Worcester Bosch Pump Assembly 8716120459

The Worcester Bosch 8716120459 is a pump assembly supplied for appliances in the Worcester Greenstar Heatslave range. It moves water around the heating circuit and through the hot water side of the appliance, so the boiler can hold a steady flow rate and temperature during demand. The assembly is a direct replacement item for the pump fitted at manufacture.

• The appliance fires and runs, but radiators or hot water stay cold or only warm at the far end of the circuit.
• The pump is noisy in operation, with humming, whining, grinding or a rattle that was not there before.
• Flow and return temperatures drift apart, or the appliance overheats and locks out on a repeated basis.
• Radiators heat unevenly, with some staying cold while others reach temperature.
• Water is visible weeping from the pump body or at the pump connections.

• Match 8716120459 against the number on the existing pump and on the appliance data badge before ordering.
• Check the appliance model against the compatibility list, as the Heatslave External and Heatslave HE Internal variants are listed separately.
• Note the alternative and previous numbers below, so an older unit carrying an earlier number can still be matched.
• Inspect the seals and gaskets at the pump connections during the swap and renew them if they are worn or flattened.