Heat Loss Survey and System Design in Rotherham and Barnsley: Size It Right the First Time

Why sizing decides everything that follows

Get the sizing wrong and you live with it for years. Too big, and the heat pump short cycles, wearing itself out while costing more to run than it should. Too small, and you're stood in the kitchen in February wondering why the radiators feel lukewarm.

This is where the room-by-room calculation earns its keep. We measure wall construction, window size, insulation levels and room orientation for every space in the house. A 1930s semi with solid brick walls and single glazing loses heat at a completely different rate than a newer extension with cavity insulation. Treat them the same on paper and the design falls apart before the heat pump's even ordered.

We've seen homes where a previous installer used a rule of thumb based on floor area. That approach almost always leaves at least one room under-heated.

How we survey: LiDAR scanning, not a tape measure and a clipboard

This is the part most installers can't offer, and it's worth understanding before you compare quotes.

We survey using LiDAR — the same laser scanning technology used in self-driving cars, built into the iPad Pro our engineers carry. Instead of measuring rooms by hand and typing numbers into a spreadsheet, we scan each room and the iPad builds an accurate three-dimensional model of the space as we walk through it.

That model feeds straight into Heat Geek's AI design software, which calculates heat loss room by room and sizes the system against it.

Why it matters to you:

• Accuracy. Hand measurement introduces small errors in every room, and those errors compound across a whole house. A scan doesn't round a bay window or forget a chimney breast.
• Nothing gets missed. Awkward spaces — under-stairs, box rooms, that bit of the landing nobody thinks about — get captured as part of the scan rather than skipped because they're fiddly.
• Speed. The survey takes a couple of hours rather than half a day, and the design comes back faster because the data doesn't need transcribing.
• You can see it. The model is a picture of your house, not a page of figures you have to take on trust.

A lot of the housing around Rotherham and Barnsley is exactly where this pays off — Victorian and 1930s properties with bay windows, extensions bolted on over the decades, and loft conversions nobody revisited the heating design for. Those are the houses hand measurement gets wrong.

What happens on the visit

• We scan every room with the iPad, capturing size, shape and layout
• We record wall type, window area and current radiator output
• We check insulation levels in the loft and walls where accessible
• We note ventilation, extractor fans, and any draughts pulling heat out of the house
• The scan and readings run through Heat Geek's design software for a true heat loss figure per room
• We match that figure against radiator and heat pump output, so the system is sized to the house rather than the other way round

Expect a couple of hours for a typical semi. Bigger or more complex homes take longer. You don't need to prepare anything — just have access to each room and any loft hatches ready.

Why room-by-room matters on older housing

Plenty of properties around Rotherham, Barnsley and the Dearne villages date from the Victorian era or the 1930s. Solid brick walls, high ceilings, bay windows. Handsome houses that lose heat very differently from a modern new build — which is exactly why a whole-house average doesn't work here.

We measure every room on its own. Not just floor area, but wall type, window size, ceiling height, and what's on the other side of each wall. A bedroom above an unheated porch loses heat faster than one tucked between two warm rooms. A lounge with a single external wall behaves nothing like a kitchen with two.

• Wall construction — solid brick versus cavity, common in older terraces here
• Window type and age — single glazing still turns up in period properties
• Room use and target temperature — bathrooms and bedrooms often need different setpoints
• Exposure — corner rooms and rooms above unheated spaces lose heat faster
• Existing radiator position and pipework routes

This is where a lot of past installs went wrong. Someone sized a boiler off the whole house, then guessed at radiators. The result: a lounge that never quite gets warm and a box room that roasts.

Each room gets its own heat loss figure in watts. That figure decides the radiator size, or the emitter output if you're moving to a heat pump. Get one room wrong and the whole system compensates by running hotter than it should, which eats into efficiency and comfort both.

When you don't need one

Not every job needs this, and we'd rather tell you than sell you a survey you don't need.

If you're swapping a broken combi for a like-for-like replacement on the same pipework, a full heat loss survey isn't the deciding factor. We still size the new boiler properly, but that's a smaller calculation, not room-by-room design work.

Same with straightforward radiator replacements. And a boiler service, a CP12, or an unvented cylinder service doesn't call for heat loss calculations at all.

• Like-for-like boiler swap on existing pipework — no survey needed
• Single radiator replacement or upgrade — standard sizing applies
• Routine boiler service or CP12 gas safety inspection
• Unvented cylinder service or repair on an existing setup

Where it genuinely earns its keep is heat pump installations. Heat pumps run at lower flow temperatures than boilers, so getting the numbers wrong has real consequences. An undersized system leaves rooms cold on the coldest mornings; an oversized one cycles inefficiently and costs more to run. That's the one job where skipping the survey is a false economy.

The Boiler Upgrade Scheme grant

The Boiler Upgrade Scheme gives you £7,500 toward an air source heat pump, and grant-funded installations are delivered through Heat Geek's Zero Disrupt and Black Label programmes, so the grant is available on your project.

Zero Disrupt is Heat Geek's streamlined route: the LiDAR survey and AI design feed into a system built to hit a guaranteed efficiency figure, with fewer parts and less time on site than a traditional retrofit. Black Label is the bespoke route for more complex properties, where the design is developed around the specific building.

You don't apply for it yourself, and you don't pay it and claim it back. The application is handled as part of the installation, and the grant comes off your quote rather than being something you reclaim afterwards. A valid EPC is no longer required to apply, which used to add weeks to the process.

The grant isn't handed out on request, though. It requires the property to be properly assessed, room by room — which is exactly what this survey produces.

Want a ballpark before you book anything?

You don't have to book a survey to find out roughly what a heat pump would cost you.

Our Heat Geek partner page gives you an indicative figure for switching from a boiler to a heat pump. Enter your address and it works from your EPC rating and whatever else it can find about the property. No visit, no obligation, no phone call.

You'll see our logo at the top of that page — it's our partner link, so the enquiry stays with us.

It's an estimate, not a quote. It works off public records rather than a survey, so it doesn't know about the loft insulation you added, the extension nobody registered, or the radiators that were never sized properly. That's what the survey is for. But it'll tell you whether you're in the right ballpark before you spend anything.

One thing worth knowing before you click through. At the end of the estimator there's a button offering a design consultation for £250. That's the same survey we do — booked directly with us it's £120, or £138 in Band A. Use the estimator for the ballpark, then come back here for the survey itself and keep the difference.

Or skip the form and ring us. We can run an estimate for you over the phone, on the spot, free — usually a keener figure than the online tool gives. It's still an estimate either way: the fixed price comes after the survey, which is where your system actually gets designed.

Whichever route you take, the installation is a Heat Geek Assured one with guaranteed performance, carried out by us.

What the survey costs

£120 including VAT at standard rate, £138 in Band A. Check your postcode band on our rates page.

It's a stand-alone piece of work, not a sales visit. The fee isn't credited against an installation, and it isn't rolled into an install quote — because what you're paying for is the survey itself: a LiDAR scan of every room, a room-by-room heat loss figure, and a system design sized to those numbers.

That document is yours. It tells you what your house actually needs, whether you go ahead with us, go ahead with someone else, or decide the timing isn't right. You are paying for the engineering, not for the visit.