REXNOVA ISA 20 BITHERMAL, Installation, Use And Maintenance Manual

Page: 25 / 36

23
Pict. 25
CHECKING PRESSURE AT BURNER AT MAXIMUM POWER
CHANGING GAS TYPE
• Activate the SERVICE function and
measure the gas pressure after
the regulator by connecting the
micromanometer to the relative pressure
outlet. Check that the measured value
is the same as that listed in the “max”
column of the “Burner pressure” table for
the specific type of gas.
When necessary, it is possible to modify
the boiler to run on types of gas which are
supported but which the boiler was not set up
for in the factory.
This modification concerns in particular the
change from NG (natural gas) to LPG (butane
/ propane) and vice versa and resulting
adjustments necessary.
AFTER FINISHING THE GAS SUPPLY PRESSURE TESTS:
•
Disable the SERVICE function
• Place the device in stand-by (off)
• Disconnect the micromanometer
connected before the gas regulator.
TIGHTEN THE PRESSURE OUTLET SCREW
UNTIL IT SEALS
• Disconnect the micromanometer
connected after the gas regulator. TIGHTEN
THE PRESSURE OUTLET SCREW UNTIL IT SEALS
• Press the gas valve regulation screws cover
closed
• Return the instrument panel to its operating
position; fastening if necessary
• Refit the lower cover; fastening it with the
screws.
If the measured value does not correspond
to the table, adjust the external adjustment
screw on the gas valve until it does, turning
it CLOCKWISE to increase the pressure and
ANTICLOCKWISE to reduce it.
•
Repeat the measurements of the
maximum and minimum pressure at the
burner twice
In order to perform this change the boiler’s
basic configuration must be modified to that
necessary to support the supplied type of gas.
The first step is to change the burner injectors,
which must be adapted to the type of gas
used in order to maintain the correct gas flow
rate and allow the boiler to operate within its
rated power range.
Pict. 26
THE BOILER’S OPERATION AND
SAFETY ARE NOT GUARANTEED
IN ANY MANNER IF IT IS SUPPLIED
W I T H G A S A T P R E S S U R E S
MEASURED BEFORE AND AFTER
THE GAS REGULATION VALVE
WHICH DO NOT CORRESPOND TO
THE SPECIFIED VALUES.
PRESSURE AT THE BURNER mbar
G20 (NATURAL GAS) G31 (PROPANE)
min max min max
1.3 10.8 4.5 37
Isa 20
Bithermal