Buderus 500 - 24/C, Servicing Manual

Page: 26 / 80

Diagnosis 6
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
26 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
step 30
Replace the servomotor of the
internal
3-way valve, see box 190.
→
box
42
step 31
Check the power supply cable of the
internal
3-way valve, see box 191.
step 32
Is the power supply cable of the
internal
3-way valve in good condition? Yes:
→
box
41
No:
→
step
33
step 33
Replace the cable loom (or the affected part thereof).
→
box
42
step 34
Check the movement of the servomotor of the Buderus 24V AC external 3-way valve, see box 211.
step 35
Does the servomotor of the Buderus 24V AC external 3-way valve operate correctly? Yes:
→
step
36
No:
→
step
39
step 36
Check to ensure that the the Buderus 24V AC external 3-way valve has been fitted correctly,
see box 227.
step 37
Has the Buderus 24V AC external 3-way valve been fitted correctly? Yes:
→
step
45
No:
→
step
38
step 38
Install the Buderus 24V AC external 3-way valve correctly, see box 227.
→
box
42
step 39
Check to ensure that the Buderus 24V AC external 3-way valve is actuated correctly,
see box 212 and box 228.
step 40
Does the Buderus 24V AC external 3-way valve actuate correctly? Yes:
→
step
41
No:
→
step
42
step 41
Replace the servomotor of the Buderus 24V AC external 3-way valve, see box 217.
→
box
42
step 42
Check the wiring of the Buderus 24V AC external 3-way valve, see box 220.
step 43
Is the wiring of the Buderus 24V AC external 3-way valve in correct condition? Yes:
→
step
47
No:
→
step
44
step 44
Replace the wiring of the Buderus 24V AC external 3-way valve.
→
box
42
step 45
Check the drive mechanism of the Buderus 24V AC external 3-way valve, see box 221.
step 46
Is the drive mechanism of the Buderus 24V AC external 3-way valve working correctly? Yes:
→
box
41
No:
→
step
47
step 47
Replace the internal components of the Buderus 24V AC external 3-way valve, see box 224.
→
box
42
step 48
Check the wiring of the Buderus 24V AC external 3-way valve between the connection box or moving plug-
and-socket connection and the DBA control panel as per box 287.
box 24
On combi boiler supply: hot water available, but no heating operation.
On system boiler supply: no heating operation.
Hot water may be available, but no heating operation.
step 1
Check to ensure that the power supply cable to the RTH converter/Junction box has been installed correctly,
see box 285.
step 2
Is the 230V connection to the RTH converter/Junction box fitted correctly? Yes:
→
step
4
No:
→
step
3
step 3
Correctly attach the switch live to terminal 1 and Neutral to terminal 2 on the 230V connector, see box 285.
step 4
Disconnect black leads from terminals 1 & 2 on the back of the DBA and test for continuity between the two
leads.
No continuity
check S/L and N connections are made correctly and that there is 230v between the two.
Replace RTH converter/Junction box.
Continuity
reconnect the cables to terminals 1 & 2 and check the connections between the terminals and
the DBA.
→ box
42
step 5
Is the volt free connection to the RTH converter/Junction box fitted correctly? Yes:
→
step
6
No:
→
step
8
step 6
Check to ensure that the connections of the external control unit are attached to terminal 1 and 2 of the
connection block, indicated by a clock inside a rectangle, see box 286 and box 285 (item 3).
box 23