What does the Vaillant S.85 fault code mean?

Your boiler is struggling to move enough water through the system, which is causing it to work harder than it should.

How much does it cost to fix Vaillant error code S.85?

Typical repair cost for the Vaillant S.85 fault is £120-280 including labour.

Service message quantity of circulation water

Check that your radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barBleed your radiators to remove any trapped air

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.

Break-even maths on monthly cover.