Worcester Bosch Retaining Nut Heatcell 87186861800

The Worcester Bosch 87186861800 is a heatcell retaining nut used on Greenstar condensing boilers. It is the threaded fixing that holds the heatcell assembly in position within the appliance, keeping the heat exchanger location secure so the combustion and water circuits stay correctly aligned. The nut is supplied as a single item and is a direct replacement for the original fixing on the listed models.

• The heatcell or heat exchanger assembly shows movement when checked, indicating the retaining fixing is no longer holding it firmly.
• The nut is seized, rounded or damaged and cannot be tightened or removed cleanly during service work.
• A rattle or vibration noise from the heatcell area that disappears when the retaining fixing is held.
• Weeping or staining around the heatcell joint where the assembly has shifted and disturbed the seal face.
• The nut has been lost or dropped during a previous strip-down and the heatcell has been refitted without it.

• Check the GC number on the appliance data badge against the compatibility list, as the same boiler range uses different fixings across variants.
• Confirm the part number 87186861800 matches the fixing currently fitted before ordering.
• If the heatcell joint has been disturbed, check whether a replacement gasket or seal is also required for the reassembly.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.