Tracer Gas Leak Detection London
For the leaks acoustic and thermal cannot reach: slow leaks, plastic pipe, underfloor heating in screed and supply pipes under driveways. We fill the pipe with a safe hydrogen mix and find the exact point where it breaks through the surface, so only one small area is opened.
020 3912 0200Tracer gas leak detection fills an isolated pipe with 5% hydrogen and 95% nitrogen, a safe gas that escapes through the leak and rises through concrete, screed, soil and paving, where a detector picks it up. In London a tracer gas test costs £200 to £350 and usually takes two to four hours. It is the method for leaks that make no sound and show no heat: plastic pipe, slow leaks, underfloor heating and supply pipes under driveways.
How Tracer Gas Finds a Leak Other Methods Miss
Most leak detection reads something the leak gives off. Acoustic equipment listens for the noise of water forced out under pressure. Thermal imaging reads the heat or cold it spreads into a floor or wall. Both work well on a pressurised copper pipe or a hot heating circuit. Neither has much to go on when the leak is slow, the pipe is plastic, the water is cold or the pipe is buried deep in a slab.
Tracer gas turns the problem round. Instead of waiting for the leak to reveal itself, we put something into the pipe that has to come out of it. The gas is 5% hydrogen in nitrogen. Hydrogen molecules are small enough to pass through the pores of concrete, sand and cement screed, tile grout, soil and block paving, and they rise because hydrogen is lighter than air. Where the gas breaks the surface, an electronic detector registers it within parts per million.
The result is a single marked point on the floor or the ground rather than a zone, which is what keeps the repair to one small opening. For a deeper look at the method itself, read our guide to how tracer gas leak detection works.
Leaks We Use Tracer Gas For
Underfloor heating in screed
A pressure drop on an underfloor heating system usually means one loop is leaking somewhere under the finished floor. We test the loops one at a time from the manifold, then gas the failing loop and trace it through the screed so the floor is opened at one point, not along the pipe run.
Underfloor heating leak detectionSupply pipes under driveways and gardens
Modern supply pipes are blue plastic, which carries sound poorly, and they run under drives, paths and lawns at 750mm or more. When the water meter keeps turning with the house isolated, gas along the pipe route finds where the water is going without digging a trench.
Water mains leak detectionHeating pipes under concrete floors
Ground floor heating pipes in older London extensions and conversions were often laid straight into the slab. A leak there can drain a sealed system in days with nothing visible. Once pressure testing has pinned the loss to that circuit, tracer gas locates it through the concrete.
Central heating leak detectionSlow leaks that make no sound
A weep that loses a little water a day may never be loud enough to hear, even on metal pipe. If the pipe holds gas pressure it is sound; if it does not, the gas finds the gap however small it is.
Signs of a hidden leakHow a Tracer Gas Survey Works, Step by Step
The pipe being tested has to be out of use for the test, so the heating or the water supply to that section will be off for part of the visit. We tell you which, and for how long, when we book.
Confirm and isolate
We confirm which system is losing water with meter readings or a pressure test on each circuit, then isolate the pipe or circuit that failed so only that section is tested.
Drain and fill with gas
The section is drained, or the water is pushed out, and the 5% hydrogen mix is introduced at low pressure. A gauge on the fill point shows whether the pipe holds pressure, which confirms the leak before any searching starts.
Sweep the surface
The engineer walks the likely pipe route with an electronic hydrogen detector, over floors, along walls and across paving or grass. Where the surface is sealed, small test holes along the route let the probe sample closer to the pipe.
Pinpoint and mark
The detector reading rises sharply where gas breaks through. That point is checked from several directions, then marked on the surface as the place to open up.
Restore and report
The pipe is purged, refilled and put back into service. You receive a written report with the readings, photographs and the marked leak position, ready for a plumber, a managing agent or an insurer.
What Tracer Gas Cannot Do
It is the most sensitive method we carry, but it has limits, and a good survey plans around them.
- It only tests a pipe that can be isolated and filled with gas. Waste pipes, gutters and roof leaks need other methods.
- A damp-proof membrane under a floor can hold the gas back or spread it sideways, so the breakthrough point needs reading with care.
- Wind disperses the gas outdoors, which is why we sample through small test holes along an outside pipe route on a breezy day.
- It confirms a leak is on the section tested. If the pipe holds pressure, the water is going somewhere else, and that section is ruled out.
Tracer Gas Leak Detection Cost in London
A tracer gas test costs £200 to £350. Where it lands in that range depends on the length of pipe, how many circuits are tested and whether test holes are needed outside. When tracer gas is one part of a wider survey, the job is priced as one of the packages below. These are our published prices:
The price is agreed before we start, the written report is included and the survey is carried out on a no find, no fee basis for leaks on your own property. The repair is quoted separately once the leak is found. Our pricing page lists every service.
Tracer Gas Leak Detection Questions
What is tracer gas leak detection?
How much does tracer gas leak detection cost in London?
Is the tracer gas safe?
When is tracer gas better than acoustic or thermal imaging?
Can tracer gas find a leak under a concrete floor?
Does the water have to be turned off for a tracer gas test?
How long does a tracer gas survey take?
What happens if tracer gas does not find the leak?
Book a Tracer Gas Survey
Tell us what the meter or the boiler gauge is doing and we will tell you whether tracer gas is the right method before you book.
020 3912 0200From £200, Report Included
Tracer gas tests run £200 to £350, agreed before we start. The written report with readings, photographs and the marked leak position is included.
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