Using Tracer Gas to Find a Leak Causing Loss of Boiler Pressure

In July 2020, one of our Trace & Access engineers attended an instruction at a detached house in Wolverhampton. The homeowner was having problems with a suspected leak causing loss of boiler pressure. It had been checked by a heating engineer prior to our arrival and parts had been replaced but there was daily pressure loss and the boiler was still needing to be topped up.

Approach – Finding the Leak:

First visit: 

When the engineer first visited the property, they determined that there did seem to be an issue with the boiler, despite the homeowner already having the pressure relief valve (PRV) changed. In under 15 minutes, the system went from full to empty when running and the pressure had dropped from 2.5 bars to 0.

Our engineer recommended the following steps to find a leak causing boiler issues:

             1. Isolate the boiler from the central heating.

This would tell us a couple of things to help find a resolution. 

A) If the pressure drops there is a fault within the boiler and it (or a part of it) would need to be replaced.

B) If the pressure remains, the issue is not solely with the boiler. We would use a non-harmful tracer gas on the central heating system to locate the leak causing the issue within the boiler.

            2. Carry out work following approval from customer/insurance company based on this outcome.


Alt: Tracer gas kit used by trace and access experts


Between our first and second visits, the homeowner had the boiler replaced as they were also experiencing some issues with hot water and we were able to run tests on the now isolated central heating system.

Second visit: 

With the separate boiler issue resolved, our engineer was able to use tracer gas to locate the leak. The drop in boiler pressure was being caused by a faulty 15mm push-fit elbow under the suspended floor in the hallway. 

Alt: Access for pipes under floor causing leak

Outcome – What Happens Next?: 

We were able to locate the leak thanks to the investigative measures on the first visit and the isolation of the boiler. When the central heating was not running there was only a very small drop in pressure. However, when the central heating was in use, the water that was escaping from the joint doubled due to the expansion of the pipes as a result of the hot water passing through. This is what was causing the boiler to shut off.

Trace and Access UK provide drying and reparative services, but none were needed in this instance as the escaped water would dry (to a normal level) due to the air in the house and the naturally damp nature of the area of the escape.

The implementation of tracer gas allowed the engineer to confirm that the leak was below the suspended floor. We were then able to access the void space from another room, crawl to the site of the leak and repair without disturbing the solid wood floor above. This provided a saving to the insurance company of several thousand pounds.

Alt: Repair of underfloor piping leak

With a simple and minimally-invasive resolution, the leak was fixed and the homeowner would no longer experience issues with loss of boiler pressure. We issued a report to the homeowner.

If you’re experiencing issues with leaks or suspected leaks in the home or at a commercial site, please get in touch on 0330 223 6457. You can also reach us on our Facebook page.