We recently attended a heating system with a very small drop in boiler pressure and no obvious signs of leaking.
There were no clear wet patches, no obvious radiator leaks, no visible pipework issues and no simple answer. Several other firms had already attended before us and had been unable to find where the water was going.
Before advising the customer to replace the boiler or spend money guessing at parts, we recommended a UV dye leak detection test.
🔦 Why we used UV dye leak detection
Small pressure drops can be difficult to diagnose because the leak is not always visible. Sometimes the system only loses pressure when hot, under pressure or after longer periods of boiler operation.
A boiler or heating system losing pressure could be caused by:
✅ A small pipework leak
✅ A radiator valve or radiator pinhole leak
✅ A pressure relief valve issue
✅ Expansion vessel problems
✅ Boiler seals or internal components
✅ A primary heat exchanger fault
✅ A leak that only appears when the system is hot
Rather than guessing, we used heating-system-safe UV dye to help prove where the water was going.
💧 No obvious leak, but the evidence was there
After the UV dye was added and the heating system had been allowed to operate, the fault eventually showed itself.
A small amount of dyed liquid began appearing inside the boiler after longer running periods. This pointed towards the primary heat exchanger letting by very slightly.
It was not a dramatic leak. It was not something that was immediately obvious. But with the correct fault-finding process, the cause was identified.
🔧 Proper boiler fault finding matters
This job is a good example of why proper diagnosis is so important.
When a boiler loses pressure, it can be tempting to jump straight to conclusions. But pressure loss can come from many different places, and guessing can become expensive very quickly.
In this case, the UV dye test helped confirm the likely cause before the customer committed to a larger decision. That meant the recommendation for boiler replacement was based on evidence, not assumption.
🔥 Hidden boiler leaks and pressure loss diagnosis in East Devon
SAFEXE LTD Gas, Plumbing & Heat Pumps carries out boiler fault finding, leak investigation, pressure loss diagnosis, boiler repairs and boiler replacement advice across Exmouth, Exeter, Sidmouth, Budleigh Salterton, Ottery St Mary, Honiton, Topsham, Lympstone, Woodbury, Exminster, Pinhoe, West Hill and surrounding East Devon areas.
If your boiler keeps losing pressure but there is no obvious leak, it is worth having the issue investigated properly before spending money on unnecessary parts or replacing the boiler too soon.
Finance options may be available on selected boiler replacement projects, subject to approval and provider terms.
SAFEXE LTD Gas, Plumbing & Heat Pumps
01395 489981
info@safexe.co.uk
www.safexe.co.uk