Buderus 500 - 24/C, Servicing Manual

Page: 27 / 80

Diagnosis 6
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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 27
step 7
Is there a permanent link between terminal 1 and 2 on the volt free connecter? Yes:
→
step
8
No:
→
step
9
step 8
Check the cable connection between the RTH converter/Junction box and terminal 1 and 2 on the DBA.
→
box
42
step 9
Check the external cable connections and control devices.
step 10
Has the malfunction been repaired? Yes:
→
box
42
No:
→
box
41
box 25
The switch optimisation program is activated. This program is activated if there is,
more frequently than once every 10 minutes, a heating water requirement from an
Buderus controller or ON/OFF controller signal. This means that the boiler cannot
be restarted until at least 10 minutes have elapsed since initial startup of the burner.
Operating code
step 1
Check to ensure that the connections of the control device are correctly fitted at the boiler and control device.
step 2
Is the control device connected correctly? Yes:
→
step
4
No:
→
step
3
step 3
Connect the control device correctly.
→
box
42
step 4
Carry out a visual examination where possible, and use a multimeter to check the electrical resistance of the
thermostat lead. Check for breakages and loose contacts.
step 5
Is the thermostat cable in good condition? Yes:
→
step
7
No:
→
step
6
step 6
Replace the thermostat cable.
→
box
42
step 7
Check to ensure that enough thermostatic valves are open on the radiators, convectors, etc.
step 8
Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
→
step
10
No:
→
step
9
step 9
Open more thermostatic valves on the radiators, convectors, etc.
→
box
42
step 10
Attempt to rectify the fault by temporarily replacing the room thermostat or external temperature-dependent
controller.
step 11
Has the malfunction been repaired? Yes:
→
box
42
No:
→
box
41
box 26
The flow NTC sensor has detected that the current CH flow temperature is higher
than the temperature entered at the control unit, or that it is higher than the CH flow
temperature calculated according to heating requirements, or that it is higher than
the CH flow temperature calculated for the purposes of hot water supply.
Operating code
step 1
Check to ensure that the CH flow temperature at the DBA control panel is higher than that entered at the
controller, see box 61.
step 2
Is the CH flow temperature at the DBA control panel adjusted correctly? Yes:
→
step
4
No:
→
step
3
step 3
Adjust the CH flow temperature at the DBA control panel to a higher setting, see box 61.
→
box
42
step 4
Check to ensure that enough thermostatic valves are open on the radiators, convectors, etc.
step 5
Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
→
step
7
No:
→
step
6
step 6
Open more thermostatic valves on the radiators, convectors, etc.
→
box
42
step 7
Check to see if a hot tap or taps have been opened on brief, consecutive occasions.
box 24
C [0a]
C [0y]