Glow-worm Motor Pump S801184

The Glow-worm S801184 is a motor pump assembly used on Glow-worm Compact sealed system and E-series gas boilers. It circulates primary water around the heating circuit and, on these appliances, is supplied as a combined unit with the HU, gasket and terminal box. The pump is driven and controlled by the boiler's own electronics via the terminal box connection.

• The pump runs noisily, with rumbling, grinding or squealing from the pump head.
• Radiators stay cold or heat unevenly because circulation has dropped or stopped.
• The boiler overheats, locks out or trips on a flow or temperature fault with no obvious system cause.
• Water is weeping from the pump body or from the pump-to-manifold joint.
• The pump head is silent and does not spin when the boiler calls for heat, indicating a failed motor or supply.

• Confirm the boiler model and GC number against the appliance data badge.
• Compare the existing pump, its terminal box connection and pipework orientation with this assembly before ordering.
• Check that the gasket face on the manifold is clean and undamaged so the new gasket seals correctly.
• If the boiler has been losing pressure, check the system for other leaks before replacing the pump.