Worcester Bosch Overheat Thermostat 87161423030

The Worcester Bosch overheat thermostat, part number 87161423030, is a temperature-sensing safety thermostat used across the CDi, CDiXtra, i Junior, Bosch and SBi boiler families. It sits in the boiler's temperature control circuit and reacts to excessive heat by interrupting the burner demand, protecting the appliance from overheating. It is a direct replacement item for the thermostat position on the listed models.

• The boiler locks out on overheat and needs repeated manual resets before it will run again.
• The appliance shuts down mid-demand, particularly once it has been running for a while.
• Temperature control becomes erratic, with the boiler cutting out before reaching the set point.
• The boiler fires and then trips shortly afterwards, with the fault recurring on each call for heat.
• A continuity or resistance check across the thermostat shows it open when it should be closed.

• Check the GC number and appliance serial plate against the compatibility list to confirm the thermostat suits your model.
• Cross-reference the alternative and previous part numbers (1018039, WB87161423030, ZAMAJ122) against the part you are removing.
• Inspect the thermostat pocket and any sealing washers on removal, as these are often disturbed during replacement.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.