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Heat Pump Design Review for Installers
Independent technical QA before you order equipment or start installation.
- Last updated: September 2026
- Heat Loss Hub · For Installers
If you already have a heat-pump design, Heat Loss Hub can review the calculations, selections and system decisions before the project reaches site.
The review can check:
- Room-by-room heat loss
- Emitters
- Design flow temperature
- Heat-pump selection
- Pipework
- Hydraulics
- Cylinder selection
- Design documentation
- Assumptions
- Revision control
The aim is not necessarily to redesign the whole project. It is to identify what looks right, what needs checking and what should be corrected before you commit to procurement or installation.
KEY TAKEAWAY
A design review is there to find the problem before the installer finds it on site.
GET IN TOUCH
Send us your existing design pack and we’ll return clear, prioritised findings before you order or install.
Review an Existing Design Without Redesigning the Whole Project
You may already have a design produced by your own internal designer, an external design company, a manufacturer, a merchant, a consultant, a software workflow or another technical partner.
You may not need a new design. You may simply want another experienced technical view before moving forward. Heat Loss Hub can review the existing information and identify:
- Contradictions
- Missing information
- Unsupported assumptions
- Marginal selections
- Potential installation risks
- Areas that need further calculation
- Areas that appear satisfactory
You do not need a new design if what you really need is confidence in the one you already have.
What a Heat-Pump Design Review Actually Checks
A design review should answer practical questions. For example:
- Are the heat-loss figures credible?
- Do the emitters match the room loads?
- Is the design flow temperature justified?
- Is the heat pump suitable at the actual design condition?
- Is the pipework adequate for the required flow?
- Does the hydraulic arrangement make sense?
- Is the cylinder suitable for the household and selected heat pump?
- Are the assumptions visible?
- Do the documents agree with each other?
- Is the latest revision clear?
- Is the project ready to order and install?
The objective is to check the design as a complete technical chain rather than review each document in isolation.
Does the Design Tell One Consistent Story?
A good heat-pump design should be traceable from the property all the way through to the final system arrangement. The chain is:
Property → Room-by-room heat loss → Emitter sizing → Design flow temperature → Heat-pump selection → Pipework → Hydraulics → Domestic hot water
Each stage should support the next. If the heat-loss report suggests one requirement, the radiator schedule another and the selected heat pump something different again, the design may contain all the right documents but still not be technically coherent.
KEY TAKEAWAY
A design can contain all the right documents and still be wrong if the numbers do not agree with each other.
Heat-Loss Review
The heat-loss calculation is the foundation of the rest of the design. The review can check whether the calculation appears credible based on the information supplied. This may include room dimensions, construction assumptions, U-values, internal design temperatures, external design temperature, ventilation assumptions, room totals and whole-property design load.
The review does not automatically mean repeating the entire calculation from scratch. Possible outcomes may include:
Reasonable
The calculation appears internally consistent and appropriate from the evidence supplied.
Verify
One or more assumptions need checking before the calculation should be relied upon.
Recalculate
The existing calculation contains enough uncertainty or inconsistency that recalculation is recommended.
KEY TAKEAWAY
The rest of the design is only as strong as the heat-loss calculation it is built on.
Emitter and Flow-Temperature Review
The review can compare each room heat loss with the proposed emitter output. This may include existing radiators, replacement radiators, towel rails, UFH, fan-assisted emitters, room design temperatures and proposed operating temperature.
The review should identify which emitters pass, which are marginal, which are undersized, which room becomes the limiting emitter, and whether the design flow temperature is justified.
A common design issue is one weak room forcing the entire system to operate at a higher temperature.
KEY TAKEAWAY
Is one weak emitter forcing the whole system to run hotter than necessary? Where that happens, a local emitter change may be a better solution than raising the operating temperature everywhere.
Heat-Pump Sizing and Selection Review
The selected heat pump should be checked against the actual design conditions. The review may compare whole-property design load, selected manufacturer and model, output at the outdoor design temperature, output at the proposed water temperature, capacity margin and supplementary or bivalent strategy where relevant.
The nominal model size alone is not enough.
KEY TAKEAWAY
The model number is not enough. The selected unit needs to work at the actual design condition. If the selected unit is marginal or relies on assumptions that are not clearly supported, that should be identified before equipment is ordered.
Pipework Review
The review can also assess whether the proposed pipework appears appropriate for the required system flow. This may include primary pipe size, main distribution, branch sizes, existing pipework, microbore, critical sections, flow requirements, velocity and pressure-loss logic where available.
The objective is not necessarily to recalculate every section unless that is part of the agreed scope. The first question is: does the proposed pipework make sense for the duty it is expected to carry?
KEY TAKEAWAY
If not, the review can identify which sections need more detailed calculation.
Hydraulic Review
Hydraulic design can be checked for overall logic and component justification. The review may consider direct vs separated arrangement, minimum flow, minimum system volume, internal pump capability, secondary pumps, buffer, volumiser, low-loss header, bypass, zoning, mixed emitters and DHW integration.
A buffer, extra pump or low-loss header should not simply appear on a schematic without a clear reason.
KEY TAKEAWAY
Every hydraulic component should have a reason for being there. If the design contains unnecessary or unexplained components, that can be flagged for review.
Explore: Heat Pump Hydraulic Design Service
Cylinder and Hot-Water Review
The domestic hot-water side can also be reviewed. This may include occupancy basis, hot-water demand, cylinder capacity, coil suitability, heat-pump compatibility, recovery assumptions, large baths, high-flow showers and available space.
The review should check whether the proposed cylinder makes sense for both the household and the selected heat pump.
Assumptions Review
Not every project input can always be measured or verified. Assumptions are sometimes necessary. The important thing is that they are visible, reasonable, supported where possible, understood by the installer and reviewed if better information becomes available.
The review can identify whether key assumptions are measured, documented, verified, assumed or unsupported.
KEY TAKEAWAY
An assumption is not automatically a problem. A hidden assumption can be. If an assumption materially affects heat loss, equipment selection or system design, it should be easy to identify.
Design-Pack Completeness
A technically sound design also needs to be documented well enough for someone else to understand and install from. The review can check whether the design pack contains appropriate information such as room-by-room heat loss, internal and external design temperatures, emitter schedule, design flow temperature, heat-pump selection, hot-water design, hydraulic information, schematic, assumptions and revision history.
The purpose is not to reward the largest number of PDFs. It is to check whether the pack tells a complete and consistent technical story.
Revision Control
A correct design can still create problems if the wrong version reaches site. The review can check whether the current revision is clearly identified, whether superseded drawings are marked, whether calculations and schedules are on matching revisions, whether later changes have been incorporated, and whether the installer is working from the latest issue.
KEY TAKEAWAY
A technically correct design is still a risk if the site team is working from the wrong revision. This is particularly important where several businesses or designers have been involved.
Risk-Prioritised Findings
Not every comment has the same importance. A useful design review should help the installer understand what needs immediate action and what is simply worth considering.
Critical
Needs resolving before procurement or installation. Examples may include the heat pump cannot meet the design load, a major heat-loss issue, a critical pipework restriction, or a hydraulic arrangement unlikely to maintain required flow.
Important
Should be reviewed because it could affect performance, efficiency, compliance, buildability or customer comfort.
Advisory
Not necessarily wrong, but worth considering. Examples might include a cleaner hydraulic arrangement, better documentation, improved revision control or an alternative component choice.
KEY TAKEAWAY
The review should tell you what matters most, not bury every comment at the same level.
Example Review Findings
A review report may include findings like:
| Area | Finding | Priority | Recommended Action |
|---|---|---|---|
| Heat loss | Wall U-value unsupported | Important | Verify construction |
| Heat pump | Output marginal at design condition | Critical | Recheck model selection |
| Emitters | Bathroom drives 52°C design temperature | Important | Increase emitter output |
| Pipework | Primary run requires further check | Important | Recalculate flow and pressure loss |
| Hydraulics | Buffer purpose unclear | Advisory | Confirm volume/separation requirement |
| Documentation | Current revision unclear | Advisory | Issue controlled final pack |
The purpose is to give the installer a practical action list rather than a generic pass or fail.
Is the Project Ready to Order?
A useful review can help determine whether the project is sufficiently resolved to move into procurement. Before ordering equipment, key questions include:
- Is the design heat loss reliable?
- Is the heat pump confirmed?
- Are emitter changes known?
- Is the cylinder confirmed?
- Are pipe upgrades understood?
- Is the hydraulic arrangement settled?
- Are critical assumptions resolved?
- Is the latest design revision clear?
KEY TAKEAWAY
A design review can be cheaper than ordering the wrong equipment. If a critical design question is still open, it may be better to resolve it before equipment arrives on site.
Is the Project Ready for Installation?
Procurement-ready and installation-ready are not always the same thing. Before the job reaches site, check:
- Final heat pump confirmed
- Final radiator schedule issued
- Pipe changes identified
- Cylinder confirmed
- Hydraulic schematic current
- Plant-room layout understood
- Technical queries closed
- Final revision issued
The goal is to prevent installation teams having to make design decisions on site without the information they need.
Full Design Review or Targeted Review
Not every project needs the complete design chain reviewed. The service can be scoped around the area you actually need checked.
Full Design Review
Review the project from heat loss through to hydraulic arrangement and DHW.
Heat-Loss Review
Check the calculation basis and assumptions.
Emitter Review
Check radiator selection and design temperature.
Equipment Review
Check heat-pump and cylinder selection.
Pipework Review
Check proposed pipe sizes and critical sections.
Hydraulic Review
Check pumps, volume, separation, buffers and schematic.
Review only the area you need, or review the whole project.
Internal Designer QA
An independent review can also support your own design team. This can be useful where a junior designer has produced the project, a new employee is learning your process, the business is growing quickly, you want periodic technical QA, or complex projects need a second opinion.
The review is not there to replace the internal designer. It provides another layer of technical checking.
KEY TAKEAWAY
External review can support an internal design team without replacing it.
Outsourced Designer or Manufacturer Design Review
You may receive design information from external designers, manufacturers, merchants, consultants or software-driven design services. An independent review can help check whether the supplied design fits the actual project. That can be especially useful before equipment is ordered, a large deposit is committed, installation dates are booked, or site teams are briefed.
KEY TAKEAWAY
Independent review gives the installer another technical perspective before committing to the job.
What You Need to Send Us
The review is based on the information available. Typical documents may include:
- Heat-loss report
- Emitter schedule
- Heat-pump selection
- Manufacturer performance data
- Pipe-sizing information
- Hydraulic schematic
- Cylinder selection
- Design pack
- Floor plans
- Survey information
- Photos
- Current revision details
The more complete the project information, the more useful the review can be. If something essential is missing, that itself may become one of the review findings.
What You Receive
The exact output depends on the agreed review scope. A design-review report may include review summary, findings by technical area, priority rating, missing information, design inconsistencies, unsupported assumptions, recommended actions, areas that appear satisfactory and current revision reference.
The output should tell the installer what needs attention, not simply return a red or green tick.
The objective is to give your team a clear route forward.
What Happens if We Find a Problem?
Finding an issue does not automatically mean the entire design needs replacing. The process can be:
- Issue identified. The review explains what has been found.
- Priority assigned. Critical, Important or Advisory.
- Recommended action provided. For example: verify survey information, recalculate heat loss, resize one emitter, recheck heat-pump selection, upgrade one pipe section, revise hydraulic layout, or reselect cylinder.
- Decide who makes the correction. You can correct it internally, return it to the original designer, or ask Heat Loss Hub to revise that specific part.
KEY TAKEAWAY
Review first. Redesign only the parts that actually need redesigning.
What the Review Does Not Do
A Heat Loss Hub design review is a technical QA service based on the information supplied. It does not automatically certify another designer’s work, transfer responsibility away from the installer, replace the original designer, produce a complete replacement design, provide MCS certification, or guarantee information that cannot be independently verified.
Where a problem is identified, further calculation or redesign can be agreed separately if required.
The installer remains responsible for ensuring the final project and installation meet the applicable requirements.
One Project, Complex Jobs or Ongoing QA
You can use design review in different ways.
One High-Risk Project
A technically unusual job needs an independent second pair of eyes.
Occasional Second Opinion
You normally design internally but want selected projects checked.
New Designer QA
A new internal or external designer’s work is reviewed while the working relationship develops.
Ongoing Quality Assurance
Regular projects are independently reviewed as part of your technical process.
This allows external QA to scale around the way your business already works.
White-Label Design Review
Design review can also sit behind your own customer-facing process. Depending on the agreed arrangement, Heat Loss Hub reviews the design, findings are returned to your business, your customer remains your customer, the review can remain behind the scenes, and your internal team decides what changes are made.
This can be useful where you want independent QA without changing the customer journey.
Heat-Pump Design Review Quality Checklist
Before progressing a project, can you answer:
- Is the heat loss credible?
- Are the assumptions visible?
- Do emitters match the room loads?
- Is the flow temperature justified?
- Is the heat pump suitable at the actual design condition?
- Is the pipework adequate?
- Does the hydraulic arrangement make sense?
- Is the cylinder suitable?
- Do all the design documents agree?
- Is the current revision clear?
- Are all critical technical queries resolved?
If not, the project may not yet be ready to progress.
Frequently Asked Questions
Yes. The service is specifically intended to provide an independent technical review of existing design information.
Yes. Manufacturer or merchant design information can be reviewed against the wider project information supplied.
Depending on the agreed scope, the review can cover heat loss, emitters, flow temperature, heat-pump selection, pipework, hydraulics, cylinder selection, documentation, assumptions and revision control.
Not automatically. The first stage is to review the existing calculation for credibility and consistency. If recalculation is required, that can be agreed separately.
Yes. The selected unit can be reviewed against the project design load and available output at the relevant design conditions.
Yes. The review can compare the room loads with the proposed emitter outputs and identify limiting rooms.
Yes. Pipe sizes, flow requirements, system volume, pumps, buffers, hydraulic separation and schematic logic can all form part of the review scope.
Yes. The review can consider hot-water demand, cylinder capacity, coil suitability, recovery basis and heat-pump compatibility.
Yes. The review can be limited to a specific area such as heat loss, emitters, equipment selection, pipework, hydraulics or DHW.
No. It is an independent technical review service. It does not replace the installer’s own certification responsibilities or act as formal MCS certification of another designer’s work.
The issue is recorded, prioritised and accompanied by a recommended next action. You can then choose whether to correct it internally, return it to the original designer or ask Heat Loss Hub to revise that part of the project.
Yes. That is one of the most useful times to carry out the review. It gives the installer an opportunity to resolve critical technical issues before committing to equipment.
Yes. A white-label review workflow can be agreed where required.
Want a Second Pair of Eyes Before the Job Reaches Site?
Send us the existing design pack. We review the calculations, selections and system decisions, then return clear prioritised findings and recommended actions.
SUBMIT A DESIGN FOR REVIEW
Send us your existing design pack and we’ll return clear, prioritised findings before you order or install.
Explore: Heat Pump Design for Installers