Worcester Bosch O-Ring Greenstar RSF 87102050570

This is an O-ring supplied by Worcester Bosch as a spare for its Greenstar RSF natural gas boiler. The O-ring forms a compression seal between mating surfaces inside the appliance, preventing water or flue gas from escaping past a joint. It is a small, low-cost component, but a perished or flattened O-ring is a common cause of weeping joints and nuisance leaks on older boilers.

• A visible weep or drip at a joint that the O-ring seals
• Water staining, scale trails or corrosion around the sealing face
• The O-ring feels hard, flattened, cracked or has lost its round section
• A joint that continues to seep after being re-tightened
• Discolouration or swelling of the rubber where it has been in contact with system water

• Check the boiler's model and serial plate against the compatibility list to confirm this O-ring suits your appliance.
• Confirm the part number on the existing component or in the appliance literature matches 87102050570 before ordering.
• If the joint also uses a gasket or fibre washer, check whether that item is serviceable at the same time.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.