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FOR INSTALLERS · REMOTE SURVEY
How to Survey Radiators for a Heat Pump
A practical guide to identifying, measuring and recording existing radiators.
- Last updated: September 2026
- Heat Loss Hub · For Installers
A heat-pump radiator survey should establish which room the radiator serves, radiator dimensions, radiator construction or type, number of panels and convectors, location in the room, available replacement space, visible valves and connections, visible pipe size where possible, photographic evidence and any uncertainty.
The purpose of the survey is to create an accurate record of the emitters already installed. That information can then be compared with the room-by-room heat loss and the radiator output at the proposed operating temperature.
KEY TAKEAWAY
The survey records what is installed. The design determines whether it is adequate.
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Send us the completed radiator survey and we’ll assess emitter suitability against the calculated heat loss.
What Information Should Be Recorded for Every Radiator?
| Information | Why It Is Needed |
|---|---|
| Room | Links the radiator to the room heat loss |
| Reference | Identifies the individual emitter |
| Height | Establishes physical size |
| Length | Establishes physical size |
| Radiator type | Helps establish output |
| Panels | Identifies construction |
| Convectors | Identifies construction |
| Manufacturer/model | Allows more accurate identification where available |
| Location | Shows installation constraints |
| Available replacement space | Helps if a larger emitter is required |
| Valves/connections | Supports installation planning |
| Visible pipework | Supports pipework assessment |
| Photos | Provides verification |
| Confidence | Shows whether information is confirmed or uncertain |
Every radiator should be traceable from the room survey through to the final emitter schedule.
Survey Radiators Room by Room
The simplest approach is to complete one room before moving to the next. For each room:
- Identify the room
- Count the emitters
- Give each emitter a reference
- Measure each radiator
- Identify its construction
- Photograph it
- Record its position
- Measure the available replacement space
- Record visible connections and pipework
- Mark any uncertainty
For example: Living Room — RAD-01, RAD-02. Once both radiators are complete, move on to the next room.
KEY TAKEAWAY
A radiator without a room reference cannot be reliably matched to the room load it is supposed to meet.
Give Every Radiator a Reference
A simple reference system makes the survey easier to understand later. Examples: Living Room — RAD-01, Living Room — RAD-02, Kitchen — RAD-01, Bedroom 1 — RAD-01.
This becomes particularly useful where a room contains several radiators, several radiators look identical, the property is large, replacement schedules are being prepared, or photographs need matching to individual emitters.
A digital survey should ideally keep the room, radiator record and photographs linked automatically.
How to Measure a Radiator
For standard panel radiators, measure the radiator body itself. Use millimetres.
Height
Measure from the bottom of the radiator body to the top.
Length
Measure from one end of the radiator body to the other.
Depth
Depth can also be useful, particularly for unusual or non-standard emitters.
Do not include TRV, lockshield or pipework in the radiator length.
Measure the radiator, not the space between the pipes.
A typical record might be: 600 mm high × 1200 mm long.
Where replacement planning later requires pipe-centre information, that can be recorded separately.
How to Identify Radiator Type
Standard panel radiators are commonly identified by the number of water panels and convector fin sets.
| Type | Panels | Convectors |
|---|---|---|
| Type 10 | 1 | 0 |
| Type 11 | 1 | 1 |
| Type 20 | 2 | 0 |
| Type 21 | 2 | 1 |
| Type 22 | 2 | 2 |
| Type 33 | 3 | 3 |
For example: Type 11 has one panel with one set of convector fins. Type 22 has two panels with two sets of convector fins.
If you know the radiator type, record it. If you do not, record number of panels, number of convectors, height, length, and take a clear side photograph.
If you are unsure of the radiator type, record what you can see rather than guessing.
Explore: Heat Pump Radiators & Heat Emitters
Take a Side Photograph
A front photograph is useful, but it may not show how the radiator is constructed. A side view can help establish number of panels, number of convector fins, overall depth and unusual construction.
A useful minimum photo set is front view, side view and room-context view.
KEY TAKEAWAY
The side of the radiator can be more useful to the designer than the front.
For a full guide to survey photographs:
Record Where the Radiator Is Installed
The physical position of the radiator can affect future replacement options. Record useful context such as external wall, internal wall, under a window, beside a door, in an alcove, behind furniture, behind curtains, inside a radiator cover, restricted by shelving, or restricted airflow.
The purpose is not to calculate the effect of every obstruction during the survey. It is to make the constraint visible to the designer.
Survey the Available Replacement Space
This is one of the most useful parts of the radiator survey. Do not only measure the radiator already fitted. Where practical, also record the space available if that radiator later needs to be replaced with a larger emitter. Record:
Maximum Practical Width
How wide could a replacement radiator reasonably be?
Maximum Practical Height
How tall could a replacement radiator reasonably be?
Depth Restrictions
Could a deeper radiator be fitted?
Also look for window sill, skirting, electrical sockets, doors, furniture, curtains, shelves, pipe positions and other fixed obstacles.
KEY TAKEAWAY
Do not only survey the radiator that is there. Survey the space available for the radiator that might need to replace it.
For example: Existing radiator: 600 × 800 mm Type 11. Available replacement space: Maximum 600 mm high × 1400 mm wide.
That information gives the designer significantly more useful options if the existing radiator is later found to be undersized.
What About Radiator Covers and Furniture?
If the radiator is affected by a decorative cover, permanent furniture, curtains, a built-in cabinet, or other airflow restriction, record it. Take a photograph where useful.
The survey does not need to decide exactly how much the obstruction changes radiator output. It simply needs to make the installation condition clear.
Record Valves and Connections
Where relevant, record visible radiator connections. Useful information may include TRV, lockshield, manual valve, bottom opposite-end connections, same-end connections, centre connections and unusual fittings.
This can help later if the radiator needs replacing or the pipework needs altering.
Do not turn the radiator survey into a system-balancing exercise. The aim is simply to document what is installed.
Record Visible Pipework
Where safely visible, also record the pipework entering the radiator. Useful information includes approximate pipe diameter, pipe material where identifiable, microbore, floor entry, wall entry and surface-mounted route.
For example: “15 mm copper visible at radiator” or “Microbore visible — upstream route unknown”.
Record what you can see. Do not assume the hidden pipework is the same.
Detailed assessment of the wider heating circuit belongs in the pipework survey.
Rooms With More Than One Radiator
If a room contains two or more radiators, each emitter should be recorded individually. For example: Living Room — RAD-01: 600 × 1200 Type 22; RAD-02: 600 × 800 Type 11.
Do not simply record “2 radiators.”
Each emitter may have different dimensions, different construction, different available replacement space, different pipework and different photographs.
Their calculated outputs can later be combined when assessing the room.
How to Survey Towel Rails
Towel rails should also be recorded individually. Useful information includes height, width, general construction, manufacturer, model where known, product label where available, photographs, available replacement space and dual-fuel element where relevant.
A towel rail should not be treated as a standard panel radiator simply because its dimensions are known.
Where the manufacturer and model cannot be established, record the information available and flag the emitter for identification rather than guessing its output.
Designer, Column and Unusual Radiators
Non-standard emitters may not be identifiable from dimensions alone. This can include column radiators, cast-iron radiators, aluminium radiators, vertical radiators, designer radiators and fan convectors.
For these emitters, prioritise:
- Manufacturer
- Model
- Product label
- Dimensions
- Clear photographs
If identification remains uncertain, mark: Emitter identification required.
Dimensions alone may not identify the output of a non-standard emitter. Do not invent an output based only on its appearance.
What About Underfloor Heating?
If a room is heated partly or entirely by underfloor heating, record that fact. Useful information may include UFH present, areas served where known, manifold location and existing documentation.
A full underfloor-heating assessment is a separate task and should not be guessed from the room survey alone.
What if You Cannot Identify the Radiator?
Do not guess. Instead: measure the height, measure the length, record depth where useful, count visible panels, count visible convectors, photograph the front, photograph the side, photograph any label, and record the uncertainty.
A simple confidence system can be used.
Confirmed
Dimensions and construction are known.
Partially Identified
Dimensions are known, but type or model remains uncertain.
Unknown
Further evidence or identification is required.
KEY TAKEAWAY
Record uncertainty rather than turning it into a guessed radiator type. This allows the designer to see exactly where further information may be required.
What Happens After the Radiator Survey?
The radiator survey itself does not decide whether the existing emitter is large enough. The process normally looks like this:
Survey records what is installed → Room-by-room heat-loss calculation establishes how much heat the room requires → Emitter calculation establishes how much heat the radiator can provide at the proposed operating temperature → Design determines whether the radiator should be retained, replaced, supplemented or reviewed further
KEY TAKEAWAY
The radiator survey records the emitter. The room-by-room design decides whether it is big enough. This distinction matters because radiator output changes with operating temperature. A radiator that performs adequately with a traditional boiler may provide considerably less output when used at lower heat-pump temperatures. The correct decision should come from the calculation rather than from appearance alone.
Common Radiator Survey Mistakes
Measuring Valve to Valve
Problem: This does not give the radiator body length.
Better: Measure from one end of the radiator body to the other.
Recording Dimensions but Not Radiator Type
Problem: Two radiators of the same height and length can have very different outputs.
Better: Record the construction as well as the dimensions.
No Side Photograph
Problem: The number of panels and convectors may remain unclear.
Better: Take a clear side view.
No Room Reference
Problem: The radiator cannot be confidently matched to the correct room heat loss.
Better: Link every emitter to the room it serves.
Missing a Second Radiator
Problem: Large rooms frequently contain multiple emitters.
Better: Count and record every radiator individually.
Guessing Radiator Type
Problem: A radiator can be misidentified from the front.
Better: Count the visible panels and convectors and mark uncertainty where necessary.
Ignoring Radiator Covers
Problem: A cover or fixed obstruction may be relevant to the final design.
Better: Record and photograph it.
Not Measuring Replacement Space
Problem: The designer may later establish that the existing radiator is undersized but have no idea what larger emitter could physically fit.
Better: Record maximum practical replacement dimensions where appropriate.
Treating Towel Rails Like Standard Panel Radiators
Problem: Their output may not be reliably established from dimensions alone.
Better: Record manufacturer and model where possible.
Guessing Unusual Radiator Output
Problem: Designer and column radiators can vary significantly.
Better: Record the evidence and flag the emitter for identification.
The aim of the survey is not to decide which radiators look too small. It is to collect enough information for the calculation to decide.
Example Radiator Survey Record
A completed radiator record might look like this:
| Field | Example |
|---|---|
| Room | Living Room |
| Reference | RAD-01 |
| Emitter | Panel radiator |
| Height | 600 mm |
| Length | 1200 mm |
| Type | Type 22 |
| Panels | 2 |
| Convectors | 2 |
| Location | External wall under window |
| Max replacement width | 1500 mm |
| Max replacement height | 700 mm |
| Visible pipe size | 15 mm |
| TRV | Yes |
| Front photo | Yes |
| Side photo | Yes |
| Context photo | Yes |
| Confidence | Confirmed |
If every radiator has a record like this, the designer should not need to reconstruct the survey from photographs and scattered notes.
Radiator Survey Completeness Check
Before leaving each room, check: room identified, every emitter recorded, reference assigned, height measured, length measured, type or construction recorded, front photograph taken, side photograph taken, context photograph taken, location recorded, replacement space recorded where relevant, visible connections recorded, visible pipework recorded where useful, and any uncertainty flagged.
The result should then be: Radiator survey complete, or Additional information required.
It is much easier to resolve a missing side photograph or wall-space measurement while still in the room than after the survey has been submitted.
Frequently Asked Questions
For each radiator, record room, reference, height, length, radiator type or construction, location, available replacement space, visible valves, visible pipework, photographs and any uncertainty. The radiator can then be assessed against the room heat loss during design.
If the existing radiators are being assessed for retention, each relevant radiator should normally be identified and measured individually.
Measure the radiator body itself. Record height and length. Do not include valves or pipework in the radiator body measurement.
No. The main radiator dimensions should refer to the radiator body. TRVs, lockshields and pipework can be recorded separately.
Count the number of water panels and convector fin sets. A side photograph is particularly useful. If you remain unsure, record the construction you can see and mark the type as uncertain.
A Type 11 normally has one panel and one convector. A Type 22 normally has two panels and two convectors. Look at the radiator from the side rather than relying only on the front view.
The side view can show the panel and convector arrangement much more clearly than the front. This helps confirm radiator construction.
It is strongly useful where the radiator may need upgrading. Recording the maximum available width, height and relevant restrictions gives the designer practical replacement options later.
Record each one separately, for example Living Room RAD-01 and Living Room RAD-02. Their outputs can later be combined when assessing the room.
Record height, width, manufacturer/model where available, label, photographs and available replacement space. Do not assume its output from dimensions alone.
Measure and photograph it, record its visible construction and mark the identification as uncertain. Do not guess.
Where it is visible, yes. This can be useful for the wider pipework assessment. Hidden pipework should not be assumed.
A useful minimum is front, side and room context. Take label or measurement photographs where useful.
Yes. A homeowner can usually record dimensions, photographs, location and available wall space. Technical interpretation and final emitter decisions should remain with the installer or designer.
No. The survey records the radiator. Its suitability is determined later by comparing its output at the proposed operating temperature with the calculated room heat loss.
No. Some existing radiators may be suitable. Others may need replacement, enlargement, supplementing or further review. The decision should be made from the room-by-room calculation rather than by automatically replacing every radiator.
Record the Radiator Once. Give the Designer Enough Information to Assess It Properly.
A useful radiator survey should establish which room it serves, its dimensions, its construction, its location, available replacement space, visible connections, relevant pipework, photographic evidence and any uncertainty.
The survey should not guess whether the radiator is adequate. That comes next.
The survey records what is installed. The design determines whether it is adequate.
RADIATOR SIZING SERVICE FOR INSTALLERS
Send us the completed radiator survey and we’ll assess emitter suitability against the calculated heat loss.
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