An annual service and gas safety inspection at a property on Weymouth Avenue in Mill Hill, London NW7 uncovered serious concerns with a 15-year-old Vaillant ecoTEC plus 635. The inspection revealed evidence of water leakage and corrosion inside the boiler, while a detector also registered a flammable gas reading. After discussing the findings and the boiler’s overall condition with the customer, we agreed that replacement was the most sensible long-term solution.

What the annual service revealed

The service began with checks of the existing boiler and heating system. Its magnetic filter contained more debris than we would normally expect from a healthy system. We also cleaned the condensate trap as part of the service work.

A closer visual inspection of the boiler interior revealed evidence of a leak from the combustion chamber area above the heat exchanger. Rust marks at the bottom of the boiler and around the pump pointed to water leakage and corrosion. Taken together, these findings meant the boiler did not pass the service and inspection checks.

Condensate trap, corrosion and gas detection

The condensate trap was removed and cleaned during the service. The internal photographs also show rust and staining around components near the lower part of the boiler. A separate detector image records a flammable gas level indication during the inspection; the photograph does not provide a numerical concentration or establish the precise source.

Why replacement was agreed

The boiler was around 15 years old and had multiple defects identified during the visit. After we explained the findings, its age and its overall condition to the customer, replacement was agreed as the practical long-term answer for this property.

A new Vaillant ecoTEC plus 635 in Mill Hill

We replaced the old boiler with the latest Vaillant ecoTEC plus 635. Through our Vaillant Advanced Installer status, the new boiler was supplied with a 10-year manufacturer’s warranty, subject to the manufacturer’s terms and annual servicing requirements.

The customer now has a modern replacement boiler and the reassurance of long-term manufacturer support. This job also illustrates why annual inspections matter: they can bring developing faults and deterioration to light before a homeowner has to make a decision during a breakdown.

Vaillant boiler replacement in Mill Hill and North London

TNG Services provides Vaillant boiler installation, servicing and repairs in North London and Hertfordshire. If a service has identified serious defects in an ageing boiler, we can explain the findings and discuss a suitable replacement.