ADI’s engineers trace hidden central heating leaks with thermal imaging, tracer gas and pressure testing, then repair the pipe once it is found.
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Most people who call us have already topped the pressure up more times than they can count. How often you do it says a lot about what is going on.
That is normal.
Every sealed heating system loses a little pressure over a year, and bleeding radiators lets some out too. Top it up to between 1 and 1.5 bar with the heating cold, and keep an eye on the gauge.
How to top up the pressure safelySomething is wrong, but it may not be a leak.
A slow drop can be the pressure relief valve, the expansion vessel or a weeping radiator valve. Check the small pipe outside where the relief valve comes out, and look at every radiator valve. If you find nothing, a survey will.
Call 0333 567 2638Water is leaving the system. Time to find out where.
At this rate the water is going somewhere, and if you cannot see it, it is often into a floor, a wall or a ceiling. Do not add leak sealer: it makes the leak harder to trace. Call the office with your postcode.
Call 0333 567 2638It is losing water fast. Call today.
A system that empties in a day is losing water fast, and it has to be going somewhere. Turn the boiler off rather than keep refilling it, look for damp downstairs, and call. The engineer will need the heating to run for thermal imaging, so tell the office how long it lasts after a top-up.
Call 0333 567 2638A sealed system is a closed loop, so when the pressure falls the water has left it somewhere. These are the six places it usually goes. Pick one to see the signs and how the engineer finds it.
What you notice. Heating pipes buried in a concrete screed or under floorboards can leak for months before anything shows. Then you notice a warm patch on a tiled floor, laminate lifting near a doorway, or a damp skirting board with no bathroom nearby.
How it is found. Thermal imaging with the heating on follows the hot pipes through the floor. Tracer gas pushed into the drained system rises through the screed at the leak, and a moisture meter and ground microphone confirm the spot before anything is lifted.
More on pipes under floors and screedWhat you notice. Flow and return pipes run between the floors and down inside walls to every radiator. A slow joint up there shows as a brown ring on a ceiling, bubbling paint or a damp patch low on a wall.
How it is found. Thermal imaging traces the pipe route behind plaster. Moisture mapping shows how far the water has travelled, and a borescope camera goes through a small hole to look at the joint before any ceiling comes down.
More on pipes in walls and ceilingsWhat you notice. Radiator valves, the pin under a thermostatic valve head, bleed screws and the radiator itself all weep as they age. Look for rust or white crust at a valve, a damp patch of carpet under a radiator, or a towel rail with a rusty seam.
How it is found. A visual check of every radiator and valve comes first, then pressure testing that isolates each circuit in turn. A passing thermostatic valve was one of two faults an ADI engineer replaced in Bracknell.
More on radiators, valves and towel railsWhat you notice. The pressure relief valve lets water out through a small pipe that ends outside the house. If it is faulty it can drain the system without a drop of water inside. A filling loop left slightly open pushes the pressure up until that valve opens, so the water goes out the same way. A weeping seal inside the boiler shows as drips or rust under the casing.
How it is found. The engineer checks the gauge, the filling loop and the relief valve outlet first. Tracer gas escaping at the outlet pipe proves it, and a pressure test with that pipe capped off shows whether the rest of the system is sound.
More on boiler, relief valve and filling loopWhat you notice. The expansion vessel soaks up the extra volume when the water heats up. When it fails the pressure jumps as the heating comes on, the relief valve lets some water go, and the gauge sits lower than before once everything cools.
How it is found. Watching the gauge from cold to hot tells the engineer a lot. Where the vessel is at fault the system usually holds pressure on test, which rules out a leak in the pipework and saves you a hunt that was never needed.
More on expansion vessel and cylinder cupboardWhat you notice. Underfloor heating is metres of pipe set into a screed, fed from a manifold of valves. A leak shows as a zone that will not warm, a damp edge where the floor meets the wall, or a manifold that needs topping up.
How it is found. Each loop on the manifold is pressure tested separately to find the leaking circuit. Thermal imaging and tracer gas then work along that loop. Underfloor heating has to be switched off from early on the day of the visit, because the heat drowns out the thermal image.
More on underfloor heatingNo single instrument finds every heating leak. ADI’s engineers use these seven together, so the floor or wall is only opened once the leak is down to a small spot.
With the heating running, a thermal camera shows the hot flow and return pipes through plaster, floorboards and screed. Water escaping from a heating pipe shows as a warm spread where there should be a clean line.
On a heating system: Mapping where the pipes run, so the other methods know where to look.
The heating is drained and filled with a safe mix of 95% nitrogen and 5% hydrogen. The gas escapes at the leak, rises through the floor or wall, and a sniffer picks up the hydrogen at the surface.
On a heating system: Pipes in concrete screed, where the leak cannot be seen and is often too quiet to hear.
The system, or one circuit of it, is held under air or gas pressure. A falling gauge proves a leak on that section; a steady one rules it out.
On a heating system: Splitting the house into sections, and proving a repair held before the boiler is refilled.
Ground microphones and listening discs amplify the hiss of water or gas escaping under pressure. The loudest point is the leak.
On a heating system: Confirming the spot tracer gas and thermal imaging have pointed to, before a floor is lifted.
Pin and pinless meters read the moisture in walls, floors and skirting. Plotted across a room, the readings show where the water has spread and where it started.
On a heating system: Following damp from where it shows back towards the pipe that caused it.
A camera on a flexible tube goes through a small, easily filled hole to look inside a floor void, a boxed-in pipe or a ceiling.
On a heating system: Seeing a suspect joint under the floorboards before anything bigger is opened.
The gauge, the filling loop, the relief valve outlet and every radiator valve are checked by eye and by hand before any equipment comes out of the van.
On a heating system: Catching the faults that are not a leak in the pipework at all, such as a relief valve that keeps discharging.
Three ADI central heating jobs, from a bone-dry house to a boiler that emptied in hours, with what the engineer found and how it was fixed.
The homeowner was recharging the boiler constantly, yet nothing inside was wet. The water was leaving through the pressure relief valve outlet on an outside wall. The engineer replaced the valve and a passing radiator valve on the same visit.
A combi boiler kept losing pressure after multiple visits had found no fault. A careful air test proved a small leak, a damp meter led to one spot in the hallway, and the floor there held a leaking 15 mm pipe inside a plastic sleeve.
The pressure fell so quickly the heating could not run. Tracer gas, a damp meter and a microphone all pointed to the same spot in an outbuilding floor. The sandstone slabs came up without breaking, and a pinhole in a corroded pipe was repaired and pressure tested.
Tell us the postcode, how often you top the boiler up, and anything you have noticed. The office team will ask about the boiler, the number of radiators and any leak sealer, then give you a price and availability.
Top the pressure up and turn the heating on, thermostats to maximum, an hour or so before the engineer arrives. Underfloor heating stays off. Clear a path to the boiler, the radiators and the loft if it is up there.
The gauge, the filling loop, the relief valve and its outlet pipe, the expansion vessel and every radiator valve. Some pressure problems are solved right here.
Thermal imaging maps the pipes while they are hot. The system is then drained and tested with air or tracer gas, section by section, until the leak is down to a small spot.
Heating pipework leaks can be quoted and repaired on the same visit, then pressure tested before the system is refilled. You see the price before any work starts.
A report with photographs and findings, written so it can go straight to your insurer under trace and access cover.
Read moreCraig was punctual, knowledgeable, efficient and very tidy. This is a large property and he traced leaks and sources of damp in walls and in heating pipes under concrete floors.
Read moreHamaad from ADI was great. He was very thorough with his work and communicated everything very clearly. He was able to locate the leak and provided a detailed report that could be shared with my insurer. He went above and beyond to answer questions about my insurance claim from both me and my insurer. I'd highly recommend their services.
Read moreWe had a major water leak of approximately 220 litres per hour and, with a holiday booked only a few days later, we urgently needed someone to find and repair it. […] Frank arrived at our house. He was extremely polite, professional and clearly very experienced. He quickly set up the equipment, carried out a tracer gas test and pinpointed the leak to an area just outside our garage underneath the driveway. […] The whole job, from arriving at our house to finding and repairing a 220 litre-per-hour leak, was completed in around three hours.
Read moreRobert Gires attended our property and was extremely professional, knowledgeable and meticulous throughout the whole process. He carefully removed part of the kitchen cabinet to gain access, dug into the floor to properly investigate and assess the leak, and explained what he was doing along the way. What impressed me most was the care he took with our property. Once the investigation was completed, Robert put everything back in place neatly and left the area tidy.
ADI started in 2011 and has more than twenty-five leak investigation engineers across England, Scotland and Wales. Central heating leaks are a regular part of the work: ADI has published dozens of heating case studies of its own.
Most sealed systems want between 1 and 1.5 bar when the heating is cold, rising a little, to around 2 bar, when it is hot. Your boiler manual gives the exact figure. When it drops too low the boiler stops and shows a low-pressure fault code, such as F22 on a Vaillant, F1 on an Ideal or E119 on a Baxi or Potterton.
No. A faulty pressure relief valve, a failed expansion vessel, a filling loop left slightly open or air let out by bleeding radiators can all drop the pressure. A good engineer rules those out first. If the pressure keeps falling once they are dealt with, the water is going somewhere, and on a sealed system that means a leak.
Once or twice a year is normal. Every few weeks means something is wrong, and every few days means water is leaving the system faster than it should. A system that goes to zero overnight is losing a lot of water, and it is worth calling before it damages a floor or ceiling.
Thermal imaging, tracer gas, acoustic listening and moisture mapping narrow the leak down to a small spot before anything is opened. A pipe in a concrete floor still has to be reached to repair it, but the aim is a single small opening in the right place, rather than a trench across the room.
Many home policies include trace and access cover, which pays for finding a hidden leak and making access to it. It does not usually cover the repair itself. Check your policy before the visit; the report you get is written to go to the insurer.
No. ADI's no find, no fee guarantee applies to certain domestic water pipe leaks only, and its booking terms exclude central heating systems. Heating investigations are quoted on the phone before you book, so you know the price up front.
Yes, and please tell the office when you book. Sealer can block the leak for a while and it also makes tracer gas and pressure testing much less reliable. ADI advises having it flushed out before the visit, and even then some residue can remain.
Heating pipework leaks can be quoted and repaired on the same visit, then pressure tested before the boiler is refilled. Faults inside a gas boiler are written up for a Gas Safe registered engineer. Relaying flooring and making good plaster are for your own trades.
Tell the office your postcode, how often you are topping the pressure up and anything you have noticed. They will talk through the survey, give you a price and availability, and book the engineer.
