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What Information Is Needed for a Heat Pump Survey?
The information a designer needs before a heat-pump system can be designed properly.
- Last updated: September 2026
- Heat Loss Hub · For Installers
A heat-pump survey needs to establish more than the size of the house. It should provide enough reliable information about:
- Property layout
- Room dimensions
- Building fabric
- Existing radiators and emitters
- Pipework
- Existing heating equipment
- Hot-water demand
- Plant space
- Outdoor-unit location
- Electrical starting point
- Photos and documents
- Customer requirements
The aim is to give the designer enough information to move from the property itself to a system that can actually be calculated, specified and installed.
A good survey does not just describe the building. It provides the inputs needed to turn the building into a buildable heating-system design.
What Information Does a Heat-Pump Survey Need?
| Survey Area | Information Needed | Why It Matters |
|---|---|---|
| Property | Type, age, layout | Establishes project context |
| Rooms | Dimensions and use | Room-by-room heat loss |
| Fabric | Walls, floors, roof, glazing | Determines heat loss |
| Emitters | Size and type | Checks output and flow temperature |
| Pipework | Sizes and routes | Checks flow capability |
| Hot water | Occupancy, baths, showers | Cylinder sizing |
| Plant space | Dimensions and access | Equipment fit and buildability |
| Outdoor unit | Position and routes | Siting and installation |
| Electrical | Supply and cable route | Electrical planning |
| Evidence | Plans, EPC, photos | Supports or verifies inputs |
| Customer constraints | Preferences and future work | Keeps the design practical |
The exact detail required depends on the property and the scope of the design. But the principle is the same: the survey should collect enough information to support the engineering decisions that come next.
Property Details
The survey should begin with the basic project context. Useful information may include property address, property type, approximate age, number of storeys, extensions, major alterations, existing heating system, project type, occupancy, existing boiler or heat source and existing cylinder.
This gives the designer an initial picture of what kind of building and heating system they are dealing with. A 1990s detached house, a Victorian terrace and a new-build property may all have similar floor areas but very different design considerations.
Room Dimensions and Room Use
A room-by-room heat-loss calculation needs room-by-room information. Typical inputs include room name, room use, length, width, ceiling height, open-plan connections, sloping ceilings, double-height areas and unusual room geometry.
These dimensions establish the geometry used in the heat-loss calculation.
KEY TAKEAWAY
If the heat loss is calculated room by room, the property needs to be described room by room.
Room use also matters because different spaces may require different internal design temperatures. A bedroom, bathroom and living room should not automatically be treated as identical.
Building Fabric
The survey also needs enough information to understand how heat leaves the building. Typical fabric information includes external wall construction, wall insulation, floor construction, floor insulation, roof construction, ceiling construction, loft insulation, windows, external doors, extensions and unheated adjacent spaces.
This is important because two rooms with exactly the same dimensions can have very different heat losses. One might have insulated cavity walls, triple glazing and an insulated floor, while another might have solid walls, older glazing and an uninsulated floor.
KEY TAKEAWAY
The room size tells you how much space is being heated. The fabric tells you how quickly the heat escapes. Where construction cannot be confirmed, that uncertainty should remain visible.
Existing Radiators and Emitters
The survey should record the emitters that may form part of the final system. This can include radiator height, radiator length, panel type, convector fins, towel rails, underfloor heating, fan-assisted emitters, other heat emitters and available wall space for replacements.
This information matters because the designer needs to compare the heat required by the room with the heat the emitter can provide at the proposed operating temperature. A radiator that performs adequately with a boiler may not provide enough output at a lower heat-pump flow temperature.
KEY TAKEAWAY
The survey therefore needs to establish what is currently installed before the designer can decide to retain, replace, supplement or increase emitter size.
Existing Pipework
Pipework is another important part of the survey. Useful information may include primary flow size, primary return size, main distribution sizes, branch sizes, microbore, cylinder connections, plant-room pipework, known routes, concealed sections and possible upgrade routes.
The heat-loss calculation establishes how much heat the property needs. The pipework information helps establish whether the heating water can actually carry that heat around the building.
KEY TAKEAWAY
The heat loss tells you how much heat the property needs. The pipework information helps establish whether that heat can actually be moved around the system.
Not every pipe will always be visible. That is fine, provided the survey makes it clear which sections are visible, partly visible, concealed or unknown.
Existing Heating System and Plant
The designer also needs to understand what is already installed. Typical information can include existing boiler or heat source, boiler location, existing pumps, zone valves, controls, hydraulic components, filters or separators, expansion vessel, existing cylinder, plant-room layout and equipment intended to remain.
This helps establish what can potentially be retained, what needs replacing, what needs reconfiguring, and what physical space is available.
A heat-pump design is not created in isolation from the existing heating system.
Hot-Water Demand
Domestic hot water is another important part of the survey. Useful information includes number of occupants, number of bathrooms, baths, large baths, showers, high-flow outlets, existing cylinder, existing cylinder capacity, proposed cylinder location and available cylinder space.
This information helps the designer assess hot-water demand, cylinder volume, recovery requirements and available installation space.
A household with one shower and modest hot-water use has different requirements from a property with several occupants, multiple bathrooms, large baths and high-flow showers.
The cylinder should therefore be designed around the actual project rather than a generic property label.
Plant Space and Access
A technically correct selection still has to fit into the property. The survey should therefore record relevant plant-space information, including cylinder cupboard dimensions, plant-room dimensions, utility-room space, door widths, ceiling height, service clearances, access route, available wall space and available floor space.
Equipment has to work on paper and fit in the property. A large cylinder or additional hydraulic equipment may be technically suitable but impractical if it cannot be brought into the space, pipe connections cannot be accessed, maintenance clearance is inadequate, or the customer cannot use the room normally afterwards.
Physical constraints are part of the design.
Outdoor-Unit Information
The outdoor-unit location needs to be recorded in enough detail for the designer and installer to understand how the system will physically work. Useful information includes proposed position, wall or ground condition, nearby windows, nearby doors, property boundaries, obstructions, available clearances, access for installation, primary pipe route, electrical route, defrost-water route and alternative location where relevant.
The location needs to work as part of the whole installation. That means thinking beyond where the heat pump physically sits.
The survey should also help establish how the pipes get back to the plant area, how the electrical route works, how defrost water is managed, and whether access remains practical.
Electrical Information
The survey should also record the electrical starting point. Typical information may include consumer-unit location, consumer-unit photographs, electricity meter, incoming supply information where available, main cut-out where safely visible, proposed cable route, indoor equipment location and outdoor-unit location.
This is survey information rather than the final electrical design.
KEY TAKEAWAY
The survey should show the electrical starting point clearly enough for the competent person to assess what is required. The final electrical assessment should be carried out by the appropriate competent person.
Photos and Videos
Measurements provide numbers. Photographs and videos often provide the context around those numbers. Useful photographs may include radiators, boiler, plant room, cylinder, cylinder label, pipework, consumer unit, meter, outdoor-unit location, loft insulation and unusual construction.
Video can be particularly useful for showing the outdoor-unit position to plant-room route, primary pipe route, plant-room layout, cylinder cupboard, difficult access and property layout.
KEY TAKEAWAY
Measurements tell the designer the size. Photos and video often explain the situation around it. Good survey evidence should make the property easier to understand without requiring the designer to be standing in it.
Plans, EPCs and Supporting Documents
Existing documents can provide useful survey information and reduce duplicated work. These may include EPC, floor plans, architectural drawings, extension drawings, building-control documents, window schedules, new-build specifications, previous heat-loss calculations, previous heat-pump designs and manufacturer information.
These documents can help establish dimensions, construction, property layout and previous design assumptions. But they should still be checked against the current property where appropriate.
KEY TAKEAWAY
A drawing can show what was intended. It does not always show what is actually there. An EPC can also provide useful background information, but it should normally support the survey rather than replace project-specific evidence.
Customer Requirements and Constraints
A good survey also records the things that matter to the customer and the practical installation. These may include preferred outdoor-unit location, preferred cylinder location, radiators the customer wants retained, rooms they do not want altered, noise concerns, appearance concerns, planned extension, planned refurbishment, future room changes, hot-water expectations and access restrictions.
The technically correct design still has to work for the property and the customer. Recording these constraints early can prevent technically unnecessary redesign later.
What Information Is Critical Before Design Begins?
Not every missing item has the same importance. Some information is usually critical before detailed design can progress reliably. Examples include room dimensions, building-fabric basis, emitter information, hot-water demand, proposed outdoor-unit location, enough pipework information to understand the system, and major plant-space constraints.
Other information may be useful but potentially collected later. Examples might include a clearer equipment label photo, additional supporting document, historic energy-use information, or supplementary customer preference.
Critical Missing Information
The design should not progress without resolving it.
Supporting Information
Useful, but not necessarily a reason to stop every part of the design process.
KEY TAKEAWAY
Not every missing item stops the design, but some gaps make the design unreliable.
What if Some Information Is Unknown?
Not everything can always be confirmed during the first survey. The important thing is to make uncertainty visible. A simple confidence system can help.
Confirmed
Measured or supported by reliable documentation. Examples: room measured, cylinder model identified, construction shown clearly on drawings.
Supported
Reasonably backed by evidence but not fully verified. Examples: EPC and photographs support the same wall type, existing drawings appear consistent with the property.
Unknown
Information still requires verification, additional evidence, or a documented design assumption.
KEY TAKEAWAY
Unknown information should stay visible until it is verified or consciously assumed. An unknown value should not quietly become a fact just because the design software needs something entered into a box.
How Do You Know When the Survey Is Complete?
A survey is sufficiently complete when the critical information needed for design has been established. That normally means property geometry is known, building-fabric basis is understood, emitters are recorded, pipework is understood well enough, hot-water requirements are known, plant-space constraints are understood, outdoor-unit location is established, electrical starting point is documented, and critical unknowns are resolved or clearly recorded.
At that point, the project can move to: Ready for design
For a practical field-use version of these requirements:
Who Can Provide the Survey Information?
The information does not necessarily have to come from one person. Different parts may be supplied by the installer, a surveyor, the homeowner, an architect, a builder, existing drawings, an EPC, or manufacturer documentation.
For example: room dimensions customer measured; wall construction from an architectural drawing; pipe size installer verified; cylinder model from a manufacturer label; loft insulation surveyor observed.
KEY TAKEAWAY
The important question is not who supplied the information, but whether its source and reliability are understood. This is particularly useful where remote, customer-led and installer-led survey methods are combined.
Explore: Customer Self-Survey for Heat Pumps
How Does the Survey Information Feed Into Design?
The survey is the starting point for the engineering process. A typical design chain looks like this:
Survey information → Room-by-room heat loss → Emitter assessment → Design flow temperature → Heat-pump selection → Pipework and hydraulic design → Cylinder selection → Final design documentation
KEY TAKEAWAY
If the starting information is weak, uncertainty can flow through every stage that follows. That is why good survey information matters.
Frequently Asked Questions
A detailed survey may need information about property dimensions, building fabric, radiators, pipework, existing heating system, hot-water demand, cylinder space, outdoor-unit location, electrical arrangement, photos, plans and documents, and customer constraints. The exact requirements depend on the property and design scope.
For room-by-room heat-loss calculations, each relevant room needs sufficient geometry and fabric information to calculate its individual design load.
Typically walls, floors, roofs or ceilings, insulation, windows and external doors. The designer needs enough information to establish the heat-transfer characteristics of the building.
If existing radiators are being assessed for retention, each relevant emitter should normally be identified and measured.
Useful information can include primary pipe sizes, distribution sizes, microbore, plant-room pipework, cylinder connections, known routes and concealed sections.
Where an existing cylinder is present, useful information includes make/model, capacity, label, coil information where available, cupboard dimensions and access. Household hot-water demand should also be recorded.
Useful information includes proposed position, nearby windows and doors, boundary, ground/wall condition, clearances, access, pipe route, electrical route and defrost-water route.
Typical survey information includes consumer unit, meter, existing supply information where available, and proposed cable route. Final electrical design should be completed by the appropriate competent person.
Useful photographs commonly include radiators, plant, cylinder, pipework, consumer unit, meter, outdoor-unit location, loft/insulation and unusual construction.
Yes. It can provide useful background information about property type, construction, insulation, floor area and existing heating. But important design information may still need verification.
Yes. Plans can provide valuable information about dimensions, room layout, openings and construction. They are particularly useful for new builds and major renovations.
Record it as unknown or uncertain. Further evidence, documentation or physical verification can then be sought. Do not hide the uncertainty.
Record the visible sections and identify what cannot be seen. The designer can then decide whether further verification is required.
Yes. Homeowners can often provide measurements, photos, videos, plans, EPC and hot-water information. Technical decisions and important verification should remain with the appropriate installer or designer.
The survey is ready to move forward when the critical information needed for design is sufficiently reliable and any remaining unknowns are clearly identified.
Want to Know Whether the Survey Contains Enough Information for Design?
A complete heat-pump survey should establish the building, the heat-loss inputs, the emitters, the pipework, the hot-water demand, the plant constraints, the outdoor-unit location, the electrical starting point and the customer requirements.
Once the critical information is sufficiently reliable, the project can move into detailed design.
A heat-pump survey needs enough reliable information to describe the building, the existing heating system and the practical installation constraints before detailed design can begin.
VIEW THE HEAT PUMP SURVEY CHECKLIST
Use the field checklist to confirm whether a project has everything the designer needs before it moves into design.
Explore: Remote Survey Guides