Operating Defects; Preliminary Tests; Possible Defects; Gas Injector Installation - Accorroni MEC25-85 Technical Information

e) screw the new injectors into place, inserting
the new aluminium seal washers and completely
tighten to guarantee a proper gas seal (fig. 27)
f) (only for models 50 - 57) unscrew the gas
fitting on the burner, remove the calibrated
diaphragm and replace it with the new
aluminium gasket. Make sure that the gasket
is in the exact position and tighten the fitting nut
(fig. 25)
(only for model 85) unscrew the fitting after
the gas unit, corresponding to the position of
the "T" fitting. Remove the calibrated diaphragm
and replace it with the new aluminium gasket.
Make sure that the gasket is in the exact
position and tighten the fitting nut (fig. 26)
g) remove the protection plug of the pressure
regulator (figures 12-13) and back off the
regulator screw 3-4 turns
h) start the air heater according to what is indicated
in point 5.2
i) Insert the manometer into the pressure inlet on
the burner (figures 24-25-26) after having
backed off the closing screw a few turns.
Check that the pressure to the burner
corresponds to what is indicated in the technical
data table. If the pressure of the gas to the
burner does not correspond to the value
indicated, use the pressure regulator screw
(figures 12-13) to obtain the correct value.
Turn it counterclockwise to decrease the
pressure and clockwise to increase the pressure
l) remove the manometer and tighten the pressure
inlet screw. Replace the regulator protection
plug.

GAS INJECTOR INSTALLATION

Burner
Injector
Aluminium washer
Fig. 27
page 30
m)use a special spray or electronic leak detector
to identify any leaks in the gas circuit, with
particular attention on the burner and gas unit
pressure inlets.
7. OPERATING DEFECT

7.1 PRELIMINARY TESTS

Before performing specific tests, make sure that:
a) the electric power supply is properly connected
(with particular attention focused on the phase-
neutral polarity and earth connector) and that
any external adjustment components, such as
a room thermostat or timer, operate correctly
b) the gas supply is correct, the gas on-off valve
is open and the pressure to the burner
corresponds to what is indicated in the technical
data table
c) the external terminals of the combustion air
intake and combustion product exhaust ducts
are not obstructed or that their material has
deteriorated
d) any remote-control panel operates properly.

7.2 POSSIBLE DEFECTS

The following is a list of possible defects along
with their probable causes. The information
indicated in italics refers to repair operations or
corrections which are the responsibility of the
authorised Technical Service Centre.
7.2.1 The appliance does not start even if the
conditions described in the previous
points are correct.
a) the flame detection circuit of the control
equipment is malfunctioning and the initial self-
check does not allow the cycle to continue.
- Replace the control equipment (see point
8.1).
b) The flame detection electrode has an earth
leakage.
- Check the correct position of the electrode.
The ceramic insulation material may be
cracked and this is difficult to determine
visually. In case of doubt, replace the electrode
(see point 8.7).
c) the contacts of the differential pressure switch
are stuck in the position they assume when the
draft is correct.
- Replace the pressure switch if its microswitch
does not reset the contacts to the regular
position (see point 8.4).