Buderus 500 - 28/C Servicing Manual page 58

7 Actions
box 179
Put the boiler into full-load operation, see box 54, 55 or 61.
If the boiler goes into heating mode within approx.
3 minutes :-h. , the cause of the fault lies outside the
boiler.
Take the boiler out of operation, see box 43 or 44.
Remove the bridge connection.
Connect the ON/OFF or modulating control element to the
boiler.
Put the boiler into operation, see box 51, 54 or 55.
box 180 Adjust the output flow rate (applies to
combination boilers only)
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CAUTION!
As the water pressure and pipework resistance in the
plumbing system can vary widely with each situation, it
is important to adjust correctly the DHW flow rate at the
boiler. Take a DHW flow rate reading, see box 12.
Adjust the DHW flow rate at the flow regulator for hot water.
To check the DHW flow rate press and hold the down "D"
arrow and read off the display in ltrs/m.
– To increase the DHW flow rate:
turn the flow regulator in direction "+".
– To reduce the DHW flow rate:
turn the flow regulator in direction "–".
Adjust the flow rate of hot water at one of taps where the
user is likely to require hot water at an ideal temperature.
Factory default setting: see factory settings in the
installation instruction.
This assumes a cold water input temperature of 10 °C.
box 181 Check the internal 3-way valve – movement of
the servomotor
Take the boiler out of operation, see box 43, 44 or 47.
We reserve the right to make technical modifications
58 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
box 182
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DANGER OF DAMAGE TO THE SYSTEM!
Before removing the servomotor, check to see if the
3-way valve is in its "heating mode" position, and wait
for the boiler display code C [0h] to appear. This
prevents sudden pressure surges occurring in the
heating circuit while the removal operation is taking
place, and the resultant accidental opening of the
pressure relief valve.
Remove the stop spring (item 1).
Remove the servomotor.
box 183
Put the boiler into operation, see box 54 and 55.
Use the "Settings" menu on the boiler DBA control panel
to adjust the temperature to 60 °C, see box 14 or 18.
Open a hot water tap.
Check to see if the servomotor of the internal 3-way valve,
during operating code C [0c], rotates through a full
revolution.
Close the hot water tap.
Check to see if the servomotor runs back again.
Buderus Ltd. • http://www.buderus-domestic.co.uk
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