Vaillant 065131 Heat exchanger dhw (12 plates)

The Vaillant 065131 is a domestic hot water (DHW) plate heat exchanger with 12 plates and a 190 mm length. It is a Vaillant spare part that transfers heat from the primary circuit to the domestic hot water supply inside the appliance. The plate stack provides a large surface area in a compact body, so the unit can raise the tap water temperature quickly while the boiler is running.

• Domestic hot water runs lukewarm or fluctuates while the heating circuit continues to work normally
• Reduced hot water flow rate at the taps compared with previous performance
• Water weeping from the plate stack or around the pipe connections
• Scale or system debris blocking the plate channels, giving poor heat transfer
• Repeated overheat faults or DHW temperature errors traced to poor transfer across the plates

• Check the appliance model and serial number against the part number to confirm the correct exchanger
• Confirm the plate count and the 190 mm length match the unit being repaired
• Have new seals or gaskets to hand if the connections are being disturbed during the swap
• Isolate the appliance and drain the relevant circuit before removing the old exchanger
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.