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Commissioning - Page 21
o) Turn off the hot tap.
When the appliance is operating, wiring in the area
around the gas valve and printed circuit boards will be
live. When it is necessary in the following sections to
work in this area temporarily isolate the electrical
supply. However this can not be done when adjusting
the gas pressure therefore extra care must be taken
during this operation. Where it is necessary to
disconnect a modulator coil wire (section 2.2 (q).) the
connection should be taped.
WARNING: The pipes under the appliance could be hot,
avoid contact with bare skin.
p) Fully open all domestic hot water outlets, vent flexible
hose connections to the washing machine and
dishwasher. Remove air from the domestic hot water
distribution system. If this is not done the internal water
flow switch will not function properly. Test for gas
soundness around the gas components using leak
detector fluid.
q) Check the minimum burner pressure (see Table 4) by
disconnecting one of the Modulating Coil electrical
connections (wire colours Red or Black).
Note:
The modulating coil connections are 24V only.
Figs. 28 & 29.
r)
Reconnect and check maximum burner pressure against
Table 4. If any adjustment is necessary see Section 3.4,
Gas Pressure Adjustment.
Note: The boiler is so designed that if required the central
heating output can be down rated to the lowest setting stated
on the data plate without affecting the D.H.W output. If
adjustment is required see Section 3.4 Gas Pressure
Adjustment.
3.4
Gas Pressure Adjustment
Note: The gas pressures are set at the factory (with central
heating output set at maximum) and should not require
further adjustment. If gas pressure readings are being
obtained which differ from that stated in Table 4, check the
inlet pressure using the inlet pressure test point on the gas
valve (Fig. 29). The inlet pressure should be checked with
the appliance at full gas rate, to ensure this occurs put a high
water flow through the domestic hot water side of the
system.
Note: When checking gas inlet pressure only connect one
tube from the measuring manometer's +ve side. Do not
connect the -ve tube as with minimum and maximum
pressure readings.
Warning:
Adjustment of the Modulating Valve
Pressures are measured by connecting the +ve connection
to the gas outlet and -ve connection to the base of the inner
casing as described in Section 3.3 (k).
Set the pressures to the values in Table 4 by adjusting the
gas valve in the following manner.
Note: It is important to note the order in which the maximum
and minimum pressures are set.
The maximum pressure must always be set before
adjustment of the minimum pressure.
Adjusting the Maximum Pressure (Fig. 21)
See boxed Warning on this page.
(i)
Cut off cable tie retaining modulator Cover.
(ii)
Remove Cover (C) by twisting it anticlockwise 90°
and levering off with a small screwdriver.
(iii)
With a 10mm spanner turn nut (B), (Clockwise to
increase pressure). Adjust to the value for maximum
pressure stated in Table 4.
Adjusting the Minimum Pressure (Fig. 21)
See boxed Warning on this page.
This adjustment is only to be made after the maximum
setting has been completed.
(i)
Disconnect one of the electrical connections of the
modulating coil and tape. (24V only)
(ii)
Using a 10mm spanner hold nut (B) and adjust screw
(A) with a screwdriver (clockwise rotation will
increase the pressure). Set to the value for minimum
pressure stated in Table 4.
(iii)
Reconnect the electrical connection to the modulator.
(iv)
Check maximum and minimum settings. Repeat
adjustment if required.
(v)
Refit cover (C), snap into place and turn.
After the setting operation remove the pressure gauge tubes
from the gas valve body and inner casing. Refit the pressure
test point screws.
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