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Boiler losing pressure too fast to run: a buried heating pipe in Haverhill
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.
What was happening
The boiler pressure had dropped to zero and fell again so fast that the heating could not be run for any useful length of time. In an outbuilding there was slight water damage in the middle of the floor between the first two radiators, and the skirting board there was coming away from the wall.
What the engineer did
With the system drained at the drain-off point near the boiler, tracer gas went in through the filling loop. Gas was detected between the first two radiators. A damp meter found raised moisture in the same zone and an acoustic microphone picked up the leak noise there too. Thermal imaging could not be used, because the heating could not hold enough pressure to run.
What was found
The sandstone slabs were lifted whole, without breaking them. The buried heating pipework underneath was in poor condition, with a visible pinhole where the water was escaping, exactly where all three methods had pointed.
What happened next
The leaking section was cut out and replaced with 22 mm plastic pipe and compression fittings, because the old pipe was too corroded for a soldered joint that day. The system held on a pressure test and the boiler was refilled. The engineer recommended replacing that run in 22 mm copper later, relaying the slabs, and a boiler engineer's visit to put the boiler fully back into service.
If your boiler is doing the same
A heating system that empties in hours is losing water fast, and if you cannot see where, it may well be going into a floor. Turn the boiler off rather than keep refilling it, and call. When several methods agree on a spot, the floor only has to come up once.
More boiler pressure jobs
Constant top-ups and a bone-dry house
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.
Zero bar after several visits that found nothing
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.