Altecnic 535 28mm 3 Bar PRV/6 Bar SRV Inlet Control Group

The Altecnic 535 Inlet Control Group is a combined control valve assembly for unvented hot water systems. It brings together a 3 bar pressure reducing valve and a 6 bar safety relief valve in one unit, with 28mm connections. It forms part of the Altecnic unvented control valve range, regulating incoming mains pressure and providing over-pressure protection on the cylinder.

• Mains pressure at the outlets is noticeably higher or lower than the set 3 bar, or fluctuates with other draw-offs
• Water is discharging from the relief valve or tundish when the system is heating, indicating the 6 bar relief is passing
• Persistent weeping or dripping from the relief valve body or its outlet
• Reduced flow rate at hot outlets despite adequate mains supply, suggesting a scaled or seized reducing valve
• Knocking, humming or chattering from the valve under flow conditions

• Confirm the pipework is 28mm at the connection points on the existing assembly
• Check the cylinder manufacturer's requirements for a 3 bar PRV and 6 bar SRV before fitting
• Verify the arrangement of the existing inlet group — PRV, relief valve, strainer and check valve positions vary between models
• Unvented cylinder work must be carried out by a competent, appropriately qualified engineer