Home / Our Services / Performance & Design Review
INDEPENDENT REVIEW · EXISTING SYSTEMS
Independent Heat Pump Performance & Design Review
Heat pump installed but something doesn’t seem right?
- Last updated: September 2026
- Heat Loss Hub · Independent Review Services
High electricity bills. Cold rooms. Constant cycling. High flow temperatures. Poor hot-water performance. Or simply a system that doesn’t appear to be delivering what you expected.
An Independent Heat Pump Performance Review looks beyond the heat pump itself.
We compare: what the system was designed to do → what was actually installed → how it is operating now.
That allows us to investigate whether the issue is likely to sit with the original design, installation, commissioning, controls, operation or the equipment itself.
Heat Loss Hub is independent. We are not reviewing your system in order to sell you another heat pump or win the remedial installation.
KEY TAKEAWAY
Understand what is happening, identify what the evidence shows and establish what should happen next.
GET STARTED
Not sure whether the issue is the design, installation, settings or the heat pump itself?
Heat pump not installed yet? If you want us to check quotations, heat-loss calculations or a proposed design before installation, see our Independent Design Review service.
When a Heat Pump Works — But Something Still Doesn’t Seem Right
A heat pump doesn’t have to stop working completely for there to be a problem.
It may still heat the house while using considerably more electricity than expected. It may achieve comfortable temperatures, but only by running at a much higher flow temperature than the original design suggested. Some rooms may be warm while others remain cold. The system may switch on and off repeatedly. Hot water may take longer than expected to recover.
Or the heat pump, installer and controls may all appear to be working individually, while the heating system as a whole still doesn’t feel right.
Typical concerns include electricity consumption much higher than expected, rooms that struggle to reach temperature, some rooms overheating while others remain cold, very high heating flow temperatures, frequent heat-pump cycling, a heat pump that appears to run almost constantly, poor hot-water recovery, radiators that only seem effective at high temperatures, noisy pumps or high water-flow rates, unexpected immersion-heater use, weather compensation that doesn’t appear to work correctly, conflicting advice from the installer and heat-pump manufacturer, or a system that simply doesn’t perform as you were led to expect.
KEY TAKEAWAY
A symptom tells us where to investigate. It does not automatically tell us the cause.
High electricity use does not automatically mean the heat pump is faulty. Cycling does not automatically mean it is oversized. Cold rooms do not automatically mean the radiators are too small.
A proper investigation looks at the heating system as a whole.
What Is an Independent Heat Pump Performance Review?
An Independent Heat Pump Performance Review is a technical assessment of an existing installed system.
It is different from an annual service. It is also different from simply checking whether the heat pump contains a fault code.
We look at how the system was designed, what equipment has actually been installed and how the system is currently being operated. That can include the original room-by-room heat-loss calculation, heat-pump sizing, radiator or underfloor-heating design, intended design flow temperature, heat-pump output at the relevant operating conditions, hydraulic arrangement, pipework information where available, pumps, buffers, volumisers and bypass arrangements, weather compensation, thermostats and zoning, commissioning settings, domestic hot-water settings, immersion-heater operation, cycling and runtime behaviour, electricity consumption, controller or app information, and any available performance data.
KEY TAKEAWAY
The objective is not simply to produce a list of possible faults. It is to narrow the problem down.
Five Areas We Investigate
Most heat-pump performance problems can be investigated by looking at five separate areas.
1. Design
Was the system designed correctly in the first place? We can review areas such as room-by-room heat loss, whole-property design heat loss, heat-pump selection, heat-pump output at design conditions, radiator and emitter sizing, underfloor-heating requirements, intended flow temperature, cylinder design, and the assumptions behind the original performance estimate.
A heat pump can be installed exactly as specified and still perform poorly if the original design was unsuitable.
2. Installation
Does the system that was actually installed match the design? Changes can happen between design and installation. A different radiator may have been fitted. Pipework may have followed a different route. A buffer, low-loss header or additional pump may have been introduced. Controls may have changed. The heat pump itself may have been substituted.
Those changes are not automatically wrong. But they need to be considered because the performance of the final system depends on what was actually installed, not simply what appears on the original drawings.
3. Commissioning
Was the finished system set up correctly? Heat pumps depend heavily on commissioning. Relevant areas can include system flow, pump settings, heating-curve configuration, maximum flow temperatures, balancing, control settings, domestic hot-water settings, immersion configuration, and other manufacturer parameters.
A good design can perform badly if the system is commissioned incorrectly.
4. Controls and Operation
Is the heat pump being asked to operate in a way that suits a low-temperature heating system? We can consider weather compensation, fixed flow temperatures, room thermostats, zoning, time schedules, night setbacks, room influence, domestic hot-water schedules, and how different controls interact.
Some apparent heat-pump problems are actually control problems.
5. Equipment
Is there evidence suggesting that the heat pump or another component may actually be faulty? An independent review cannot replace hands-on manufacturer fault diagnosis or refrigeration testing. But it can help establish whether the available evidence points towards the heat pump itself, the heating system around it, the controls, or the original design.
That can make the next step much clearer.
What Was Your System Originally Supposed to Do?
The first stage of a performance review is understanding the original design intent.
Where available, we review documents such as room-by-room heat-loss calculations, heat-pump selection information, radiator schedules, underfloor-heating information, design flow temperatures, system schematics, performance estimates, commissioning records, quotation and specification, cylinder information, handover documents, and installation photographs.
We want to establish the answer to a basic question: what was this heating system designed to achieve?
KEY TAKEAWAY
That gives us something meaningful to compare against what was eventually installed.
What Was Actually Installed?
The next stage is comparing the design with the finished system.
For example: the design may specify a particular radiator size. A smaller model may actually have been installed. The design may assume a 45°C heating flow temperature. The property may only achieve comfortable temperatures at 52°C. The design may show one hydraulic arrangement. The finished plant room may contain additional pumps, a buffer or a different control arrangement. The original heat-loss calculation might indicate a 7kW requirement. A significantly larger heat pump may have been installed.
None of those observations automatically proves that the system is wrong.
KEY TAKEAWAY
But differences between design intent and installed reality are important and should be understood.
How Is the System Actually Operating?
The third part of the review is the operating evidence.
Depending on what information is available, this may include heating flow temperature, return temperature, outdoor temperature, weather-compensation settings, target room temperatures, actual room temperatures, heat-pump runtime, number of starts and stops, domestic hot-water temperatures, immersion-heater use, controller history, app screenshots, electricity consumption, smart-meter information, and heat-meter data where available.
This is where the original design and the real system begin to come together.
For example: if the original design assumed the house could be heated at 40°C but the system now requires 50°C to maintain temperature, we need to understand why.
It might be an emitter issue. It might be a heat-loss issue. It might be a control issue. Or the original design assumption may simply have been unrealistic.
Common Heat Pump Problems We Can Investigate
Different symptoms point towards different areas of the system.
| What You Are Experiencing | Areas Worth Investigating |
|---|---|
| High electricity use | Heat demand, flow temperature, controls, hot water, immersion use, cycling, tariff and system settings |
| Cold rooms | Room heat loss, radiator output, balancing, flow, control settings and design temperature |
| Frequent cycling | Heat-pump minimum output, zoning, system volume, heat demand and controls |
| Heat pump appears to run continuously | Building heat demand, output, weather conditions and operating temperatures |
| High flow temperature | Radiator sizing, heat loss, heating curve and control strategy |
| Poor hot-water recovery | Heat-pump output, cylinder coil, water temperature, controls and immersion settings |
| Some rooms hot and others cold | Balancing, radiator sizing, zoning, room heat loss and controls |
| Noisy pumps or high water-flow rates | Hydraulic resistance, flow requirements, pipework and pump configuration |
These are investigation routes, not automatic diagnoses.
Was the Heat Pump Sized Correctly?
Heat-pump sizing is more involved than comparing the property’s heat loss with the number printed on the front of the heat pump.
We need to consider the calculated design heat loss, the design outdoor temperature, intended heating water temperature, the heat pump’s actual output under those conditions, modulation range, minimum output, and how the heat pump behaves during milder weather.
A heat pump can be too small. It can also be considerably larger than the building requires. But size alone does not tell us how well a system will perform. The heating system, controls and operating temperatures still matter.
If you want to understand the principles in more detail:
Explore: Heat Loss & Heat Pump Sizing
Do the Radiators Match the Heat Loss?
Heat pumps usually work most efficiently when they can heat the home using relatively low water temperatures. That means the radiators or other heat emitters need enough output at those temperatures.
During a review we may compare: room heat loss → installed radiator → output at the intended design temperature.
This is particularly useful where one or two rooms remain cold, the system needs unusually high flow temperatures, radiators were changed during installation, the original radiator schedule is missing, or the homeowner was told that existing radiators would be suitable but performance suggests otherwise.
A radiator being physically large does not automatically mean it has enough output. Its output depends on its type, dimensions and operating temperatures.
Does the Plumbing Allow the Heat Pump to Perform Properly?
The heat pump may be correctly sized and the radiators may be suitable, but the system still needs to move enough water around the property.
Depending on the system, relevant areas can include pipe sizes, design flow rates, circulator settings, hydraulic resistance, buffers, volumisers, low-loss headers, bypass valves, primary and secondary circuits, zoning, and minimum flow requirements.
We don’t assume that every additional component is a problem. Different system designs can work successfully. The important question is whether the arrangement allows the heat pump and heating system to operate as intended.
Are the Controls Helping or Hurting Performance?
Heat pumps generally behave differently from traditional boilers. A control strategy that worked well with a gas or oil boiler is not automatically ideal for a heat pump.
During a performance review we may look at weather compensation, heating curves, target flow temperatures, room thermostats, multiple heating zones, setbacks, timers, room influence, domestic hot-water schedules, legionella cycles, and immersion-heater configuration.
We also look for controls that may be competing with each other. For example, weather compensation may be trying to operate the heat pump continuously at a low water temperature while another control repeatedly switches the heating circuit off.
The result can be very different from the original design intention.
High Electricity Bills Don’t Automatically Mean the Heat Pump Is Faulty
A high electricity bill is one of the most common reasons homeowners begin questioning their heat-pump installation.
But the bill alone does not tell us what is wrong.
Electricity consumption can be influenced by the heat loss of the property, outdoor weather, indoor temperature, heating hours, domestic hot-water use, flow temperature, immersion use, heat-pump efficiency, control strategy, household behaviour, and electricity tariff.
For example, maintaining a home at 23°C will require more energy than maintaining the same property at 20°C. Likewise, a colder-than-average winter will affect consumption.
The review therefore looks for evidence before drawing conclusions.
What Can We Actually Prove About Heat Pump Performance?
The word performance can mean several different things. It is important not to confuse them.
Design Performance
What the system was expected to achieve based on the original heat loss, heat-pump selection, emitter design and operating temperatures.
Operational Performance
How the system is actually behaving. For example: flow temperatures, runtime, cycling, room temperatures, control behaviour, and hot-water performance.
Electricity Consumption
How much electrical energy the system is consuming. This can be compared with available information about the property and how the system is being used.
Measured Efficiency
Calculating actual system COP or seasonal performance requires suitable information about both electrical energy consumed and useful heat delivered.
Where sufficiently reliable heat and electricity metering exists, more detailed performance analysis may be possible. Where it doesn’t, we will not manufacture a precise efficiency figure from incomplete data.
KEY TAKEAWAY
We will tell you what the evidence can support — and what it cannot.
What Information Should You Send Us?
The more relevant evidence we have, the more useful the review can be.
Original Design Documents
Room-by-room heat-loss calculation, radiator schedule, system design, heat-pump selection, schematic, performance estimate, commissioning documents, quotation, handover information.
Equipment Information
Heat-pump make and model, cylinder details, controls, buffer or volumiser information, pumps, underfloor-heating manifolds.
Photographs and Video
Useful photographs can include the outdoor unit, plant room, cylinder, circulation pumps, controls, pipework, radiators, UFH manifolds, electrical meters, and controller displays.
A video walkthrough can also be extremely useful where the system arrangement is difficult to explain in photographs.
Operating Information
This may include heating-curve settings, flow temperatures, room-temperature settings, schedules, controller screenshots, app information, error history, electricity consumption, smart-meter records, and any existing heat-meter data.
A Description of the Problem
Tell us what you expected, what is actually happening, when you first noticed it, whether the problem affects the whole house or individual rooms, and what has already been changed or investigated.
What If I Don’t Have the Original Design Documents?
You can still ask us to review the system. Missing paperwork doesn’t automatically prevent an assessment.
Depending on the information available, we may be able to establish a great deal from installed equipment, radiator sizes, photographs, system settings, property information, controller data, bills, and a homeowner survey.
However, there are limits. If the original room-by-room heat-loss calculation is unavailable and understanding the heat demand is critical to the investigation, a new heat-loss calculation may be required. Likewise, concealed pipework or undocumented system changes may require further investigation.
KEY TAKEAWAY
We would rather identify those limitations than pretend they don’t exist.
Can the Review Be Carried Out Remotely?
Many performance reviews can begin remotely. This works particularly well where good documentation and photographs are available.
A remote review may be suitable where we can obtain the original design documents, clear system photographs, heat-pump settings, radiator measurements, controller data, electricity records, and a detailed description of the problem.
Remote assessment is especially useful for reviewing heat-loss calculations, heat-pump sizing, radiator sizing, design flow temperatures, control strategy, weather compensation, expected versus actual electricity use, and documented system design.
When Might a Site Visit Be Required?
Some issues cannot be established confidently from paperwork and photographs alone.
A physical inspection may be more appropriate where we need to verify undocumented pipework, hydraulic arrangements, concealed or unidentified components, physical installation details, actual equipment dimensions, flow or balancing problems, or other conditions that require measurement or testing on site.
If the information provided indicates that a remote assessment is unlikely to answer the question, we will tell you.
What You Receive
The purpose of the review is to leave you with something useful.
Depending on the scope agreed, your Independent Performance Review Report can include:
System Overview
A summary of the heat pump, emitters, controls and relevant system arrangement.
Original Design Assessment
Our findings on the available heat-loss information, heat-pump sizing, emitter design, intended flow temperature and other relevant design decisions.
Installed-System Comparison
Material differences between the original design and what appears to have been installed.
Operational Findings
Relevant observations from settings, temperatures, electricity consumption, controls and other performance evidence.
Issues Identified
Findings can be classified clearly as:
Confirmed issue — Evidence is sufficient to identify a specific technical issue.
Likely issue — The available evidence strongly suggests an issue, but additional verification may be appropriate.
Requires further investigation — The evidence is insufficient to reach a reliable conclusion.
No issue identified — The available evidence does not indicate a technical problem in that area.
Recommended Next Actions
Recommendations are prioritised wherever practical.
Priority 1 — Correct first: Issues most likely to materially affect operation or performance.
Priority 2 — Optimisation: Changes that may improve how the system operates.
Priority 3 — Optional improvement: Changes worth considering but not essential to resolve the immediate problem.
What Happens If We Find a Design Problem?
Not every performance issue needs a complete redesign. The outcome may be relatively simple.
Settings or Optimisation
The underlying design is sound but the controls, weather compensation or operating temperatures need adjustment.
Minor Remedial Work
A radiator, pump setting, control arrangement or other part of the system may need attention.
Significant Design Issue
The review may identify more fundamental problems with heat-pump sizing, emitters, hydraulics or the original design assumptions.
Where substantial changes are required, a separate Remedial Heat Pump Design may be appropriate.
KEY TAKEAWAY
The review identifies the problem. Any detailed redesign or remedial specification can then be agreed separately rather than being hidden inside the initial assessment fee.
What an Independent Performance Review Does Not Include
It is equally important to understand what the service is not.
Unless specifically agreed, an Independent Performance Review is not an annual heat-pump service, refrigerant fault diagnosis, an F-Gas repair, an electrical safety inspection, destructive investigation of concealed pipework, physical repair of the heating system, a guarantee that every concealed installation detail is correct, a guaranteed calculation of actual seasonal COP without suitable measurement data, or an expert-witness report prepared for court proceedings.
If the evidence indicates that a specialist engineer, electrician, manufacturer or other contractor needs to investigate something physically, the report can identify that as the next step.
Installer Says It’s the Manufacturer — Manufacturer Says It’s the Installation
This is a particularly frustrating position for homeowners.
The heat-pump manufacturer may say the unit is working correctly. The installer may say the equipment is faulty. The controls may have been installed by someone else. Meanwhile the homeowner is left in the middle with a system that still isn’t working as expected.
An independent review can help separate the different parts of the system. For example: is the heat pump producing the temperature being requested? If yes, why is the house still cold? Does the heating system provide enough emitter output at that temperature? Is the system achieving the required water flow? Are the controls asking the heat pump to behave sensibly? Does the original design support the system that was installed?
The purpose is not to automatically decide who is to blame. It is to establish where the technical evidence points.
Can the Report Help With a Complaint Against My Installer?
Potentially.
A written independent technical assessment can help you understand what the evidence shows before continuing discussions with your installer. It may also help you explain clearly what the concern is, what part of the system is affected, what evidence supports that concern, and what further investigation or remedial action may be required.
However, the purpose of the Performance Review is not to manufacture a case against the installer.
If the system appears correctly designed and the evidence does not support the concern, we will say so. Likewise, if something cannot be determined from the available information, we will identify that rather than presenting an assumption as a fact.
Our role is to assess the technical evidence independently.
Independent Performance Review or Independent Design Review?
These are two different Heat Loss Hub services.
Independent Design Review
Choose this if your heat pump has not yet been installed. We can review installer quotations, proposed heat-loss calculations, heat-pump sizing, radiator schedules, flow temperatures, system design, and competing proposals.
The aim is to help you understand the design before committing to an installation.
Independent Performance Review
Choose this if your heat pump is already installed and isn’t performing as expected. We look at the original design, what was actually installed, controls and commissioning, operating behaviour, electricity consumption, and the available performance evidence.
The aim is to establish why the finished system is behaving as it is.
Frequently Asked Questions
Potentially. We can compare the available room-by-room and whole-property heat-loss information with the selected heat pump’s performance and operating characteristics. However, we don’t determine oversizing simply from the nominal model number. Outdoor temperature, heating water temperature, modulation range and system behaviour all need to be considered.
We can investigate likely causes and compare consumption with the available design and operating information. High electricity use can result from several factors, including heat demand, operating temperature, controls, domestic hot water, immersion use and system efficiency. A bill by itself is not enough to identify the cause.
Not always. Many design, sizing, emitter and control issues can be investigated remotely where sufficient documentation, photographs and performance information are available. If a physical inspection or measurement is needed, we will identify that.
Yes, where the available information is suitable. We may ask for documents, photographs, video, radiator dimensions, controller information and electricity-consumption data.
We can still review the information that is available. If understanding the building heat loss is essential to answering the problem, a new room-by-room heat-loss calculation may be recommended.
Yes. Where we have suitable room heat-loss information and the radiator details, we can assess whether the emitters appear capable of meeting the room requirement at the intended operating temperature.
Only where sufficiently reliable data is available. A meaningful COP calculation requires information about both the electricity consumed and useful heat delivered. Controller estimates or electricity bills alone may not provide enough evidence for an accurate measured COP.
Not automatically. The service is normally carried out for you as the homeowner. If communication with another party is required, that can be discussed separately.
You can use your report when discussing technical concerns with your installer or other relevant organisations. However, a standard Performance Review is not automatically an expert-witness or litigation report.
Not automatically. The Performance Review identifies and assesses the problem. If significant design changes are required, a separate remedial design scope can be agreed afterwards.
No. Heat Loss Hub specialises in independent design, assessment and technical review. We do not position the Performance Review as a servicing or heat-pump repair service. Where physical repairs or specialist fault diagnosis are required, the report can help identify what should be investigated by an appropriate contractor.
Then we will tell you. An independent assessment should not begin with the assumption that somebody has made a mistake. Sometimes a system is operating broadly as designed and the issue lies elsewhere — perhaps expectations, tariff, unusually high indoor temperatures or another factor. The purpose of the review is to establish what the evidence supports.
Get an Independent View of Your Heat Pump
If your heat pump is already installed but you are concerned about its performance, the first step does not have to be replacing equipment or changing settings at random.
Start by establishing what the system was designed to do. Then compare that with what was installed and what is happening now.
Heat Loss Hub can independently review the available design information, system configuration, controls and performance evidence to help establish where the problem is likely to lie and what should happen next.
NOT SURE WHERE THE PROBLEM LIES?
Not sure whether the issue is the design, installation, settings or the heat pump itself?
Explore: Independent Heat Pump Design Reviews
Explore: Heat Loss & Heat Pump Sizing
Explore: Independent Heat Pump Design
Explore: Room-by-Room Heat Loss Calculations