Diagnosis
6
We reserve the right to make technical modifications
Buderus Ltd. • http://www.buderus-domestic.co.uk
24
Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
step 48
Check the standing and working gas pressures, see box 230.
step 49
Are the standing and working pressures correct?
Yes:
→
step
51
No:
→
step
50
step 50
If the standing and working gas input pressures are not detected, consult your gas utility company.
→
step 51
Check the gas/air ratio, see box 233.
step 52
Is the gas/air ratio correct?
Yes:
→
step
54
No:
→
step
53
step 53
Adjust the gas/air ratio, see box 233.
→
step 54
Check the plate heat exchanger or the external hot water cylinder for furring.
step 55
Is the plate heat exchanger or hot water cylinder
furred up?
Yes:
→
step
56
No:
→
step 56
Decalcify the plate heat exchanger and/or hot water cylinder, see from box 269.
→
step 57
3-way valve: Check the startup of the servomotor of the
internal
3-way valve, see box 181 and box 185.
step 58
Does the servomotor of the
internal
3-way valve start up correctly?
Yes:
→
step
59
No:
→
step
60
step 59
Replace the servomotor of the
internal
3-way valve, see box 190.
→
step 60
Check the wiring of the
internal
3-way valve, see box 191.
step 61
Is the cable correctly connected and free of damage?
Yes:
→
No:
→
step
62
step 62
Replace the cable loom (or the affected part thereof).
→
step 63
Check to ensure that the Buderus 24V AC external 3-way valve has actuated correctly,
see box 212 and box 228 parts 1 and 2.
step 64
Does the Buderus 24V AC external 3-way valve actuate correctly?
Yes:
→
step
65
No:
→
step
66
step 65
Replace the servomotor of the Buderus 24V AC external 3-way valve, see box 217.
→
step 66
Check the wiring of the Buderus 24V AC external 3-way valve, see box 220.
step 67
Is the wiring of the Buderus 24V AC external 3-way valve in correct condition?
Yes:
→
step
71
No:
→
step
68
step 68
Replace the wiring of the Buderus 24V AC external 3-way valve.
→
step 69
Check the drive mechanism of the Buderus 24V AC external 3-way valve, see box 221.
step 70
Is the drive mechanism of the Buderus 24V AC external 3-way valve working correctly?
Yes:
→
step
42
No:
→
step
71
step 71
Replace the drive mechanism of the Buderus 24V AC external 3-way valve, see box 221.
step 72
Check the wiring of the Buderus 24V AC external 3-way valve between the connection box or moving plug-
and-socket connection and the motor of the Buderus 24V AC external 3-way valve, see box 287.
step 73
Is the wiring in order?
Yes:
→
No:
→
step
74
step 74
Replace the cable loom (or the affected part thereof).
→
box 23
On combi boilers: hot water available, but no heating operation.
On system boilers: no heating operation.
Hot water may be available, but no heating operation.
step 1
Check to ensure that the power supply cable to the mains switch box has been installed correctly, see box 54.
box 22