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Heat Engineer heat pump design — why we trained in it, and who it’s for
Installers and homeowners ask what sits behind our drawings. Until now the honest answer was Spruce, every time. It still is by default — but we have now subscribed to Heat Engineer and completed the training, so if your project needs Heat Engineer heat pump design, it can happen here. This is what the platform does, how we use it, and when we would reach for it instead.
- 9 min read
- Published 25 July 2026
- By Phil · Heat Loss Hub
IN ONE PARAGRAPH
Heat Engineer is a UK-built heat loss and system design platform, running since 2017 from offices in Lancashire, Oxfordshire, Devon and Yorkshire. It calculates room-by-room heat loss using the CIBSE Domestic Heating Design Guide and BS EN 12831-1:2017, and meets MCS MIS 3005 and MIS 3004 for heat pump and biomass work. Survey apps for phone and tablet sync to a web platform; a CAD measuring tool, Magicplan 3D scanning and a LiDAR quick estimator cover the measuring end; radiator and emitter sizing, underfloor pipe centres, pipe and pump sizing, bivalent design and MCS system performance calculations cover the design end. We are subscribed, trained and working in it — and, as with everything we publish about tools, this is an unpaid and unaffiliated write-up.
On survey: four ways to measure a house
Heat Engineer’s most immediately useful trait is that it does not insist on one way of measuring. There are four survey methods, and the right one depends on the property and how much of it you can actually reach.
For a full technical survey we work in the mobile and tablet app, room by room, with data syncing straight to the web platform so nothing has to be re-typed at the desk that evening. Where a property has already been scanned, Magicplan’s 3D scanning feeds dimensions in automatically. Where the only record is a drawing or a PDF, the CAD measuring tool on desktop takes accurate dimensions off the plan rather than leaving us to guess from a scale bar. And for an early conversation — the “is this house even a candidate?” call — the LiDAR quick property estimator produces a defensible ballpark in minutes without committing anyone to a full survey.
That flexibility matters more than it sounds. A Victorian terrace with a cellar and three roof pitches wants a properly walked survey. A new build at plan stage has no house to walk. Software that only does one of those forces the designer to fudge the other, and fudged inputs are where oversized heat pumps come from.
At the desk: from dimensions to MCS paperwork
Once the fabric is in, the calculation runs to the CIBSE Domestic Heating Design Guide and BS EN 12831-1:2017 — room by room, against the property’s local design temperature, with our verified U-values in place of hopeful defaults.
Then the design proper. Emitter sizing covers radiators, fan convectors, fan coil units and underfloor heating pipe centres, so a mixed system does not have to be split across two tools and reconciled by hand. Pipe and pump sizing is built in, which proves its worth the first time you find a 22 mm run feeding a 3 kW emitter. Bivalent designs are supported for the properties where a heat pump alone is the wrong answer and saying so is the honest thing to do. And the MCS heat pump system performance calculations produce compliance figures aligned to MIS 3005, so an installer is not left reverse-engineering them out of a PDF.
What Heat Engineer will not do — and should not — is the judgement. It cannot tell you the 1996 cavity fill has slumped, that the “solid” wall is a rendered cavity, or that this family really does want the lounge at 21 °C. It sizes what you tell it about. Getting what you tell it right is the entire job.
Where Heat Engineer earns its place
A few things stand out after the training and a subscription’s worth of real use:
Survey breadth. Four measuring methods under one licence, from a fully walked survey to a LiDAR estimate, is unusual. Most tools pick a lane and expect you to live in it.
MCS-aligned output. The performance calculations map onto MIS 3005 and MIS 3004 directly, which shortens the distance between a design leaving our desk and an installer filing it.
Assisted emitter sizing. The radiator and emitter sizing is AI-assisted, which speeds up the first pass considerably. We still check every room by hand — assistance is not authority, and a plausible number is not a correct one.
Integrations. Magicplan is live, with Commusoft field service management and Grundfos hydronic balancing announced. For an installer already running their jobs through Commusoft, that closes a real gap.
Longevity. Heat Engineer has been at this since 2017, and publishes its own running totals: more than 30,800 completed surveys, over 440,000 kW calculated and more than 6.2 million m² of heated floor area assessed, with British Gas, Grundfos and Testo among its listed partners. Those are the company’s figures rather than ours, and we quote them as context rather than as a verdict. Years on the market and jobs on the counter tell you a platform is stable, supported and unlikely to vanish. They do not tell you it is the best way to design a heat pump in 2026.
Which brings us to the comparison we would rather make openly than let you infer. Spruce is the younger platform of the two, and in our judgement it is still some way ahead — because the LiDAR-scan-to-drawing-pack continuity is a change in kind rather than a change in degree. One dataset carries from the scan through the calculation to the finished schematic with nothing re-typed in between, and every re-keying you design out is a transcription error that never gets the chance to happen. That is a harder thing to catch up with than a feature list suggests.
None of which makes Heat Engineer a poor tool. It is capable, standards-compliant, properly supported and entirely fit for the work — we would not have trained in it otherwise, and we are glad to design in it when a project calls for it. It simply is not the platform we would choose if the choice were ours alone.
DESIGNER'S INSIGHT
“I did not train in Heat Engineer because Spruce was failing me. I trained in it because a good share of the installers who send me work for review already have their entire business inside it — and telling them to re-key a design into my preferred platform is exactly the kind of friction that breeds transcription errors. Meeting a client in their own software is not a compromise. It is the same argument I make about heat pumps: fit the system to the house, not the house to the system.”
Phil
Founder & Lead Designer, Heat Loss Hub
Why we now offer Heat Engineer heat pump design
Spruce remains our default, for the reasons above. Unless there is a specific reason to work elsewhere, that is where a Heat Loss Hub project gets built — the full argument is set out in our write-up on Spruce.
Heat Engineer is what we reach for when there is a reason, and three come up repeatedly. When an installer already runs their business in Heat Engineer, delivering the design inside their own account means they open it, read it and build from it — no export, no re-keying, no quiet divergence between two sets of numbers. When we are reviewing a calculation someone else produced in Heat Engineer, working in the same platform lets us interrogate their assumptions directly instead of rebuilding the job to check it. And when a project is bivalent, or unusually mixed across radiators, fan coils and underfloor, having all of those emitter types in one place is simply less error-prone than stitching two tools together.
Put plainly: our preference is not the point. A design you cannot open is worth nothing, and a marginally better workflow is a bad trade against numbers that arrive in a format your business actually uses.
For installers and designers weighing it up for themselves: heat-engineer.com. As with Spruce, there is no affiliate link and no referral fee here — we recommend software the way we recommend heat pumps, which is to say only where we would use it ourselves.
What it means for your project
If you are a homeowner, none of this changes anything you can see. You get the same survey, the same room-by-room calculation you can audit line by line, and the same emitter schedule with the arithmetic shown. Which platform it was built in is our problem, not yours.
If you are an installer — or a homeowner whose installer has already started work in Heat Engineer — it changes the one thing that matters: we can hand you a finished design in the software you already use, checked by someone with no stake in the sale. You no longer have to choose between an independent designer and a workflow that fits your business.
CONTENTS
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