Air Pressure Switch; 2/2-Way Solenoid Valve (Choke Valve); (For Cm2 186 Burner Only) - Viessmann Vitocrossal 200 CM2 186 Service Instruction

Burner Service

Air Pressure Switch

Legend
A Air pressure switch of blower (APS1, connection hose
with nozzle and electrical plug marked with 131).
B Air pressure switch of combustion chamber (APS2,
connection hose with nozzle and electrical plug
marked with 131A).

2/2-Way Solenoid Valve (choke valve)

34
Vitocrossal 200 CM2 186 to 311 Service
1. Disconnect the air tube from the air pressure switch.
2. Remove the M6 (5 mm hex key) screw and ground
wire from the burner control bracket and set aside.
Loosen the second bracket screw and carefully pivot
the control bracket to access the pressure switch.
3. Remove the two cover screws and remove cover.
4. Remove two M4 (3 mm hex key) screws and remove
the pressure switch.
5. Loosen the two programming unit screws to access
the switch cable connector.
6. Cut the cable tie, loosen the locking tab on the
connector and remove the cable.
7. Reinstall the pressure switch and torque the burner
control bracket M6 (5 mm hex key) screw to 5 lb.in
(0.6 Nm).
Note: Ensure the ground wire is securely fastened.
Note: Set new air pressure settings to the exact same
settings as the old air pressure switch.
8. Reinstall in reverse order.

(for CM2 186 burner only)

During the ignition timing of the burner unit, the solenoid
is activated for approximately 5 seconds. This will open
the valve and allow fan positive pressure pneumatically
linked to the gas pressure regulator. Positive pressure
will allow more gas to be introduced into the burner for
a smoother ignition.
1. Remove connection hoses.
2. Loosen two screws and remove valve
(note the direction of the installation).
3. Loosen plug screw and remove plug.
4. Loosen hose fitting.
5. Reinstall in reverse order.