After having adjusted the maximum pressu-
re, calibrate the minimum pressure as fol-
lows (fig. 25):
– Disconnect the electric power to the
modulator.
–
With the D.H.W. potentiometer knob on
maximum, the D.H.W. cock open and the
burner ignited, turn the screw (2) keeping
locked the nut (3) to achieve the mini-
mum pressure value given in Table 4: to
reduce the pressure, turn the screw
counterclockwise; to increase the pressu-
re, turn it clockwise.
–
Operate the main switch a number of
times, keeping the D.H.W. tap open all the
time, and check that the pressure corre-
sponds to the values given in Table 4.
– Restore electric power to the modulator.
– Replace the plastic cap (1) in position.
4.3.2 Maximum and minimum
pressure adjustment
HONEYWELL VK 4105M
To set the maximum pressure, proceed as
follows (fig. 26):
–
Connect the pressure column to the pres-
sure inlet downstream of the gas valve.
– For the “BF” models connect the pressu-
re column as shown in fig. 24.
– Remove the plastic cap on the modula-
tor (1).
– Set the knob of the D.H.W. potentiome-
ter to the maximum value.
– Ignite the boiler and open the D.H.W. cock.
– Using a ø 9 spanner, turn the nut (3) to
achieve the maximum pressure value
given in
Table 4
: to reduce the pressure,
turn the nut counterclockwise; to increa-
se the pressure, turn it clockwise.
–
Operate the main switch a number of
times, keeping the D.H.W. cock open all the
time, and check that the pressure corre-
sponds to the values given in Table 4.
After adjusting maximum pressure, pro-
ceed to calibrate minimum pressure (fig.
26):
–
Disconnect the electric power supply
from the modulator.
–
With the hot water potentiometer
knob set to the maximum, the hot
water tap turned on and the burner lit,
hold nut (3) locked in place and simulta-
neously turn nut (2) using a fixed ø 7
wrench to identify the minimum pres-
sure value shown in Table 4: turn the
nut anti-clockwise to reduce pressure
or clockwise to increase it.
– Turn the boiler on and off repeatedly
while keeping the hot water tap turned
on, checking that pressure corresponds
to the values shown in Table 4.
– Connect up the power supply to the
modulator again.
– Replace the plastic cap (1).
4.3.3 Minimum and maximum
pressure adjustment
WHITE-RODGERS 91B05S
To set the minimum and maximum pressu-
res, proceed as follows:
–
Connect the manometer as shown in
fig. 24.
– Set the knob of the D.H.W. potentiome-
ter to the maximum value.
– Ignite the boiler and open the D.H.W. cock.
–
Turn the screw (7 fig. 24) to achieve the
minimum pressure value given in Table 4:
to reduce the pressure, turn the screw
counterclockwise; to increase the pressu-
re, turn it clockwise.
– Turn the screw (6 fig. 24) to achieve the
maximum pressure value given in Table 4:
to reduce the pressure, turn the screw
counterclockwise; to increase the pressu-
re, turn it clockwise.
–
Operate the main switch a number of
times, keeping the D.H.W. cock open all
the time, and check that the pressure cor-
responds to the values given in Table 4.
4.4 ADJUSTMENT OF HEAT
OUTPUT FOR HEATING
To adjust boiler heat output for heating pur-
poses, i.e., modifying the setting made at the
factory which is approximately 16 kW, use a
screwdriver to adjust the C.H. heat output
trimmer (1 fig. 19). To increase working
pressure, turn the trimmer clockwise; to
reduce pressure, turn the trimmer coun-
terclockwise. To facilitate the operations of
adjusting heat output, see the
pressure/heat output diagrams for natural
gas (methane) and butane or propane gas
(figg. 27 - 27/a - 27/b).
84
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