Viessmann CU3, Service Instructions Manual

Page: 13 / 56

13
Initial start−up, inspection and maintenance
Further details regarding the individual steps
(cont.)
Checking the gas valve control pressure
1. Start up the boiler.
2. Operate the boiler at the higher
rated output (see page26).
3. Remove the caps from test
nipples
A
of the gas combination
valve.
4. Connect the gauge to both test
nipples
A
.
The differential pressure should
be 4.0mbar (400Pa).
If the actual value deviates by
more than
"
0.4mbar (40Pa)
H
Check the settings of the DIP
switches (see page27)
H
Check the flue gas and
ventilation air lines
H
Check pressure limiter
B
for
soundness (sealing washers).
Please note:
Use suitable test equipment with a
range from 0 to 1000Pa.
Vacuum pressure is applied to
both test nipples. The vacuum
pressure at the test nipple with the
"+" symbol is lower, and that at
the test nipple with the ""
symbol is higher.
Connect the pressure gauge
accordingly.
5. Record the actual values in the
service report from page46.
Checking the draught
1. Check the draught in Pa
(1Pa=0.01mbar) at connection
A
(flue gas, see page12) of the
boiler adaptor.
2. Record the actual values in the
service report from page46.
5692500GB
A
B