Worcester Bosch Boiler Spares & Replacement Parts

Identify and source genuine Worcester Bosch OEM replacement parts for Greenstar combi, system, and regular gas boilers using official 10-digit part numbers.

Where to Find Your Model or Part Number

To guarantee 100% compatibility, check these standard locations for model badges, OEM stampings, and serial numbers:

Gas Council (GC) Number: 7-digit number (e.g. 47-311-87) on the drop-down fascia flap or top casing
10-Digit Worcester Part Number: Stamped on components in format "8 716 106 845 0"

Frequently Replaced Components & Spares

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Greenstar Diverter Valve Assembly

3-way diverter valve cartridge (87161068450) and stepper motor (87161068470)

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Central Heating Circulation Pumps

Wilo and Grundfos high-efficiency modulating boiler pump heads

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NTC Primary & DHW Thermistors

Temperature sensor thermistors (87145000870 / 87161028620)

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Condensate Trap & Siphon Assemblies

Flue siphon traps and drain discharge pipes

Common Symptoms & Fault Diagnostics

Observed Symptom	Likely Root Cause	Recommended Action
Hot water only warm unless central heating is turned on	Diverter valve cartridge stuck in mid-position bypassing domestic hot water heat exchanger	Replace diverter valve cartridge
EA fault code (flame not detected)	Frozen condensate pipe, defective electrode lead, or faulty gas valve	Inspect condensate drainage and test ignition electrode

Compatibility Verification Checklist

Before ordering replacement components, verify these technical specifications to avoid returns:

Always quote the 7-digit Gas Council (GC) number (e.g. 47-311-85) to distinguish between Junior, Si, and CDi models

How to Photograph Your Part for AI Identification

1Photograph the data plate inside the drop-down control cover and the part stamping.

Safety & Legal Compliance Notice

All gas boiler repairs must be conducted by a registered Gas Safe installer. High voltage electricity is present inside boiler control boxes.