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5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Service
Gas Valve
Note:
Reinstalled gas valve in the same orientation as
originally
installed.
1. Undo screws and pull connectors from the gas valve and
both gas pressure switches.
2. Pull the compensation line from the gas valve.
3. Undo nuts on the gas line flange. Remove the flange.
4. Undo nuts on the Venturi flange. Remove the flange.
Assembly
Assembly in reverse order
Check for correct orientation when fitting.
Replace the gaskets on the inlet and outlet sides.
Secure the gas valve free from stress on the flange
using screws. Torque: 13 lb.in (1.5 Nm)
For further steps, see chapter “Further assembly”
on page 117.
Note:
Never interchange the connecting cables of the two
gas pressure switches (GDW 1 and GDW 2).
WARNING
Escaping gas leads to a risk of explosion.
Check the fitting for gas tightness.
CAUTION
The use of leak detection spray can result in faulty
operation. Leak detection spray must not come into
contact with electrical contacts.
Fan pressure monitoring function (LDW1)
The switching threshold of the air pressure switch 1,
(LDW1) is monitored in all fan start-up phases and
tested during modulating operation of the burner.
This way a minimum amount of pre-aeration will be
ensured, among other things.
The air pressure switch
A
triggers a fault shutdown
on the burner control unit in the following situations:
If the system cold-state checkup is not successful
after approx. 5 minutes,
If the air pressure during the pre-aeration phase is
outside of the permissible range (tolerance period
approx. 5 minutes),
If the air pressure switch fails during normal operation
or the air pressure is outside of the permissible range.
A fault shutdown is registered on the burner control unit
display (see page 194) with fault indicators “
F F5
” and
“
F F7
”.
The fault shutdown can be released by pressing the reset
button
R
.
Air Pressure Switches
Boiler model
Burner model
Setting value LDW1
CA3
2.5 and 3.0
1.25 MMBTU
0.4”w.c. (1 mbar)
1.5 MMBTU
0.4”w.c. (1 mbar)
CA3
3.5 to 6.0
1.5 MMBTU
0.4”w.c. (1 mbar)
2.0 MMBTU
0.4”w.c. (1 mbar)
