Troubleshooting
3
Subject to modifications resulting from technical improvements!
Buderus Ltd. • http://www.buderus-domestic.co.uk
56
Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
3.1.19 Checking the feed sensor
z
Unplug cable connection from sensor.
z
Measure resistance of sensor (fig. 67, item 1).
z
Use a second-reading thermometer to measure the
temperature around the sensor.
z
Compare readings with values shown in table 3 on
page 57. If there is any mismatch (i.e. > 5%), the sensor is
defective.
z
If the sensor is working correctly, plug it in once more.
3.1.20 Replacing the feed sensor
z
Shut the servicing cock.
z
Drain the 600 Series 11S / 19S / 24S / 24C as per the
"Installation and Servicing Instructions".
z
Loosen the plug-in connection (fig. 68, item 1).
z
Unscrew the sensor (fig. 68, item 2) and replace with a new
unit.
z
Plug in cable connection.
z
Open servicing cocks.
3.1.21 Checking the feed sensor connection lead
Check to ensure that all plug-in connections on the sensor and
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.
z
Set the mains switch to “
0
”.
z
Disconnect the system from the power supply.
z
Unplug cable connection from feed sensor.
z
Disconnect 20-pin plug from UBA.
z
Use a continuity tester to check the cable between the
plug-in connection and the 20-pin plug in the UBA.
The test should be carried out on connections 05-20 and
18-20 (fig. 69).
z
If the cables are in order, plug them in.
z
Connect system to mains power supply.
z
Turn the mains power switch to “
I
”.
Fig. 67 600 Series 11S / 19S / 24S / 24C:
Checking the feed sensor
1
Fig. 68 600 Series 11S / 19S / 24S / 24C:
Replacing the feed sensor
1
1
2
NOTE
Fill the 600 Series 11S / 19S / 24S / 24C and
purge the system of air as indicated in the
installation and servicing instructions.
Fig. 69 600 Series 11S / 19S / 24S / 24C:
Checking the feed sensor connection lead
