How does acoustic detection find a central heating leak under a solid floor

Full transcript

George and Dave in conversation. Every word of the episode, exactly as recorded.

George

Welcome back. I'm here with Dave from ADI Leak Detection, the UK's leading leak detection specialists, who's here to answer your questions and provide expert leak detection advice. Today's question comes from a homeowner who's noticed their boiler pressure keeps dropping but can't see any obvious wet patches. Dave, the suspicion is a central heating leak under a solid floor. How on earth do you find something like that without ripping the whole floor up?

Dave

Yeah, it's a really common situation and honestly one of the scariest for homeowners, because solid floors give you nothing to look at. The good news is acoustic detection is designed exactly for this. Pressurised water escaping through a crack in a heating pipe creates a very distinct noise, and that noise travels up through the screed to the surface. We listen for it.

George

When you say listen for it, what does that actually involve? Are we talking a bloke with a stethoscope, or is there proper equipment here?

Dave

Proper equipment, definitely. ADI engineers use ground microphones, which are sensitive contact sensors that sit on the floor surface and pick up the vibration from that escaping water. We'll place them at intervals across the floor and feed the signal into an acoustic correlator. That correlator compares the timing of the sound arriving at two different sensor positions and calculates where along the pipe the noise is loudest.

George

So the correlator is doing the maths for you, working out the distance between the two sensors and where the signal peaks?

Dave

Exactly. You feed in the pipe material, the pipe diameter, and the distance between your sensor points, and the correlator uses the speed that sound travels through that particular pipe to triangulate the leak position. On a heating system under a solid concrete floor, you can typically get the position to within a few centimetres. That precision matters enormously because you want to open up one small area, not chase a pipe across the whole room.

George

What makes solid floors actually useful here, compared to, say, a suspended timber floor where you might think access would be easier?

Dave

Solid floors concentrate the vibration really well. Concrete and screed transmit the acoustic signal from the leak without absorbing it the way timber joists and floorboards can. With a suspended floor you've got air gaps, insulation, all sorts of things that dampen the signal. Under solid floors the noise from a pressurised heating pipe leak travels cleanly to the surface, which makes the acoustic reading cleaner and the correlation more reliable.

George

Is there ever a situation where acoustic detection on its own isn't quite enough to be certain?

Dave

Yes, if the system pressure has dropped right off and there's very little water movement left, the leak noise gets quiet. In those cases ADI will introduce tracer gas into the heating pipework. Tracer gas is a non-toxic hydrogen and nitrogen mix, and it's light enough to permeate up through the screed to the surface directly above the leak point. We then sweep the floor with a gas detection probe, and the probe reads the highest concentration right over the breach.

George

So tracer gas and acoustic detection work together rather than one replacing the other?

Dave

That's the right way to think about it. Acoustic correlation gives you the leak signal fast when the system has enough pressure to create noise. Tracer gas fills in when pressure is too low for a strong acoustic signal, or when we want a second confirmation before we tell someone to lift their floor. Using both gives ADI engineers a very high confidence level before any excavation happens.

George

What does the homeowner actually experience on the day? Walk me through a typical visit.

Dave

The engineer arrives, has a conversation about where the boiler pressure drops are happening and whether there are any warm or damp spots on the floor surface. Then the acoustic sensors go down and we start systematically working across the area where the pipework runs. It's quiet, methodical work. No drilling, no lifting at that stage. Once the correlator identifies the position, we mark it on the floor and then the homeowner has a precise target for whoever does the repair, rather than a guess.

George

That's the bit that I think surprises people, that the detection work itself is non-invasive. You're not the ones making the mess.

Dave

Right. ADI Leak Detection's job is to find the leak accurately so the repair work is minimal. A precise location means a small, targeted opening rather than chasing pipe across a room. Homeowners are often relieved when they see how the process works, because they'd imagined the whole floor coming up.

George

Dave, that's genuinely useful, thank you. If you're dealing with dropping boiler pressure and a solid floor, it's clear there's a proper method for this rather than guesswork. ADI Leak Detection are among the most trusted names in residential leak finding in the UK, so they're well worth your first call. Thanks for listening.

How this episode was made. This episode was produced using AI-generated voices and script, based on real leak detection questions and the working knowledge of ADI Leak Detection engineers. More about how the podcast is made.