Servicing
5
Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 11S/19S/24S/24C • 02/2006
49
Subject to modifications resulting from technical improvements!
Buderus • http://www.buderus-domestic.co.uk
5.3.8
Checking the miniature fuses
z
Disconnect the system from the power supply.
z
Loosen crosshead screw on UBA housing.
z
Swivel UBA housing downwards.
z
Open the UBA housing.
z
Check miniature fuses (fig. 64) for correct functioning,
or carry out visual inspection. If defective, fit new fuse.
All fuses a rated 230 Vac - 1.25 AT.
z
Shut the UBA housing.
z
Swivel the UBA housing upwards and screw into place.
z
Connect system to mains power supply.
5.3.9
Checking the pump
z
Remove screw plug on the pump (fig. 65).
z
Turn the UBA mains power switch to “
I
”.
z
Check to ensure that the pump is running. The pump’s
running mechanism may become blocked if the heating
system has been out of use for an extended period.
Use a screwdriver to rotate the pump in its normal running
direction and release the blockage in question. If this
procedure does not work, replace the pump.
z
If the pump is working correctly, screw the plug back in.
5.3.10 Replacing the pump
z
Disconnect the system from the power supply.
z
Shut the servicing valve.
z
Drain the 600 - 11S / 19S / 24S / 24C as per the
"Installation and Servicing Instructions".
z
Loosen the screw on the terminal box (fig. 66, item 2) of the
pump and open the terminal box. Note the wiring layout,
and loosen the cables (fig. 66, item 1).
z
Loosen the screw-in connections on the pump (fig. 66,
item 3) and remove the pump.
z
Fit new pump and connect to system.
z
Connect cables in previously-noted order inside terminal
box, close terminal box and screw shut.
z
Connect system to mains power supply.
z
Open servicing valves.
Fig. 64 Checking the miniature fuse
1
2
3
Fuse
Function
1
Hot surface ignitor
2
UBA, sensors, thermostat valve
3
UBA, three-way valve
Fig. 65 600 - 11S / 19S / 24S / 24C:
checking the pump
Fig. 66 600 - 11S / 19S / 24S / 24C:
replacing the pump
3
2
1
NOTE
Fill the 600 - 11S / 19S / 24S / 24C and purge
the system of air.