10. Remove the syringe hose from the + side of the air pressure
differential switch and reconnect the original hose.
11. Disconnect the silicon hose from the - side (P2) of the air pressure
differential switch.
12. Connect the - side of the air pressure differential switch the hose
coming from the T piece.
13. Pull out the syringe very slowly until error code E.04.08 appears on
the display.
14. Check the pressure indicated by the pressure gauge at that point. This
is the switch pressure.
A switch pressure between -5.5 and -6.5 mbar is good. A lower or
higher switch pressure indicates a problem with the air pressure
differential switch.
11.3.8 Checking the gas leakage monitoring (VPS)
The VPS check consists of two actions: checking the VPS for leaks and
checking the switch value. Proceed as follows:
1. Switch off the boiler.
2. Close the boiler gas valve.
3. Remove the pressure from the gas pipe by unscrewing the screw in
measuring point P1.
4. As soon as the gas pipe is pressure-free, re-tighten the screw.
5. Open the screw at measuring point 3 on the gas control valve.
6. Connect a hose to measuring point 3 of the gas valve.
Fig.115 Negative (-) side of the air pressure
differential switch
AD-3001571-01
X mbar
(+)
14
13
11
12
P
2
(-)
P
1
(+)
10
Fig.116 Preparing the gas circuit
AD-3001572-01
P1
2
3
4
Fig.117 Connecting a hose
AD-3001573-01
3
2
P
3
5
6
5
7
11 Maintenance
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