Servicing
5
Installation and servicing instructions condensing gas boiler 800 - 24/29/43/60 and 800 - 24T25/29T25 H/V • edition 02/2006
49
Subject to modifications resulting from technical improvements !
Buderus • http://buderus-domestic.co.uk
5.3.7
Checking the modulating pump
z
Unscrew the plug on the modulating pump.
z
S
et the mains switch to “
I
”.
z
Check to ensure that the modulating pump is running.
The modulating pump’s running mechanism may become
blocked if the heating system has been out of use for an
extended period.
z
If the modulating pump fails to run:
Set the mains switch to “
0
”.
z
Use a spanner to rotate the modulating pump in its normal
running direction. If this fails to unblock the mechanism, the
modulating pump is defective.
z
If the modulating pump is working correctly, screw the plug
in.
5.3.8
Replacing the modulating pump
z
Disconnect the system from the power supply
(fig. 62, item 1).
z
Close maintenance isolating valves.
z
Drain the 800 Series.
z
Loosen screws on modulating pump terminal box and open
terminal box (fig. 62, item 2).
z
Loosen cable (fig. 63, item 1).
Note order of cable terminals.
z
Loosen modulating pump screw-in adapters and remove
pump (fig. 62, item 3).
z
Fit new pump and connect to system (fig. 62, item 4).
Ensure when doing so that the heat-exchanger spacer
washer is inserted correctly.
z
Connect cables in correct order inside terminal box, close
terminal box and screw shut.
z
Connect system to mains power supply.
z
Open maintenance isolating valves.
fig. 61 Checking the modulating pump
CAUTION!
Water will flow out.
fig. 62 Replacing the modulating pump
1
2
3
2
3
4
fig. 63 Cable modulating pump
1
NOTE
Fill the 800 Series and purge the system of air.
