Central Heating Leak Detection in London
A central heating system that keeps losing pressure, or a boiler that trips off repeatedly, is often not a boiler fault at all. Water is escaping somewhere in the pipework, usually under a floor or within a wall, and the system is doing exactly what it should: telling you something is wrong. The difficulty is that the leak itself can be metres from where any visible sign appears.
Signs Your Central Heating System Has a Leak
A central heating system that keeps losing pressure, or a boiler that trips off repeatedly, is often not a boiler fault at all. Water is escaping somewhere in the pipework, usually under a floor or within a wall, and the system is doing exactly what it should: telling you something is wrong. The difficulty is that the leak itself can be metres from where any visible sign appears.
ClearFlow uses acoustic listening equipment and thermal imaging cameras to trace the escape point without disturbing your floors. Acoustic technology detects the vibration that pressurised water creates as it escapes a pipe joint or hairline fracture, while thermal imaging picks up temperature differentials on floor and wall surfaces caused by moisture migration. Together, they allow us to mark the exact location of the fault before any access work begins.
We work on central heating systems throughout London, covering everything from conventional radiator circuits in period Victorian terraces to modern underfloor heating loops in new-build flats. Our written report documents the fault location with photographs and a repair recommendation, accepted by all major UK insurers. If we cannot find the source, you do not pay for the investigation.
- Boiler pressure drops regularly without any visible water loss
- Damp patches or staining on floors or skirting boards
- Radiators failing to reach temperature despite the system running
- Persistent cold spots in specific areas of flooring
- Unexplained increase in water usage or utility bills
- Rust-coloured staining or corrosion near radiator valves
- Musty smell in rooms with underfloor heating
- Boiler shutting down or displaying low pressure fault codes
How We Locate Central Heating Leaks
We review the symptoms, building type and pipe layout before selecting any equipment.
One or more methods are deployed to identify the source zone, typically narrowed to within 10–30 cm.
A second method cross-checks the result before we mark the repair point — no guesswork.
A written report with findings and photographs is issued — suitable for insurance claims.
Central Heating Leak Situations We Investigate
Boiler repeatedly losing pressure
When a boiler drops pressure without any external sign of leakage, the fault is usually a weeping joint or micro-fracture in the buried pipework. Acoustic detection identifies the point of escape by isolating the frequency of water leaving the circuit under pressure, even through concrete or screed.
Underfloor heating pipe failure
Underfloor heating circuits run through screed and are impossible to inspect visually. A breach in the plastic pipe loop causes slow water loss and can saturate the subfloor over months before any surface sign appears. We pressurise the affected loop and use acoustic and tracer gas methods to mark the exact breach point.
Radiator or pipework joint leak
A corroded valve body or a failing compression joint behind a plasterboard wall is difficult to locate without the right equipment. We scan the wall cavity with thermal imaging to identify the warm, wet zone, and confirm the breach location before any wall surface is opened.
Old copper pipe corrosion
In London's older housing stock, copper heating pipes develop pinhole leaks through internal corrosion, often in runs that pass through partition walls or under suspended timber floors. We trace these circuits non-invasively and provide a written finding that supports a full repipe decision or targeted section replacement.
Leak in a communal heating system
Multi-unit buildings often share a central heating loop, and a fault in one section can affect pressure across the whole system. We work with building managers and contractors across London to locate faults within communal plant rooms and riser runs, minimising disruption to residents.
New build underfloor leak
Modern underfloor heating systems occasionally develop faults at manifold connections or in joints embedded during construction. We carry out pressure testing and acoustic detection on individual circuits to confirm whether the fault lies in the screed, at the manifold, or in the boiler feed pipework.
What You Can Expect
We've been detecting hidden leaks across London for years. Every engineer is directly employed by us, DBS-checked and WaterSafe registered. We don't subcontract.
- No Find No Fee: if we cannot locate the leak, you pay nothing
- Acoustic and thermal imaging used together for cross-confirmed results
- No floor or wall access until the exact fault point is marked
- Written, insurer-accepted report included with every investigation
- Covers all central heating types: radiators, underfloor loops and wet systems
- Directly employed engineers across London, available 7 days a week
Trusted Across London
Absolutely quality service and what plumbers should exemplify. Turned up when they said, was kind, answered all my questions and wasn't being dodgy with anything. Skilful and efficient! Would highly recommend.
The technician arrived on time, was polite, and explained the process clearly before starting. They used advanced, non-invasive equipment to locate the leak quickly without causing any unnecessary damage to my property.
Really impressed with the service. They responded quickly and were able to accurately detect the leak without causing unnecessary damage. Professional, efficient, and clearly experienced — would highly recommend to anyone dealing with a hidden leak.
Wayne and his colleague came and within an hour found the leak deep underneath my cellar and came up with a perfect plan which made the pipe redundant and re-routed it the following morning. An excellent option if you're having a problem with a leak you cannot find.
Called Wayne Monday and he was round Tuesday evening — came out of hours to help me out. Very professional, punctual and great with communication. Fair priced too. Will definitely recommend and use again.
Contacted them and they were at the property within an hour. Honest, well priced and gave a detailed report that will likely save me hundreds of pounds. Will definitely recommend and if necessary will use again.
Wonderful efficient service — came out the same day, nothing was too much trouble. Engineers were professional and polite, explained the problem and persevered until the blockage was cleared. Would highly recommend this company.
The staff were so professional and friendly. The technician was nice and informative — he advised me the leak was outside and wrote me a report which I sent to Thames Water. In a few days they sent a repair team and found the leak. Clear Flow are great at what they do.
I received a letter from Thames Water about high water usage. Wayne arrived on time, was so professional, guided me through what he was doing and advised me of the next steps. He also wrote me a report to send to the water board. 100% recommend.
Locating Hidden Central Heating Pipes
Central heating pipework is typically installed under screed, beneath suspended timber floors, or within stud walls, which makes visual inspection impossible. When a joint fails or a pipe develops a pinhole fracture, water leaks slowly into the surrounding structure. The boiler compensates by drawing in more water from the fill loop, which is why persistent pressure loss is often the first symptom. Left unaddressed, that water saturates subfloor materials, causes timber to rot, and can reach plasterwork and joists before any surface sign appears.
Acoustic Detection Explained
An acoustic survey works by isolating the frequency band in which pressurised water escapes through a fault. The engineer clips the listening probe to exposed sections of pipe and works methodically across the floor surface with a ground microphone, moving from the boiler outward through each circuit. When the signal strengthens, the location is cross-referenced with the thermal camera, which identifies the warm moisture zone created by leaking water. This dual-method approach eliminates false positives and confirms the breach location before any investigative access is made.
Underfloor Heating: A Specific Challenge
Underfloor heating systems present a specific challenge because the pipework is fully embedded in screed and not accessible without drilling. We use tracer gas for these investigations: a safe hydrogen-nitrogen mix is introduced into the isolated loop under controlled pressure, and a calibrated surface probe detects where the gas permeates through the screed. This method is accurate to within a few centimetres, allowing targeted core drilling rather than wholesale screed removal. It is the same technique used for mains supply trace work and is accepted by all major loss adjusters.
Your Investigation Report
At the end of the investigation, you receive a written report that includes the method used, photographs of the fault location, the precise coordinates on a floor or wall plan, and a repair recommendation. This report is accepted by UK insurers for trace and access claims and provides the information a plumber needs to carry out a targeted repair. ClearFlow does not carry out the physical repair work, which means our findings are fully independent and there is no financial incentive to recommend unnecessary access.
Central Heating Leak Investigations
FAQs About Central Heating Leak
Can't find what you're looking for? Call us on 0203 886 2316 and we'll answer on the spot.
What is central heating leak detection and how does it work?
Central heating leak detection is the process of locating a fault in a pressurised heating circuit without opening up floors or walls. ClearFlow uses acoustic listening equipment to detect the vibration of escaping water, combined with thermal imaging cameras to identify moisture migration through surfaces. Together these methods allow the engineer to mark the exact breach point before any access work begins. The investigation typically takes one to three hours depending on the size and complexity of the system.
How much does central heating leak detection cost?
The cost of a central heating leak detection investigation in London depends on the size of the property and the complexity of the heating circuit. Most residential investigations are completed within a fixed-price visit. ClearFlow provides a clear quote before attendance and operates a No Find No Fee guarantee: if we cannot locate the source, you are not charged for the investigation.
How do I know if my central heating system has a leak?
The most reliable sign is a boiler that needs topping up regularly, particularly if there is no visible water around the boiler or radiators. Other indicators include unexplained damp patches near skirting boards, radiators that fail to heat properly despite the system running, and cold zones in rooms with underfloor heating. If your boiler is displaying low pressure fault codes more than once a month, a leak investigation is advisable.
Can you find a central heating pipe leak under the floor without lifting floorboards?
Yes. Acoustic detection equipment identifies the sound signature that pressurised water creates as it escapes a buried joint or pipe fracture, allowing the engineer to pinpoint the location through the floor surface. In most cases we can mark the fault point to within a few centimetres without removing any boards. Floorboards or screed are only opened once the location is confirmed.
Where can I find central heating leak detection near me in London?
ClearFlow covers all 32 London boroughs for central heating leak detection, with engineers based across the city. We aim to attend within 2 to 4 hours for urgent jobs and offer scheduled appointments throughout the week. Call us or use the contact form to confirm availability and get a quote for your area.