Worcester Bosch Limit Thermostat LM7 P9024 87161423070

The Worcester Bosch LM7 P9024 is a limit thermostat used in Worcester Bosch gas boilers. It is a safety control that monitors temperature at the heat exchanger and interrupts the burner circuit if the boiler overheats, so it works alongside the main control thermostat rather than replacing it. This version is the Ranco LM7 P9024 pattern, listed by Worcester Bosch under part number 87161423070.

• The boiler fires, runs briefly and then locks out on overheat.
• The overheat cut-out trips repeatedly and the boiler needs resetting by hand.
• No heating or hot water because the burner circuit is held open by the limit stat.
• The thermostat reads open circuit on a continuity test when the boiler is cold.
• The boiler reaches temperature but the limit stat fails to interrupt the burner, allowing the appliance to run hotter than normal.

• Check the GC number on the appliance data badge against the compatibility list; the 24i RSF Combi NG appears with two different GC numbers depending on build date.
• Confirm the part number on the existing thermostat matches 87161423070 before ordering.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.