Nu-Way MDFL 2800 - 38 Instruction Manual

Installation & Maintenance Manual
MDFL 2800 –38
MDFL 2800 –41
Dual Fuel Burner
Tel:[phone] Fax: [phone] Email: [email protected] Web: www.nu-way.co.uk

CONTENTS
BURNER & COMPONENT INDENTIFICATION FOR MDFL 3300 & 4000 ………………………………… 3
INTRODUCTION …………………………………………………………………………………………………... 7
FEATURES ………………………………………………………………………………………………………… 7
Burner Capacity ……………………………………………………………………………. 7
Fuel ……………………………………………………………………………. 7
Air Fan Size ……………………………………………………………………………. 7
Controls and Safety Systems ……………………………………………………………………………. 7
Operating Mode ……………………………………………………………………………. 7
SITE CONDITIONS AND SERVICES ……………………………………………………………………………. 8
Flue and Chimney Requirements ……………………………………………………………………………. 8
Plant Room Ventilation ……………………………………………………………………………. 8
Combustion Chamber Conditions ……………………………………………………………………………. 8
Gas Supply ……………………………………………………………………………. 8
Gas Boosters ……………………………………………………………………………. 8
Electrical Power Supply ……………………………………………………………………………. 9
Oil Supply ……………………………………………………………………………. 9
Pumped Oil Ring Main ……………………………………………………………………………. 10
UNPACKING AND ASSEMBLY………………………………………………………………………………….. 11
INSTALLATION ……………………………………………………………………………………………………. 11
BURNER CONTROL AND OPERATION ……………………………………………………………………….. 12
Air Controls ……………………………………………………………………………. 12
Gas Controls ……………………………………………………………………………. 12
Air Damper Motor ……………………………………………………………………………. 13
Gas train ……………………………………………………………………………. 15
Oil Controls – Single Spill-Back Nozzle ……………………………………………………………………….. 19
Control Panel ……………………………………………………………………………. 24
Burner Controller ……………………………………………………………………………. 25
BURNER OPERATING SEQUENCE ……………………………………………………………………………. 26
MODULATING CONTROLS ……………………………………………………………………………………… 27
Controller ……………………………………………………………………………. 27
Commissioning Controls ……………………………………………………………………………. 27
Temperature Detector ……………………………………………………………………………. 27
Pressure Detector ……………………………………………………………………………. 27
General ……………………………………………………………………………. 27
COMMISSIONING : GENERAL ………………………………………………………………………………….. 28
Safety and Emergency Notes ……………………………………………………………………………. 28
Inspection ……………………………………………………………………………. 28
Initial Settings ……………………………………………………………………………. 29
COMMISSIONING : OIL …………………………………………………………………………………………… 30
Burner Dry Run …………………………………………………………………………………………………… 30
Burner Live Run …………………………………………………………………………………………………… 31
COMMISSIONING : GAS ........................................................................................................................... 36
Burner Dry Run …………………………………………………………………………………………………… 36
Burner Live Run …………………………………………………………………………………………………… 37
FINAL COMMISSIONING STAGES – OIL and GAS ………………………………………………………..... 40
Checking the Flame Signal ……………………………………………………………………….. 40
Setting the Air Pressure Switch ……………………………………………………………………….. 40
Modulating Control : Siemens RWF 40 ……………………………………………………………………….. 41
Final Checks ……………………………………………………………………….. 42
On Completing Commissioning ……………………………………………………………………….. 42
MDFL 2800
-
38 & 2800
-
41 Issue 1 08/08 Pa
g
e 1

FULL CHANGEOVER PROCEDURE …………………………………………………………………………… 43
Switching from Gas to Oil ………………………………………………………………………………….. 43
Switching from Oil to Gas …………………………………………………………………………………. 43
ROUTINE SAFETY CHECKS …………………………………………………………………………………… 43
Combustion Air ………………………………………………………………………………….. 43
Flame Detector ………………………………………………………………………………….. 43
Valve Proving System (if fitted) ………………………………………………………………………………….. 43
ROUTINE MAINTENANCE ……………………………………………………………………………………… 44
Combustion Air Fan …………………………………………............................................. 44
Replacing the Air/Gas Ratio Controller ………………………………………………………........................... 44
Oil Filters ………………………………………………………........................... 44
FAULT FINDING …………………………………………………………………............................................... 45
Burner Motor fails to Start ………………………………………………………………………….. 45
Fan Starts and Burner goes to Lockout ………………………………………………………………………….. 45
Start Flame Failure ………………………………………………………………………….. 46
Incorrect Rotation of Burner Motor ………………………………………………………………………….. 46
Main Flame is Not Established ………………………………………………………………………….. 46
Burner Motor only runs Continuously ………………………………………………………………………….. 46
SPARE PARTS ……………………………………………………………………………………………………. 46
APPENDIX …………………………………………………………………………………………………………. 47
Burner Head Details ………………………………………………………………………………………… 47
Electrode Setting Detail ………………………………………………………………………………………… 48
Performance Envelopes ………………………………………………………………………………………… 49
Oil Commissioning Sheet ………………………………………………………………………………………… 50
Gas Commissioning Sheet ………………………………………………………………………………………… 51
BURNER SERVICE RECORD …………………………………………………………………………………… 52
NOTES ………………………………………………………………………………………………………………. 53
IMPORTANT – SAFETY
It is essential that the following instructions and adjustments are carried out by qualified engineers
that are experienced in forced draught gas and pressure jet oil burner commissioning. In the UK it is
a legal requirement that these engineers should also be CORGI registered. Nu-way cannot be held
responsible for any consequential damage, loss or personal injury as a result of customers failing to
follow these instructions, or as a result of misuse. Your attention is drawn to the Emergency
Instructions on Page 28.
EUROPEAN BOILER EFFICENCY DIRECTIVE (B.E.D.)
A
ll burners and boiler bodies marketed separately should comply with EN 267 (oil burners) or EN676
(gas burners) and EN303-1 (boiler bodies).
Burner adjustments must be made in accordance with boiler manufacturer’s instructions, and these
must include flue gas temperatures, average water temperature, and CO2or O2concentration.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 2

MDFL 2800-41 & 2800-38 Issue 1 08/08 Page 3
BURNER AND COMPONENT IDENTIFICATION FOR MDF MODULATING BURNER
(MODEL MDFL 2800-41 SHOWN)
Item Description Item Description
1 Burner Casing 13 Valve Proving Pressure Switch
2 Hinged Extension 14 Modulating Cam Box
3 Flame Tube 15 Valve Proving System
4 Fan Motor 16 Pilot Solenoid Valve
5 Air Inlet 17 Pilot Governor
6 Damper Motor 18 Low Gas Pressure Switch
7 Burner Terminal Panel 19 Flexible Oil Pipe
8 Casing Access Lid 20 Quick Release Oil Couplings
9 High Gas Pressure Switch 21 Pressure Gauges
10 Valve Body 22 Oil Manifold
11 Control Valve 23 Manual Gas Interlock Valve
12 Main Valve
Dimensions (mm)
Model A B C D E F G
MDFL 2800-41 1240 920 345 580 416 1196 440
MDFL 2800-38 1081 920 165 550 385 1196 372
BURNER DIMENSIONS

MGN 3300 & MGN 4000 Page 4
BURNER MOUNTING ARRANGEMENT
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 4

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 5
BURNER AND COMPONENT IDENTIFICATION FOR MDF TWO STAGE (HIGH/LOW)
BURNER (MODEL MDFL 2800-38 SHOWN)
Item Description Item Description
1 Burner Casing 14 Connection Box
2 Hinged Extension 15 Valve Proving System
3 Flame Tube 16 Pilot Solenoid Valve
4 Fan Motor 17 Pilot Governor
5 Damper Motor 18 Low Gas Pressure Switch
6 Burner Control Panel 19 Flexible Oil Pipe
7 Air Inlet 20 Oil Pump
8 Casing Access Lid 21 Pressure Gauge
9 High Gas Pressure Switch 22 Isolation Valve
10 Valve Body 23 Micro Switch
11 Control Valve 24 Twin Solenoid Valve
12 Main Valve 25 Oil Manifold
13 Valve Proving Pressure Switch 26 Manual Gas Interlock Valve

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 6

INTRODUCTION
This manual has been produced to enable users to install, commission and use the MDFL burners
safely and efficiently. At each stage the conditions that should be met, the adjustments and other
actions that should be carried out are detailed. The locations of the various components and
adjustment mechanisms are identified. Where appropriate, this information is supported by tables
and graphs.
FEATURES
Developed through extensive field experience in the UK and overseas markets, the MDFL series of
dual fuel burners meets all current test authority requirements in these markets and sets new
standards in efficient and reliable operation.
MDFL burners are designed for flange mounting to the appliance frontplate and they are delivered
ready to install.
Burner Capacity Burner Model Capacity kW
The figures quoted are nominal burner MDFL 2800-38 774 - 2730
outputs based on the nett calorific value. MDFL 2800-41 774 - 2730
Please refer to the Appendix of this handbook for detailed burner performance data.
Fuel
MDFL burners are suitable for light distillate oil (Class D) and Natural Gas
Air Fan Size
To match MDFL burners with the appliance, with
respect to both burner output and appliance
resistance, a number of combustion air fan sizes
are available for each model, as detailed in the
table opposite.
The fan size quoted is the diameter of the fan impellor (measured in cm) and appears as a suffix to
the model number. For example, a burner designated MDFL 2800-38 is a model 2800 with a 38cm
diameter combustion air fan impellor.
Controls and Safety Systems
MDFL burners are fitted with a combustion airflow control and an air/fuel ratio control system which
together ensure smooth starting and optimum operating efficiency.
An air pressure switch provides safe burner shutdown if the combustion air supply becomes
insufficient for complete combustion. The burners additional safety systems include for gas pressure
monitoring (low and high) whilst gas firing. Continuous flame supervision is provided by an ultraviolet
(UV) cell and automatic programming control unit.
Operating Mode
The MDFL 2800 burners operate in fully modulating mode when firing on gas, and 2 stage (high/low)
mode when firing on oil (Fully modulating mode is an optional extra for the MDFL 2800-38).
Oil Firing – 2 stage Operation
MDFL 2800-41 burner is supplied with a system designated ‘Sliding High/Low’ which uses a single
spillback oil nozzle (similar to that employed in the fully modulating mode) which is constrained to
operate at either of two fixed oil flows corresponding to the high and low fire rates. If the burner has
been correctly matched to the appliance, a turndown ratio of up to 3.0:1 may be achieved. The
MDFL 2800-38 is supplied with twin simplex oil nozzles, one for low and both for high fire.
Gas Firing – Both Models
When gas firing, the fuel gas flow is controlled by an automatic valve which, following commissioning,
precisely matches the fuel flow to the air flow to achieve the required fuel/air ratio at any point in the
full turndown range. If the burner has been correctly matched to the appliance, a turndown ratio
between 2.0 and 2.5:1 may be achieved.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 7
Burner Model Available Fan Sizes
MDFL 2800 38, 41

SITE CONDITIONS AND SERVICES
Flue and Chimney Requirements
It is important that:
- The flue pipe from the appliance and the joint between this flue and the chimney are sealed to
prevent leakage of combustion products.
- The flue pipe from the appliance does not protrude into the chimney beyond the inside wall.
- The top of the flue or chimney shall be higher than any roof within a radius of 10 metres.
- Checks are made to ensure that the chimney is suitable for gas and oil fired appliances and that
the proposed installation complies with all Local Authority and other regulations covering such
installation.
- The flue must be balanced at the appliance outlet.
- 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.
Plant Room Ventilation
The burner must be supplied with dust-free air at sufficient rates for all firing conditions, in
accordance with the appropriate Standards.
Combustion Chamber Conditions
When the burner is fitted to an appliance designed to work under balanced or negative combustion
chamber pressure conditions the over-fire draught must not exceed 0.25 mbar.
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 should be used to monitor the pressure downstream of the booster and
prevent the burner going to high fire if the pressure is insufficient.
The booster should be installed as near to the burner as possible. It should be noted that CE marked
burners fitted with a low gas pressure switch will not run if the gas pressure from the booster is
insufficient. This is due to the low gas switch being set to safeguard combustion quality at the high
fire setting. In this situation the booster outlet pressure switch will have no bearing on the burner
control, but can only be used to indicate booster failure.
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. Flexible
connectors, which reduce both pipework stresses and transmitted noise, must be fitted. 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.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 8

ELECTRICAL POWER SUPPLY
A 400 Volt, three-phase, 50Hz supply is required. Power requirements are listed in the table below.
The power supply provided must comply with all relevant Codes and Standards.
BURNER Fan Motor
kW/hp Pump Motor kW/hp Start Current A/Phase FLC A/Phase Cable Size (mm2) HRC Fuse
(A)
MDFL 2800-38 7.5 / 10.0 1.5 / 2.0 (If
supplied) 101.3 17.3 4.0 40
MDFL 2800-41 11.0 / 15.0 1.5 / 2.0 97.0 25.3 6.0 40
Note: 7.5 kW burner fan motors are started D.O.L. Above 7.5 kW Star/Delta starters are fitted.
OIL SUPPLY
The oil 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 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 oil flow rate anticipated. Galvanised steel pipe should not be used. The supply
pipework should include an appropriate filter. The final connection to the oil pump inlet port should be
made using the flexible pipes supplied with the burner.
MDFL burners may employ a pumped ring main or a gravity feed oil supply system.
Where a gravity feed system is used it should be designed and sized such that the oil pressure at the
pump inlet is not less than 350 mbar and not more than 689 mbar. When a two-pipe system is used,
it is important to ensure that the return pipe is not obstructed as this may result in damage to the
pump.
Where it is thought desirable, a pumped ring main (refer to schematic diagram on page 8) of
appropriate capacity may be used for MDFL burners. The capacity of the ring main pump should be
at least 1.25 times that of the burner pump(s) that it is required to supply.
OIL HANDLING TEMPERATURES AND PRESSURES
Fuel Handling Temperatures (°C) Fuel Delivery Pressures
(At Inlet to Burner Oil Pump)
Fuel Class Viscosity
(Seconds)
Minimum
From Tank
Burner
Inlet Atomising kg/cm2psi
D 35 Minimum 5 recommended 0.35 to 0.70 5.0 to 10.0
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 9

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 10
Notes:
1. Duplex pumps are recommended for continuity and serviceability.
2. Pre-heating Class D fuel is not normally required, but a minimum temperature of 5°C should be
maintained and all exposed pipework must be lagged.
3. If a shut-off valve is fitted in the supply line to the burner oil pump inlet then a pressure relie
f
valve MUST also be fitted to prevent damage should the shut-off valve be inadvertently left
closed during the burner start-up cycle. The relief valve must be set at 0.70 kg/cm2(10 psi)
above the normal supply pressure.
A TYPICAL PUMPED OIL RING MAIN

UNPACKING and ASSEMBLY
To safeguard against damage in transit, MDFL burners are supplied in partly assembled form.
Spill-back Burners
MDFL burners systems comprise of the following units:
- The burner body, complete with hinged extension, flame tube assembly and control panel if fitted
- The gas control train
- The oil pump unit (Optional extra for the Model 2800-38)
- A free-standing or wall-mounted control panel, if supplied
To assemble the burner:
- Fit the gas control train to the burner body using the gasket supplied, ensuring that the gasket is
fitted correctly with all holes corresponding with those on the burner flange.
- Connect the combustion air impulse pipe from the SKP75 air/gas ratio controller to the left side of
the hinged extension.
- Connect the multi-pin plug on the gas valve train to the socket on the rear of the burner-mounted
terminal panel.
- Place and secure the oil pump/pumping and heating unit in the desired position. The floor
mounting arrangements are shown on page 21 (distillate fuels). Connect the unit to the burner
pipework using the flexible connectors provided.
- Fix the control panel in an appropriate position and make the electrical connections to the burner
package and oil pump unit, as shown in the wiring diagram contained in the instruction pack
attached to the burner.
Note: In some circumstances it may be advisable to fit the burner casing to the appliance before
attaching the gas control train. It is recommended that lifting gear should be employed if necessary.
INSTALLATION
General
Ensure that the appliance is suitable for the heat input of the burner. If there is any doubt in this area
reference should be made to the appliance manufacturer. Detailed burner performance data are
presented in the Appendix of this handbook.
Fitting to the Appliance
If the burner is to be fitted to a new appliance, refer to the appliance manufacturer’s
recommendations.
If the burner is to be fitted to an existing appliance, a mounting flange must be provided as detailed in
the section of Burner and Components Identification. Ensure that the joint between the burner and
the mounting flange is sealed effectively using the gasket provided.
The flame tube should be flush with the inner face of the appliance combustion chamber. Up to
10mm protrusion may be acceptable (refer to the appliance manufacturer) however it is not generally
permissible for the flame tube to sit within the appliance firing tunnel.
Special extensions may be specified by the appliance manufacturer, for example in the case of a
reverse flame boiler.
Electrical Power Connection
Connect a three-phase, 50 Hz electrical supply to the burner, observing all applicable Codes and
Standards. The electrical connections required are shown in the wiring diagram contained in the
instruction pack attached to the burner. These diagrams also show the external auxiliary control
connections which must be made.
If the burner is supplied as part of a packaged appliance/burner unit, refer to the appliance
manufacturer’s instructions.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 11

BURNER CONTROL and OPERATION
AIR CONTROLS
Air Regulator (MDFL 2800-41)
The flow of combustion air into the burner is controlled by a multiple-aperture rotary type damper,
fitted to the burner casing within the air inlet silencer on the right hand side of the burner.
Air Damper Motor
In all cases, the air damper is controlled by a servomotor containing adjustable limit switches for the
low and high fire positions.
Single Spill-back Burners (MDFL 2800-41)
The single spill-back burners employ a Landis & Staefa SQM10 motor, as shown on Page 13. This
motor activates the damper through an adjustable cam and cable system, and is mounted above the
air inlet on all models.
Twin Pressure Jet Burners (MDFL 2800-38)
On twin pressure jet burners a Berger Lahr STM6 5 cam motor is used, as shown on page 14. A
fully closed position is provided to prevent air flowing through the appliance when the burner is not in
operation. On these burners the servomotor is mounted on the rear face of the air inlet and directly
coupled to the air damper blade.
Air Diffuser
The air diffuser is fitted to the front of the burner assembly, within the flame tube (refer to the
Appendix). This diffuser controls the combustion air flow and creates a pressure drop across the
burner head, promoting good fuel/air mixing and flame stability.
Air Pressure Switch
The air pressure switch is located on the left side of the burner casing. Its function is to ensure that
combustion air flow is adequate under all operating conditions.
Air flow failure at any stage beyond the first few seconds of the pre-purge sequence will result in
burner lockout.
GAS CONTROLS
A typical gas train fitted is shown on page 15.
High Gas Pressure Switch
A high gas pressure switch is fitted at the outlet of the gas train to ensure that any increase in gas
supply pressure above the level needed to maintain the set conditions results in a safe burner
shutdown. In most cases, high gas pressure would indicate a fault with the air/gas ratio controller.
The pressure switch, which is fitted with an illuminated fault indicator and manual reset button, is
factory set to the maximum value. Final adjustment of the setting of this switch is described in the
section on Commissioning.
Low Gas Pressure Switch
Provision of a low gas pressure switch is required by European Standard EN676 – Automatic forced
draught burners for gaseous fuels. The pressure switch is fitted to all burners which carry the CE
marking but it may not be fitted to non-CE marked burners.
The low gas pressure switch monitors inlet gas pressure and ensures that any decrease in gas
pressure below the value needed to maintain satisfactory combustion results in a safe burner
shutdown. Final adjustment of the setting of this switch is described in the Section on Commissioning.
Gas Valve Train
In addition to the pressure switches noted above, the gas control train includes an air/gas ratio
controller, automatic safety shut-off valves and a governor in the start gas line. A manual isolation
valve must be fitted at the inlet to the gas train during installation. This valve must be in the closed
position when firing the burner on oil.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 12

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 13
AIR DAMPER SERVOMOTOR : SINGLE SPILL-BACK NOZZLE BURNERS
Model : Landis & Staefa SQM 10
Factory Settings
Cam Function Setting
1 High Fire Air 160°
2
Gas
Firing Low Fire Air 0°
3 High Fire Air 160°
4
Oil
Firing Low Fire Air 0°
5
6
7
Not Used
Notes:
1. The servomotor operates both the air damper mechanism and the oil spill adjusting
valve via mechanical cam arrangements mounted on a common shaft within the
‘Modulating Cam Box’.
2. The operation and adjustment of the ‘Modulating Cam Box’ arrangement should be
fully understood before attempting to adjust the motor settings.
3. Cams 1 and 4 represent the low and high limits of the mechanism. These are
factory set and should not require further adjustment.
4. Cams 2 and 3 may be adjusted to give the correct related burner firing rates on gas
and oil.
5. The cam assembly can be rotated manually by disconnecting it from the drive motor
using the disengagement lever. The cams are adjusted with the special ‘C’ spanner
provided.

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 14
AIR DAMPER SERVOMOTOR : TWIN PRESSURE JET BURNERS
Model : Berger Lahr STM6
Factory Settings
Cam Function Setting
1 Full Air Shut-off 0°
2 Low Fire Air 20°
3 High Fire Air 60°
4 High Flame Oil Valve Out 50°
5 High Flame Oil Valve In 40°
Notes:
1. The burner air damper should be set to give optimal combustion whilst firing
on oil. When firing gas, the SKP70 air/gas ratio control valve should be
adjusted to give optimal combustion with the same air damper settings.
2. The fully closed cam (1) is factory set and under normal circumstances
should not require further adjustment.
3. Operation of the low and high fire air switches (cams 2 and 3) is made by
manually adjustable cams. A setting scale is provided at the end of the cam
stack for guidance. Adjustments are made using the screw adjusters
situated within the cam disk body.
4. The position at which the main flame oil valve is activated is controlled by
adjusting cams 4 and 5. A setting should be made to ensure a smooth
changeover whilst maintaining a god combustion quality.
5. The motor will traverse 90° within a maximum of 6 seconds.

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 15
TYPICAL GAS TRAIN
Item Description Item Description
1 Manual Gas Interlock Valve 5 Control Valve
2 Low Gas Pressure Switch 6 Pilot Solenoid Valve
3 Main Valve 7 Pilot Governor
4 Valve Proving System 8 High Gas Pressure Switch

SKP75 Air/Gas Ratio Controller
The air/gas ratio controller, shown below, 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. Two impulse pipes (both factory supplied) are
connected to the air/gas ratio controller.
The first is connected to the burner hinged extensions 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.
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 combustion 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 vice versa.
Installation of combustion chamber impulse pipe
A minimum inside pipe diameter of 8mm is recommended. The impulse pipe should be as short as
possible 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 trap must be
provided.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 16
GAS CONTROL VALVE (SKP 75)
Item Function
1 Adjustment and indication of the
gas/air ratio (high fire settings)
2
Adjustment and indication of the
parallel displacement of the
characteristic (low fire setting)
3 Vented to atmosphere
4 Connection to the fuel gas line
5 Connection to the combustion air
supply at the burner head
6 Indication of the valve stroke

Valve Proving System
Valve proving systems are standard on both MDFL 2800 burners. The standard model fitted is the
Landis & Staefa LDU11. (See page 18)
When the burner operating sequence is initiated the burner control box energises the proving system,
which then carries out the following checks:
The LDU11 control unit is designed to provide automatic gas valve proving (leakage test) based on
the pressure proving principle. The system comprises the control unit, which is fixed to a
bracket/terminal box assembly close to the main valve block, and a dual pressure switch which is
connected to the test space between the main valves. The unit comes pre-wired as part of the gas
train harness.
Gas valve proving is initiated automatically on completion of the burner control circuit prior to burner
start-up. The proving test is based upon the 2-stage pressure proving principal. First, the main
safety valve (V1) on the upstream side of the gas circuit is tested by evacuating the test space (via
the pilot valve V3) and by monitoring the atmospheric pressure in it, then the valves (V2 and V3) on
the burner side are tested by pressurising the test space and monitoring the gas pressure. If the
pressure increases excessively during the first test phase (TEST 1) or decreases excessively during
the second test phase (TEST 2), the control unit inhibits burner start-up and goes to lockout. The
lockout reset button lights up and signals a fault.
A programme indicator, which stops whenever a fault is signalled, indicates which valve(s) set is
leaking.
The control unit requires to be reset manually, either on the unit itself or by a remote resetting if this
has been fitted.
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 17

MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 18
VALVE PROVING SYSTEM : LDU 11
(Standard fitting)

OIL CONTROLS - Single Spill-back Nozzle
The oil control system comprises the burner mounted components and a fuel pump.
Note: When a separate oil pumping set is used it is connected to the burner utilising the braided high
pressure hoses supplied. The burner lance incorporates hydraulic tip shut-off for the oil nozzle whilst
the system controlling valves are closely mounted at the burner head.
Oil Pumps Fitted: MDFL 2800-41 - Suntec T3C 1006
Manual Valve
A manual valve is fitted to the output of the fuel pump and must be closed before firing on gas.
Oil Nozzle
MDFL burners use a single oil nozzle (see drg) within the inner assembly (refer to the Appendix).
This nozzle is factory-specified to deliver optimum performance under the specified operating
conditions. Any queries regarding the size of the nozzle should be referred to Nu-way.
The nozzle is held in position by the inner assembly lance, through which oil flows from the manifold
block to the nozzle and recirculated through the spill regulating valve.
Oil Manifold Block
The oil manifold block is located on the left side of the hinged extension. It carries gauges which
indicate pump pressure, hydraulic pressure and spill pressure.
Oil Spill Regulating Valve
The oil spill is actuated by the motor which actuates the air damper. It varies the spill pressure in
order to provide the required oil flow rate at each operating condition.
Oil Pump
The oil pump is incorporated into a free-standing packaged unit, as shown schematically on page 22.
This package includes the oil filters and separation bottle. (Optional extra for the MDFL 2800-38).
MDFL 2800-38 & 2800-41 Issue 1 08/08 Page 19
Fluidics W1 Nozzle