Ariston microGENUS 23 MFFI User guide

Servicing
Instructions
Type C Boilers
G.C.N: 47-116-14
47-116-15
LEAVE THESE INSTRUCTIONS
WITH THE END-USER
Country of destination: GB

2B063
1. SERVICING INSTRUCTIONS
1.1 REPLACEMENT OF PARTS
1.2 TOGAIN GENERAL ACCESS
- Removing the front panel
- Removing the sealed chamber frontal cover
- Removing the side panels
1.3 ACCESS TO THE COMBUSTION CHAMBER
- Removing the combustion cover
- Removing the burner and jets
- Removing the electrodes
- Removing the main heat exchanger
- Removing the air pressure switch
- Removing the fan
- Removing the venturi device
1.4 SERVICING AND REMOVAL OF THE GAS VALVE
- Setting the gas pressures
- Removing the spark generator
- Removing the gas valve
1.5 ACCESS TO THE WATER CIRCUIT
- Removing the D.H.W. (secondary) exchanger
- Removing the safety valve
- Removing the automatic air vent
- Removing the main circuit flow switch
- Removing the pump
- Removing the pressure gauge
- Removing the expansion vessel
- Removing the overheat thermostat
- Removing the heating temperature sensor (N.T.C.)
- Removing the D.H.W. temperature sensor (N.T.C.)
- Removing the divertor valve actuator
- Removing the D.H.W. flow switch
1.6 ACCESS TO THE CONTROL SYSTEM
- Checking the fuses
- Removing the time clock
- Removing the P.C.B.
2. FAULT FINDING
2.1 FAULT FINDING GUIDE (FLOW-CHART)
3. ELECTRICAL DIAGRAMS
4. SHORT SPARE PARTS LIST
TABLE OF CONTENTS

2. The control panel moves downward and when pulled forward,
rotates on two lateral hinges; the panel stays in a semi-
horizontal position, which allows access to the inner parts of
the boiler (FIG. 1.2);
3. In order to increase the manouvering space, it is possible to
raise the control panel and rotate it to a fully horizontal position
(FIG. 1.3);
4. Remove the screws “B” from the front panel bottom lip
(FIG. 1.4);
5. Lift the front panel from the raised screws at the the top of the
casing (FIG. 1.5).
FIG. 1.4
B
FIG. 1.5
3
B063
1. SERVICING INSTRUCTIONS
The life of individual components varies and they will need
servicing or replacing as and when faults develop.
The fault finding sequence chart in chapter 2 will help to locate
which component is the cause of any malfunction, and instructions
for removal, inspection and replacement of the individual parts are
given in the following pages.
1.1 REPLACEMENT OF PARTS
1.2 TOGAIN GENERAL ACCESS
All testing and maintenance operations on the boiler require the
control panel to be lowered. This will also require the removal of
the casing.
Removing the front panel
1. Loosen the fastening screws“A”of the control panel located on
the lower part of the panel itself. (FIG. 1.1);
A
FIG. 1.3
FIG. 1.1
FIG. 1.2
To ensure efficient safe operation, it is recommended that the
boiler is serviced annually by a competent person.
Before starting any servicing work, ensure both the gas and
electrical supplies to the boiler are isolated and the boiler is
cool.
Before and after servicing, a combustion analysis should be made
via the flue sampling point (please refer to the Installation Manual
for further details).
After servicing, preliminary electrical system checks must be
carried out to ensure electrical safety (i.e.polarity, earth continuity,
resistance to earth and short circuit).
19.eps
14.eps
13.eps
FO016A/15.eps
16.eps

4B063
Removing the sealed chamber frontal cover
1. Remove the screws “C”(FIG. 1.6);
2. Lift the sealed chamber frontal cover from the locating pins
(FIG. 1.7).
FIG. 1.6
C
C
FIG. 1.7
Removing the side panels
1. Remove the four screws “D”for each side panel (FIG.1.8);
2. Pull the panel away from the boiler, then lift the panel up and
remove from the boiler (FIG.1.9).
D
D
D
FIG. 1.8
FIG. 1.9
18.eps 98.tif
17 eps 97.tif

Removing the electrodes
Before carrying out this procedure, unscrew and slide the
burner forward (see previous section).
1. Remove rubber gasket “G”(Fig. 1.13);
2. To remove the detection electrode disconnect the cable
at its connection point close to the P.C.B. (Fig. 1.14);
FIG. 1.13
G
FIG. 1.14
Removing the burner and jets
1. Remove the screws “F”from the burner (FIG. 1.11);
2. Remove the burner (FIG. 1.12);
3. Remove the jets using a No. 7 socket spanner;
4. Replace in reverse order.
5
B063
Removing the combustion cover
1. Remove the screws “E”(FIG. 1.10);
2. Lift off the combustion cover.
1.3 ACCESS TO THE COMBUSTION CHAMBER
E
E
E
FIG. 1.10
FIG. 1.11
Fig. 1.12
F
F
99.tif
12 eps
78 eps
49 eps
50 eps

6B063
3. Remove screw “H”(FIG. 1.15);
4. Gently slide the electrode downward (FIG. 1.16).
To replace, repeat the steps in reverse order, paying
particular attention to the following:
a-Centre the electrode in the positioning hole carefully,
otherwise the electrode may break;
b-Check that the cables have been connected correctly;
c-Check that the rubber gasket covers the cable/ electrode
connection point completely.
FIG. 1.15
FIG. 1.16
H
1. Drain the boiler of water;
2. Release the overheat thermostat sensor “I”(FIG. 1.17);
3. Release the two connection nuts “J”connecting the
exchanger to the flow and return pipes (FIG. 1.18);
4. Pull it straight out (FIG. 1.19).
Removing the main heat exchanger
FIG. 1.18
J
Fig. 1.17
I
FIG. 1.19
51 eps
11 eps
52 eps
75 eps
76 eps
6 eps

1. Disconnect electrical connections “N”and silicon pipes
“O”(FIG.1.23);
2. Remove screw “P”and remove the fan collar clamp “Q”
(FIG.1.24);
3. Remove screws “R”(FIG.1.25);
4. Remove fan and mounting plate (FIG.1.26).
Removing the fan
1. Disconnect the electrical connections “K”and silicon pipes
“L”from their connection points (FIG. 1.20);
2. Remove screws “M”on the top of the sealed chamber
(FIG. 1.21);
3. Unscrew to remove switch from the plate (FIG. 1.22).
FIG. 1.21
FIG. 1.20
7
B063
Removing the air pressure switch
L
K
M
M
FIG. 1.22
FIG. 1.25
RR
FIG. 1.24
P
Q
FIG. 1.23
NN
O
FIG. 1.26
91.tif
90.tif 93.tif
94.tif
95.tif
96.tif

8B063
1.4 SERVICING AND REMOVAL
OF THE GAS VALVE
Setting the gas pressures
1
2
Recommended pressure for
soft-light ignition 8 mbar
NATURAL GAS (G20) BUTANE GAS (G30) PROPANE GAS (G31)
16 mbar 16 mbar
3
4
A
B
C
E
F
D
Setting the minimum and the maximum power of the boiler
1. Check that the supply pressure to the gas valve is a minimum of 20 mbar
for natural gas.
2. To do this, remove the screw “A”.
Fit the pipe of the pressure gauge to the pressure connection of the gas
valve “B”.
When you have completed this operation, replace the screw “A”securely
into its housing to seal off the gas.
3. To check the pressure supplied by the gas valve to the burner, remove the
screw “C”. Fit the pipe of the pressure gauge to the pressure outlet of the
gas valve “D”.
Disconnect the compensation pipe either from the gas valve or from the
sealed chamber.
4. Set the On/Off button to position < I > and the “summer/winter”switch to
the winter position.
To set the maximum power, turn on the hot water tap and allow the hot
water tap to run at a rate of about 8 litres/minute so that the main burner
lights.
Adjust nut “E”on the modureg to set the gas pressure (displayed on the
pressure gauge) corresponding to the maximum power (see TABLE “A”page
9).
5. To set the minimum power, disconnect a supply terminal from the modureg
and adjust screw “F”.
Turn the screw clockwise to increase the pressure and coun-
ter-clockwise to decrease the pressure (displayed on the
pressure gauge) corresponding to the minimum power (see TABLE “A”page
9).
6. When you have completed the above operations, turn off the
hot water tap, re-connect the supply terminal to the modureg
on the gas valve and replace the cap on the screw of the
modureg.
Setting the maximum heating circuit power
7. To set the maximum heating circuit power, place the
On/Off button to position < I > and the “summer/winter”switch to winter
position.
Turn the knob of the heating thermostat clockwise to maximum.
8. Remove the inspection panel of the P.C.B. and fit a small cross-head
screwdriver in to the right hand potentiometer. Turn clockwise to increase
the pressure or counter-clockwise to reduce the pressure. Adjust the
setting to the required heating pressure value (displayed on the pressure
gauge), as indicated in the diagrams shown in page 10.
9. Turn off the boiler by placing the main switch to the "Off" position.
Setting pressure for soft ignition.
Disconnect the detection electrode connection from the P.C.B..
Start the boiler and during the ignition sequence adjust the left hand
potentiometer until the gas pressure reads the required gas pressure as
per the table below.
Once the gas pressure is set turn off the boiler and re-connect the
connection to the P.C.B.
NB.:It may be necessary to reset the flame failure reset a number of times
during this operation.
VG001Aa
VG001Ac
VG001Ab
VG001Ad

9
B063
model 23
model 27
Regulating the heating power for
natural gas (G20)
model 23
model 27
Regulating the heating power for
butane gas (G30)
model 23
model 27
34
36
38
40
Regulating the heating power for
propane gas (G31)
23 MFFI
2.70
20
11.0
2.0
1.16
2.01 Kg/h
0.87 Kg/h
27.7 mbar
6.0 mbar
28 mbar
12 x 0.77
2.00 Kg/h
0.85 Kg/h
35.5 mbar
7.3 mbar
37 mbar
12 x 0.77
27 MFFI
3.15
20
11.0
1.6
1.26
2.34 Kg/h
0.94 Kg/h
27.7 mbar
4.6 mbar
28 mbar
2.31 Kg/h
0.93 Kg/h
35.5 mbar
6.0 mbar
37 mbar
14 x 1.30 14 x 0.77 14 x 0.77
TABLE “A”
CG007A
CG008A
CG009A
TB012A

10 B063
Removing the spark generator
1. Disconnect ignition leads “T”by pulling upward
(FIG. 1.27);
2. Remove the screw “V”(FIG. 1.28);
3. Remove the spark generator (FIG. 1.29).
10. Remove the pipe from the pressure gauge and connect
screw “C”to the pressure outlet in order to seal off the
gas.
11.Carefully check the pressure outlets for gas leaks (valve
inlet and outlet).
IMPORTANT!
Whenever you disassemble and reassemble the gas
connections, always check for leaks using a soap and water
solution.
FIG. 1.27
FIG. 1.28
FIG. 1.29
T
V
Soft-light
Adjustment Max Heating Adjustment
61.eps
45.eps
43.eps
44.eps
VR015A.eps