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We reserve the right to make technical modifications
Buderus Ltd. • http://www.buderus-domestic.co.uk
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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
box 146
z
Set the multimeter to “measure direct current”.
Measuring range: Microamperes [µA].
z
Connect the multimeter in series the ionisation circuit.
z
Put the boiler into service mode, see
z
Check to see if the ionisation current, during service mode,
operating code
C [lo]
, > 5 µA (micro amperes) and,
with operating code
C [hi]
, > 25 µA.
The value is 0 (zero), or between 1.3 and 50 µA.
box 147
z
Take the boiler out of operation, see box 43 or 44.
z
Detach the multimeter.
z
Connect the plug of the ionisation electrode.
z
Turn the operating switch on the boiler to position “
0
”,
z
Put the boiler into operation, see box 51, 54 or 55.
box 148 Check the ionisation electrode – short circuits
z
Take the boiler out of operation, see box 43, 44 or 47.
z
Loosen the plug-in connection of the ionisation electrode,
see box 144.
box 149
z
Set multimeter to “measure resistance”.
z
Take a reading at the electrode to check whether there is
a possible short circuit between the ionisation electrode
and earth (ground). The electrical resistance between the
ionisation electrode and earth (ground) must be infinitely
high.
box 150
z
Connect the plug of the ionisation electrode.
z
Put the boiler into operation, see box 51, 54 or 55.
box 151 Check the ionisation electrode – cable
H
DANGER OF FATAL ACCIDENT
due to electric shock
z
Take the boiler out of service and tip the DBA control panel
forwards, see box 43, 44, 47 or 63.
z
Loosen the six screws and remove the rear section,
z
Remove the plug of the ionisation electrode, see box 144.
box 152
z
Set the multimeter to “measure resistance”.
z
Take a reading at the ionisation electrode to check
whether there is a possible break in the cable of the
electrode. The electrical resistance of the cable must be
approximately 0
Ω
.
box 153
z
Take an earth (ground) reading check whether there is a
possible short circuit between the cable of the ionisation
electrode and earth (ground). The electrical resistance
between the ionisation electrode cable and earth (ground)
must be infinitely high.
JP4
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