Buderus 800-24 Installation And Servicing Instructions page 52

5 Servicing
5.3.11 Replacing the mains-water sensor
Unplug cable connection from mains-water sensor.
Pull mains-water sensor out and push new unit in.
Plug in cable connection.
5.3.12 Checking the cables to the flow, return and safety
sensors, and to the burner thermostat
Check to ensure that all plug-in connections to the
sensors/burner thermostat ­ and in the UBA ­ are in order. Note
that an incorrectly-inserted plug can lead to the generation of
error messages. Start up the boiler by pressing the "reset"
button.
Set the mains switch to "0".
Disconnect the system from the power supply.
Unplug the cable connection from the sensor/burner
thermostat.
Check the cable between the plug-in connection and the
24-pin plug in the UBA with a continuity tester.
If the cables are in order, plug them in.
Connect system to mains power supply.
Set the mains switch to "I".
Subject to modifications resulting from technical improvements !
52 Installation and servicing instructions condensing gas boiler 800 - 24/29/43/60 and 800 - 24T25/29T25 H/V • edition 02/2006
fig. 70 Replacing the mains-water sensor
Rear side
of UBA
fig. 71 Checking the cable to the flow/return sensors
fig. 72 Checking the cable to the safety sensor
Flow sensor
Red wire slee ve
Retur n sensor
Buderus • http://buderus-domestic.co.uk