This system was losing a tiny bit of pressure, with no wet patches, no leaking radiators and nothing visible on the pipework. Several other firms had already been and couldn’t find where the water was going.
Rather than guess at parts or tell the customer to replace the boiler, we suggested a UV dye leak test. Slow pressure loss can come from a small pipe or radiator leak, the pressure relief valve, the expansion vessel, internal seals or the heat exchanger, and sometimes it only shows when the system’s hot.
What we found
We added heating-safe UV dye and let the system run. After longer running periods, dyed water started showing inside the boiler. It pointed to the primary heat exchanger letting by very slightly. It wasn’t dramatic, but now there was evidence. So when we recommended a new boiler, it was based on proof, not a guess.
Boiler keeps losing pressure? Get it properly diagnosed before you spend money on parts or a new boiler. See our servicing and repairs page and our rates.