Nu-Way MGN 2800N Instruction Manual

MGN 2800N
Gas Burner
Installation & Maintenance
Manual

MGN 2800N HP 1
Thank you for choosing a Nu-way burner. As you would expect from a Company who has a
pedigree of more than 75 years in the heating industry, our after sales service is second to none.
Your relationship with Nu-way does not stop with the purchase of a burner. We have a team of
highly experienced Service Engineers who travel throughout the UK and around the world, to
service and react swiftly to breakdowns. Preventative maintenance is clearly the most cost
effective way of ensuring that the burner is running at its most efficient, but also that business
critical activities are not interrupted with potentially costly breakdowns. A Nu-way Service
contract is a cost effective way of ensuring that the correct and most efficient output and
reliability from your Nu-way burner is maintained at all times.
Nu-way Spares Department carry more than four thousand spares, all of which are available from
stock at competitive prices. Nu-way has the largest range of commercial spares available to the
market. Our Spares sales team collectively have more than 170 years employment with Nu-way
and are therefore more than experienced in offering advice and practical backup by ensuring the
correct part is identified and despatched in a timely manner.
In addition to these departments we also offer a dedicated technical helpline which is manned
during office hours. (Please note this is a premium rate line)
The Nu-way promise is that your investment in a Nu-way burner is fully supported throughout the
life of the product.
Please call us to discuss how we can ensure you benefit from the many services we have to offer.
Burner Sales: 01905 791640
Service: 01905 791680
Spares: 01905 791650
Technical Helpline: To be advised
Note:
The burner performance and boiler suitability is based on testing methodology and combustion
chamber dimensions, as described in EN 303, EN 267 and EN 676 standards.
Nu-way cannot guarantee the performance of burners fitted to boilers that have combustion
chambers that do not conform to EN 303, and customers should refer to Nu-way for further
information.

MGN 2800N HP 2
CONTENTS
BURNER &COMPONENT IDENTIFICATION ..................................................................................................................4
FEATURES ....................................................................................................................................................................6
Burner Capacity ............................................................................................................................................................6
Air Regulation ...............................................................................................................................................................6
Controls.........................................................................................................................................................................6
Operation ......................................................................................................................................................................6
Fuel...............................................................................................................................................................................6
GENERAL......................................................................................................................................................................6
Flue And Chimney Requirements.................................................................................................................................6
Plant Room Ventilation .................................................................................................................................................6
Existing Appliances.......................................................................................................................................................7
Combustion Chamber Conditions.................................................................................................................................7
PACKAGING FOR TRANSIT..........................................................................................................................................7
Mode One: Comprising Two Units................................................................................................................................7
Mode Two: Comprising Three Units.............................................................................................................................7
Assembly.......................................................................................................................................................................7
SERVICES &SITE CONDITIONS...................................................................................................................................8
Gas Supply....................................................................................................................................................................8
Gas Boosters ................................................................................................................................................................8
INSTALLATION..............................................................................................................................................................8
General .........................................................................................................................................................................8
Fitting To The Appliance...............................................................................................................................................8
Electrical Power Supply................................................................................................................................................8
BURNER AIR CONTROLS.............................................................................................................................................9
Air Diffuser ....................................................................................................................................................................9
Air Pressure Switch.......................................................................................................................................................9
BURNER GAS CONTROLS ...........................................................................................................................................9
Gas Nozzle....................................................................................................................................................................9
High Gas Pressure Switch............................................................................................................................................9
Low Gas Pressure Switch.............................................................................................................................................9
Gas Valve Train ............................................................................................................................................................9
ELECTRICAL DATA TABLE ..........................................................................................................................................9
WIELAND PLUG &SOCKET CONNECTIONS..............................................................................................................10
Air/Gas Ratio Controller..............................................................................................................................................11
Valve Proving Systems...............................................................................................................................................11
Landis & Staefa LDU11 ..............................................................................................................................................11
CONTROLS .................................................................................................................................................................11
FLAME MONITOR........................................................................................................................................................11
BOOSTER WIRING DETAILS………………………………………………………………………………….. 11
GAS VALVE TRAIN -LANDIS &STAEFA SKP75 /SKP15......................................................................................12
LANDIS &STAEFA SKP75 VALVE ACTUATOR........................................................................................................13
AIR DAMPER MOTORS -H/L .....................................................................................................................................13
CONTROL BOX SEQUENCE AND TIMING CHART......................................................................................................14
AIR DAMPER MOTOR -MODULATING.......................................................................................................................14
MODULATING OPERATION.........................................................................................................................................15
Burner Control Panel. .................................................................................................................................................15
Manual Operation .......................................................................................................................................................15
Temperature detector. ................................................................................................................................................15
Pressure detector........................................................................................................................................................15
Gas controls................................................................................................................................................................15
SKP75 combustion chamber impulse connection. .....................................................................................................16
Installation of the combustion chamber impulse pipe.................................................................................................16
EMERGENCY INSTRUCTIONS.................................................................................................................................16
BURNER OPERATING SEQUENCE .............................................................................................................................16
Initial Burner Setting....................................................................................................................................................16
Air/Gas Ratio Controller..............................................................................................................................................16

MGN 2800N HP 3
Start Rate Gas Governor............................................................................................................................................16
BURNER PRE-COMMISSIONING .................................................................................................................................17
BURNER COMMISSIONING .........................................................................................................................................17
Check For Valve Closure (Burners Without Valve Proving System)..........................................................................17
Gas Supply Pressure..................................................................................................................................................18
ESTABLISHING MAIN FLAME.....................................................................................................................................18
General Notes.............................................................................................................................................................18
Landis & Staefa SKP75 ..............................................................................................................................................18
BURNER START GAS RATE.......................................................................................................................................19
Check Flame Signal....................................................................................................................................................19
Air Pressure Switch Setting ........................................................................................................................................19
High Gas Pressure Switch Setting..............................................................................................................................20
Low Gas Pressure Switch Setting ..............................................................................................................................20
FINAL CHECK .............................................................................................................................................................20
RWF40 MODULATING CONTROL..............................................................................................................................20
Basic display...............................................................................................................................................................20
To change the working set point.................................................................................................................................20
To enter a new parameter...........................................................................................................................................20
ROUTINE SAFETY CHECKS ............................................................................................................................................22
Combustion Air ...........................................................................................................................................................22
Flame Detector ...........................................................................................................................................................22
Valve Proving System.................................................................................................................................................22
ROUTINE MAINTENANCE ...........................................................................................................................................22
Combustion Air Fan....................................................................................................................................................22
Inner Assembly...........................................................................................................................................................22
Air Diffuser And Gas Nozzle.......................................................................................................................................22
Ignition Electrode........................................................................................................................................................22
FAULT FINDING ..........................................................................................................................................................23
Burner Motor Fails To Start.........................................................................................................................................23
Starting Flame Failure Without Ignition.......................................................................................................................23
Starting Flame Failure Without Flame........................................................................................................................23
Burner Fails To Establish Main Flame........................................................................................................................24
Burner Motor Only Runs Continuously.......................................................................................................................24
Replacement Of Air/Gas Ratio Controller...................................................................................................................24
Incorrect Rotation Of Burner Motor.............................................................................................................................24
Motor & Fan - Removal...............................................................................................................................................24
SERVICE &REPLACEMENT .......................................................................................................................................24
BURNER HEAD DETAILS............................................................................................................................................25
BURNER PERFORMANCE CURVES............................................................................................................................26
BURNER SERVICE RECORD ......................................................................................................................................28
IMPORTANT -SAFETY
It is essential that the following instructions and adjustments are carried out by qualified engineers that are
experienced in blown gas burner commissioning. In the U.K. it is a legal requirement that anyone working on
gas installation should be ‘Gas Safe Registered’.
The manufacturer cannot be held responsible for any consequential damage, loss or personal injury as a result
of failure to follow these instructions, or as a result of misuse. Your attention is drawn to the Emergency
Instructions on Page 16.
EUROPEAN BOILER EFFICIENCY DIRECTIVE (B.E.D.)
All burners and boiler bodies marketed separately should comply with EN676 (gas burners) and EN303
(Heating Boilers).
Burner adjustments must be made in accordance with boiler manufacturers’ instructions, and these must
include flue gas temperatures, average water temperature, and CO2or O2concentration.

MGN 2800N HP 4
BURNER & COMPONENT IDENTIFICATION
1
8
15 4
6
17
13
2
3
16
7

MGN 2800N HP 5
Item Description Item Description
1 Burner Fan Casing 10 Gas Control Valve & Regulator
2 Burner Hinged Extension 11 Gas Main Safety Valve
3 Burner Flame Tube 12 Valve Proving Pressure Switches
4 Combustion Fan Motor 13 Electrical Connection Box
5 Combustion Air Inlet 14 Valve Proving Control Box
6 Combustion Air Damper Motor 15 Pilot Gas Solenoid Valve
7 Burner Sequence Control 16 Burner Control Panel
8 High Gas Pressure Switch 17 Low Gas Pressure Switch
9 Gas Valve Body
14
11
12
10
9
5

MGN 2800N HP 6
FEATURES
Burner Capacity
MGN 2800N HP - 2121 kW – 2753 kW
Developed from field experiences in the UK and overseas markets, the MGN series sets new
standards in efficient and reliable operation, having been developed to current test authority
requirements in UK and overseas markets. It is delivered ready to install with pre-wired packaged
control system and simple plug in gas train arrangements.
Air Regulation
Air for combustion can be adjusted to give maximum efficiency. An air control device produces
smooth start conditions. A fully closing air control is fitted as standard.
Controls
Flame supervision is by UV cell, and automatic sequence control.
Operation
Two stage (high/low) and fully modulating operation.
Fuel
Natural Gas. Special requirements on request - i.e. Liquid Petroleum Gas / Town Gas.
GENERAL
The MGN 2800N HP burner is supplied for two stage (high/low) or fully modulating operation and for
use with a three phase electrical supply.
This manual is structured to enable the user to proceed from the delivery of the burner to its
commissioning and use.
The conditions to be fulfilled and the controls and adjustments to be used are dealt with in the
sequence that should be followed for the correct assembly installation and use. Pre-commissioning
and Commissioning are described and the location of necessary controls and adjustments to
undertake these runs are illustrated and supported by appropriate tabular matter and graphs.
Routine Maintenance, Fault Finding and Spare Parts Identification complete the manual; literature on
proprietary components is available on request.
Flue And Chimney Requirements
It is important that:
a) the flue pipe from the appliance and the joint between this flue and the chimney are sealed to
prevent leakage of combustion products.
b) the flue pipe from the appliance does not protrude into the chimney beyond the inside wall.
c) the top of the flue or chimney shall be higher than any roof within a radius of 10 metres.
d) checks are made to ensure that the chimney is suitable for gas fired appliances and that the
proposed installation complies with all Local Authority and other regulations covering such
installations.
e) if more than one appliance is connected to a common flue or chimney the cross-section of this
flue or chimney should be adequate for the total volume of combustion products from the
appliances.

MGN 2800N HP 7
Plant Room Ventilation
An adequate dust free supply of fresh air is required for the burner at both high and low level in accordance with the
appropriate standards.
Existing Appliances
In preparing the appliance to receive the burner a careful inspection should be made of its condition.
If in doubt as to its suitability for gas firing refer to the appliance manufacturer.
In preparing the appliance for gas firing it should be cleaned thoroughly removing all adhering tars,
scale and dirt.
Combustion Chamber Conditions
When the burner is fitted to an appliance designed to work under balanced or negative combustion
chamber conditions, the over-fire draught must not exceed 0.25 mbar.
Should the over-fire draught exceed this figure, then steps should be taken to reduce it to this level.
PACKAGING FOR TRANSIT
To safeguard against transit damage and for Export shipment, the burner may be despatched in
partly assembled form in one of two modes.
Mode One: Comprising Two Units
a) Burner Body, complete with Control Package, Hinged Extension and Flame Tube Assembly.
b) Gas train complete.
Mode Two: Comprising Three Units
a) Burner Body complete with Control Package.
b) Gas Train Complete.
c) Hinged Extension and Flame Tube Assembly.
Assembly
Mode One
Fit the gas valve train to the burner body using the gasket provided. Ensure that the gasket is fitted
correctly with all holes corresponding with those on the burner flange. Connect the combustion air
impulse pipe from SKP75 gas valve to left hand side of the hinged extension.
Mode Two
Fit the hinged extension and flame tube assembly to the burner body with the eight studs provided.
Ensure the gas inlet flange is at the bottom. Fit the gas valve train to the burner body, with the four
studs and using the gasket provided. Ensure that the gasket is fitted correctly with all holes
corresponding with those on the burner flange. Connect the combustion air impulse pipe from SKP75
gas valve to left hand side of the hinged extension.
Modes One & Two
Open the hinged extension and connect the Ignition cable to the electrode. Close hinged extension.
Connect the multi-pin plug from the gas valve train to the socket located on the rear of the control
package on the left of the burner body.

MGN 2800N HP 8
SERVICES &SITE CONDITIONS
Gas Supply
The gas supply pipework to the burner must be appropriate to local conditions and must be
constructed and installed in compliance with appropriate Codes and Standards. It shall be of
sufficient size to satisfy the pressure and volume flow requirements of the burner under all firing
conditions. Checks should be made to ensure that all meters and other components are
appropriately rated for the maximum gas flow rate anticipated.
It is essential that a 90° manual isolation valve is fitted upstream of the gas control train to allow the
burner to be isolated for maintenance. The size of this valve should not be less than that of the
burner control train in order to avoid any restriction in gas flow.
Gas Boosters
When a gas booster is used the gas pressure at the booster inlet must not fall below 10 mbar under
any conditions. A low gas pressure switch must be fitted on the upstream side of the booster to
prevent it starting if the supply pressure is insufficient. An additional pressure switch can be used to
monitor the pressure downstream of the booster to prevent the burner operating if the pressure is
insufficient.
The booster should be installed as near to the burner as possible. It should be positioned on a firm,
flat, horizontal surface using anti-vibration mountings. All connecting pipework should be well
supported and accurately positioned in order to avoid stressing the booster casing. The use of
flexible connectors, which reduce both pipework stresses and transmitted noise, is strongly
recommended. The gas supplier should be asked to recommend the size of pipework between the
meter and the booster to ensure that the required pressure and flow are available.
Installation
General
Check that the burner is appropriate for appliance rating. Detailed burner performance data is given
at the back of this handbook.
Fitting To The Appliance
If the burner is to be fitted to a new packaged unit, refer to the manufacturers recommendations.
If the burner is to be used with an existing appliance prepare the mounting flange as detailed in the
Burner And Components Identification section. Ensure the joint between appliance and burner is
effectively sealed with the gasket provided. The flame tube should be flush with the inner face of the
appliance combustion chamber except where extensions are specified by the appliance manufacturer
(i.e. reverse flame boilers).
Electrical Power Supply
Connect a three phase 50 Hz electrical supply to the burner observing all applicable IEE Regulations.
Refer to the connection diagrams on pages 10 or the wiring diagram contained in the instruction pack
attached to the burners. If supplied as a packaged appliance/burner unit refer to the manufacturers
instructions.
Connect the external auxiliary controls by reference to the appropriate connection/wiring diagram.

MGN 2800N HP 9
BURNER AIR CONTROLS
The air for combustion is controlled by an adjustable air flap located inside the air inlet on the right
hand side of the burner viewed from the rear. Its purpose is to regulate and control the volume of
combustion air flowing through the burner. Combustion air is controlled by a three position servo
motor. Positions for high and low flame air are adjustable. A fully closed position is incorporated for
when the appliance temperature/pressure is satisfied.
Air Diffuser
The air diffuser is fitted to the front end of the inner assembly and located within the flame tube.
Its function is to control the volume of combustion air and create a pressure drop over the burner
head to ensure good fuel/air mixing and flame stability.
Air Pressure Switch
The air pressure switch is located on the right side of the burner casing viewed from the rear. It is
required to prove adequate air flow throughout the burner operating cycle. Air flow failure at any
stage will result in burner lockout.
BURNER GAS CONTROLS
Gas Nozzle
The gas nozzle is fitted to the front end of the inner assembly and located in the flame tube. The
holes in the gas nozzle are designed to suit the output of the particular burner model and gas type
being used.
High Gas Pressure Switch
A high gas pressure switch is fitted and pre-wired to the gas train to ensure that if the gas pressure at
the burner head increases above the gas pressure at maximum continuous running, then the burner
will shut down to a safe condition, thus indicating a fault on the governing valve (air/gas ratio valve).
The switch is factory set to the maximum position.
Final adjustment of this switch is described in the Commissioning section on page 20.
Low Gas Pressure Switch
The low gas pressure switch is located on the inlet side of the gas valve block on the left of
the burner, viewed from the rear. It is required to monitor inlet gas pressure during the
burner operating cycle. Gas pressure failure will result in safe shutdown of the burner. Final
adjustment of this switch is described in the Commissioning section on page 20.
Gas Valve Train
The gas valve train system includes an air/gas ratio controller, safety shut-off valve, and gas
regulator in the start rate line. Three impulse pipes are connected to the air/gas ratio
controller. All are factory supplied. One pipe is connected to the burner hinged extension
and supplies combustion air pressure to the ratio controller. A second pipe is connected
downstream of the valve set and supplies gas pressure to the ratio controller. The third pipe
is vented to atmosphere. Valve adjustments are detailed in Valve Adjustment Diagram on
page 13.
ELECTRICAL DATA 3 Phase 400V 50Hz
Burner
Model Motor (kW / rpm) Start Current (A) Full Load Current (A) Main Fuse (A) Cable Size (mm2)
MGN 2800N HP 7.5 /2800 57 15.2 40 4.0

MGN 2800N HP 10
WIELAND PLUG & SOCKET CONNECTIONS
Control circuit connections using Wieland plugs and sockets.
High/Low burners = 7 & 4 pin sockets
Modulating burners = 7 & 6 pin sockets
Item Description
F2 Appliance Limit Instrument
H1 Burner Fault Signal
H2 Burner Operating Signal
H3 Burner High Flame Signal
N1 Appliance On/Off Instrument
N2 Appliance High/Low Instrument
P1 Burner Operating Hours Run Counter
P2 Burner High Flame Hours Run Counter
S1 Supply On/Off Switch
123
B4 S3 T2 T1 NL1 T8 T7 T6 B5
3 PHASE FUSED &
ISOLATED SUPPLY
1 PHASE FUSED &
I
SO
LATED
SU
PPLY
P1 H2 H1 F2
N1
L1 L2 L3
NL
hh
H3 P2
N
N2
7 PIN WIELAND SOCKET
(BROWN/BLACK)
4 PIN WIELAND
SOCKET (GREEN)
4 PIN HIGH/LOW BURNER
CONNECTIONS
S1
T
TT
10 14
LIVE SUPPLY TO BOOSTER
6
PI
N
WIEL
AN
D
SOC
KET
(BROWN/BLACK)
B M
PT 100 HOT WATER - TEMPERATURE
S3 T2 T1 NL1
6 PIN WIELAND SOCKET
(BROWN/BLACK)
QAE22 HOT WATER - TEMPERATURE
S3 T2 T1 NL1
QBE 2002 STEAM - PRESSURE
S3 T2 T1 NL1
GL M U1

MGN 2800N HP 11
Air/Gas Ratio Controller
The air/gas ratio controller varies the gas pressure in response to changes in combustion air pressure
to ensure that the air/gas ratio remains constant over the operating range of the burner. A separate
gas pressure governor is not necessary. Three impulse pipes (all factory supplied) are connected to
the air/gas ratio controller. The first is connected to the burner body and supplies air pressure to the
ratio controller. Note that in installations with negative air pressure in the combustion chamber, this
pipe must always be under positive pressure. A second pipe connected to the gas line downstream of
the valve set provides gas pressure to the ratio controller whilst the third pipe is vented to
atmosphere.
Valve Proving Systems
A valve proving system, as shown schematically below, is standard on all burners with outputs
greater than 1200 kW (nett) or 1325 kW (gross).
Landis & Staefa LDU11
When the burner operating sequence is initiated, the burner control box energises the proving
system, which then carries out the following checks.
a) Valves V1, V2 and V3 are initially closed. The proving system then opens V3 (in the start gas line)
and then closes it after 2 seconds.
b) V1, V2 and V3 remain closed for 23 seconds while the minimum side of the gas pressure switch
(PS) checks for an increase in pressure. If no increase occurs there is no leakage past V1 and
the sequence continues.
c) V1 is opened for 2 seconds and then closed. V1, V2 and V3 again remain closed for 23 seconds
while the maximum side of the gas pressure switch checks for a decrease in pressure. If no
decrease occurs there is no leakage past V2 or V3 and the burner operating sequence will
continue.
CONTROLS
The control package is fitted on the left hand side of the burner viewed from the rear. It includes a
sequence control box of the cyclic type, ignition transformer and all necessary contactors, terminal
strip, motor starter, On/Off switch and two neon lights. The amber light indicates “BURNER ON” and
the red light is illuminated when the burner stops as a result of “EXCESS TEMPERATURE” in the
appliance.
FLAME MONITOR
An ultraviolet cell is fitted as standard.
BOOSTER WIRING DETAILS
Link terminals 4 to 7
Live wire from burner to terminal 13 on the burner
terminal block
BOOSTER WIRING: This applies to a Nu-way single booster wired to drawing numbers
WA4-6278 or WA4-6770 only. For further details please refer to Nu-way.
1 2 3 4 5 6 7 8 9 10
Booster terminals

MGN 2800N HP 12
GAS VALVE TRAIN – LANDIS & STAEFA SKP75 / SKP15
Item Description
1 Main Safety Valve (SKP15)
2 Combined Valve & Regulator (SKP75)
3 Pilot Solenoid Valve
4 Pilot Gas Governor
5 High Gas Pressure Switch
6 Burner Connection Flange
7 Low Gas Pressure Switch
8 Gas Sensing Probe
1
8
7
6
5
4
3
2

MGN 2800N HP 13
LANDIS & STAEFA SKP75 VALVE ACTUATOR
2
3
4
5
6
1
Adjustment Description
1 Adjustment and indication of the gas/air ratio (main
Flame setting)
2
Adjustment and indication
of the parallel
displacement of the
characteristic (Low Flame
setting)
3 Vented to atmosphere
4 Connection to the gas line
5 Connection to the combustion air supply at
the burner head
6 Valve stroke indicator
Valve Adjustment Diagram
(air/gas ratio valve and regulator)
FRONT VIEW REAR VIEW
AIR DAMPER MOTORS – H/L
987654321N
Ber
g
er Lahr STM 30 B2
Berger Lahr
STM 30 Q5
Note:
The fully closed cam is factory set, and under normal
circumstances should not require further adjustment.
Operation of the low and high flame air switches is made by
manually adjustable cams. A setting scale is provided at the
end of the cam stack for guidance, while adjustments are
made using the screw adjusters situated within the cam disk
body (STM30 Q5), or with levers and fine setting screw
adjusters (STM30 B2).
Motor STM30 B2 STM30 Q5
Air Damper
Position Cam Factory Setting Cam Factory Setting
Full Air
Shut-off II 0° 1 0°
Low Flame
Air V 15° 2 15°
High Flame
Air I 60° 3 60°

MGN 2800N HP 14
AIR DAMPER MOTOR - MODULATING
CONTROL BOX SEQUENCE & TIMING CHART
B
A
Start Run Off
Rea
d
y
For
Restart
Burner Motor
Ignition
Start Rate
Gas Valve
Main Gas Valve
(low flame on h/l)
High Flame
(h/l only)
Operation
T1 T2
T8
T3
T4
T5 T6
T7
T9
Ttotal
Landis & Staefa SQM10
Motor SQM 10
Air Damper
Position Cam Factory Setting
Full Air
Shut-off 2 0°
Low Flame
Air 3 20°
High Flame
Air 1 60°
The fully closed cam (2) is factory set and under normal circumstances should not require further adjustment.
Operation of the low and high flame air switches (cam 3 & 1) is made by manually adjustable cams. Setting
scales provided between the cams simplifies the adjustment. An additional scale at the end of the cam stack
serves as a position indicator.
The air damper assembly can be rotated manually by disconnecting from the drive motor using the lever ‘A’.
The cams should be adjusted by using the special C spanner ‘B’.
Timing
Segment TMG 740-3 LFL1.3 Operating Mode Timing
Segment TMG 740-3 LFL1.3 Operating Mode
T1 40 40 Pre-purge T6 6 12
Delay – Release to High
Flame / Modulation
T2 4 6 Pre-ignition T7 10 18 Post-purge
T3 3 3 Safety Lockout Time T8 8 12 Air Proving Switch Interlock
T4 Delay – Start Rate to Main Flame T9 80 91 Total Start Time
T5 9 12 Delay – Start Rate to Main flame T Total 90 106 Total Cycle Time of Controller
Note:
The pre-purge tomes shown above refers to the control box only. The air damper control will extend the total burner
purge time up to a maximum of 127 seconds depending on the firing rate and air requirements of the appliance.

MGN 2800N HP 15
MODULATINGOPERATION
Nu-way MGN modulating burners are similar in construction and operation to the two stage, high/low
versions, utilising identical fan blower, combustion head and gas train components.
The standard method of operation is based on the Landis & Staefa RWF40 Universal Controller,
which provides temperature or pressure control of modulating burners, with continuously adjustable
fuel throughput.
The control output of the RWF40 is a potential free, 3-position switch, which is used to control the air
damper motor.
When the boiler control calls for heat, the modulating servomotor will travel to the ‘high flame’ position
and interlock the control circuit. An air pre-purge will take place at this position for a pre-determined
period, at the end of which the burner sequence controller will stop until the modulating servo has
travelled to the ‘low flame’ position and interlocked the control circuit again. The sequence control
will now recommence its operational cycle and the burner will light and remain at low flame until the
high flame release signal is given by the sequence control. The modulating servo will now move to
high flame and remain at this position until the desired boiler temperature/pressure is attained. From
this stage the modulating unit will commence to move towards the low flame position, but, depending
on the temperature/pressure, will stop in any intermediate position between low and high flame.
Burner Control Panel
The control panel is fitted to the rear left hand side of the burner fan casing. The panel is of the fully
enclosed type containing the fan motor starter, relays, burner sequence control, RWF40 modulating
controller. Access to the panel is gained by loosening the two crosshead screws on the right hand
edge of the panel door. The door may then be swung open to the left and removed from its hinge
pins if required.
Manual Operation
Check that the RWF 40 controller is configured correctly refer to page 20). Press and hold ‘EXIT’ key
until the ‘manual operation’ indicator illuminates. The modulating motor can now be inched using the
‘increase and reduce’ buttons on the controller face. Press and hold the ‘EXIT’ key until the ‘manual
operation’ indicator extinguishes to return to automatic mode.
Temperature Detector
The immersion temperature detector type QAE22 is used on all Hot Water boiler applications. The
detector has a plastic casing to IP42 with a snap-on cover and an immersion stem. The connection
terminals can be accessed by removing the cover.
Cable entry is made via a cable entry gland, page 10. In all applications an immersion pocket with a
flat seal is supplied.
The detector should be installed in an elbow such that the pocket points against the direction of flow.
With all detector versions, the immersion length must be a minimum of 60mm.
Pressure Detector
The pressure sensor type QBE 2002 is used in all steam boiler applications. The sensor has a
casing to IP65 and a 1.5 metre long, 3-core connecting cable. The mounting instructions supplied
with the sensor are to be strictly adhered to.
Gas Controls
The gas train is of the same type and design as fitted to 2-stage high/low models.

MGN 2800N HP 16
SKP75 Combustion Chamber Impulse Connection
The impulse connection to the combustion chamber is not required in the majority of applications and
is therefore not supplied as part of the burner package. This is because the resistance of the
combustion chamber / flue assembly is assumed to remain constant and that the pressure within this
chamber will change in proportion to the burner gas and combustion air pressure. (As the burner
output changes).
If however, the pressure in the combustion chamber does not change in proportion to the burner gas
or air pressure, i.e. the plant is fitted with a flue gas fan, continuously operating flue gas damper, or
the chamber pressure changes from negative to positive whilst moving from Low to High flame, then
a compensating circuit is required. This means that the pressure in the combustion chamber must be
connected to the SKP75 so that the controller can automatically offset the pressure changes.
This compensating circuit should also be used if pressure shocks and vibrations, which adversely
affect the burner start-up, develop in the combustion chamber during the start-up phase.
Naturally, it must always be taken into consideration that the burner output decreases as the pressure
in the combustion chamber increases, and visa-versa.
Installation of the Combustion Chamber Impulse Pipe
A minimum inside pipe diameter of 8mm is recommended. The impulse pipe should be as short as
possible so as to allow the controller to respond quickly to sudden burner output changes. It must be
installed such that the gases will cool down in the area of the impulse pipe and condensing gases will
not enter the controller but run back into the combustion chamber. If necessary, a water separator
must be provided.
EMERGENCY INSTRUCTIONS
This product has been designed and constructed to meet all of the essential requirements of the GAS
APPLIANCE DIRECTIVE 90/396/EEC, and under normal circumstances should not give occasion to
any hazardous conditions. If such a condition should occur during commissioning or subsequent use
of this product, be it a fault of the burner, the appliance or of any instrument, machine or service in
the proximity of the burner, then the GAS and ELECTRICITY supply to the burner should be
IMMEDIATELY ISOLATED until such time that the fault has been investigated and rectified.
BURNER OPERATING SEQUENCE
The operating sequence begins with an air pre-purge on full air, followed by start rate gas flame
which, when proved, allows the burner to operate on the High/Low/Off or Modulating principle. The
sequence is determined by the demand of the appliance control instruments.
Initial Burner Setting
Remove the cover from the air damper motor on the end of the air inlet casing. Check the cam
positions and adjust if necessary (refer to settings on pages 13 & 14.
Air/Gas Ratio Controller
Remove the small plate on top of the regulator and keep it in a safe place, Set the air/gas ratio at 0.8
on the visual scale by adjusting the screw (1) anticlockwise to increase, or clockwise to decrease.
Set the air/gas ratio on the visual scale, adjusting screw 92) to half a division on the ‘+’ side of ‘0’.
turn the adjusting screw clockwise to decrease, or anticlockwise to increase.
Start Rate Gas Governor
Remove the metal cap from the top and turn the adjusting screw until it is approximately halfway
between the maximum and minimum setting, clockwise to increase, and anticlockwise to decrease.
Never adjust to its maximum limit.

MGN 2800N HP 17
BURNER PRE-COMMISSIONING
Check both gas and electricity supplies to the burner are turned off. Remove the cover and fit a link between
terminals 2 & 3 of the low gas pressure switch. Remove the control panel cover and remove the low flame hold
link (two stage burners). Set the air pressure switch to minimum. Replace the control panel cover.
Momentarily switch on the burner and check the motor rotation, which should be anticlockwise, viewed from the
motor end.
If the direction of rotation is incorrect, please refer to Fault Finding to correct it. Switch on the burner.
Depending on the type of the control box, the burner will go through its operating sequence.
a. Immediately if it has previously been working but switch off during a normal operating cycle.
b. On pressing the reset button on the control box.
The burner motor will run. If at this stage the burner goes to lockout, please refer to the Fault Finding section
on page 23.
Check that the ignition spark is present. For actual timings refer to the Sequence Diagram and Timing Chart on
page 14.
If at this stage there is no ignition spark and the burner goes to lockout, the air pressure switch may require
adjustment. Following the safety lockout time (T3) the ignition spark should cease and the burner go to lockout.
Switch off the electrical supply to the burner.
Remove the control panel cover and refit the Low Flame Hold Link. Replace the control panel cover.
Remove the temporary link between terminals 2 & 3 of the low gas pressure switch and refit and secure the
cover.
Safety system proved. Burner commissioning can proceed. Switch off the power to the burner.
BURNER COMMISSIONING
Check that the appliance is in a proper and safe state to be fired (for instance, is there water in the
boiler?).
Set the appliance controls to call for heat.
Check for Valve Closure (Burners Without Valve Proving System)
All gas train assemblies are fully tested for function and valve security before despatch.
A soundness test of the gas valve is difficult without specialised pressure testing equipment.
However, the following check can be performed to measure the security of the valve system.
Ensure that the gas supply pipework to the burner gas line is sound and that gas is available at
the required inlet pressure for the burner. Fit a manometer to the test point at the inlet to the
upstream main safety valve. Open the main upstream manual valve for a few seconds and then
close and secure the gas supply.
The space between the upstream manual valve and the gas train inlet should now be filled with
gas at inlet pressure. If the pressure remains stable over one minute then this indicates that the
valve train is secure, but not necessarily in the main valve. If the pressure decreases then this
indicates that the main and one other valve is leaking or that there is a leak between the upstream
manual valve and the main gas valve.
Secure the upstream test point and fit the manometer to the test point situated between the main
and control valves.
Check the reading on the manometer, this should now show near atmospheric pressure. Open
the upstream manual valve and look for an increase in pressure over one minute. If no rise is
detected, this indicates that the main valve is closing correctly.
The next stage of the procedure requires the burner to be momentarily started. Open the
upstream manual valve and switch the burner on. The burner will attempt to start and will either
establish a flame (in which case switch the burner off immediately) or “lockout”. Isolate the
electricity supply.
The space between the main and control valves should now be filled with gas at near inlet
pressure. If the pressure remains stable over a period of one minute, this indicates that the valve
system is secure.
If the pressure decreases, this indicates that there is a leak in the valve system and the valve train
assembly should be returned to the factory for a full examination. Remove the manometer and
close the test point.

MGN 2800N HP 18
Gas Supply Pressure
The main gas safety valve is capable of withstanding gas inlet pressures up to 200 mbar. For MGN
2800N
HP burners it is essential that the inlet gas pressure shall not be less than 45 mbar and not be more
than 100 mbar in order to maintain good control characteristics of the air/gas ratio controller. Before
proceeding with commissioning:
a. Fit a manometer or other approved pressure measuring instrument to the pressure test point on
the upstream side of the first safety shut-off valve.
b. Open the manual gas isolation valve at the inlet to the gas train.
c. Check that the gas pressure is adequate.
ESTABLISHING MAIN FLAME
General Notes
In the following sections, reference is made to checking gas flow rates at the gas meter. This is the
most accurate method of determining throughputs and should always be used whenever possible.
Information regarding the burner head gas pressures is included in the appendix at the back of this
manual. These may be used as a guide to initial burner settings, but should not be relied upon to
offer proof of actual throughputs.
IMPORTANT - after each adjustment, gas flow rate and flue gas analysis should be checked.
ALWAYS - use approved test equipment.
NEVER - rely on a visual inspection of the flame as a guide to combustion quality.
Landis & Staefa SKP75
Refer to the Valve Adjustment Diagram on page 12. Set up the air damper for initial firings as
follows.
Low Flame air 15°; High Flame air 60°. Close the upstream manual valve until it reaches an opening
of approximately 20%.
Set the gas inlet pressure switch to minimum. Remove the low flame check link. Switch the burner
on and allow it to establish low flame. Gradually open the upstream manual valve to the fully open
position keeping a watchful eye on the CO level.
If the CO content is excessive, adjust the low fire adjustment screw (2) on the SKP75 valve to
achieve acceptable figures. In extreme cases it is possible to run out of adjustment on the low fire
screw without achieving the desired results. If this happens adjust the High Fire setting screw (1) to
bring the CO content down to an acceptable level.
Switch the burner off and refit the low flame link. Restart the burner. Low flame will be established,
expanding to main flame after the expiry of period T6 on the control box timing chart.
It is important to monitor the flame visually during the change from low to high. If the flame becomes
more compact, this indicates an excess of combustion air. If the flame becomes large and
shapeless, this indicates an excess of fuel. Both conditions are acceptable at this stage providing
that the burner remains stable and immediate actions are taken to correct the situation. If in doubt
SWITCH OFF the burner and adjust the High Flame screw (1) on the SKP75 in the appropriate
direction.
With the burner stable on high flame, adjust the High Flame screw (1) to bring the CO2to an
acceptable level. It is possible at this stage that the burner may be overfiring the appliance with a
resultant excess of CO.
With the burner firing at low flame, adjust the Low Flame screw (2) on the SKP75 valve to bring the
CO2content within an acceptable range.
Adjustment of the Low Flame setting will have marginal effect on High Flame. To achieve optimal
results repeat the above procedures on High and Low flame several times until acceptable figures are
obtained without any further adjustment.
It should not be necessary to make any further adjustments to the gas valve.

MGN 2800N HP 19
With the burner now running on high flame, the gas throughputs should be checked at the gas meter.
Ensure that any other appliances served by the meter are isolated during the checks. The gas rate
can be altered by adjusting the air damper opening in the appropriate direction. Similarly the low
flame throughput can be adjusted by altering the low flame position of the air damper. Care should
be taken so as not to exceed the limits of the burner performance envelope as shown on page 26.
With the gas flow rate set for both Low & High flame a final check should be made on the flue gases.
For reasons of safety, the CO (carbon monoxide) level should be checked and should not exceed a
maximum of 93 ppm (dry air free).
BURNER START GAS RATE
Switch off the electrical supply to the burner, close the main manual gas valve, remove the control
panel cover, disconnect the pilot check link, and replace the control panel cover.
Switch on the electrical supply to the burner and allow the burner to establish start rate flame.
The start gas rate can now be adjusted by turning the adjusting screw in the start gas pressure
governor clockwise to increase and anticlockwise to decrease. A start rate of approximately 30% and
not more than a maximum of 33% of main flame is required.
Too small a start gas rate results in burner lockout on changeover during the initial and final running.
Never exceed the stated percentage start gas rate.
Switch off the electrical supply, remove the control panel cover. Open the main manual gas valve.
Switch on the electrical supply to the burner.
Check Flame Signal
Switch off the burner. Remove the control panel cover and disconnect the flame signal check link.
Connect a DC microammeter
Refer only to the wiring diagram appropriate to the control fitted on the burner
Switch on the burner and observe on the microammeter the flame response signal. A steady reading
in excess of 75µA indicates the burner is in a reliable run situation.
If the current recorded is too low, it may be due to some maladjustment of the flame and intermittent
lockout may occur. Check and reset if necessary. Refer to the Fault Finding section. Switch off the
burner and disconnect the microammeter. Refit the link and control panel cover.
Air Pressure Switch Setting
Switch off the electrical supply to the burner.
Remove the air pressure switch cover. Fit a manometer to the pressure switch to check the actual air
pressure against the pressure switch dial setting.
Remove the control panel cover and disconnect the low flame hold link to hold the burner in the low
flame position.
Switch on the electrical supply and allow the burners to establish the main flame.
Slowly turn the adjusting dial clockwise until the flame is extinguished. The burner will go to lockout.
Turn the dial one division anticlockwise and reset burner lockout. The burner will then continue
through its cycle until either the start rate flame is established or the burner goes to its lockout
position. If the burner goes to lockout repeat the procedure once per burner cycle until the start rate
flame is established. Allow the burner to cycle to low flame and then turn the adjusting dial a further
two divisions anticlockwise.
Switch off the electrical supply to the burner, reconnect the low flame hold link, replace the control
panel cover and also the air pressure switch cover, and remove the manometer.