Underfloor Heating Leak Detection London
Losing pressure on your underfloor heating? Our thermal imaging cameras map your entire UFH system and pinpoint the exact leak location without lifting a single tile. Targeted repairs, minimal disruption, full insurance reports.
020 3912 0200Underfloor heating leak detection finds a leak in pipes buried under screed or boards without lifting the floor to look for it. We pressure test each loop at the manifold to find the leaking circuit, then thermal image the floor with the heating running to pinpoint the escape. Surveys in London start from £300, with a written report and thermal images included.
Finding Underfloor Heating Leaks Without the Destruction
Underfloor heating is one of the most efficient ways to heat a home, but when the pipework develops a leak, the consequences can be serious. The pipes are buried in screed or concrete beneath your finished floor, which means a leak can run undetected for weeks or months. By the time you notice damp on the surface or the system pressure dropping, water may have already caused damage to the screed, insulation, and the flooring above.
The traditional approach to finding a UFH leak was to lift sections of floor until you found the wet area. This was expensive, slow, and created enormous disruption. At Leak Detect London, we use thermal imaging cameras to see your entire underfloor heating system through the floor surface without removing anything.
When your UFH is running, the hot water inside the pipes heats the screed and floor above in a pattern that matches the pipe layout. Our FLIR cameras capture this pattern in detail. A leak shows up as an anomaly, an area where hot water has escaped the pipe and spread into the surrounding screed, creating a thermal signature that is distinctly different from the normal pipe pattern.
Signs Your Underfloor Heating Has a Leak
- System pressure keeps dropping below 1 bar and needs frequent topping up
- Warm or hot patches on the floor in areas away from the pipe runs
- Damp or discolouration visible on the floor surface
- Higher than expected heating bills without increased usage
- The boiler firing up more frequently to maintain temperature
- Moisture or water appearing at skirting boards or floor edges
- One zone of the UFH system not heating properly while others work fine
Thermal Imaging for Underfloor Heating
Thermal imaging is the gold standard for UFH leak detection because it exploits the very nature of the system. Underfloor heating pipes carry water at 30 to 50 degrees Celsius through screed or concrete. This creates a strong temperature contrast with the surrounding floor structure that our cameras detect with ease.
During the survey, we ask you to run the heating system for at least 30 minutes before our arrival so the floor is up to temperature. Our engineer then scans the entire heated area with the FLIR camera, building a complete thermal map. The normal pipe pattern shows as a series of parallel heated lines. A leak appears as an irregular warm area where water has escaped and spread through the screed.
For multi-zone systems, we can isolate individual zones at the manifold and test each circuit separately. This is particularly useful when the leak is small and the thermal signature needs to be distinguished from the normal heating pattern. We also use acoustic detection equipment to listen for the sound of water escaping, providing a second confirmation of the leak location.
How We Detect an Underfloor Heating Water Leak, Step by Step
Before you book, it is worth ruling out the simple causes. Our guide to underfloor heating pressure drop checks covers the manifold, the boiler and the gauge readings you can take yourself. If those point to a buried leak, the survey runs like this.
1. Manifold and Boiler Checks
We check the manifold valves, pump, boiler, pressure relief valve and expansion vessel, so a fault that only looks like a floor leak is ruled out first.
2. Loop by Loop Pressure Test
Each loop is isolated at the manifold and pressurised on its own. The loop that loses pressure is the one we survey, often a single room.
3. Thermal Mapping
With warm water running through that loop, the camera records the pipe pattern across the floor and the warm spread where water has escaped.
4. Confirmation and Marking
Acoustic listening or tracer gas confirms the spot. We mark it on the floor, photograph it and write it up with the recommended repair.
What Each Method Can and Cannot Find Under a Heated Floor
Thermal Imaging
Shows the loop layout and escaped warm water through tiles, stone and screed. It needs the heating on, and it is slower and less sharp through thick timber, carpet and underlay, or where loops sit tightly together near the manifold.
Acoustic Detection
Useful on copper pipe and on larger leaks. Most modern underfloor systems use plastic pipe, which carries sound poorly, so on those floors we treat it as a second check rather than the main method.
Tracer Gas
Works on plastic pipe and without heat. The leaking loop is drained and filled with a hydrogen and nitrogen mix, which escapes at the leak and rises through the floor to a detector. It takes longer, so we use it when the loop is known but the spot is not.
For more on the kit itself, see leak detection equipment explained and how tracer gas leak detection works.
No-Dig Repair Options
Once we have pinpointed the exact leak location, the repair is often far simpler than most homeowners expect. Because we know precisely where the leak is, we only need to open up a small area of floor directly above the damage point. For most repairs, this means removing less than half a square metre of flooring and screed.
For modern plastic UFH pipes such as PEX or PE-RT, we use specialist press-fit or electrofusion couplings to repair the damaged section. These fittings are designed specifically for underfloor heating applications and create a permanent, leak-proof joint. For older copper pipe systems, we can solder or compress-fit a repair coupling.
After the repair, we pressure test the system to confirm it holds, then the small floor opening is made good with fresh screed. The repaired area can then be re-tiled or re-floored to match the surrounding surface. The entire process, from detection through to repair, is typically completed in a single day.
Underfloor Heating Leak Detection Cost
Underfloor heating leak detection in London starts from £300. These are our published prices, including VAT:
The number of loops, the size of the heated area, the floor finish and whether tracer gas is needed all affect the figure. You get a fixed price before we book, the survey is no find, no fee, and the report is written for a trace and access insurance claim.
How Long It Takes and What to Do Before We Arrive
A single loop in one room is usually surveyed within a morning or an afternoon. Large floors, several zones or a tracer gas test take longer. If your underfloor loops share a boiler with radiators, the leak may be in radiator pipework buried in the slab instead, which our guide to central heating leaks under concrete floors covers.
Before the visit, run the heating for at least 30 minutes, keep the system topped up to its normal pressure, clear rugs and furniture from the heated rooms, and make sure we can reach the manifold. Pipe layout drawings from the installer are very helpful if you have them.
Common Causes of UFH Leaks in London Properties
Installation Damage
The most common cause of UFH leaks is damage caused during or shortly after installation. Screws driven through the screed for skirting boards, door frames, or kitchen units can puncture the pipe below. We regularly see this in London new-builds and renovations where follow-on trades were not given pipe layout drawings.
Ground Movement and Settlement
London sits on a mixture of clay, gravel, and sand. Seasonal ground movement, particularly on clay soils in South and West London, can create stress on buried pipes. Over time, this stress can cause joints to fail or pipes to crack at stress points, particularly where they pass through structural movement joints.
Poor Quality Connections
Leaks at the manifold connections are common, particularly where push-fit or compression fittings were used instead of proper press-fit connections. Manifold leaks are usually easier to find and repair because the manifold is accessible, but they can still cause significant water damage if left undetected.
Underfloor Heating Leak Detection Questions
How do you detect a leak in underfloor heating?
What are the signs of an underfloor heating leak?
Can underfloor heating leaks be repaired without digging up the floor?
How much does underfloor heating leak detection cost in London?
What causes underfloor heating pipes to leak?
How do I know which underfloor heating loop is leaking?
Is a pressure drop on underfloor heating always a leak?
Can you find an underfloor heating leak under tiles, wood or carpet?
Can you detect a leak if the underfloor heating is not working?
Does insurance cover underfloor heating leak detection?
UFH Losing Pressure?
Do not wait for the damage to spread. We find underfloor heating leaks quickly using thermal imaging. Same-day service across London.
020 3912 0200Minimal Floor Disruption
Thermal imaging pinpoints the exact leak location so we only need to open a small area for repair. No lifting the entire floor, no unnecessary damage.
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