Buderus 500 - 24/C, Servicing Manual

Page: 28 / 80

Diagnosis 6
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
28 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
step 8
Have a hot water tap or taps been opened briefly and consectutively on several occasions? Yes:
→
step
9
No:
→
box
15
step 9
Inform the user that the fault has been caused by opening hot taps on many brief, consecutive occasions.
→
box
42
step 10
Check the electrical resistance of the DHW temperature sensor, see box 104.
step 11
Is the electrical resistance of the DHW temperature sensor in order? Yes:
→
box
41
No:
→
step
12
step 12
Replace the DHW temperature sensor.
box 27
The flow NTC sensor or safety sensor has detected that the current CH flow
temperature is higher than 95 °C.
Blocking boiler-fault code
The flow NTC sensor and safety sensor have not, after burner startup, detected any
temperature increase in the heating system water, or the temperature difference
between the flow NTC sensor and safety sensor is excessive.
Blocking boiler-fault code
The flow NTC sensor has detected a temperature increase in the heating system
water of more than 5 °C/sec.
Blocking boiler-fault code
The flow NTC sensor and safety sensor have detected a CH flow temperature of over
105 °C.
Locking boiler-fault code
Short circuit between flow NTC sensor or safety sensor.
Locking boiler-fault code
step 1
Are the servicing valves open? Yes:
→
step
3
No:
→
step
2
step 2
Open the servicing valves, see box 53.
step 3
Is the pressure in the heating system at least 1 bar? Yes:
→
step
5
No:
→
step
4
step 4
Fill and vent the heating system, see box 52.
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 the flow NTC sensor and safety sensor, see box 104.
step 8
Are the flow NTC sensor and safety sensor in order? Yes:
→
step
10
No:
→
step
9
step 9
Replace the flow NTC sensor or safety sensor, see box 116.
→
box
42
step 10
Check the cable between the flow NTC sensor or safety sensor for short circuits, see box 112.
step 11
Check the pump, see box 89 to 100.
step 12
Is the pump working correctly? Yes:
→
step
14
No:
→
step
13
step 13
Replace the pump, see box 101.
step 14
Check to ensure that the internal by-pass valve in the boiler or the external overflow valve in the heating
system are working correctly. Possible to adjust external overflow valve to max. 25 kPa (if fitted).
step 15
Is the by-pass valve working correctly? Yes:
→
box
41
No:
→
step
14
box 26
C [0y]
C [2f]
C [2p]
[4a]
[4e]