Neat pipework, secure insulation, considered equipment locations and tidy work areas all contribute to a result that works well and looks appropriate in your home.
The details that are less visible matter just as much. These include water flow, pipework sizing, valves, filtration, pressure testing, electrical protection and system balancing.
A careful installer will communicate throughout the work, keep you informed about progress and leave your home clean and tidy once the installation is complete.
Commissioning and handover
A heat pump is not finished when the equipment has been fitted. It needs to be commissioned correctly.
Commissioning involves testing the system, checking flow and pressure, confirming heating and hot water operation, setting up controls, balancing the heating system where needed and configuring the heat pump for the agreed design.
Your installer should then provide a full handover.
This should include an explanation of:
Your heating controls and schedule
Hot water settings and timing
How weather compensation works
Why radiators may feel warm rather than very hot
What to expect when outdoor temperatures change
How to make sensible comfort adjustments
Basic system checks you can carry out
Maintenance needs
Warranties and certificates
Who to contact for support
A thorough handover makes a real difference. It helps you feel confident with the new system and understand how it differs from a boiler.
What to expect in the first few months
A heat pump can take a little time to get used to. It often runs for longer than a boiler and aims to maintain a stable temperature rather than produce short bursts of high temperature heat.
In the first few months, you may notice:
More consistent room temperatures
Radiators that feel warm rather than very hot
Longer heating periods
Heating water temperatures that change with the weather
Hot water heating that follows a schedule
Small changes to settings having an effect on comfort
Your Energy Your Way provides a 90 day Hypercare period after installation. This gives you a clear route to support as you get used to your new system. If you have questions about controls, hot water schedules, room temperatures or how the system is behaving, we are available to help.
The first few months are an important time for getting comfortable with a different way of heating your home. Good support can help you make the most of the system from the start.
Plan for servicing and long term support
Like any heating system, a heat pump benefits from routine maintenance.
Regular servicing can help protect performance, check important components, inspect filters, review water quality, identify any early issues and support manufacturer warranty requirements.
Ongoing maintenance can include:
Regular servicing
Filter inspections and cleaning
Water quality checks
Control and performance checks
Advice on settings and seasonal operation
Warranty support
Help if household requirements change
Your Energy Your Way offers ongoing maintenance and support, so you have a clear route back to the team that understands how your system was designed and installed.
Ready to take the first step?
Buying a heat pump should feel like a well planned home improvement, not a leap into the unknown.
The best place to begin is with a conversation about your home, your current heating, your hot water needs and what you want from an upgrade. From there, a detailed survey and heat loss calculation can show what a well designed system could look like.
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