Vokera Expansion Vessel 20135787

The Vokera 20135787 is a 10 litre expansion vessel used in Vokera Unica MAX boilers. It absorbs the volume increase of water as the heating system heats up, limiting pressure rise and protecting components such as the pressure relief valve and heat exchanger. It is a sealed diaphragm vessel that sits within the appliance's hydraulic circuit.

• System pressure rises sharply when the boiler is running and falls again once it cools
• The pressure relief valve discharges water, often onto the wall or through the discharge pipe
• Boiler pressure needs topping up frequently, or drops to the point of lockout
• Water is present at the vessel's air valve, or the air charge will not hold
• The vessel feels heavy or full of water when the system is depressurised

• Confirm the boiler model and GC number from the appliance data badge against the fit list above
• Check the existing vessel's connection size and physical dimensions before removal
• Confirm whether the vessel is fitted internally or mounted remotely on the system
• Verify the fault is with the vessel rather than the filling loop, pressure gauge or relief valve