Expansion Vessel Check & Replacement London

If your boiler keeps losing pressure, a failed expansion vessel is one of the most common causes. This is a targeted diagnostic and component visit, distinct from a full annual service, for when you suspect this specific part is the problem. The sealed expansion vessel absorbs the extra volume water takes up as it heats, and if it fails, your system will struggle to maintain pressure.

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During the check, our engineer will confirm whether the expansion vessel is the cause of the pressure loss, and not a leak elsewhere in the system. This involves inspecting the vessel's air pressure and checking its diaphragm. It's a routine diagnostic procedure to pinpoint the exact reason your boiler needs constant repressurising.

If the expansion vessel needs replacing, we'll explain the work required and provide a clear quote. No work beyond the initial diagnostic check will be carried out without your approval. All work is done by our fully Gas Safe registered engineers.

Pricing for an expansion vessel check and replacement is confirmed by a detailed quote once our engineer has assessed your specific boiler make and model. For typical UK price ranges for other common services like an annual service, please see our pricing page.

What you get

Targeted: A specific diagnostic visit focused on the expansion vessel, separate from a general boiler service.
Diagnostic: We check the vessel's air pressure and diaphragm to confirm it is the cause of your pressure loss.
Expert: All checks and replacements are performed by fully qualified, Gas Safe registered engineers.
Routine: Replacing a failed expansion vessel is a standard job for a qualified heating engineer.
Clear: You receive a straightforward explanation of the fault and a quote before any replacement work begins.
Guaranteed: Our work is fully guaranteed, giving you peace of mind the job is done correctly.

How it works

A method, not a guess

Book Your Diagnostic Visit

Contact us to book a targeted expansion vessel check. We'll schedule a convenient time for one of our engineers to visit.

Initial System Assessment

Our engineer will discuss the symptoms with you and perform an initial visual check of your boiler and heating system.

Expansion Vessel Check

The engineer will test the expansion vessel's air pressure and diaphragm to confirm if it has failed and is causing the pressure loss.

Quote and Replacement

If a replacement is needed, we'll provide a clear quote. Once approved, our engineer will fit a new expansion vessel and restore your system to correct working order.

Questions

Expansion Vessel Check FAQs for London homeowners

How do I know if my expansion vessel has failed?

The most common sign is a boiler that loses pressure repeatedly, often requiring you to top it up via the filling loop. If you see water discharging from the pressure relief valve (PRV) pipe outside, this can also indicate a vessel problem.

Is this check part of a normal boiler service?

A basic check of the expansion vessel is part of a full annual service. This standalone service is a targeted diagnostic visit for when you are already experiencing pressure loss and suspect this specific component.

Who can replace an expansion vessel?

Anyone working on a gas boiler must be Gas Safe registered by law. Our engineers are fully registered, ensuring the work is done safely and to the correct standards.

Will replacing the expansion vessel affect my boiler's warranty?

Most boiler manufacturers require an unbroken annual service record by a qualified engineer to keep a warranty valid. Using a Gas Safe registered engineer for this work helps protect your warranty.

What if the check finds a different problem?

We will explain any other issues found during the diagnostic check. You would then receive a separate quote for any additional work required, with no obligation to proceed.

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