DeDietrich MCA 10 Manual

Q 1/7 IT2652C-en
Technical Information
MCA 10, MCA 15, MCA 25
MCA 25/28 MI, MCA 25/28 BIC, MCA 35
Wall-hung gas condensing boilers
Diagnostic aid / Heating body
JS N° IT2652C-en 09/05/2022
1. Preliminary checks to be carried out
In the case of a drop in the boiler output, for example hot water not hot enough, although the
settings have not been changed:
► Check the gas supply pressure,
► Check that the siphon and the condensate discharge pipe are clean,
► Flue gas discharge and the air supply pipes: Check that the pipe and the terminal are empty along their entire length,
► Check the Ohmic value of the sensors (DHW sensor, Tank sensor,...),
► MCA 25/28 BIC and MCA 25/28 MI : Check the state
- of the plate exchanger : clean it if required
- of the water filter cartridge : clean it if required.
2. Heating body checking procedur e
If all the above-mentioned causes have been eliminated, check the condition of the burner and
the heating body using the following procedure:
1. Check the boiler type and the gas type indicated on the rating plate:
T001539- B
2. Check the value of parameter MAX.VENT.BOIL (in menu #PRIMARY LIMITS) and correct it if necessary (See
values in APPENDIX hereafter).
EN

Q 2/7 IT2652C-en
3. Check the combustion settings O2at PMAX and PMIN, to do so:
a) Connect the flue gas analyser. Ensure that the opening around the sensor is perfectly sealed when
taking measurements.
b) In the main display, press key : the menu EMISSION MEASURMENTS is displayed
•Setting at PMAX* :
= MAX.VENT setting.
(See table below)
c) Turn the button and select PMAX : the boiler runs at PMAX maximum speed or full load.
d) Check that the fan speed displayed corresponds to the value indicated in the table below:
(Settings for France. For other countries: Refer to the instruction manual delivered with the boiler)
Values at full load
PMAX
(For France)
Gas H (G20)
Gas L (G25)
Propane (G31)
O2 (%)
MAX.VENT.BOIL
rpm O2 (%)
MAX.VENT. BOIL
rpm O2 (%)
Diaphragm
Ø mm
MAX.VENT. BOIL
rpm
MCA 10
4.7 - 5.2(1)
3300
4.4 - 4.9(1)
3300
4.7 - 5.2(1)(2)
3.00(2)
3200
MCA 15
4.7 - 5.2(1)
4500
4.4 - 4.9(1)
4500
4.7 - 5.2(1)(2)
3.00(2)
4400
MCA 25
4.7 - 5.2(1)
5600
4.4 - 4.9(1)
5600
4.7 - 5.2(1)(2)
4.00(2)
5300
MCA 25/28 MI
4.7 - 5.2(1)
4600
4.4 - 4.9(1)
4600
4.7 - 5.2(1)(2)
4.00(2)
4300
MCA 25/28 BIC
4.7 - 5.2(1)
4600
4.4 - 4.9(1)
4600
4.7 - 5.2(1)(2)
4.00(2)
4300
MCA 35
4.3 - 4,8(1)
6200
4.1 - 4.6(1)
6200
4.7 - 5.2(1)
-
6200
(1) Nominal value
(2) Fit the diaphragm for
propane into the
gas valve
e) If necessary, adjust the fan speed parameters.
For France: See APPENDIX hereafter
For other countries: Refer to the instruction manual delivered with the boiler.
f) Mesure the O2rate at PMAX (Front panel removed)
If this rate does not match the required value:
correct the gas/air ratio using the adjustment screw A on the gas valve unit:
•The screw A is a worm screw, which adjusts the restrictor A’.
Depending on the position of the restrictor A’, the O2level decreases or increases.
•Check the flame through the flame inspection window: The flame must not be detached.
*Remark: Note: In the case of the previous gas valve type VK4115V E1311, only the setting at PMIN is possible.
A’
A
Value at
PMAX
Value at
PMAX
Value at
PMAX
G000235

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•Setting at PMIN* :
= Adjustment MIN.VENT.
(see table below)
C002348-E-01
a) Turn the rotary button to select PMIN:
The boiler runs at minimum speed PMIN or low load.
b) Check that the fan speed displayed corresponds to the value indicated in the table below depending on the gas
type and the boiler model:
(Settings for France. For the other countries: Refer to the instruction manual delivered with the boiler)
Values at low load
PMIN
(For France)
Gas H (G20)
Gas L (G25)
Propane (G31)
O2 (%)
MIN.VENT.
rpm O2 (%)
MIN.VENT.
rpm O2 (%)
MIN.VENT.
rpm
MCA 10
5.9(1) - 6.3
1800
5.7(1) - 6.1
1800
5.8(1) - 6.1
2200
MCA 15
5.9(1) - 6.3
1800
5.7(1) - 6.1
1800
5.8(1) - 6.1
2200
MCA 25
5.9(1) - 6.3
1800
5.7(1) - 6.1
1800
5.8(1) - 6.1
1800
MCA 25/28 MI
5.9(1) - 6.3
1800
5.9(1) - 6.3
1800
5.8(1) - 6.1
1800
MCA 25/28 BIC
5.9(1) - 6.3
1800
5.7(1) - 6.1
1800
5.8(1) - 6.1
1800
MCA 35
5.5(1) - 5.9
1700
5.3(1) - 5.7
1700
5.8(1) - 6.1
1700
(1) Nominal value
c) If necessary, adjust the fan speed parameters :
For France: See APPENDIX hereafter.
For other countries: Refer to the instruction manual delivered with the boiler.
d) Mesure the O2value at PMIN (Front panel removed):
e) If this rate does not match the required value:
•correct the gas/air ratio using the adjustment screw B on the gas valve unit :
Turn the screw B clockwise to increase the O2value and anti-clockwise to decrease the value.
•Check the flame through the flame inspection window: The flame must be stable and blue in colour with
orange particles around the edge of the burner.
f) Repeat the high speed test at PMAX and the low speed test at PMIN as often as necessary until the O2
values are in the indicated range.
*Remark: In the case of the previous gas valve type VK4115V E1311, only the setting at PMIN is possible.
B
B
Value at
PMIN
Value at
PMIN
Value at
PMIN

Q 4/7 IT2652C-en
4. Read the control value in the table below:
Table 1 : Control values:
Gas type: G20/G25 G31 G20/G25 BE G31 CH G20 CH
MCA 10
MAX.VENT. (rpm)
3300
3200
3300
3200
3300
Control pressure
(mbar) 4,3 3,8 4,5 3,8 4,3
MCA 15
MAX.VENT. (rpm)
4500
4400
4500
3600
4500
Control pressure
(mbar) 8,8 8,5 8,8 5,1 8,8
MCA 25
MAX.VENT. (rpm)
5600
5300
5200
2800
5600
Control pressure
(mbar) 8,1 7,4 7,4 1,84 8,1
MCA 25/28 MI
MAX.VENT. (rpm)
6200
5900
5800
Control pressure
(mbar) 10,7 9,4 9,2
MCA 25/28 BIC
MAX.VENT. (rpm)
6300
5900
5800
Control pressure
(mbar) 11,2 9,4 9,2
MCA 35
MAX.VENT. (rpm)
6200
6200
5700
3100
6200
Control pressure
(mbar) 10,6 9,8 9,3 2,4 10,6
MCA 35/40 MI
(Belgium)
MAX.VENT. (rpm)
6400
6300
Control pressure
(mbar) 11,4 11,4
Table 1 : Control values (continued)
Gas type: G20 AT G25.3 G27 G2.350 G25.1 G230
MCA 10
MAX.VENT. (rpm)
3300
3300
3200
3200
3300
3200
Control pressure
(mbar)
4,3 4,3 3,8 3,8 4,3 3,8
MCA 15
MAX.VENT. (rpm)
4500
4500
4400
4400
4500
4200
Control pressure
(mbar)
8,8 8,8 8,2 8,2 8,8 7,5
MCA 25
MAX.VENT. (rpm)
5600
5600
5300
5300
5600
4900
Control pressure
(mbar)
8,1 8,1 7,1 7,1 8,1 5,9
MCA 25/28 MI
MAX.VENT. (rpm)
6200
6200
6000
6000
6200
5400
Control pressure
(mbar)
10,7 10,7 9,8 9,8 10,7 7,4
MCA 25/28 BIC
MAX.VENT. (rpm)
6300
6300
6000
6000
6200
5400
Control pressure
(mbar) 11,2 11,2 9,8 9,8 10,7 7,4
MCA 35
MAX.VENT. (rpm)
6200
6200
6200
6200
6200
Control pressure
(mbar) 10,6 10,6 10,6 10,6 10,6

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5. In order to determine the actual control pressure, Proceed as follows:
a) Set the boiler to holiday mode ( ) using the MODE key and
the rotary button, to supress any heating demand.
b) Use an electronic pressure gauge, which will allow to
measure a negative pressure (depression). Connect the
pressure gauge pipe on its tip marked with (-).
c) Connect the pressure gauge to the upper measuring
connection of the gas valve.
Caution: Do not forget to open the screw in the nipple!
d) Operate the boiler in chimney-sweeping mode at DHW full
load (PMAX setting) and wait until the fan has reached its
maximum speed.
e) Press key ESC to exit the chimney-sweeping mode PMAX
and read off the highest measured value displayed on the
pressure gauge during the post-operation time of the fan: the
gas valve closes and the burner goes out.
Note: if a heating request remains (antifreeze mode or
DHW demand), the burner will not go out.
6. Read off the highest measured value displayed on the
pressure gauge during the fan post-operation time (burner
off): This is the measured control pressure.
Important: The control pressure should only be measured during the post-operation time of the fan
when leaving chimney-sweeping mode PMAX, when the burner is no longer operating.
7. Compare the measured control pressure to the minimum control pressure given in the table above (Point 4).
•If the measured control pressure is equal to or higher than this value, the heat exchanger is working properly
and no further step is necessary.
•If the measured control pressure is lower than the minimum control pressure given in the table above (point
4), go to step 8.
8. Dismantle the burner to determine if it is dirty. If possible, clean the burner using compressed air (Maximum 2 bar).
If this is not possible, the burner must be replaced by a new one.
9. After cleaning or replacing the burner: repeat steps 5 to 7.
10.If this value is lower, the heat exchanger is dirty and needs to be replaced by a new one.
See hereafter: : 3. Spare parts.

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3. Spare parts
Boiler type
Reference to order in spare parts
MCA 10
MCA 15
MCA 25
MCA 25/28
MI MCA 25/28 BIC
7701124
Heating body -
(All countries)
MCA 35 7701123
Heating body -
(All countries)
CAUTION: Chemical cleaning and/or mechanical cleaning of the new heat exchanger is prohibited !

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APPENDIX:
SETTING THE FAN SPEEDS DEPENDING ON THE GAS TYPE
► Display menu #SYSTEM and set the INTALLATION parameter to EXTENDED
► Display menu #PRIMARY LIMITS, and set parameters MIN.VENT., MAX.VENT.BOIL, MAX.VENT.DHW, START
RPM to the values indicated below, according to the boiler and gas type:
iThe settings given below are for France.
For other countries: Refer to the instruction manual delivered with the boiler.
•MCA 10
Parameter
Unit
Gas H (G20)
Gas L (G25)
Propane (G31)
MIN.VENT.
rpm
1800
1800
2200
MAX.VENT.BOIL
rpm
3300
3300
3200
MAX.VENT.DHW
rpm
3300
3300
3200
START RPM
rpm
3300
3300
3200
•MCA 15
Parameter
Unit
Gas H (G20)
Gas L (G25)
Propane (G31)
MIN.VENT.
rpm
1800
1800
2200
MAX.VENT.BOIL
rpm
4500
4500
4400
MAX.VENT.DHW
rpm
4500
4500
4400
START RPM
rpm
3700
3700
3700
•MCA 25
Parameter
Unit
Gas H (G20)
Gas L (G25)
Propane (G31)
MIN.VENT.
rpm
1800
1800
1800
MAX.VENT.BOIL
rpm
5600
5600
5300
MAX.VENT.DHW
rpm
5600
5600
5300
START RPM
rpm
3000
3000
3000
•MCA 25/28 MI
Parameter
Unit
Gas H (G20)
Gas L (G25)
Propane (G31)
MIN.VENT.
rpm
1800
1800
1800
MAX.VENT.BOIL
rpm
4600
4600
4300
MAX.VENT.DHW
rpm
6200
6200
5900
START RPM
rpm
3000
3000
3000
•MCA 25/28 BIC
Parameter
Unit
Gas H (G20)
Gas L (G25)
Propane (G31)
MIN.VENT.
rpm
1800
1800
1800
MAX.VENT.BOIL
rpm
4600
4600
4300
MAX.VENT.DHW
rpm
6300
6300
5900
START RPM
rpm
3000
3000
3000
•MCA 35
Parameter
Unit
Gas H (G20)
Gas L (G25)
Propane (G31)
MIN.VENT.
rpm
1700
1700
1700
MAX.VENT. BOIL
rpm
6200
6200
6200
MAX.VENT.DHW
rpm
6200
6200
6200
START RPM
rpm
4000
4000
4000