Worcester Bosch 3-Way Diverter Valve 87170100620

The Worcester Bosch 3-way diverter valve (part number 87170100620) is a hydraulic component used only in combi boilers. It sits in the water circuit and switches the flow of heated water between the central heating system — radiators, underfloor circuits and the like — and the domestic hot water supply at the taps. Because a combi has no stored hot water cylinder, this valve is what decides which outlet is served at any given moment.

• Hot water runs at the taps while the heating is switched off, or radiators warm up when only hot water is demanded.
• No hot water from the taps even though the boiler fires and the heating circuit works normally.
• The valve body or its connections weep, leaving water staining or scale around the hydraulic block.
• The actuator head moves sluggishly or fails to travel through its full stroke, so the boiler cannot switch between heating and hot water modes.
• Intermittent loss of heating or hot water that clears when the valve is manually exercised.

• Check the appliance GC number and serial plate against the compatibility list to confirm the valve suits your model.
• Cross-check the alternative numbers 1019907 and N0011 against the number on the part being removed.
• Inspect the seals and connections on removal and renew any that are worn or hardened before refitting.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.