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Independent Heat Pump Report for Installer Disputes
Structured technical evidence for installer complaints and disputes.
- Last updated: September 2026
- Heat Loss Hub · Independent Reports
When a heat-pump problem turns into a disagreement between homeowner and installer, opinions are rarely enough.
The homeowner may believe the system was incorrectly designed or installed. The installer may believe the system is operating correctly. Both sides may have documents, photographs, calculations or explanations supporting their position.
An Independent Heat Pump Dispute Report is designed to bring that technical evidence together and answer a more useful question: what does the available evidence actually support?
Heat Loss Hub can independently assess what was agreed, what was designed, what was installed, and how the system is performing, then provide a structured written report setting out the technical findings, limitations and appropriate next steps.
KEY TAKEAWAY
The purpose is not to take sides or to produce a report that simply confirms the homeowner’s existing view. If the evidence supports the installer on a particular point, the report should say so. If it supports the homeowner’s concern, it should explain why. And where there is not enough evidence to reach a reliable conclusion, that should also be made clear.
DISPUTE EVIDENCE
Bring the design, installation, commissioning and performance evidence together into one structured report.
Who Is This Service For?
This service is intended for homeowners with an already-installed heat-pump system where a technical disagreement has developed.
You may be preparing a formal complaint to your installer, challenging an installer’s explanation of a performance problem, dealing with a complaint that has not been resolved, preparing evidence for an MCS-related complaint, considering an ADR or consumer-protection dispute, seeking a technical opinion before discussing the matter with a solicitor, or trying to establish what remedial work is actually required.
The report is particularly useful where the disagreement involves questions such as: was the heat-loss calculation correct? Was the heat pump appropriately sized? Were the radiators or underfloor heating correctly designed? Does the installed system match the design? Was the system correctly commissioned? Should the property be able to heat properly at the stated design flow temperature? Could an identified design or installation discrepancy explain the reported problem?
What Is an Independent Heat Pump Dispute Report?
It is a structured independent technical assessment of the heat-pump system and the available evidence surrounding it.
Depending on the instruction, we may review original survey information, heat-loss calculations, design documents, emitter schedules, heat-pump selection, manufacturer performance data, system schematics, commissioning documents, photographs and video, controller settings, performance information, electricity-consumption data, correspondence between homeowner and installer, and subsequent remedial reports or alterations.
The objective is to turn a technical disagreement into a clear evidence trail. Instead of “the installer says it is fine” versus “the homeowner says it does not work”, we can ask: what was the system supposed to achieve, what evidence exists about what was installed, and does its actual performance support the original design?
What This Report Is Not
An Independent Heat Pump Dispute Report is a technical report. It does not determine legal liability, whether a contract has legally been breached, compensation, damages, who must pay for remedial work, or the eventual outcome of a complaint or dispute.
Those decisions belong to the relevant complaint handler, dispute-resolution body, professional adviser or court.
We also do not begin with an instruction such as “prove my installer did this wrong.” The instruction needs to allow for an independent conclusion.
KEY TAKEAWAY
A technically credible report must be able to find that the homeowner’s concern is supported, the installer’s explanation is supported, both parties are partly correct, another problem appears to be responsible, or there is currently insufficient evidence to determine the issue.
What Question Are We Being Asked to Answer?
A strong technical report works best when the issue is clearly defined.
Rather than asking “can you tell me everything that is wrong with my heat pump?” we may break the dispute down into specific questions. For example:
Was the original heat-loss calculation reasonable? Was the installed heat pump appropriately selected against that heat loss? Do the installed radiators match the original design schedule? Are the installed emitters capable of meeting the room heat losses at the stated design temperatures? Does the installed heat-pump model match the model specified in the design? Does the available commissioning evidence demonstrate the required system flow and control setup? Is the system operating at a significantly different flow temperature from the original design? Could the identified discrepancy reasonably explain the reported comfort or electricity-consumption problem?
Specific questions lead to clearer evidence and clearer conclusions.
Our Evidence Framework
The investigation follows a simple sequence.
What was agreed? What did the quotation, contract or agreed specification say would be provided?
What was designed? What do the heat-loss calculation, emitter schedule, heat-pump selection and system design show?
What was installed? What equipment and system arrangement were actually fitted?
How does it perform? What happens in real operation?
What does the evidence support? Which concerns can be substantiated, which cannot, and which require further investigation?
This distinction matters because these stages do not always match. A sound design can be installed incorrectly. A correctly installed system can be commissioned poorly. A system may also have been altered after the original installation.
Desktop Evidence Review or Site Inspection?
Not every dispute requires the same type of investigation.
Remote / Desktop Technical Review
A desktop review may be possible using evidence such as drawings, calculations, reports, photographs, videos, controller screenshots, performance data, and correspondence.
This can be particularly useful where the dispute centres on documentary issues such as heat-loss calculations, heat-pump sizing, emitter schedules, design flow temperature, or equipment selection.
But conclusions are limited by the evidence supplied. For example, we should not state that concealed pipework is incorrectly sized if that pipework has never been inspected or reliably documented.
Site Inspection
Where required, a physical inspection can provide additional evidence about installed heat-pump model, radiator sizes and types, cylinder, controls, visible pipework, pumps and valves, buffer or volumiser arrangements, system configuration, controller settings, and other visible installation details.
The appropriate level of investigation depends on what is actually being disputed.
What Evidence Should I Provide?
The more complete the evidence, the better the investigation can be. Useful documents include:
Contract and quotation — what was promised and what equipment was specified?
Original survey — what information about the property was recorded?
Heat-loss calculation — including room-by-room figures where available.
Radiator or emitter schedule — what output was required and what was selected?
Heat-pump selection — exact manufacturer and model.
System schematic — where available.
Cylinder specification — including model and capacity.
Commissioning documents — flow rates, settings and other recorded commissioning information.
MCS documentation — where applicable.
Performance estimate — predicted energy use and assumptions where available.
Handover information — controller instructions and system settings.
Photographs and videos — particularly useful if parts of the original installation have since been altered.
Performance evidence — room temperatures, electricity use, controller data, flow temperatures and error information.
Installer correspondence — including technical explanations provided in response to the complaint.
Complaint correspondence — this helps establish which issues are actually disputed.
Previous remedial reports — including reports from other engineers.
Establishing the Timeline
A dispute becomes much easier to understand when the chronology is clear. Where possible, establish:
Contract agreed → survey completed → design produced → system installed → commissioned → certified/handed over → problem first identified → installer notified → installer revisited or altered system → complaint escalated.
This matters because the system inspected today may not be identical to the system originally installed.
Which Technical Requirements Apply?
Heat-pump standards and industry requirements change over time. A system installed several years ago should not automatically be judged against a requirement introduced later.
For a dispute report we therefore need to understand dates such as contract date, design date, installation date, commissioning date, and certification date.
The relevant technical assessment may consider the design requirements applicable to the work, manufacturer requirements, agreed contractual design, commissioning requirements, and industry standards relevant at the time.
The purpose is to make a fair technical comparison rather than retrospectively applying whichever document happens to be current today.
Contract, Design and Technical Standards Are Different Things
These are related, but they should not be treated as interchangeable.
Imagine the quotation says 14kW heat pump, but the final design specifies 12kW heat pump, and a 10kW unit is actually installed.
There are several separate questions: what did the customer agree to? Why did the design change? Was the installed unit technically appropriate? Was the change agreed? Does it affect system performance?
A difference between the quotation and installation is not automatically proof of a technical design failure. Likewise, a system matching the quotation does not automatically prove that the technical design was correct.
The evidence needs separating.
Was the Original Heat-Loss Calculation Reasonable?
Where heat loss forms part of the dispute, we can review the assumptions behind it — room dimensions, wall construction, insulation, floor construction, roof or loft construction, windows and doors, ventilation, airtightness assumptions, internal design temperatures, and external design conditions.
The objective is not simply to compare two final kW numbers. It is to understand why they differ.
If a complete new calculation is required, an Independent Heat Loss Report may form part of the wider investigation.
Was the Heat Pump Correctly Sized?
Heat-pump sizing should not be assessed from the number printed on the model name alone.
The useful comparison is credible building heat requirement against output from the exact installed heat pump under the relevant outdoor and water-temperature conditions. This matters because the output available from a heat pump can change with operating conditions.
If sizing is the only disputed issue, an Independent Heat Pump Sizing Review may be sufficient. If sizing is only one part of a wider dispute, it can be considered within the broader evidence.
Were the Radiators or Underfloor Heating Correctly Designed?
Individual room heat losses determine the amount of heat that must be delivered into each space.
The report may therefore compare room heat loss with specified emitter and installed emitter at the relevant water temperatures.
For example: original schedule 1400 × 600mm Type 22 radiator; installed 1000 × 600mm Type 21 radiator.
The existence of that discrepancy is one finding. Whether it is large enough to explain the room’s reported heating problem is a separate technical question.
Does the Installed System Match the Design?
Where evidence allows, we can compare the design against the completed installation.
| Design item | Installed-system check |
|---|---|
| Heat-pump make/model | Does the exact model match? |
| Radiator schedule | Were the specified sizes/types fitted? |
| UFH | Does the visible/recorded layout match the design? |
| Cylinder | Is the specified unit installed? |
| Pumps | Does the arrangement match the design? |
| Valves | Are relevant components present/configured? |
| Buffer/volumiser | Does the hydraulic arrangement match? |
| Controls | Are the intended controls fitted? |
| Pipework | Do visible/documented routes and sizes match? |
A difference does not automatically mean the system is defective. But it needs explaining where it affects the disputed issue.
Was the System Properly Commissioned?
Correct design and installation still need correct commissioning.
Depending on the available evidence, this may include reviewing system flow, balancing, heating flow temperature, weather compensation, pump settings, control configuration, zoning, and commissioning documentation.
A design may depend on the system achieving a particular operating condition. If the evidence shows that condition was never achieved, that may be technically significant.
If there is no commissioning evidence available, the report should say so rather than assume that commissioning was either correct or incorrect.
How Is the System Actually Performing?
The dispute may involve symptoms such as rooms not reaching temperature, whole house becoming cold in winter, high electricity consumption, unexpectedly high flow temperatures, excessive cycling, reliance on backup heating, domestic-hot-water problems, or control issues.
Performance evidence can help establish whether the problem is consistent with the design concern being raised.
But a performance symptom does not automatically reveal its cause. For example, “the house is cold” does not by itself prove “the heat pump is undersized.” The rest of the evidence needs to support that conclusion.
Fact, Calculation and Technical Opinion Are Kept Separate
This is an important part of an independent report. Consider this example.
Observed fact: the radiator installed in the living room measures 1000 × 600mm and is identified as Type 21.
Documented design: the supplied emitter schedule specifies a 1400 × 600mm Type 22 radiator.
Calculation: at the stated design temperatures, the installed radiator has a lower calculated output than the radiator specified by the design.
Technical opinion: on the information available, the installed radiator does not appear capable of delivering the output contemplated by the original emitter schedule.
Separating those stages makes it clear which parts of the conclusion come from direct observation, supplied documents, calculation, and professional interpretation.
How Each Finding Is Assessed
Where practical, significant findings follow the same structure.
Requirement — what should the system have achieved?
Evidence — what documents, photographs, measurements or data are available?
Finding — what does the evidence actually show?
Technical significance — does the finding matter to the disputed problem?
Conclusion — what can reasonably be concluded?
Next step — is remediation, further testing or redesign required?
This makes the reasoning behind the report traceable.
A Discrepancy Does Not Automatically Prove the Cause
This distinction is extremely important in disputes.
Suppose three radiators do not match the original schedule. That may establish an installation discrepancy. It does not automatically establish that those radiators caused high whole-house electricity consumption, excessive cycling, a heat-pump fault, or every cold room in the property.
The report should separately consider whether the finding is technically capable of explaining the reported symptom. This helps prevent a genuine issue being overstated.
We Consider Evidence That Supports Either Side
Independence means considering the installer’s explanation as well as the homeowner’s concerns.
For example. Homeowner: “the heat pump is undersized.” Installer: “the system was intentionally designed to use supplementary heating at particular conditions.”
The appropriate response is not to choose a side first. It is to examine the design, heat-load figures, exact heat-pump performance, control strategy, relevant technical requirements, and actual system behaviour.
If the installer provides a technically credible explanation that is supported by the evidence, that should be reflected in the report.
What If Important Evidence Is Missing?
Not every dispute can be resolved conclusively from the available information.
Examples might include no original heat-loss calculation, no commissioning record, concealed pipework, no evidence of the original controller settings, major alterations made before inspection, or no reliable heat or electricity monitoring.
KEY TAKEAWAY
In those circumstances the report may conclude “further information required” or “unable to reach a reliable conclusion from the available evidence.” That is preferable to filling missing evidence with assumptions.
Preserve Evidence Before Remedial Work
If a dispute is developing, try to document the existing installation before major changes are made.
Useful evidence includes photographs of the heat-pump model plate, cylinder, radiators, visible pipework, pumps, valves, buffer or volumiser, controls, and controller settings.
Also retain screenshots, error histories, electricity data, design documents, and installer correspondence.
If urgent repairs are necessary, safety and restoring essential heating take priority. Where possible, simply document before the work, what was changed, and after the work. This preserves a clearer evidence trail.
Has Another Installer Already Changed the System?
That does not necessarily prevent an assessment.
But the report needs to distinguish between original installation, subsequent remedial work, and current system.
For example, if another contractor has already replaced several radiators, the current radiators cannot automatically be used as evidence of what the original installer fitted.
Contemporaneous photographs, invoices and reports become particularly valuable in this situation.
How Significant Is Each Finding?
Not every discrepancy has the same importance. A report may identify findings as broadly falling into categories such as:
Material Finding
Potentially relevant to the reported performance problem.
Minor Finding
A discrepancy exists but appears unlikely to materially affect the disputed issue.
Further Investigation Required
There is evidence of a possible problem, but additional testing is required.
No Material Issue Identified
The concern was investigated but the available evidence does not currently support it.
KEY TAKEAWAY
That last outcome is just as important as identifying a fault.
What Remedial Recommendations Can the Report Make?
Where technically appropriate, the report can identify possible next steps. These may include correcting an identified installation discrepancy, carrying out further measurements or tests, recalculating part of the design, changing emitters, recommissioning the system, reviewing weather compensation, investigating hydraulic flow, obtaining specialist electrical or refrigeration testing, or redesigning a specific part of the system.
KEY TAKEAWAY
A technical recommendation does not decide who must pay for it. That is a separate contractual or dispute-resolution question.
What Does the Final Report Contain?
The exact content depends on the instruction, but a detailed dispute report may include:
1. Instructions and scope — what we were asked to investigate.
2. Property and system details — property, heat pump and relevant system information.
3. Chronology — key dates and events.
4. Evidence reviewed — documents, photographs and data considered.
5. Technical requirements considered — relevant design, manufacturer or industry requirements.
6. Original design assessment — heat loss, sizing, emitters and relevant design assumptions.
7. Installed-system assessment — what the available evidence shows was installed.
8. Commissioning and performance evidence — where relevant and available.
9. Findings — clearly identified technical findings.
10. Technical significance — why each material finding matters.
11. Limitations — what could not be inspected or verified.
12. Recommended further work — remediation or further investigation.
13. Conclusions — a concise summary of what the evidence supports.
14. Appendices — calculations, photographs and supporting information where appropriate.
How Are Photographs Used?
Where photographs form part of the evidence, they should be easy to identify and understand.
Where appropriate, the report may record photograph number, what is shown, source, date where known, and relevant finding.
For example: “Photograph 12 — Living-room radiator. Shows the installed emitter identified during the site inspection.”
This can then be cross-referenced directly to the relevant technical finding.
Every Report Has Limitations
A transparent report should state what has and has not been established.
Possible limitations might include concealed pipework was not inspected, refrigerant pressures were not measured, electrical testing was outside the scope, original commissioning records were unavailable, heat output was assessed from manufacturer data rather than a direct heat meter, some photographs were supplied by the homeowner and their date could not independently be verified, or alterations had been made before the inspection.
KEY TAKEAWAY
Limitations do not mean the report has no value. They define how far the evidence allows the conclusions to go.
Independence Matters
Heat Loss Hub approaches the investigation independently. We are not the original installer and have no interest in defending the original design or proving it wrong.
The report should reflect the evidence even when the conclusion is not what the person commissioning the report originally expected.
That can mean finding a significant design problem, but it can equally mean the original concern is not supported by the evidence currently available.
Independence makes the technical findings more useful.
Some Issues May Require Other Specialists
Heat Loss Hub’s assessment can focus on areas such as heat-loss calculations, heat-pump sizing, emitters, heating-system design, flow temperature, system configuration, commissioning evidence, controls, and performance.
Some disputes may also involve areas requiring a different specialist — electrical safety, structural defects, refrigerant-system diagnosis, building defects, or legal interpretation of a contract.
Where an issue falls outside the technical scope of the report, we should identify that rather than provide an opinion outside our area of expertise.
Can I Use the Report for an MCS Complaint?
An independent technical report may provide useful supporting evidence where the complaint concerns technical aspects of an MCS-certified installation.
The report itself does not determine whether MCS will accept a complaint or what outcome MCS will reach. Eligibility, complaint scope and the weight given to evidence are matters for MCS and the relevant complaints process.
If you intend to use the report for an existing complaint, tell us at the start so that the technical questions can be clearly defined.
Can I Use the Report for ADR or Consumer Dispute Resolution?
An independent technical report may also form part of the evidence you choose to provide during an eligible dispute-resolution process.
Again, Heat Loss Hub does not decide the dispute. Our role is to provide clear technical evidence. The dispute-resolution body decides how that evidence is considered alongside contracts, correspondence, photographs, installer responses, other reports, and the wider circumstances of the case.
Can I Give the Report to My Solicitor?
Yes.
The standard dispute report can provide useful technical information when discussing the matter with a professional adviser.
However, if legal proceedings are being contemplated, you should tell your adviser how the report was prepared and ask whether a different form of expert instruction is required.
Important — This Is Not a CPR Part 35 Expert-Witness Report
Our standard Independent Heat Pump Dispute Report is an independent technical report intended to assist with installer complaints, dispute-resolution processes, technical discussions, and conversations with professional advisers.
It is not automatically prepared as formal CPR Part 35 expert evidence for court proceedings. Court expert evidence is subject to separate procedural requirements, instructions and duties.
KEY TAKEAWAY
If formal court proceedings have started, or your solicitor specifically requires Part 35 expert evidence, this should be identified before any instruction is agreed.
What If New Evidence Appears After the Report?
That can happen. For example, after receiving the report the installer may provide previously unavailable commissioning information, a revised design, manufacturer correspondence, additional photographs, or monitoring data.
Where new evidence could materially affect the findings, it may be appropriate to produce an addendum or a supplementary technical assessment rather than simply changing the original report without an evidence trail.
Which Heat Loss Hub Service Do I Need?
I Just Want to Know Why My Heat Pump Is Performing Badly
Start with an Independent Heat Pump Performance Review. The main objective is diagnosis rather than dispute evidence.
I Specifically Question the Original Heat-Loss Calculation
An Independent Heat Loss Report may be more appropriate.
I Specifically Question the Heat-Pump Size
Choose an Independent Heat Pump Sizing Review.
I Already Have an Installer Dispute and Need Written Technical Evidence
Choose an Independent Heat Pump Report for Installer Disputes. This can bring the relevant design, installation, commissioning and performance evidence together into one structured report.
Frequently Asked Questions
It is a written technical assessment of an installed heat-pump system and the evidence surrounding a complaint or dispute. It may review design calculations, installed equipment, commissioning information, performance and correspondence before setting out independent findings.
That is not how the service works. We assess the technical evidence independently. If the evidence supports your concern, the report will explain why. If it does not, that will also be recorded. Questions of legal responsibility are separate from the technical findings.
Yes, where heat loss forms part of the dispute. Depending on the instruction, this may involve reviewing the original calculation or producing a fresh independent room-by-room heat-loss assessment.
Yes. Heat-pump sizing can be assessed against a credible building heat load and the performance of the exact installed model at relevant operating conditions.
Yes. Where sufficient information is available, room heat loss can be compared with the specified and installed emitter output at the relevant design temperatures.
Not always. Some disputes can be assessed substantially from design documents, photographs, videos and performance information. Others require a physical inspection. We can determine the appropriate scope after reviewing what the dispute is about and what evidence already exists.
Potentially. A remote assessment works best when there is good documentation and clear photographs or video. The report will make clear which findings are based on supplied evidence rather than direct physical inspection.
Useful documents include quotation, contract, heat-loss calculation, radiator schedule, design, schematic, MCS paperwork, commissioning sheet, performance estimate, photographs, controller screenshots, installer correspondence, complaint correspondence, and previous technical reports. Do not worry if you do not have everything. We can identify what is missing.
A report may still be possible. However, we need to distinguish the original installation from later modifications. Original photographs, invoices and reports can become particularly important.
You can choose to provide relevant technical evidence as part of a complaint where appropriate. MCS determines its own complaint eligibility and how submitted evidence is considered.
It may be used as supporting technical evidence where relevant to the particular ADR process. The dispute-resolution body remains responsible for evaluating the evidence and deciding the dispute.
You can provide the report to your solicitor or other professional adviser. If formal court expert evidence is required, they should advise you on the appropriate instruction.
Not as part of the standard service. An Independent Heat Pump Dispute Report is a technical report. It is not automatically prepared under CPR Part 35 for use as formal expert evidence in court proceedings.
The report should say so. Independence means reporting what the evidence supports rather than producing a predetermined conclusion.
The report should identify the limitation. It may recommend additional documents, further measurements, site inspection, performance monitoring, or testing by another specialist. We should not present an uncertain conclusion as a proven fact.
Yes. Where the technical evidence supports it, the report can identify appropriate corrective work or further investigation. It does not decide who is legally or financially responsible for carrying that work out.
Need Independent Evidence for a Heat Pump Installer Dispute?
When the homeowner and installer disagree about what has gone wrong, the next step should not be another unsupported opinion.
A structured investigation can compare what was agreed, what was designed, what was installed, how the system performs, and what the evidence actually supports.
Heat Loss Hub can independently assess the relevant documents, calculations and installation evidence and provide a clear written report identifying confirmed technical findings, their significance, areas where evidence is insufficient, further investigation required, and appropriate technical remedial steps.
DISPUTE EVIDENCE
Bring the design, installation, commissioning and performance evidence together into one structured report.