Mark MEGAFLEX Technical Manual

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Technical manual

MARK MEGAFLEX

0660440

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INSTRUCTIONS FOR USER

If you have questions concerning the use of your boiler or heating system, please ask your installer. It is in
your own interest and that of the installer that you are aware of how to operate your boiler and heating

system safely and efciently.

The appliance is not to be used by children or persons with reduced physical, sensory or mental
capabilities, or lack of experience and knowledge.
Children, even if being supervised, must not play with the appliance

In the case of failure or malfunction of the appliance, do not attempt to repair it yourself.

Please contact your installer. Repairs must only be carried out by qualied technicians. Failure to

comply with these requirements can compromise the safety of the appliance.

Operation

Water, coming from the radiators or from the DHW unit is heated in the aluminium heat exchanger. The
CH or DHW pump guarantees circulation of water. The air needed for combustion is sucked in by a rpm

controlled fan. At low boiler temperatures the ue gases can be cooled sufciently for condensation of

the water. This water is drained to the sewer via a built in syphon. This drainage must never be blocked. A
burner controller with built in micro processor provides the electrical control of the boiler.

Topping up

The built in manometer indicates if the waterpressure is sufcient. As soon as the water pressure drops

below 1 bar topping up is necessary. If topping up becomes a regular ocurrance, your installation should
be checked by an installer.

Disconnect from the main. Connect the lling hose to the cold water tap and to the ll and drain valve
of the boiler. Before tightning the coupling in the installation slowly ll the hose with water allowing any
air present to escape. Open the ll and drain valve and slowly ll the installation until a pressure between

1.5 and 2.0 bar is reached. When nished connect again to the main.

Bleeding

To remove any air present in the heating system and boiler, bleeding is necessary. Disconnect from the
main. Open all the radiator valves. Bleed the air from all the radiators starting with the ones at the
lowest point in the system. After bleeding, check the water pressure and top-up if required (if water
pressure has dropped below 1 bar). Connect to the main again.

Starting the boiler

Please ask your installer how to start the boiler. Depending on how your heating system is controlled,
this could be via an external timeclock, thermostat, switch or otherwise. Once the boiler volt-free enable
contacts are closed, the boiler will commence its starting sequence.

Boiler ow temperature

The burner controller can adjust the ow temperature between 20 ° and 85 °C. The temperature setting

can be changed using the control panel.

The installation manual provides the instructions for setting the ow temperature.

DHW (Hot Water) temperature ( if applicable)

From the factory, the DHW temperature is set to a value of 60 °C. This set value can be changed to any
value between 35 and 65 °C using the buttons on the control panel. If the DHW device has a thermostat

the DHW temperature can be adjusted by setting this thermostat.

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Switching off the boiler

During summer time the room thermostat can be set to a lower value to turn off the boiler. During
winter or during a longer period of absence this temperature never should be set to a lower value than

15 °C. Don’t switch off the power. During a period of frost all the radiators should be partly or totally

opened to avoid danger of freezing.

The integrated pump control will activate the pump every 24 hours for a short period even if no
demand is present. This prevents the pump jamming.
Only when work on the boiler is being carried out may the main electricity supply and gas supply be
turned off (your installer can show where these are located).

Errors

If an error occurs rst check the following

• Is the room thermostat properly set?

• Is the boiler connected to the main? Power supply present?

• Is the gas valve opened?

• Are the radiator valves open?

• Is the water pressure in the installation higher than 1 bar?

• Is the installation bled thoroughly?

An error is indicated by a code on the display. It is very important for the sake of a correct diagnosis to
mention this code when calling your installer. Reset the burner controller by pressing the ok button on
the control panel. If the error occurs frequently contact your installer.

Maintenance

A yearly inspection of the boiler must be done by your installer. The lifespan and the reliability of the
installation are improved by doing so.The casing of the boiler may be cleaned with a soft cloth (no
abrasives). Never use solvents like thinner!

Caution

The air supply (for air needed for combustion) and the ue parts are essential parts for safe and efcient
operation of the boiler. Changes on these systems by non qualied persons are not allowed e.g. the

settings of the gas valve. The gas/air ratio is set to a lambda value of approximately 1.26. This corresponds
with a CO2 level of 9,3 % (full load).

For further information see installation manual.

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1 Description boiler 6

2 Technical data 9

2.1 Component Matrix 10

3 Dimensions 11

4 Operation 13

4.1 General 13

4.2 Central Heating (CH) 13

4.2.1 On-off room thermostat 13

4.2.2 Optional 0-10V 13

4.2.3 Outside Temperature Control OTC (optional) 14

4.2.4 Optional digital communication 14

4.2.5 Slow start 15

4.2.6 Protection against insufcient ow through boiler 15

4.3 Domestic Hot Water (DHW) 16

4.3.1 External storage tank (choice by manufacturer between opt. 1 and opt. 2) 16

4.3.2 External storage tank with NTC sensor 16

4.3.3 DHW priority/General behaviour with external storage tank 17

4.4 Cascade 17

5 Boiler control 18

5.1 Control Panel 18

5.2 Push buttons on control panel 18

5.3 User menu 19

5.3.1 Parameter/value setting 19

5.3.2 Parameters accessible by user 19

5.4 Installer (technician) menu 23

5.4.1 Parameters accessible by installer (technician) 23

5.5 Manual Chimney sweep mode 30

5.6 Disabling CH request 30

5.7 Service code 30

5.8 Tacho fan speed 30

5.9 Errors 30

5.10 ECO working mode 30

5.11 Holiday mode 30

5.12 Schedules for CH and DHW 30

5.13 Cascade and Modbus 30

5.14 Parameter settings 30

6 Installation 34

6.1 Installing the boiler 34

6.2 Frost protection 34

6.3 Water connection 35

6.3.1 Pump 35

6.3.2 Minimum ow 35

6.3.3 Water-treatment 35

6.3.3 Water connection general 35

6.4 Gas connection 37

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6.5 Air-supply and ue-gas connection 37

6.5.1 B23 37

6.5.2 C33 37

6.5.3 C63 38

6.5.4 Pressure drop calculations 39

6.5.5 Installing ue-exhaust and air inlet 41

6.6 Electrical connection 43

6.6.1 Wiring diagram 45

6.6.2 NTC resistance table 47

6.7 Pneumatic connections 48

6.8 PC-connection 48

7 Commissioning 48

7.1 Gas category 48

7.2 Adjustment % CO2 (O2 %) and check input 50

8 Errors 51

8.1 General 53

8.2 DHW errors 53

8.3 CH-errors 53

8.4 Errors (hard and soft lockouts) 53

9 Annual service 55

9.1 Service-maintenance table 57

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1 DESCRIPTION BOILER

1 Manometer
2 Display LCD
3 Power switch
4 Fuse
5 Burnerhood

6 Sight glass
7 Flow NTC

8 Ignition electrode
9 Ionisation ame detector

10 Inspection cover

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11 Gas pipe
12 Gas valve
13 Air supply
14 Fan
15 Overheat limiter
16 Flow
17 Flue gas NTC

18 Exhaust

19 Return
20 Maxsys
21 Terminal strip
22 Syphon pressure switch
23 Air pressure switch

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24 Sump inspection cover
25 Syphon
26 Fill and drain valve
27 Water pressure switch

28 Return NTC

29 Automatic air vent
30 Venturi

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2 TECHNICAL DATA

Technical data Megaex series

Type 850-11 range rated 1020-13 range rated

Central heating

Nominal input max load (Hi) 850 680 1020 850 kW
Power range percentage %

Manual technician menu advanced setting CH 100 75 100 80

Nominal input min load (Hi) 170 170 204 204 kW

Nominal ouput max load 80-60 °C 828,8 663 994,5 828,8 kW
Nominal output min load 80-60°C 165,4 165,4 198,5 198,5 kW
Efciency max load 80-60 °C (Hi) 97,5 97,5 97,5 97,5 %
Efciency min load 80-60 °C (Hi) 97,3 97,3 97,3 97,3 %
Efciency max load 50-30 °C (Hi) 103,1 103,1 103,1 103,1 %
Efciency 30 % load 30 °C (return) (Hi) 108,3 108,3 108,3 108,3 %

Flue gas

Temperature ue gas max load 80-60 °C 65-70 65-70 65-70 65-70 °C
Temperature ue gas min load 80-60 °C 60-65 60-65 60-65 60-65 °C
Mass ow ue gases at max load 1221 977 1465 1221 m3/h
Mass ow ue gases at min load 245 245 294 294 m3/h
Maximum ue resistance 500 310 500 480 Pa

Emission CO 96 96 ppm
Emission NOx class 6 6 6 6
Types B23,C33,C63 yes yes yes yes

Gas

Gas ow max load G25 104,5 83,6 125,4 104,5 m3/h
Gas ow min load G25 21 21 25,1 25,1 m3/h
Gas ow max load G25.3 99,9 79,9 119,8 99,9 m3/h
Gas ow min load G25.3 20 20 24 24 m3/h
Gas ow max load G20 90 72 108 90 m3/h
Gas ow min load G20 18 18 21,6 21,6 m3/h

CO2 content max load G25/G20/G25.3 9,3 9,3 9,3 9,3 %
CO2 content min load G25/G20/G25.3 9,1 9,1 9,1 9,1 %
O2 content max load G25 3,90 +0,10-0,30 3,90 +0,10-0,30 %
O2 content min load G25 4,30 +0,35-0,20 4,30 +0,35-0,20 %
O2 content max load G25.3 3,95 +0,10-0,35 3,95 +0,10-0,35 %
O2 content min load G25.3 4,35 +0,35-0,25 4,35 +0,35-0,25 %
O2 content max load G20 4,25 +0,10-0,35 4,25 +0,10-0,35 %
O2 content min load G20 4,60 +0,40-0,20 4,60 +0,40-0,20 %

Water

Maximum ow temperature 90 90 90 90 °C
Content heat exchanger 100 118 ltr
Minimum/maximum operating pressure 0,8/6 0,8/6 bar
Hydraulic resistance 200 225 mbar

(DT 20 nominal ow at full load 80-60 °C)
Maximum DT max load/min load 25/35 25/35 25/35 25/35 °C
Maximum water ow DT 10 K 71,3 57 85,6 71,3 m3/h

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Weight

Mass heat exchanger* 348,4 412,6 kg
Total mass Megaex boiler kg

Sizes of casing

Width 877 877 877 877 mm
Depth without manifold ange 2096 2096 mm

Height excluding feet 1551 1551 1551 1551 mm

Electrical

Electrical voltage/frequency 400V~3N/50 400V~3N/50 V/Hz
Standby power consumption* 15 15 15 15 W
Min load power consumption* W
Max load power consumption* W
Maximum allowable power consumption 6900 6900 W
Fuse 400V~3N/10 400V~3N/10 V/A

* as coming from factory without extra devices connected

2.1 COMPONENT MATRIX

Overview of main components used in MegaFlex series

Part 850-11 1020-13

Boiler control Honeywell Maxsys S4966V2052 S4966V2052
Display (user interface) DSP 49G2193 DSP 49G2193
2 Line EMC Filter 250 V EPCOS B84112G
Fan MVL 230 VAC G3G250MW5001 G3G250250MW5001
Gas-valve Dungs 230 VAC MBC-700-SE-S02 MBC-1200-SE-S02
Venturi type DT DT850 DT1020
Texi Burner round 140 mm Worgas 1011 1200

Silencer ue-gas round 250 mm L=500mm yes yes
NTC-12k, L=50 mm x D5 , ¼” BSP 3 3

NTC 12 k OTC optional optional
Water low pressure device 1,4/0,8 bar yes yes
Pressure difference switch 40 Pa in and 25 Pa out yes yes
Syphon pressure difference switch 15 mbar out yes yes
Gas pressure switch : in 11,7-14,3 and out 8,6-11,4 mbar yes yes

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3 DIMENSIONS

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The appliance is not to be used by children or persons with reduced physical, sensory or mental
capabilities, or lack of experience and knowledge.
Children, even if being supervised, must not play with the appliance.

In the case of failure or malfunction of the appliance, do not attempt to repair it

yourself. Please contact your installer. Repairs must only be carried out by qualied technicians.

Failure to comply with these requirements can compromise the safety of the appliance.

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4 OPERATION

4.1 General

The Megaex is a oor standing boiler, equipped with a cast aluminium heat-exchanger. During heat

demand the controller activates the pump. The controller checks the air pressure switch (zero check)

and increases the fan speed to perform an airow-check. Once the air pressure switch closes, the fan

speed increases to ignition speed and a 5 second pre-purge is performed. The water pressure sensor, gas
pressure switch and siphon pressure switch are checked. When all pressure switches are closed and the
water pressure is ok, the ignition is started.
The air needed for combustion is taken in from the outside (if room sealed) or the boiler house (type

B ue installation) by the fan. The air is transported through a gas/air mixing device creating a negative

pressure. This negative pressure is an indication of the amount of air being transported. The negative
pressure is supplied to the gas valve by an internal tube. The gas valve automatically adjusts the amount

of gas that will be injected into the venturi and that will be mixed with the air-ow. This mixture is

supplied to the burner.

Ignition and ame-control of the mixture is done by two electrodes mounted on the burnerhood.
Temperature control and safeguarding is done using two NTC’s. The boiler monitors the sensors

continuously in order to control operation and ensure safe operation.

4.2 Central Heating (CH)

4.2.1 On-off room thermostat

As standard the boiler is programmed for using an on-off room thermostat. The room thermostat has to
be connected to the pin nrs. 1 + 2 on the terminal strip. Open Therm will be recognized if connected on

1 + 2. The desired ow temperature is adjustable, but as standard is set to 85 °C.

At CH heat request from the room thermostat (and no DHW heat request present) the CH-pump

is activated after 10 seconds. The controller will adjust the burner-input in such a way that a ow­temperature of 85 °C towards the CH-circuit is achieved.

Warning : do not supply any voltage to these terminals as you may damage the controller

4.2.2 Optional 0-10V

The boiler may be controlled using a 0-10 V DC signal. Connect the negative (0V DC) to No. 3, and the
positive (0-10V DC) to No.4 on terminal strip C2.
A loop of wire must be placed between the pin nrs. 1 and 2 of terminal strip C2.
In the technician menu, enable 0-10V in the advanced CH settings menu by setting, CH request to either
0-10V DC % or 0-10V DC SP.

4.2.2.1 0-10V DC % power control

A value between 2 and 10V DC generates a CH power demand proportional to this value between 0

and 100% (0% = minimum load, 100% = nominal load). The heat demand is removed when the control

signal falls below 1 volt.

The setpoint of maximum ow temperature is set to 90°C.

In the user/technician menu, under diagnostics, boiler information the actual voltage input and target
power are displayed.

4.2.2.2 0-10V DC Setpoint

A value between 2 and 10V DC generates a CH setpoint demand proportional to this value between

CH minimum ow temperature and maximum CH ow temperature. The heat demand is removed when

the control signal falls below 1 volt.

The minimum and maximum CH ow temperature can be set in the technician menu, advanced CH

settings, CH temperatures.

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In the user/technician menu, under diagnostics, boiler information the actual voltage input and boiler
setpoint are displayed.
Caution : Ensure that the 0-10V DC signal is free from electrical interference!

4.2.3 Outside Temperature Control OTC (optional)

The boiler may use an outdoor sensor to provide weather compensation (OTC).
To activate weather compensation connect an oudoor sensor to numbers 5 and 6 on the terminal strip
C2. Pin numbers 1 and 2 have to be bridged by a wire. Alternatively those pin numbers (1 and 2) can
be used for connecting room thermostat on/off. In the technician menu, under advanced CH settings,
CH request, OTC only must be selected. The outdoor sensor is then automatically detected by the

controller. The parameters corresponding with A-E in the gure below can be set in the technician menu

(advanced CH settings).

A OTC offset: minimum CH setpoint value
B OTC setpoint maximum: maximum CH setpoint value
C OTC weather cold: external temperature value at which the maximum CH value will be used.
D OTC weather warm: external temperature value at which the minimum CH value will be used
E OTC warm weather shutdown: external temperature value at which the CH demand will end

In the user menu an eco setpoint reduction (night reduction) can be set.
Day, week and weekend options are also available (on, eco, off)

The outdoor sensor is available as an optional accessory.

The sensor should be installed on the north-side of the building at a height of approximately 2 meters.

Note: The resistance of the outdoor NTC should be 12 kOhm at 25 °C.
Also see table of resistance for NTC’s at 6.6.2

4.2.4 Optional digital communication

The boiler supports digital communication with room thermostats using Open-Therm communication
protocols (automatically recognised if connected to pins 1 + 2 on terminal strip C2, also see 4.2.1.)

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4.2.5 Slow start

The boiler uses the “slow start” procedure to prevent the boiler from supplying excessive power in low

load situations.

After “zero check” APS and closure APS with pre purge ignition starts. Following, a stabilization period,

the boiler modulates down to low capacity and maintains this capacity for 1 minute. Subsequently the

boiler power increases at a target rate of 4°C/min until maximum capacity or set temperature has been
reached. Once heat demand has nished the burner will turn off following a set post purge period.

The graph below illustrates this;

4.2.6 Protection against insufcient ow through boiler

When the requirements of 6.3.2 are fullled the boiler will protect itself against insufcient ow. This is
done by checking the difference in temperature between ow and return (so called ΔT).
In a low ow scenario the ΔT will rise rapidly. The ΔT safe-guarding principle is as follows ;
At ΔT > 22 the boiler starts modulating
At ΔT between 22 and 27 the boiler continues modulating
At ΔT > 27 boiler the fan speed will reduce until ΔT < 25

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4.3 Domestic Hot Water (DHW)

4.3.1 External storage tank (choice to be made by manufacturer between option 1 and option 2)

4.3.1.1 Option 1. External storage tank with thermostat (hydraulic 3-way valve)

As standard the DHW conguration is factory pre-set for an external storage tank + tank thermostat.

For hydraulic connection of an external storage tank to the boiler one should either
use :

• the default conguration with 2 pumps: 230 VAC DHW pump (terminal strip C1:6,7,8) and CH pump
(terminal strip C1: 9,10,11) or

• a hydraulic 3-way valve (terminal strip C1: 6,7,8)

The 2 wires of the tank thermostat must be connected to numbers 7 and 8 on terminal strip C2.

In the case of using a hydraulic 3-way valve adjust setting in technician menu, system settings, boiler
parameters, number of pumps to: pump and 3-way valve.

4.3.1.2 Option 2. External storage tank with thermostat (electric 3-way valve)*

As standard the DHW conguration is factory pre-set for an external storage tank + tank thermostat.

For hydraulic connection of an external storage tank to the boiler via an electric 3 way valve one should
either use :

• the default conguration 2 pumps: 230 VAC DHW pump (terminal strip C1: 6,7,8) and CH pump
(terminal strip C1: 9,10,11)

• an electric 3-way valve with a maximum travel time of 255 sec. (terminal strip C1: 6,7,8,9). At the end
of the travel time in either direction DHW or CH the 230 VAC on the 3-way valve will be switched
off.

The 2 wires of the tank thermostat must be connected to numbers 7 and 8 on terminal strip C2.

In the case of using an electric 3-way valve adjust the setting in the technician menu, system settings,
boiler parameters, number of pumps to: pump and 3-way valve.

The 3-way valve travel time can be changed in the technician menu, system setting, boiler parameters,
3-way valve travel time.

*The 3-way valve can either be a hydraulic valve or an electric valve. This is an OEM factory setting and
CAN NOT be changed from the (technician) menu. The default setting is a hydraulic 3-way valve

In case an electric 3-way valve should be the default one, please ask your OEM supplier for

the correcty settings

4.3.2 External storage tank with NTC sensor

In case the storage tank is equipped with an NTC sensor, adjust the setting in technician menu, advanced
DHW settings, DHW request to sensor.

Note: The resistance of the NTC sensor must have a value of 12 kOhm at 25 °C.
The 2 wires of the tank NTC sensor must be connected to numbers 7 and 8 on terminal strip C2.

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The set point temperature of the storage tank is adjustable (default set at 60°C,the ow temperature is
DHW setpoint + 20K). Warning : if a CH heat demand exists immediately after nishing the heat request
for DHW, it is possible for high temperatures to ow into the CH system regardless of CH set point

(hot shot).

4.3.3 DHW priority/General behaviour with external storage tank

Disabling hot water operation: press Summer-Winter button R2-C4 (not active in main screen). See
later in manual for further explanation.

Enabling hot water operation: press Summer-Winter button R2-C4 (active in main screen). See later
in manual for further explanation.

In the default boiler conguration, (2 pumps-DHW and CH pump), a DHW request has priority over

CH request

In the technician menu, advanced DHW settings, DHW priority, the DHW priority over CH can either
be disabled or a maximum DHW priority time may be set.

In the case where the DHW priority is disabled and both demands are active at the same, both pumps

(CH and DHW) will be activated. During this time the ow temperature is set to either 80 °C (tank
thermostat) or DHW setpoint + 20K (NTC sensor).

Notice: At outputs ≥ 40 kW double separation between exchanging media is required.

4.4 Cascade

For cascade application see appendix “cascade”

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5 BOILER CONTROL

5.1 Control Panel

The control panel has 12 buttons and a display as shown in the gure below.

5.2 Push buttons on control panel

Description of push button use

R1-C1, R2-C1 and R3-C1 (back) buttons follow, if pressed, the associated icon in the display (left)
R1-C2 and R3-C2 (up-down) buttons, scroll, if pressed, through the different menus

R2-C2 button conrms, if pressed, the highlighted selection, or conrms what is requiered by LCD

R1-C3 button (escape) returns, if pressed, to main screen
R1-C4 (on-off) button puts boiler in off mode, main logo and date/time stay displayed
R2-C3 (menu) button enables, if pressed, access to both user and installer menu
R2-C4 (summer-winter) button enables-disables, if pressed, CH and DHW in main screens
R3-C3 (holiday) button enables, if pressed, holiday function in main screens
R3-C4 (eco) enables, if pressed, eco function in main screens

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5.3 User menu

By pressing the “menu-button” the display will show the text as given in the gure below.

By pressing the button marked “3” in the gure above the user menu is accessed. Pressing the button
marked “5” returns back to the main screen. By pressing the button marked “4” the installer menu is

accessed.

In the user menu the following options will be shown :

1. HEATING

2. DOMESTIC HOT WATER

3. HOLIDAY

4. MAINTENANCE

5. SETTINGS

6. CHIMNEY-SWEEPER

7. DIAGNOSTICS

By pressing up and down (R1-C2 and R3-C2) one of the six options as shown above will highlight the

desired parameter. By pressing the OK button (R2-C2) the chosen option will be selected.

Once an option has been slected it is possible to change the parameters corresponding with the chosen
option

5.3.1 Parameter/value setting

Pressing the up and down (R1-C2 and R3-C2) buttons will highlight the desired parameter. Pressing the

OK button (R2-C2) will allow the chosen parameter to be modied. This is shown below.

The actual value can be changed by pressing the R1-C1 and R2-C1 buttons. The changed value can

be conrmed by pressing the OK (R2-C2) button. Pressing the back (R3-C1) button leaves the actual

displayed parameter. If there are more parameters shown in the parameter value area (4) the desired
parameter can be selected by pressing the up and down ((R1-C2 and R3-C2) buttons.

5.3.2 Parameters accessible by user

An overview of the parameters accessible by the user is given on the next pages

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User menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

1. HEATING Heating user settings

1. CH temperature/OTC set Set the CH temperatures and OTC curves parameters

1. CH setpoint Adjust setpoint of CH circuit

2. Outside temperature for CH off Set the external temperature at which heat demand is

removed. If set OFF, heat demand will never be removed

by controller (only by removing RT or bridge between

terminal strip C2:1,2)

2. Eco setpoint reduction Set the temperature that will be subtracted from the actual

setpoint when ECO mode is activated

3. Scheduler set Invoke scheduler menu

1. Enable/disable on board scheduler Based on selection is possible to enable/disable on board

scheduler

Enable Enable on board scheduler

Disable Disable on board scheduler

2. Scheduler set Select to set scheduler

1 Monday

2 Tuesday

3 Wednesday

4 Thursday

5 Friday

6 Saturday

7 Sunday

8 Monday-Friday

9 Monday-Sunday

10 Saturday-

Sunday

Used to program on board scheduler (On, Off, Eco)

2. DOMESTIC

HOT WATER

Domestic hot water user settings

1 DHW set point Set the DHW temperature (in case of a DHW with sensor

this is the actual DHW temperature, in case of DHW with

thermostat this is the base boiler ow temperature).

2. ECO set point reduction Set the temperature that will be substracted from the

actual setpoint when ECO mode is activated.

3. Scheduler set Invoke scheduler menu

1. Enable/disable on board scheduler Based on selection possible to enable/disable DHW on

board scheduler

Enable Enable on board scheduler

Disable Disable on board scheduler

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User menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

2. Scheduler set Select to set scheduler

1 Monday

2 Tuesday

3 Wednesday

4 Thursday

5 Friday

6 Saturday

7 Sunday

8 Monday-Friday

9 Monday-Sunday

10 Saturday-

Sunday

3. HOLIDAY Holiday temperatures settings

1. CH holiday set point Set CH temperature used when Holiday mode active

2. DHW holiday set point Set DHW temperature used during Holiday mode

4. MAINTE-

NANCE

1. Service information Used to display service company phone number or entered

info

2. Service due date Show next service due date. When date expire a MSG is

shown on lower part of main screen asking for service.

5. SERVICE Boiler option settings

1. Select Language Allow selection of different language

English Select for English

Italian Select for Italian

German Select for German

Russian Select for Russian

Spanish Select for Spanish

2. Select units Allow selection of different unit

Fahrenheit Select for Fahrenheit

Celsius Select for Celsius

3. Set date Allow RTC date setting

4. Set time Allow RTC time set. When selected a screen asking for

time format 24/12 Hours is opened. When selected appro-

priate format screens jump to time entering screen.

24 hours Select for 24 hours clock

12 hours Select for 12 hours clock

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5. Restore factory data Pressing OK all the user settings will be restored to the

original factory default settings. See 1)

6. CHIMNEY

SWEEPER

Manual mode. Hitting OK will force boiler to operate at

% of power Timeout 15 minutes. While test in progress

navigating through other menus is allowed.

7. DIAGNOS-

TICS

Will display boiler usage information and errors

1. Boiler information Boiler information

1 CH request

2 DHW demand

3 Firing rate

4 Flame ionization current

5 Boiler set point

6 Boiler supply temperature

7 Return temperature

8 Flue temperature

9 Outdoor temperature

10 DHW storage temperature

11 Boiler fan speed

12 CH ignitions

13 CH runtime

14 DHW ignitions

15 DHW runtime

16 System pressure

17 Heat Exchanger Temp.

18 0-10V input

19 Target power

Will display the information shown in SUBMENU 2. When

the line has a * at the end of the line means that hitting OK

when the line is highlighted will open a graph that shows

the latest 120 variable values stored every 12 minutes

(24 hour history)

EN

23

5.4 Installer (technician) menu

If the button marked “4” (page 21) is pressed the screen as given in the gure below will appear.

The installer (technician) access code is 231
+- (R1-C1 and (R2-C1) buttons are used to increment/decrement value

Up and down (R1-C2 and R3-C2) buttons are used to select character to be modied
ok (R2-C2) button conrms value

Once the menu is accessed by entering the code the following options will be shown

1. ADVANCED CH SETTINGS

2. ADVANCED DHW SETTINGS

3. SYSTEM SETTINGS

4. DIAGNOSTICS

5. USER SETTINGS

6. CASCADE

7. RESTORE FACTORY SETTINGS

Pressing the up and down (R1-C2 and R3-C2) buttons will highlight the desired parameter group.

Pressing the up and down (R1-C2 and R3-C2) buttons will highlight the desired parameter subgroup.

Pressing the OK button (R2-C2) selects the chosen parameter subgroup.

Once a parameter subgroup option has been chosen it is possible to change the parameters correspon­ding with the selected subgroup.
Follow the instructions as per 5.3.1 to set or change a parameter.

5.4.1 Parameters accessible by installer (technician)

An overview of the parameters accessible by the installer (technician) is given on the following pages.

24

Technician menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

Lockout history Show a list of recent errors. Hitting OK on the highlighted error will open screens

that contain details on boiler status when error occured.

1. ADVANCED CH

SETTINGS

Heating installer advanced settings

1. CH power set Set power of boiler in CH mode

1. Maximum power Set % of boiler maximum power in CH mode

2. Minimum power Set % of boiler minimum power in CH mode

2. CH temperatures Set (selecting OK) and show CH temperatures

1. Absolute max

temp

Set CH absolute max temperature (CH temperature boiler settings will never

exceed)

2. CH maximum set

point

Determine higher boundary of CH setpoint

3. CH minimum set

point

Determine lower boundary of CH setpoint

4. Setpoint Set CH setpoint hysteresis (temperature above setpoint at which boiler will be

switched off)

3. OTC parameters Set the OTC parameters

1. Outside temp for

max CH

Dene external temperature at which OTC will set maximum CH setpoint

2. Outside temp for

CH

Dene external temperature at which OTC will set the minimum CH setpoint

3. Outside temp for

CV off

Set the external temperature at which Heat demand is removed. If set OFF heat de-

mand will never be removed by controller (only by removing RT or bridge between

terminal strip C2:1,2)

4. OTC set point

table

Show in a table the link between external temperature and actual setpoint deter-

mined by the OTC parameter selection

5. OTC curve Show in a curve the link between external temperature and actual setpoint deter-

mined by the OTC parameter selection

4. CH pump settings Set pump usage related parameters

1. Post pump time Set the CH pump overrun time

5. CH anti cycling

timer

Set the anti cycling timer (minimum time between boiler goes off till next ignition)

6. CH request type Allow selection of different CH requests:

Only OTC Select OTC: outdoor Temperature controller 3)

Room Tstat Select RT/OT: Room Thermostat or OpenTherm

0-10V Signal (%) Select 0-10Vdc input for Power mode 3)

0-10V Signal (SP) Select 0-10Vdc input for setpoint mode 3)

EN

25

Technician menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

2. ADVANCED

DHW SETTINGS

Domestic hot water advanced settings

1. DHW power Set power of boiler in DHW mode

1. Maximum power Set % of boiler maximum power in DHW mode

2. Minimum power Set % of boiler minimum power in DHW mode

2. DHW temperatures Set (selecting OK) and show DHW temperatures

1. Storage tempera-

ture set point

Set Flow temperature during DHW mode when DHW done via a thermostat

(Switch)

2. Boiler temperatu-

re set point

Set DHW temperature setpoint when DHW done with temperature sensor

3. DHW set point

hysteresis

Set DHW setpoint hysteresis (temperature below setpoint at which the boiler will

be switched on)

3. DHW pump set-

tings

Dene pump usage in DHW mode

DHW post pump

time

Set the DHW pump overrun time added to the prexed time of 3 minutes

4. DHW priority Dene DHW priority over CH

1. DHW priority

status

Enable/disable DHW priority over CH

Enabled Enable

Disabled Disable

2. DHW priority

timeout

Dene after how much time DHW priority is ended. (CH can be served if present

for the same amount of time).

Off Select for no timeout (while DHW priority status is enabled)

1...60 minutes Set timeout in minutes (while DHW priority status is enabled)

5. DHW request type Dene DHW request switch or sensor

Switch DHW start when DHW thermostat closes

Sensor DHW start based on requiered vs actual DHW temperature

3. SYSTEM

SETTING

Boiler and system parameters

1. Boiler parameters Boiler related parameters

1. Ignition power Set power % used when igniting burner

2. Delay siphon

check

Delay time to validate a syphon error 4)

26

Technician menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

3. Number of boiler

pump

Dene pump and 3-way valve or 2 pumps

Pump and 3-way

valve

System with pump and 3-way valve

Two pumps System with 2 pumps

4. Pump speed max Maximum % of PWM pump speed

5. Pump speed max Minimum % of PWM pump speed

6. Antilegionella Based on selection possible to enable/disable Antilegionella protection

Enabled Enable Antilegionella protection

Disabled Disable Antilegionella protection

7. Modbus parame-

ters

Set Modbus parameters

Address Set address default: 1

Baudrate Set baudrate default: 38400 bps

Frame Set frame 8N!

8 3-way valve travel

time

Select for setting travel time 3Wv in seconds

1-255 sec Set travel time 3Wv (DHW<- ->CH)

2. User interface

settings

1. Select language Allow selection of a different language

English Select for English

Italian Select for Italian

German Select for German

Russian Select for Russian

Spanish Select for Spanish

2. Select unites Allow selection of different unit

Fahrenheit Select for Fahrenheit

Celsius Select for Celsius

3. Set date Set system date

4. Set time Set system time

3. Service settings Service information

1. Service informa-

tion

Used to insert service company phone number (selection done as per technician

password enter)

2. Service due date Next service due date (input done as per date entering)

EN

27

Technician menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

4. DIAGNOTICS Boiler information and lockout history

1. Boiler information Boiler information

1. CH request

2. DHW demand

3. Firing rate

4. Flame ionization

current

5. Boiler set point

6. Boiler supply

temperature

7. Return tempera-

ture

8 Flue temperature

9 Outdoor tempe-

rature

10 DHW storage

temperature

11 Boiler fan speed

12 CH ignitions

13 CH ignitions

14 DHW ignitions

15 DHW runtime

16 System pressure

17 Heat Exchanger

Temp.

18. 0-10V input

19. Target power

Will display the information shown in SUBMENU 2.

When the line has a * at the end of the line means that hitting OK when the line is

highlighted will open a graph that shows the latest 120 variable values stored every

12 minutes (24 hour history).

2. Lockout history Shows the list of recent errors. Hitting OK on the highlighted error will open new

screen that contains details of the boiler status when the error occured.

3. Manuel test See chimney sweeper.

5. USER

SETTINGS

Access the user settings from the advanced menu

1. Heating Heating user settings

1. CH temperature/

OTC set

Set the CH temperature and OTC curves parameters

1 CH set point Adjust setpoint of CH circuit

2 Outside tempera-

ture for CH off

Set the external temperature at which Heat demand is removed

2. ECO set point

reduction

Set the temperature that will be substracted from the actual setpoint when ECO

mode is activated

28

Technician menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

3. Scheduler set Invoke scheduler menu

1. Enable/disable on

board scheduler

Based on selection is possible to enable/disable on board scheduler

Enable Enable on board scheduler

Disable Disable on board scheduler

2. Scheduler set Select to set scheduler

1. Monday

2. Tuesday

3. Wednesday

4. Thursday

5. Friday

6. Saturday

7. Sunday

8. Monday-Friday

9 Monday-Sunday

10 Saturday-Sunday

Used to program on board scheduler

2. Domestic hot water Domestic hot water user settings

1. DHW set point Set the DHW temperature (in case of a DHW with sensor this is the actual DHW

temperature, in case of DHW with thermostat this is the base boiler ow tempera-

ture)

2. ECO set point

reduction

Invoke scheduler menu

3. Scheduler set Invoke scheduler menu

1. Enable/disable on

board/scheduler

Based on selection is possible to enable/disable on board scheduler

Enable Enable on board scheduler

Disable Disable on board scheduler

2. Scheduler set Select to set scheduler

1. Monday

2. Tuesday

3. Wednesday

4. Thursday

5. Friday

6. Saturday

7. Sunday

8. Monday-Friday

9 Monday-Sunday

10 Saturday-Sunday

Used to program on board scheduler

EN

29

Technician menu Submenu 1 Submenu 2 Submenu 3 Submenu 4 Notes

3. Holiday Holiday temperatures settings

1. CH holiday set

point

Set CH temperature used when Holiday active

2 DHW holiday set

point

Set DHW temperature used during Holiday mode

6. CASCADE Access to cascade information and settings

1. Cascade set

1. Cascade switch

delay

Delay between switching on and off different boilers

2. Cascade min

power

Minimum power of boiler in cascade

3. Burner power Max power of SINGLE boiler in cascade

4. Boiler for DHW Number of boilers assigned to DHW

5. PI loop period Base time for PI loop calculation

6. Burner water ow

delay

Water propagation time delay

7. Different boiler

size

Heterogeneous mode with 2 power groups DHW+CH/CH only

Disabled Disable Heterogeneous mode

Enabled Enable Heterogeneous mode

8. Cascade pump

speed

Cascade pump full speed

9. Cascade pump min

speed

Cascade pump min speed

2. Cascade info 1. Cascade role Role of boiler in cascade mode = MASTER, SLAVE, TERMINAL SLAVE

If not in cascade mode: STANDALONE

2. System tempera-

ture*

Cascade temperature value. Hitting OK when highlighted will open graph that

shows the latest 120 variable values stored every 12 minutes (over the past 24

hours). Samples will not be averaged over the 12 minutes period.

3. Number of

burners on

Number of burners that are switched on

4. Modulation level Actual percentage of cascade modulation level

3. Cascade auto detect Pressing OK will start the auto detection of the cascade conguration. Can only be

started from the master boiler.

7. RESTORE FAC-

TORY SETTINGS

Pressing OK all the advanced settings will be restored to the original factory de-

faults 2)

30

5.5 Manual Chimney sweep mode

For routine maintenance and/or service purposes a CH request can be generated to force the burner to

a specic load from minimum to nominal (0-100%). This is only possible if no error condition is present.

The chimney sweep function can be started from the user menu and will be active for 15 minutes.While
active it is possible to navigate through other menus to check the boiler status and functionality.

5.6 Disabling CH request

The CH function can be disabled. See 5.3.2 parameters accessible by user at 1 HEATING nr 3 scheduler
set.

5.7 Service code

To access the service-level of the controller it is necessary to enter the service-code. How this done is
explained in 5.4 installer (technician) menu.

5.8 Tacho fan speed

For service purposes it is possible to read the fan speed.
See 5.4.1 parameters accessible by installer (technician) at 4 DIAGNOSTICS nr 1 boiler information.

5.9 Errors

For service purposes it is possible to see a list of recent errors. See 5.3.2 parameters accessible by user
at 6 DIAGNOSTICS nr error history.

5.10 ECO working mode

When the ECO button (R3-C4) is pressed a programmable value (see user menu 1.HEATING under 2
ECO set point reduction) is automatically subtracted from the ow temperature setpoint weather com­pensated (OTC) set point, or 0-10V setpoint. . The same principal is applicable for DHW (see user menu

2.DOMESTIC HOT WATER under 2 ECO set point reduction)

5.11 Holiday mode

When the Holiday button (R3-C3) is pressed a start and end date of a holiday period may be entered.

The desired ow temperature and the DHW temperature for this period can be set (see user menu 3.

HOLIDAY under 1 and 2).

5.12 Schedules for CH and DHW

For CH and DHW separate schedules can be set.
Both schedules are set to enabled and always on by default.
Schedules may be set (ON, ECO, OFF) for each day, for a group of weekdays, for weekend days or for an
entire week. The status of the schedule is shown on the main screen (ON, ECO, OFF).
The schedule can be set in the user menu, heating or domestic hot water or in the technician menu, user
settings, heating or domestic hot water.
Eco mode can also be forced by pushing the ECO button on the control panel (R3-C4).

5.13 Cascade and Modbus

Cascade and Modbus options are shown in two separate attachments “Modbus” and “Cascade”.

5.14 Parameter settings

The parameter settings are listed on the following pages

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31

USER MENU

Recommended Min Max

After factory

reset

1. HEATING 1. CH tempera­ture/OTC set

1. CH setpoint 85 20 90/Technician 75

2. Outside temperature
for CH off

OFF 7 30 OFF

2. ECO set­point reduction

50 0 50 50

3. Scheduler set 1. Enable/disable on

board scheduler

Enabled Disabled Enabled Enabled

2. Scheduler set ON ON|OFF ECO ON

2. DOMESTIC

HOT WATER

1. DHW setpoint (Switch) 80 35 85 80

1. DHW setpoint (NTC sensor) 60 10 65 60

2. ECO setpoint reduction 20 0 50 20

3. Scheduler set 1. Enable/disable on

board scheduler

Enabled Enabled Enabled Enabled

2. Scheduler set ON ON|OFF ECO ON

3. HOLIDAY 1. CH holiday setpoint 20 20 90/Technician 20

2. DHW holiday setpoint (Thermostated) 80 35 85 80

2. DHW holiday setpoint (NTC sensor) 60 10 65 60

4. MAINTENANCE 1. Service information Service tel. set by Technician

2. Service due date Date set by Technician

5. SETTINGS 1. Select language English

English|Italian|German|Russian|Spanish

2. Select units Celsius Fahrenheit Celsius

3. Set date set date

4. Set time 24 hours 24 hours 12 hours

5. Restore factory settings Reset to factory/check settings

6. CHIMNEY

SWEEPER

OFF 0 100

1. Boiler information Real time boiler status

2. Lockout
history

Overview lockout
history

Status boiler at time of lock/block

TECHNICIAN MENU

Recom-

mended

Min Max

After factory

reset

1. ADVANCED

CH SETTINGS

1. CH power set 1. Maximum power 100 0 100 100

2. Minimum power 0 0 100 0

2. CH
temperatures

1. Absolute max. temperature 90 20 90 80
Higher than 90 not allowed

2. CH maximum setpoint

85 20

Abs. max CH

temp.

75

3. CH minimum setpoint 20 20 70 40

4. CH setpoint hysteresis 5 2 10 3

3. OTC
parameters

1. Outside temp for max CH -10 -34 10 -10

2. Outside temp for min CH 18 15 25 18

3. Outside temp for CH off OFF 7 30 OFF

4. OTC setpoint table OTC table

5. OTC curve OTC curve

4. CH pump set­tings

1. Post pump time

10 1 30 5

5. CH anticycling timer 3 0 15

6. CH request type RT+SP/
OT

onlyOTC|RT

0-10Vdc %

| SP

RT+SP/OT

32

Recom­mended

Min Max

After factory

reset

2. ADVAN­CED DHW
SETTINGS

1. DHW power 1. Maximum power 100 0 100 100

2. Minimum power 0 0 100 0

2. DHW
temperatures

1. Storage temperature setpoint 80 35 85 80

2. Boiler temperature setpoint 60 35 65 60

3. DHW setpoint hysteresis 6 2 10 3

3. DHW pump
settings

1. DHW post time
1 OFF 180 30

4. DHW priority 1. DHW priority status Enabled Enabled Disabled Enabled

2. DHW priority TimeOut Off 1 60 Off

5. DHW request type Switch Switch Sensor Switch

3. SYSTEM
SETTINGS

1. Boiler
parameters

1. Ignition power 25 0 100

Higher than 30 not allowed

2. Delay siphon check 3 0 20

Check syphon is not empties by new value

3. Number of boiler pumps

2 pump

Pump

3-w-valve

2 pump 2 pump

4. PWM pump speed max 100 1 100 100

5. PWM pump speed min 40 1 100 30

6. Antilegionella Enabled Disabled Enabled Disabled

7. Modbus parameters Adress Baudrate Frame

8. 3 Way valve travel time 180 1 255 10

2. User interface
settings

1. Select language

English

English|Italian|German|

Russian|Spanish

2. Select units Celsius Fahrenheit Celsius

3. Set date Set date

4. Set time 24 Hours 24 Hours 12 Hours

3. Service settings 1. Service information Set telephone number

2. Service due date Set service date

4. DIAGNOS­TICS

1. Boiler information Real time boiler status

2. Lockout history Overview lockout history Status boiler at time of lock/block

3. Manuel test See chimney sweeper

5. USER
SETTINGS

0 Heating 1. CH tempera-

ture/OTC set

1. CH set point
85 20

90/abs max

CH temp

75

2. Outside tempe-

rature for CH off

off 7 25 off

2. ECO setpoint reduction 50 0 50

3. Scheduler
set

1. Enable/disable

on board sche­duler

Enabled Disabled Enabled

2. Scheduler set Set time scheduler (Time/On/ECO/OFF)

2. Domestic hot
water

1. DHW setpoint (NTC sensor) 60 35 65

1. DHW setpoint (Thermostated) 80 35 85

2. ECO setpoint (NTC sensor) 20 0 50

3. Scheduler
set

1. Enable/disable

on board sche­duler

Enabled Disabled Enabled

2. Scheduler set Set time scheduler (Time/On/ECO/OFF)

3. Holiday 1. CH holiday setpoint
20 20

90/Abs max

CH temp

1 DHW holiday setpoint (Thermo­stated)

80 35 85

2. DHW holiday setpoint (Sensor) 60 10 65

EN

33

Recom­mended

Min Max

After factory

reset

6. CASCADE 1. Cascade set 1. Cascade switch delay 30 0 255

2. Cascade min power 20 0 100

3. Burner power (default value x =
17,21,25,29 boiler specic)

x 0 2550

4. Boiler for DHW 0 1 6 0

5. Pi loop period 5 0 15 5

6. Burner water ow delay 30 0 255 30

7. Different boiler size Disabled Disabled Enabled Disabled

8. Cascade pump speed mx. 100 15 100 100

9. Cascade pump speed min 40 15 100 30

2. Cascade info 1. Cascade role: see Cascade auto

detection

Standalone Standalone Master|Slave

2. System temperature

Actual temperature cascade system sensor

3. Number of boilers on

Actual number of burners/boilers on in

cascade

4. Modulation level

Actual cascade modulation level

3. Cascade auto detect: press OK to start detecting role

boiler in cascade chain

Standalone Standalone Master|Slave

7. RESTORE
FACTORY
SETTINGS

Reset to factory/check settings

34

6 INSTALLATION

6.1 Installing the boiler

The installation must be done in accordance with all local and national codes, regulations and standards,
and in accordance with the directives of all relevant authorities.

1. The boiler must only be installed in an area where it is allowed to install it. Make sure that this area is
protected against the danger of freezing.

2. The area should have sufcient ventilation and cooling to prevent overheating.

3. When delivered the boiler is on a pallet. Install the boiler on a at non-combustible oor and level it
by using its positioning bolts.

4. A minimum free space of 50 cm should be left on each side of the boiler for service access.

5. Remove the sealing/protection caps from the connection tubes. Warning : take care as residual water
from testing may drip

6. Fill the condensate trap with clean water. This can be done by ushing some water into the cast alu-

minium exhaust connection from the rear. This water will then drain into the syphon and ll it.

6.2 Frost protection

The boiler is protected against frost.

If the boiler detects an NTC ow temperature below 8 ºC, the CH-pump will be activated. If tempe­ratures continues to fall the boiler will start at a ow temperature of 6 ºC and it will run on minimum
load until the ow NTC senses a temperature of 15 °C. The CH-pump will stay running for another

10 minutes. This only protects the boiler and does not protect the installation, pipework or

radiators against freezing.

During longer periods of absence in the winter, the installation itself should be protected by activating
the heating periodically and by partly opening the radiator valves. Where a room thermostat is control-

ling the demand, do not set the room thermostat to a value below 15 °C.

To protect frost sensitive radiators against frost it is possible to connect a frost thermostat in parallel
with a Volt free room thermostat.
It is also possible to set the CH pump to activate automatically under OTC settings when an outdoor
sensor is present (this must be set by the installer). In this case,the CH pump will be activated if the out-

door temperature drops below 8 ºC.

EN

35

6.3 Water connection

6.3.1 Pump

The boiler does not have a built in CH-pump. Therefore a CH-pump must be mounted separately . Select
a pump that matches the hydraulic resistance of the boiler and the installation. The graph below shows
the resistance characteristics for the different boiler models.

For electrical connections see chapter 6.7.

6.3.2 Minimum ow

The minimum ows shown below must be guaranteed.

Input in kW Flow [m3/h] @ delta

T 25 full load

Flow [m3/h] @ delta

T 30 Start=25%

Flow [m3/h] @ delta

T 30 part load

850-11 29,2 9,7 4,9
680-11 23,4 9,7 4,9

1020-13 35,1 11,9 5,8

850-13 29,2 11,9 5,8

6.3.3 Water-treatment

Before lling up the installation (old and new), the installation should be rinsed

thoroughly with clean water from the tap.There are some rinsing/cleaning products
listed below and it is recommended that these are used.

36

• The water hardness of the heating system must be according the German VDI guideline 2035.
See table beneath.

Water hardness in heating systems according VDI 2035 guideliness

< 0,11 °dH means demine-

ralised °dH means German

hardness

installation < 20 ltr/kW installation between 20 and

50 ltr/kW

installation > 50 ltr/kW

50-300 kW total boiler capacity < 11,2 °dH < 8,4 °dH < 0,11 °dH

300-600 kW total boiler capa-

city

< 8,4 °dH < 0,11 °dH < 0,11 °dH

> 600 kW total boiler capacity < 0,11 °dH < 0,11 °dH < 0,11 °dH

This means for the Megaex boilers that the system should be lled with demineralised water (smallest
capacity > 600 kW). Before lling, rinse the complete installation with water from the tap.

Note that water softening by means of ion exchange principle is not allowed.
Check after lling with demineralised water that the pH is between 7 and 8,5. If not water must be trea­ted.

• The pH must be kept between 7 and 8,5 at all times

• The maximum allowed content of chlorides is 150 mg/ltr

• The conductivity of the non treated installation water must not exceed the value of 300 μs/cm in

combination with max O2 of 0,1 mg/ltr. If the O2 content is lower than 0,02 mg/ltr a higher conducti­vity limit of 600 μs/cm is allowed.

• If the conductivity is higher than the values mentioned, empty the system, ush and ll with clean tap

water, preferably by adding the recommended cleaning products. Especially in low tempereature hea-

ting systems normal degassing systems are insufcient. The use of an advanced system is required.

• Water pressure must be higher than 0,8 bar

• The water quality must be checked on a regular base (at least once every year)

• There are many products available on the market which pretend to clean and

• protect heating systems. Unfortunately there are only a few that have really

• proven this in practice.Therefore Mark Climate Technology only allows the following quality

• products for water treatment ;

Producer : Fernox, www.fernox.com

- Cleaner F3 : removes corrosion, lime and sludge

- Protector F1 : protects against corrosion, lime and sludge

- Alphi-11 : anti-freeze and protection against corrosion and lime

Producer : Sentinel www.sentinelprotects.com

- X100 : Inhibitor scale and corrosion protection

- X200 : Noise reducer long life system treatment to eliminate noise

- X300 : System cleaner for new hydronic heating systems

- X400 : System restorer non acid cleaning of older systems

- X500 : Inhibites antifreeze against scale and corrosion in all types of indirect heating systems at low

temperatures

Note that these products must be used strictly in accordance with the water treatment manufactu­rers instructions.

Furthermore we strongly recommend the following ;

• Use the above mentioned water treatment protection products to ll and protect the installation

• Use a log book to record water lling, relling, topping up, water quality measurements and water

treatment

• Only use diffusion tight material, especially for under oor heating

EN

37

• Always mount air vents at the highest points in the installation.

• Install isolation/check valves near the boiler and on strategic locations (anticipating any future expansi-

ons of the system) to avoid lls, rells and topping up as much as possible.

• Install a water meter to check the amount of lled, relled and topped up water.

• Install a lter (magnetite and dirt) in the return.

• Install an isolation heat-exchanger to separate the boiler from the installation to protect dirt or lime

in the secondary system from affecting the boiler.

• avoid leaks and if there is a leak, repair as soon as possible.

6.3.4 Water connection general

1. Water connections for ow and return are size DN125

2. The installation must have a pressure relief valve (with a capacity higher than the boiler output) and

an expansion vessel. The capacity of this vessel should be sufcient for the installation.

3. To avoid blocking and non volatile lock-out of the boiler control it is recommended to install a by-

pass in the installation to guarantee the minimum ow through the boiler. The by-pass valve should

be mounted as far away from the boiler as possible to have the biggest possible content of the by­pass-circuit (also a big radiator without valves could be used).

4. Drain the condensate via a tundish and an U-trap to the sewer.

5. At the highest point of the installation a de-airing device should be mounted.

6.4 Gas connection

1. The gas connection must be done in accordance with all local and national codes, regulations and
standards, and in accordance with the directives of all relevant authorities.

2. The gaspipe of the boiler has a R 2” connection.

3. In order to avoid blockage of the gas valve, ensure that there is no dirt in the gas pipework prior to
commissioning.

4. The maximum allowable inlet pressure for the gas valve is 50 mbar.

5. Check the heat input of the boiler.The load as given on the type plate should be checked.

6.5 Air-supply and ue-gas connection

Air connection : All types have air connection ø 200 mm Flue gas connection : ø 250 mm for all types

Allowed Appliance types:

Possibilities for air / ue system ; B23, C33, C63

6.5.1 B23

As standard the boiler is delivered as type B23 where the supply air is taken from the room where the
boiler has been installed in.

If the inlet air contains dust or dirt one should install a lter or a leaf catcher in the air supply.

A vertical terminal is recommended.

Roof terminals and extensions and/or condensate trap/collector must be obtained by M&G. See page 40.

For pressure drop calculation of appliance type B23 use the table for pressure drop per component and
the table for total pressure drop calculation. See page 39.

For total available pressure drop see table on page 38.

6.5.2 C33

Roof terminals and extensions and/or condensate trap/collector must be obtained from M&G. See page

39.

38

For pressure drop calculation of appliance type C33 use the table for pressure drop per component and

the table for total pressure drop calculation. See page 38.

For total available pressure drop see table on page 38.

Terminals should be installed in the same pressure area (within a plane of 1m²)

6.5.3 C63

C63 appliances may only be equipped with Gastec QA materials and terminals or according

NEN14989-2

Note: When using a C63 type ue conguration it is essential to ensure that C63 is allowed
in the country were the boiler is installed.

It is recommended to use a full aluminium ue system. A PP (Temperature class T120) or stainless steel
ue system can also be used (See TPW table below). In this case the condensate must be drained before
it ows back into the aluminium parts of the boiler. Otherwise aggressive condensate from the non-alu­minium ue system can corrode the aluminium parts of the boiler. A condensate trap/collector must be

mounted just before entering the silencer(s) of the boiler (also see 6.5.5.1 general).

T-P-W Class
Temperature range T120
Pressure range P1
Condensate resistance

(W=wet / D=Dry)

W

The minimal combustion products temperature, mass ow rate and CO2 are given in the table below.

Vol. Flue Vol. Air CO

2

T uegas rho

MegaFlex part load m³/h m³/h % °C kg/m³

850-11 170 220 191 9,1 30 1,12
1020-13 204 264 229 9,1 30 1,12

The maximum allowed recirculation rate under wind conditions is 10 %

Maximum allowable combustion air temperature 45 °C

The tables below give an indication of maximum lengths (in mtrs) for parallel air supply and ue outlet
pipes. The equivalent of pipe length in mtrs of bends 90° and 45° is given.

type max. allowed

pressure drop (*)

Parallel
Air/Fluegas

Ø200/ø250
850-11 500 Pa 42 m (**)
1020-13 500 Pa 25 m

(*) : Without roof terminal, bend(sump) and condensate trap

(**) : Maximum allowed draught is 120 Pa, this means that in case of vertical ue the maximum length is

limited to 30 mtrs

EN

39

Equivalent of pipe length in meters

Bend Parallel

Air/uegas

Ø200/ø250 mm

Bend 90° 5.8
Bend 45° 4.0

Warning : Do not install the terminals for supply of combustion air and for the exhaust of
combustion products on opposite walls of the building
Terminals should be installed in the same pressure area (within a plane of 1m²)

6.5.4 Pressure drop calculations

The rst 90 ° bend must be mounted directly to the boiler and followed by the chimney silencer (this

bend is not part of the calculation (as it is already taken into account).

Flue-outlet and air-supply calculations;

Total pressure drop available for ue-outlet and air-supply is given in the table below.

Air connection: All types have air connection ø 200 mm
Flue gas connectio : ø 250 mm for all types

Type Boiler Total available Pressure drop In

[Pa] for B23, C33, C63

850-11 500
1020-13 500

For pressure drop calculation of appliance types B23,C33 use the next two tables on the following pages.

Pressure drop table per component

1 2 3 4

Component 680-850 (11) 850-1020 (13)

Pressure drop
[Pa]

Flue gas [Pa] Air [Pa] Flue gas [Pa] Air [Pa]

Pipe length 1 m
Ø 250mm

2,6 3,8

Pipe length 1 m
Ø 200mm

6,2 8,9

Bend 90°

Ø 250mm

15,9 22,9

Bend 90°

Ø 200mm

35,4 50,9

Bend 45°

Ø 250mm

10,9 15,7

Bend 45°

Ø 200mm

23 33,2

Terminal C33
Ø250m­m,Ø250mm

128,9 185,6

Terminal B23
Ø250mm

38,0 54,6

Note : Maximum allowed draught is 120 Pa, this means that in case of vertical ue the maximum length is

limited to 30 mtrs

40

Table for total pressure drop calculation

1 2 3 4 5 6 7 8 9

Number Flue

gas

Ø250mm

Number Air

Ø200mm

delta

pressure

component

Fluegas

delta

pressure

component

Air

Total

pressure

drop Fluegas

out [Pa]

(2*4)

Total

pressure

drop Air in

[Pa] (3*5)

Total

Pressure

Terminal In

[Pa]

Total

pressure

drop
Fluegas +
air in [Pa]

(6 + 7 + 8)

1 Meter Pipe

Bend 90°

Bend 45°

Terminal:

Total delta pressure [Pa]

How to use the table:

- Column 1 : used material

- Column 2: total number of used material of column 1 for ue gas out

- Column 3: total number of used material of column 1 for air in

- Column 4: pressure drop from pressure drop table /component for ue gas components

- Column 5: pressure drop from pressure drop table /component for air components
Select the correct column for the selected boiler type

(850-11: 1,2 , 1020-13: 3,4)

- Column 6: total pressure drop ue gas: multiply column 2 *4

- Column 7: total pressure drop air: multiply column 3 *5

- Column 8: total pressure drop terminal

- Column 9: total pressure drop ue gas and air: column 6 + 7 + 8

- Finally add all together column 9

Total pressure drop must be lower than 500 Pa (Megaex 850-11) and (Megaex 1020-13).

If the combined inlet/outlet system exceeds the maximum allowed pressure, this will result in a decrease
of more than 5 % of heat capacity. This is not allowed.
All components must be obtained from M&G
A list of allowed articles of M&G with corresponding OEM nrs is given below and on the next page.

APPLIANCE TYPE FLUEGAS OUTLET SUPPLY AIR INLET

ROOF TERMINAL ALU 250 LEAF CATCHER ALU

ROOF TERMINAL ALU
250/250-250/350

EXPANDER

B23

C33

EN

41

Components OEM Art. no M&G

Roof terminals

ROOFTERM ALU 250 B23 40.045.26.65
ROOFTERM ALU 250/250-250/350 C33 41.007.65.59
EXPANDER AIR Ø200- Ø250 Pending
LEAF CATCHER (AIR INLET GRILL) Pending

Flue gas

ALUMINUM Ø 250 mm

ELBOW ALU 250 90° 40.045.16.86

ELBOW ALU 250 45° 40.045.16.88

EXTENSION ALU 250x1000 40.045.16.84
EXTENSION ALU 250x500 40.045.16.83

Combustion air

ALUMINUM Ø 200 mm

ELBOW ALU 200 90° 41.008.05.40

ELBOW ALU 200 45° 41.008.05.41

EXTENSION ALU 200x2000 41.008.05.33
EXTENSION ALU 200x1000 41.008.05.32
EXTENSION ALU 200x500 41.008.05.31

PP Ø 200 mm

ELBOW PP 200 90° EPDM 41.007.04.11
ELBOW PP 200 45° EPDM 41.007.04.12

EXTENSION PP 200x1900 41.007.04.04
EXTENSION PP 200x1000 41.007.04.02
EXTENSION PP 200x500 41.007.04.01

GENERAL

WALL BRACKET 250 40.045.22.35

WALL BRACKET 200 41.008.71.98

SEAL SIL 250 mm ( for DN250 ALU) 40.045.18.15
SEAL SIL 200 (ALU 200) 41.002.73.70
SEAL EPDM 200 (PP DN 200) 41.007.52.95

WEATHER SLATE FLAT ALU 368 0° (for

41.007.65.59)

41.007.65.71

WEATHER SLATE FLAT ALU 275 (for 40.045.26.65) 40.045.31.98

6.5.5 Installing ue-exhaust and air inlet

6.5.5.1 General

• Do not use materials from different manufacturers for either exhaust or air inlet

• Only the manufacturers of exhaust gas and air inlet components as mentioned in this manual may be
used

• Both systems (exhaust and air) should be mounted free of tension

Condensate, ice-free terminal, tundish and U-trap

The boilers can produce ue gasses with very low temperatures, which can lead to condensation in the
ue pipes and ue terminal. Therefore one should always mount an ice free terminal.

Drain the condensate via a tundish and a U-trap to the sewer.

42

Air inlet

If PP material is used for the air inlet a minimum distance of 35 mm between exhaust and air inlet should
be respected.
The minimum insert length of the sleeve, leaf catcher or pipe must be 40 mm.

Flue exhaust

A horizontal ue exhaust pipe must be installed with a fall of 3° (50 mm per mtr) downwards towards
the boiler to allow condensate to ow back in the sump or condensate collector.

The minimum insert length into the sleeve and the minimum length of the pipe end for aluminium and
stainless steel must be 40 mm.

If PP is used pay attention to the expansion (elongation) of the PP due to rise in ue gas temperature.

Insert the PP pipe into the sleeve and redraw over a length of 10 mm (10 mm for maximum pipe length
of 2 mtr).
After mounting the minimum insert length into the sleeve and the pipe end must be 40 mm.

Condensate trap/collector

The condensate trap/collector must be either connected by
a tube to a syphon that provides the same height of water column as the one supplied with the boiler or
by a T-piece to the syphon as supplied with the boiler
Note: The chimney pieces (silencers) that are delivered with the boiler need to be mounted correctly as

shown in the gure beneath.

Silencer mounted on a 13 section boiler (850-1020 kW)

EN

43

6.5.5.2 Brackets, mounting

Air inlet

• The rst bracket should be mounted 0.5 mtr away from the boiler

• Horizontal and non vertical pipes should be bracketed equally divided with a maximum distance of 1

mtr between the brackets

• Vertical pipes should be bracketed equally divided with a maximum distance of 2 mtrs between the

brackets

• In case of a chimney shaft, rst identify the air inlet. The end of the air inlet pipe should be at least 0.5

mtr above the shaft. The last component before entering the shaft should be xed. If a bend is the last
component also x the component before the bend.

Flue exhaust

• A bracket must be mounted to every component except in the case that the length of the pipe befo-

re and after the bend < 0.25 mtr. In this case mount the rst bracket at a length of max 0.5 mtr away

from the boiler

• Horizontal and non vertical pipes that have a distance between the xing brackets > 1 mtr should be

equipped with a non clamping (to allow minor movement) bracket in between

• Vertical pipes should be bracketed equally divided with a maximum distance of 2 mtrs between the

brackets

• In case of a chimney shaft, rst identify the ue outlet. Check if the used shaft pipes are damaged or

blocked.The ends of the exhaust pipe should be at least 0.5 mtr above the shaft. The last component

before entering the shaft should be xed. If a bend is the last component also x the component

before the bend.

All brackets must be obtained from M&G

6.5.5.3 Seals and joining

• Prevent incorrect or damaged seals by shortening pipes squarely and by deburring after shortening.

• Joins or connections in the exhaust ue may not be screwed.

• In the air inlet only aluminium or stainless steel joins or connections may be screwed. It is not allo-

wed to screw PP joins or connections.

• Do not use glue or foam like silicon or PUR.

• To assure soundness all components must be sealed.

• For smooth joining only use a soap solution (1% in water). Do not use oil, grease or (acid free) Vase-

line

Important notice

If instructions as written above are not followed and or the materials for air inlet and ue gas exhaust

as quoted above are not used Mark Climate Technology can not be held responsible for eventual conse­quences.

6.6 Electrical connection

1. The electrical installation should be in accordance with national and local codes and regulations.

2. As standard the boiler is congured for 400 VAC + 3N/50Hz

3. The terminal strip is accessible by opening the side cover (unscrew with screw driver) behind which

the control is mounted.

4. A means of disconnection must be incorporated in the xed wiring in accordance with the wiring ru-

les. Use the cable guide indicated with a 400 VAC +3N/50 Hz sticker on the backpanel of the boiler.
As it is a stationary appliance without means for disconnection from the supply a contact separation
in all poles that provide full disconnection under voltage category III must be provided. The minimum
cross section of the supply wire is 5 x 2.5 mm2 and must be connected to the circuit breaker 400V 4

44

pole 10 A (see gure beneath).The supply wire should be secured by a pull relief.

5. It is not permissible to alter the internal wiring as tted by the manufacturer.

6. The enable connected to numbers 1 and 2 of the strip C2 must be Volt free (also see warning un-

der 4.2.1). To set, select from the technician menu, advanced settings, CH request to Room Tstat.

The 0-10 V DC (Power or Setpoint mode) should be connected to the numbers 3 (=negative-) and
4 (=plus+) and a short wire loop should be placed between the numbers 1 and 2 of strip C2. To set,

from the technician menu, advanced CH settings, CH request select either 0-10V % (power mode) or
0-10 V SP (setpoint mode). Digital communication (open Therm OT+ version 3.0) should be connec­ted to the numbers 1 and 2 of the strip C2. Select from the technician menu, advanced CH settings,
CH request for Room Tstat. For digital communication with EBV like RS30 or Theta an additional
communication module is required. For the internal OTC (outdoor temperature controller) a 12

kohm at 25º C (see NTC table at 6.2.2) should be connected to the numbers 5 and 6 of strip C2 and

a short wire loop should be placed between the numbers 1 and 2 of strip C2. Finally from the techni­cian menu, advanced CH settings, CH request, select only OTC.

7. If a storage tank is connected to the boiler, the tank thermostat (or the tank NTC) should be con-

nected to the numbers 7 and 8 on the strip C2. Select from the technician menu, advanced DHW
settings, DHW request. Note that a tank NTC should be12 kohm at 25 ºC (see NTC table at 6.6.2.)

8. The CH system pump should be connected to the numbers 7 (=PE), 8 (=L), 9 (=N) on strip C1 if in

use in combination with a 3-way valve. (also see chapter 4.3). A PWM pump should be connected to

21 (=PE), and 22 (=N) on strip C1. If 230 VAC is applicable than 23,24 or 25 can be used for L.The

PWM signal should be connected to 14 (PWM signal) and 13 (PWM ground) om strip C2. From the
technician menu, system settings, boiler parameters the max and min pump speed can be set.

9. The DHW pump (or 230 VAC 3-way valve) should be connected to 10 (=PE), 11 (=L1), and 12 (=N)

on strip C1. If a CH pump is used it should be connected to 13 (=PE), 14 (=L1) and 15 (=N) on strip

C1.

10. If the system pump, CH pump, PWM pump, DHW pump, alarm connection or the 3-way valve consu-

mes more than 0,8 A, it needs to be switched by an auxiliary relay.

11. The alarm output on the numbers 19 and 20 on strip C1 is a potential free relay output (230 VAC),

max 0,8 A).

12. The cascade/system pump output on the numbers 29 and 30 on strip C1 is a potential free relay

output (230 VAC, 0,8A).

13. The B-B (Burner Block) on the numbers 31 and 32 on strip C1 provides an external (remote) burner

block (error 76). The external contact must be a potential free contact (rated at 230 VAC).

14. The SPS_B (Burner Block) on the numbers 11 and 12 on strip C2 also provides an external (remote)

burner block (error 77). In this case the external contact must be a potential free contact (24 VDC).

15. The B-L (Burner Lock) on the numbers 9 and 10 on strip C2 provides an external burner lock (error

3). The external contact must be a potential free contact (rated at 24 VDC).

16. The main-fuse is a circuit breaker as shown in the gure below 4 pole 10 A.

17. If the supply wire needs to be replaced, act as described under 4.

18. Connect current carrying conductors in such a way that they become taut before earthing conduc-

tor. See gure next page.

EN

45

General remarks :
Use the 5 tubes on the left side on the back to guide the high
voltage
The lowest of the 5 is for 400 VAC + 3N/50 Hz (supply)
The upper 4 are for 230 VAC or eventually 400 VAC + 3N/50Hz
Use the 2 tubes on left side on the back to guide the low voltage
connections from C2 and C3
Also see wiring diagram on next pages

6.6.1 Wiring diagram

BC Burner control
D Display

AUT Automate 380V with fuse

C1 Connector high voltage
C2 Connector low voltage
C3 Connector service

C4 Connector 380V

CH-P Central heating pump
DHW-P Domestic hot water pump
PWM-P Modulating pump

A-P Appliance pump max 0,8A

HE Heat exchanger
NTC1 Flow temperature sensor
NTC2 Return temperature sensor
NTC3 Domestic hot water sensor or switch
NTC4 Outside temperature sensor
NTC5 Flue gas temperature sensor
NTC6 Cascade sensor
MT Maximal thermostat (1-4)
WPS Waterpressure sensor
APS Air pressure switch
SPS Siphon pressure switch
GPS Gas pressure switch
GV Gas valve
S Swith on/off
3WV 3 way valve
OT-RT Open therm or room thermostat on/off

OTC Outdoor temperature control 12K

SPS-B Siphon pressure switch block
B-L Burner lock
A Alarm
C-P Cascade pump potential free contact
B-B Burner block
PE Earth cable or connector

N EMC netlter

46

EN

47

6.6.2 NTC resistance table

Temperature

[°C]

Resistance

[Ω]

12K

-30

-20 98.200

-15 75.900

-10 58.800

-5 45.900
0 36.100
5 28.600

10 22.800
15 18.300
20 14.700

25 12.000

30 9.800
35 8.050
40 6.650
45 5.520
50 4.610
55 3.860
60 3.250
65 2.750
70 2.340
75 1.940

80 1.710
85 1.470

90 1.260

95 1.100
100 950
105
110
115
120

48

6.7 Pneumatic connections

A pneumatic diagram for the Intermodul 850 kW (11 sections) and the Intermodul 1020 kW (13 secti­ons) is given in the gure below.

The siphon pressure switch, connected to the sump, prevents overow of the syphon in the case of ex­cess back pressure in the ue.

The air pressure switch, connected to the venturi, checks the amount of air (by means of a Δp measure-

ment) before startup.

6.8 PC-connection

For information regarding connection of a PC to the boiler please contact your supplier.

7 PUTTING INTO OPERATION

1. Fill and bleed the system. Fill the boiler until a pressure between 1.5 and 2 bar is achieved. The maxi­mum working pressure is 6 bar. The boiler (not the installation !) is automatically bled by a built in
automatic air vent.

2. Check all gas and water connections thoroughly for leaks.

3. Bleed the gas pipe.

4. As standard the boiler is set for G20 or G25 Check that the installation provides the correct type of
gas to the boiler.

5. Check the inlet pressure : 20 mbar or 25 mbar

6. Turn on the boiler by setting the main switch on the control panel of the boiler to position 1 (on).

7. Generate (create) a heat demand.

8. Just before ignition the control checks if the contacts of the gas pressure,syphon pressure and water
pressure switches are closed. If not, the boiler will block and the display will show E76.

9. If gas, water syphon pressure switches are closed the burner will be ignited.

10. Perform a thorough check on ue-gas joints for leakage.

11. Check the heat input and the gas pressure at maximum load.

12. Heat up the installation. Stop the heat request.

EN

49

13. Bleed the installation again, topping up the water system pressure if required.

14. Explain the operation of the boiler to the user.

15. Explain to the user the signicance of error codes and the need to report them when requesting
service engineer support.

16. After installation the datasheet as shown in chapter 9.1 should be lled in. This should be repeated at
every service-interval.

17. Safely store the installation and the user manual preferably in close proximity to the boiler.

7.1 Gas category

The types of gas and supply pressures vary by country.
In the table below the gas category and supply pressure are listed by country.

Countries Category Pressure

[mbar]

AT Austria 12H 20
BE Belgium 12E(R) 20/25
BG Bulgaria 12H 20
HR Croatia 12H 20
CY Cyprus 12H 20
CZ Czech Republic 12H 18
DE Germany 12E 20
DK Denmark 12H 20
EE Estonia 12H 20
ES Spain 12H 20
FI Finland 12H 20
FR France I2Esi , I2Er 20/25
GB United Kingdom 12H 20
GR Greece 12H 20
HU Hungary 12H 25
IE Ireland 12H 20
IT Italy 12H 20
LT Lithuania 12H 20
LU Luxembourg 12E 20
LV Latvia 12H 20
NL The Netherlands I2L , I2EK 25
PL Poland 12E 20
PT Portugal 12H 20
RO Romania I2E, I2H 20
SE Sweden 12H 20
SL Slovenia 12H 20
SK Slovakia 12H 20
NO Norway 12H 20
CH Switzerland 12H 20
LI Liechtenstein 12H 20
IS Iceland
MT Malta

50

As the responsible manufacturer of my products, I’m aware that the above mentioned countries have

adopted the Gas Appliance Directive 2009/142/EC in their national law. I understand that the CE mark
has meaning only in these countries, where the GAD is implemented in the national regulations. Although
other countries might value and respect the CE mark, it has no formal value.

This boiler can be adjusted for category K(I2K) and is in this case suitable for the use of G and G+ dis­tribution gasses according to the specications as shown in NTA 8837:2012 Annex D with Wobbe-index
43,46-45,3 MJ/m3 (dry, 0 °C, Hs) or 41,23 – 42,98 (dry, 15 °C, Hs)

This boiler can also be converted and re-adjusted for category E (I2E)
This means that the boiler is : either is suitable for G+ gas and H-gas or provable suitable is for G+ gas

and provable can be made suitable for H-gas as meant by “Besluit van 10 Mei 2016” until changes in this

document are made.

7.2 Adjustment % CO2 (O2 %) and check input

The boiler is equipped with an automatic gas/air regulator. This means that the amount of gas is regulated
depending on the amount of air. The % CO2 needs to be adjusted according to the table below;

Type of boiler Gas type inlet pressure %CO2 * on max load %CO2 * on min load
850-11 G20 / G25/G25.3 20 / 25 mbar 9,3 +0,2-0,05 9,1 +0,15-0,2
1020-13 G20 / G25/G25.3 20 / 25 mbar 9,3 +0,2-0,05 9,1 +0,15-0,2

*For O2 percentage see Chapter 2 Technical data

The boiler has a gas valve that is connected to a venturi. See gure below ;

Adjustment for max. load ;

• wait until the boiler is stable and measure % CO

2

• if required, correct CO2 with the throttle ; turning towards + gives a higher CO2 percentage (a ½ turn

(180°) causes a change of approximately 0,85 % CO2)

Adjustment for min. load ;

• wait until the boiler is stable

• if required, correct the CO2 with the off-set ; turning to-

wards + gives a higher CO2 percentage. Note : this offset ad-

justment is very sensitive : half a turn (180°) causes a change

of approximately 1 % CO2.

Check on heat input

In the table below the relationship between nominal maxi-

mum input and fan speed and gasow is given for

G20 as sample. The nominal fan speed can be ± 5%
due to adjustments in production. Write down your

initial settings (between 680 and 850 or between
850 and 1020 kW) for input in the table as shown

in 9.1

Nominal input 850 1020 [kW Hi]
Fan speed nominal 5800 6100 [rpm]

Gasow G20 90 108 [m3/h]

If the gas ow is too low it may be due to an obstruction
(dirt) in the air/ue system. Check and if necessary clean.
The gas ow must then be re-checked.

Throttle

Off-set

EN

51

8 ERRORS

8.1 General

If there is no data visible on the display, the circuit breaker must be checked on the panel that can be

accessed after removal of the rst side panel on the right. Main switch on the front panel should be

checked (as well as the position of the on/off switch) and should if required be replaced (after the cause

for break down has been determined and rectied).

WARNING! THIS CIRCUIT BREAKER IS PART OF THE HIGH VOLTAGE CIRCUIT. DIS­CONNECT THE BOILER FROM THE MAINS ELECTRICITY SUPPLY BEFORE REPLA­CING!

If there is still no data visible on the display, one has to check if there is 230 VAC present on the connec-

tions “L” and “N” of connector X00 in the MAXSYS.

Also see electrical wiring diagram.

If there is 230 VAC present (terminal connector C1: 25,22) , then the 230 V fuses F1 and F2 inside the
Maxsys should be renewed. Disconnect the boiler from the main supply and remove the connectors
from the Maxsys.
Notice : for this it is not necessary to unscrew the Maxsys from the mounting plate
Release the six security clips with a long thin screw driver. Then remove the protective cover of the
Maxsys. Replace the 230 V fuse(s) F1: T3.15 AL 250V and/or F2 T3.15 AL 250V inside the Maxsys.

A blown fuse in the Maxsys controller could be caused by a short-circuited pump. It is recommended to
also check the CH-pump and also the DHW pump in this case.

If the 230 V fuses are OK and the display is still blank, then the cable of the display to the Maxsys (X15)

should be checked. If this is also ok, the Maxsys should be renewed.

six security clips

52

F1: T3.15A 250 V
F2: T3.15A 250 V

If you are not sure that there is any heat demand, you can force the boiler to start as described in 5.5.

On heat demand, the boiler control will perform a zero-check of the air pressure switch before starting
the fan. Following this, the fan will start and wait for air pressure switch to close. As soon as APS has
closed, starting procedure will continue.

APS closes at ΔP > 40 Pa.

If there is a problem with APS, the display will show blower speed error.

The boiler control checks the status of the built-in pressure switches for water, gas and syphon just befo­re ignition ;

Water pressure should be > 1,4 bar (E47);
Gas pressure should be > 14 mbar (E76);
Syphon pressure should be < 15 mbar (E77)

EN

53

8.2 DHW errors

Boiler does not respond to DHW heat request

- Check the storage tank-NTC or thermostat and its wiring (also see electrical wiring diagram).

- Check if DHW is enabled using the control panel

Insufcient DHW ow

- Dirty lters in taps.

- Insufcient water pressure.

DHW temperature too low

- Tapping ow too high

- Temperature set point too low

- Leakage 3-way valve (towards CH-circuit), 3-way valve not fully in DHW position

- Faulty DHW pump

- DHW operation set to off

- Storage tank-NTC or thermostat and or wiring defect.

- Input too low due to too much resistance in air/ue system.

Boiler operates only for DHW

- Storage tank-NTC or thermostat defect and or its wiring.

- 3-way valve stuck (remains in direction towards storage tank)

8.3 CH-errors

CH circuit stays cold

- Incorrect connection to the mains electricity supply.

- Main switch on control panel is switched off (boiler off).

- Room thermostat defect, incorrect wiring, temperature set too low

- Outdoor sensor and/or its wiring defect.

- CH operation off

- 3-way valve defect (remains in direction towards storage tank)

8.4 Errors (hard and soft lockouts)

Errors are indicated by a text and an E-code on the bottom line on the display.

The error message can be displayed by pressing the ”information” button.

Following an error with a hard lockout, the boiler will not re again until a manual reset is performed (eg

max temp limit).

These errors can be found under column “hard lockout code” in the following table.

Following an error with a soft lockout the boiler will automatically resume normal operation after the

cause of block is solved (eg gas pressure too low). They can be found under column “soft lockout code”

in the following table.

The cause of error (hard or soft lockout) can be found with the help of the error-list below.
After the cause of error has been determined and the error has been resolved, the boiler can be put
back into operation again.

54

EN

55

9 ANNUAL SERVICE

Maintenance should only be done by a qualied installer or technician. the following main­tenance routine should be done annually (see also 9.1).

The appliance is not to be used by children or persons with reduced physical, sensory or
mental capabilities, or lack of experience and knowledge.
Children, even if being supervised, must not maintain or clean the appliance or play with

the appliance.

In the case of failure or malfunction of the appliance, do not attempt to repair it yourself.
Please contact your installer. Repairs must only be carried out by qualied technicians.
Failure to comply with these requirements can compromise the safety of the aplliance.

Put the boiler into operation on max. load (see section 5.5). Determine the heat input of the boiler.
Check % CO2 . Compare the heat input with that measured at installation. If the heat input is now con-

siderably lower then there is probably an obstruction in the air inlet or the ue-outlet or in the boiler

itself.

Switch off the boiler. First check the air-inlet and the exhaust ue-outlet.

Disconnect from the mains electricity supply. Remove the front cover, top cover and side cover.
Remove the syphon and clean it.

Remove the inspection cover* of the sump on the front side beneath the controls.
The inner part of the sump and the bottom part of the heat-exchanger should be inspected and, if neces­sary, be cleaned.
If the bottom part of the heat-exchanger is clogged, the inspection covers on the left-hand side of the

heat-exchanger should be removed*. Using a special tool (see gure below) makes it possible to clean

the heat-exchanger lids partially . In case of dirt in the sump it is also advisible to inspect the upper part
of the heat-exchanger as well. Remove the fan* together with the burner hood*, the gas valve* and the
gas pipe*. Now the burner* is visible and can be taken out and inspected. If necessary clean the cold side
with a vacuum cleaner (or carefully with compressed air) and a nylon brush (never use a steel brush).
Inspect the combustion chamber. In case of a dirty heat-exchanger it can be cleaned with water. Check
the burner seal* and replace if necessary.

Rell the condensate trap with clean water and reconnect it.

Check the electrode, especially the distance between the two pins (3,5± 0,5 mm).
Replace electrode if necessary.
Put everything back in its place. Check the CO2-content and correct if necessary.
Check the gas-parts for leakages.

Check the ue-gas parts for ue-gas leakages and condensate leakages.

*Note : be careful during inspection not to damage seals.
Any seals damaged by ageing or other causes should be replaced.

56

EN

57

9.1 Service-maintenance table

When commissioning the boiler, it is recommended to measure load, CO2 or O2, CO, T ow, T return,

ΔP air pressure switch and Psyphon pressure switch and write the values down in the table below.

Measure these values when the boiler is in equilibrium at maximum load (also see chapter 5.5).
During annual maintenance we advise to measure and write down these values also and compare them
to the previous values and analyse any changes.

Date gasow [m3/h]

or load [kW]

CO2 [%] CO [ppm] T

ow

[ºC] T

return

[ºC]

ΔP air

pressure switch

[mbar]

ΔP siphon

pressure

switch
[mbar]

At the factory the maximum load of the boiler was measured within 5% tolerance from the nominal
maximum load.

In the eld the load can decrease due to increased resistance in the boiler, the air inlet or the exhaust

outlet or due to malfunctioning of the fan or other causes.

At maximum load the installation should be designed for nominal ΔT of 15 K to 20 K.
When the ΔT is higher than 25 K, the boiler cannot continue at maximum load anymore and will start to
modulate because water ow through the boiler is insufcient.
T ow and T return can be read in “info mode” on the display (see 5.4 diagnostics)
Valves, malfunctioning pumps, dirt, corrosion products from the installation, dirty lters etc. can have
negative impact on water ow through the boiler.

Before ignition the boiler control checks ΔP aps during prepurge. During burner operation this check

will be carried out. If the value decreases over successive years, this could indicate a problem, e.g.
malfunctioning of the fan, dirty air inlet, dirty burner, dirty heat exchanger or dirty exhaust system.

Syphon pressure (P sps) should be lower than the maximum allowable ue resistance. If P sps is too high
(> 15 mbar), the boiler will be stopped.

In this case the exhaust system may be blocked.

MARK BV

BENEDEN VERLAAT 87-89

VEENDAM (NEDERLAND)
POSTBUS 13, 9640 AA VEENDAM

TELEFOON [phone]
FAX [phone]

[e-mail]
www.mark.nl

MARK EIRE BV

COOLEA, MACROOM

CO. CORK

P12 W660 (IRELAND)
PHONE [phone]

FAX [phone]

[e-mail]
www.markeire.com

MARK BELGIUM b.v.b.a.

ENERGIELAAN 12

2950 KAPELLEN

(BELGIË/BELGIQUE)
TELEFOON [phone]

FAX [phone]

[e-mail]
www.markbelgium.be

MARK DEUTSCHLAND GmbH

MAX-PLANCK-STRASSE 16

46446 EMMERICH AM RHEIN
(DEUTSCHLAND)

TELEFON [phone]
TELEFAX [phone]

[e-mail]
www.mark.de

MARK POLSKA Sp. z o.o

UL. KAWIA 4/16

42-200 CZE˛S T O C H O W A ( P O L S K A )
PHONE [phone]
FAX [phone]
[e-mail]
www.markpolska.pl

S.C. MARK ROMANIA S.R.L.

STR. KOS KAROLY NR. 1 A

540297 TARGU MURES
(ROMANIA)
TEL/FAX [phone]

of[e-mail]

www.markromania.ro

CERTIFICATION N°: 17.07.011
AIRSTREAM

CERTIFICATION N°: 17.07.011
AIRSTREAM

CERTIFICATION N°: 17.07.011
AIRSTREAM