MHS Boilers STRATA 3 220 User guide

HIGH OUTPUT, FULLY MODULATING,
FULLY CONDENSING, GAS FIRED BOILERS
WITH SINGLE UNIT OUTPUTS UP TO 331kW
INSTRUCTIONS FOR INSTALLATION,
SERVICING & OPERATION
STRATA3
L 258

2
STRATA3
Index
page section
3 . . . . . . . . . 1.0 General
1.1 General Notes
1.2 Certification Details
3-4 . . . . . . 2.0 Product Description
5 . . . . . . . . . 3.0 Technical Details
3.1 Technical Data
6 . . . . . . . . . 3.2 Critical Dimensions
3.3 System Guidance
3.4 Flue Options
7 . . . . . . . . . 3.5 Thermal Performance -
Heat Output Limits
4.0 Appliance Installation
Requirements
4.1 Statutory Requirements
4.2 Boiler Position
8 . . . . . . . . . 4.3 Flue Systems
4.4 Ventilation Requirements
9-10 . . . . 4.5 Hydraulic System
Design
10 . . . . . . . 4.6 Filling the System
11 . . . . . . . 4.7 Gas Supply
4.8 Electrical Supply
5.0 Installation Instructions
5.1 Unpacking the Boiler
12 . . . . . . . 5.1 Unpacking the Boiler
(cont’d)
5.2 Positioning the Boiler
5.3 Gas Connection
5.4 LPG Conversion
Instructions
5.5 Water Connections
13 . . . . . . . 5.6 Condensate Waste
Connections
5.7 Electrical Connections -
General
14 . . . . . . . 5.7 Electrical Connections -
General (cont’d)
5.7.1 Connecting the
Water Supply
5.7.2 Fuses
15 . . . . . . . 5.7.2 Fuses (cont’d)
5.7.3 Connecting a Boiler
(Transport) Pump
5.7.4 External Temperature
Sensor
5.7.5 Room Unit RE2132
5.7.6 External On/Off
Control
16 . . . . . . . 5.7.7 Cascade Controller
KKM2
17 . . . . . . . 5.7.7 Cascade Controller
KKM2 (cont’d)
5.7.8 Domestic Hot Water
Temperature
Sensor (TF)
page section
17
. . . . . . . 5.7.9 LPG Operation
5.7.10 Connecting the DHW
Primary Pump
18 . . . . . . . 5.7.11 Circuit Diagram
19 . . . . . . . 5.8 Add On Modules
5.8.1 Pump Module PRø1
20 . . . . . . . 5.8.1 Pump Module PRø1
(cont’d)
21-23 . . 5.8.2 Mixer Module MR03
23 . . . . . . . 5.8.3 Alarm Contacts
. . . . . . . . . . . for Common
. . . . . . . . . . . Fault Indication
24 . . . . . . . 6.0 Commissioning &
Testing
6.1 Filling the Boiler
25 . . . . . . . 6.2 Appliance Operation
25-26 . . 6.3 Initial Lighting/
Commissioning
27 . . . . . . . 6.4 Potentiometer
Adjustments
6.4.1 Limiting the Output for
Heating Operation
27-29 . . 6.4.2 Setting Weather
Compensation
30 . . . . . . . 6.4.3 Adjusting the Fixed Point
of the Mixer Circuit
6.4.4 Adjusting the Domestic
Hot Water Temp.
6.4.5 Hot Water Thermostat
6.5 Switching Off the
Appliance
31 . . . . . . . 6.6 Screen Display
6.6.1 Operation Message
(Non Flashing)
6.6.2 Operation Data Display
32 . . . . . . . 6.6.3 Engineers Button
6.6.4 STB Test Button
7.0 Boiler Operation
Adjustment
32-33 . . 7.1 Adapting the Control
to the Heating System
34 . . . . . . . 7.2 DIP Switch Settings
35 . . . . . . . 8.0 Maintenance
and Inspection
8.1 Maintenance Procedure
36 . . . . . . . 9.0 Fault Diagnosis
9.1 Fault List
37 . . . . . . . 9.2 Error Correction List
38 . . . . . . . 10.0 Guarantees
39-46 . . 11.0 Parts List

3
1.0 general
STRATA3
1.1 general notes
These instructions are intended to assist the installer, commissioning engineer, maintenance engineer
and user with the installation, maintenance and use of the Strata 3 gas fired condensing boiler.
Please read this manual fully before commencing the installation of the appliance. MHS Boilers Ltd shall
not be responsible for any damage resulting from failure to carefully observe the instructions given.
The Strata 3 must only be installed by persons deemed to be competent i.e. Corgi Registered. This
manual must be handed to the user following completion of the installation.
1.2 certification details
The Strata 3 complies with all relevant European Directives and has been independently Certified to
comply with the requirements of prEN 483 for use in GB and IE with Gas Category II2H3P. (Natural gas
G20 @ 20 mbar inlet pressure, and Propane G31 @ 37 mbar inlet pressure).
The flue classification (depending upon the required flue option) is either B23, C33, C43 or C63X.
PI. No: 0085/AR/0462
2.0 product
description
With modulating outputs of 44 to 220kW and 66 to 331kW the Strata 3 models 220 and 330 are high
output, floor standing, fully condensing boilers. Both appliances are suitable for either Natural Gas or LPG.
The Strata 3 offers ultra high efficiency and low harmful emissions whilst maintaining very compact
dimensions. Each appliance may be room sealed if required and is suitable for flow temperatures of up to
85°C and a maximum working pressure of 6 bar. The boilers include a wealth of enhanced operating
features as standard and create bench marks for their appliance class.
Fully modulating heat output
The output of each boiler is fully variable, modulating between 20% and 100% of maximum output
automatically, and instantly adjusts to match the needs of the system. The percentage of heat output at
any given time can be dictated by either outside air temperature, flow temperature, room temperature (or
a combination of each) or stored domestic hot water temperature.
Ultra high efficiency – fully condensing
The Strata 3 boilers are geared towards optimum operating efficiency and reduced fuel consumption.
Hot flue gases pass from the primary heat exchanger through the cool return water zone created by the
parallel downstream secondary spiranox stainless steel condensing heat exchangers. This principle allows
efficiencies up to 109% nett to be achieved under condensing conditions and results in the exhaust gas
temperature being at most only 10K above the return water temperature.
High quality materials
The use of high alloy 316L stainless steel for the Econox premix radiant burner and the Spiranox
condensing heat exchangers achieves excellent corrosion resistance, heat conduction and strength affording
long life and reliability.
Extremely low harmful emissions
At the heart of the boilers combustion system is the 5:1 modulating radiant cylindrical burner. The
burner is fed with premix gas and air, which burns almost without a visible flame. The heat of combustion
is released predominantly by radiation and the very low thermal surface loading guarantees low combustion
temperatures and extremely low emission of harmful substances.
The Strata 3 boiler releases <40mg/kWh NOx (28ppm DAF) and <20mg/kWh CO (19ppm DAF)
which is particularly environmentally friendly for a boiler of this size.

4
STRATA3
2.0 product description (contd)
Low Noise
The Special burner system employed in the Strata 3 boiler is extremely quiet in operation and in many
cases it emits less noise than a gas fired atmospheric boiler of equivalent output.
Room sealed option
If required the boiler may be completely room sealed, taking combustion air directly from outside
the building.
Note: Ventilation to boiler space will be required for cooling purposes.
Extended flue lengths
The excess fan pressure from the combustion system is 200Pa which allows the boiler to be flued over
long distances using small diameter flue components.
Low water pressure cut off
The boiler includes a pressure sensor, which constantly monitors the water pressure within the boiler
and will prevent the appliance from operating if the pressure falls below 0.5 bar.
Comprehensive microprocessor control
The boiler control panel includes a user friendly microprocessor control centre which manages the
entire function of the appliance and encompasses:-
1. Management of the essential safety functions of burner ignition and flame monitoring.
2. Operational temperature control.
3. Safety interlock for high water temperature, high flue gas temperature, low gas inlet pressure and low
system water pressure.
4. LCD display screen with 2 lines of text to continuously display operation or fault status.
5. Display of boiler temperature and water pressure.
6. Inbuilt direct-on-boiler weather compensator with automatic summer/winter changeover which
provides variable flow temperature (if required).
7. Control of domestic hot water temperature (if required).
8. Self diagnostic control system.
9. PC compatibility with data logging functions, which allows communication via a laptop computer to
review/modify operation parameters and access operational history as an aid to fault finding and
preventative maintenance.
10. Facility to connect optional matched control components such as:- intelligent optimising modulating
room temperature control unit (RE2132), under floor circuit pump (PR01) and mixing valve control
unit, heating zone pump controller (MR03).
11. Facility to connect HWS primary pump or diverter valve.
12. Facility to be driven by a modulating cascade manager (KKM2) which allows multiple boilers to serve a
larger load system with full modulation of the power of all of the connected boilers.
13. Inbuilt common alarm BMS volt free contacts.
14. Facility to connect a boiler pump with anti seize control and frost protection operation.

5
STRATA3
3.0 technical
details
3.1 technical data
Table 1
Model Strata 3
Nominal Heat Input (Nett) kW
Nominal Heat Output @ 80/60°C kW
Nominal Heat Output @ 50/30°C kW
Input Rate Nat Gas G20 (max) m3/h
Input Rate LPG G31 (max) kg/h
Minimum/Maximum Gas Pressure mbar
Max Flue Gas Volume hot (Nat Gas) m3/h
Max Flue Gas Volume hot (LPG) m3/h
Max Condensate Volume l/h
pH Value Condensate Water
CO Emission mg/kWh
NOx Emission mg/kWh
Pressure at Flue Outlet Pa
Min/Max Working Pressure bar
Max Flow Temperature °C
Power Supply V
Power Consumption Min/Max W
Water Content L
Design ∆t°C
Weight Empty kg
CE Product Indentification No.
220
42 – 210
40.7 – 203.7
44.1 – 220.5
18.87
15.54
18/50
254.59
210.18
19.0
4 – 5.5
<20
<40
200
0.5 – 6.0
85
230
60/770
72
20
277
330
63 – 316
61.1 – 306.5
66.2 – 331.8
28.31
23.31
18/50
381.96
315.34
28.5
4 – 5.5
<20
<40
200
0.5 – 6.0
85
230
60/770
91
20
315
CE-0085AR0462

6
STRATA3
3.2 critical dimensions
Dimensions in millimetres
H
E
B
P
R
A
D
F
G
J
K
O
35 : 50
C
360
S
L1 L2
N
M
I
Depth A
Height B
Width C
Height to gas connection D
Dimension K
Gas Inlet Connection O
Safety Valve Connection E
Height to Flue Gas Connection F
Flue Gas Connection Diameter M
Height to Air Supply Connection G
Air Connection Diameter N
(used when room sealing the Boiler)
Dimension H
Height to Condense Waste Outlet I
Height to Flow/Return Connections J
Spare Tapping P
Flow Connection L1
Return Connection L2
Dimemsion to Air Supply Connection R
Condense Waste Connection S
Strata 3-220
1755
1430
628
1235
500
1”BSP M
1”BSP M
555
ØDN150 *
930
ØDN100 **
150
170
1270
1”BSP M
DN 40 PN6
DN 40 PN6
575
DN 40
Strata 3-330
1755
1700
628
1515
500
11/2”BSP M
11/2”BSP M
496
ØDN200 *
1310
ØDN100 **
250
175
1735
1”BSP M
DN 50 PN6
DN 50 PN6
575
DN 40
Fig 3.2a
Table 2
* Female socket with M + 10mm ID
** Male spigot with N + 10mm OD
3.3 system guidance
The Strata 3 boilers are designed to operate on a flow to return temperature drop of 20K. Systems
must be sealed and pressurised to operate within the range 0.5 bar to 5.3 bar.
3.4 flue options
The Strata 3 boiler may be used with either an open or room sealed flue/air system. Approximately
200Pa is available as residual flue pressure at the exit from the appliance. Full details regarding flue
specification are given in section 4.3.

STRATA3
7
3.5 thermal performance –heat output limits
The Strata 3 –220 can be limited to a maximum thermal loading between 42kW and 210kW.
The Strata 3 –330 can be limited to a maximum thermal loading between 63kW and 316kW.
4.0 appliance
installation requirements
4.1 statutory requirements
Gas Safety (Installation and Use) Regulations (Current Issue).
It is the law that all gas appliances are installed by a registered person, in accordance with the above
regulations. Failure to install appliances correctly could lead to prosecution. It is in your own interest, and
that of safety, to ensure that the law is complied with.
In addition to the above regulations, this appliance must be installed in accordance with the current IEE
Wiring Regulations for electrical installation, (BS 7671), Local Building Regulations, the Building Standards
(Scotland) (Consolidation) Regulations, Bye laws of the Local Water Undertaking and Health and Safety
Document No.635 ‘The Electricity at Work Regulation 1989’.
It should also be in accordance with the relevant recommendations in the current editions of the
following British Standards and Codes of Practice, plus any others that are relevant to the proposed
installation: BS6644, BS6880, IGE/UP/2, IGE/UP/7, & IGE/UP/10.
Important Note: Manufacturer’s instructions must NOT be taken in any way as overriding
statutory obligations.
4.2 boiler position
The following considerations must be observed when siting the Strata 3 boiler:
The boiler is not suitable for external installation. The position selected for installation should be within
the building, unless otherwise protected by a suitable enclosure, and MUST allow for adequate space for
installation, servicing, operation, and for adequate air circulation around it. (Refer to fig 4.2a).
This position MUST allow for a suitable flue system and terminal position (Refer to section 4.3). A
connection to a suitable termination point for the discharge of condensate must be available. If this is not
present, a condensation pump with an elevation level of 5 metres (available from MHS) may be fitted to
the appliance. The Strata 3 –220 and 330 must be installed on a flat horizontal floor capable of supporting
the boiler and any ancillaries (circa 320kg for the 220 and 360kg for the 330).
In boiler plant rooms where there is a risk of air contamination as a result of halogenated hydrocarbons
(eg contained in spray cans, solvents and cleaning agents, dyes, adhesives) or heavy dust deposits, the boiler
must be provided with a room sealed air supply. (See figure 4.2a) for plant room clearances. If the Strata
3 is operated on a room air dependent basis in these (or similar) conditions, faults may arise. In this case,
no guarantee claim will be accepted. The boiler room must be dry and frost free.
Dimensions & Clearances mm Strata 3 220 & 330
A 500
B 1000
C 650
D 628
E 1755
Above Boiler Model 220 370
Above Boiler Model 330 600
ADA A
C
A
E
boiler plant room
B
Fig 4.2a

8
STRATA3
4.3 flue
systems
4.3 flue systems
Strata 3 boilers are fully condensing, fully modulating appliances and it is recommended that each boiler
is flued independently, however, it is possible to connect multiple boiler flues together providing no part of
the common flue pipe is horizontal. A suitable flue must be connected to the boiler and routed to
discharge above the roof of the building.
Where it is required that the boiler should be room sealed, an air supply duct must be connected to
the appliance to take air directly from outside the building via suitable fittings.
Under all circumstances, plant rooms must be ventilated in accordance with BS 6644:1991, ventilated
for combustion air and cooling or cooling only dependent on flue type.
The combustion system includes a high pressure fan which is able to overcome a flue or a flue duct plus
air duct total resistance of 200Pa.
Extended horizontal flue duct routes are possible but there must be at least a 3°fall on the flue duct
back towards the boiler, to facilitate condensate removal. (3°= 5.0cm of fall per metre of duct).
Flue ducts must be gas and watertight and resistant to flue gas condensate and suitable for a working
temperature of not less than 120°C. Flue termination position must meet the requirements of BS
6644:1991 and the Clean Air Act Memorandum on Chimney Heights.
Note: The Clean Air Act Memorandum prevents the use of balanced flue appliances discharging at low
level where the total heat input to the plant room exceeds 150kW Gross.
4.4 ventilation requirements
Where the appliance is room sealed, use guidance given in BS 5440:2/2000 for ventilation provision.
Where the appliance takes air for combustion from the boiler house, an adequate supply of fresh air for
combustion and ventilation of the boiler house must be supplied in accordance with BS 6644:1991,
or IGE/UP/10.
The air supply should be achieved using either:
a. Natural ventilation with low level and high level openings.
b. Using a fan to supply air to a low level opening with natural discharge through a high level opening.
c. Using a fan to supply air to a low level opening and a fan to extract air at a high level opening.
Where natural ventilation is used, suitable permanent openings connected directly to the outside air
must be provided. The openings should be fitted with grilles that cannot be easily blocked or flooded or
permit the entry of any foreign bodies.
The free area of the grilles should be as follows:-
Low Level (inlet) 540cm2plus 4.5cm2per kW in excess of 60kW Gross of total rated input.
High Level (outlet) 270cm2plus 2.25cm2per kW in excess of 60kW Gross of total rated input.
Note: Total rated input is the sum of the heat input of all gas appliances in the boiler room.
This guidance is taken from BS 6644:1991, alternative guidance is given in IGE/UP/10.

9
STRATA3
4.5 hydraulic system design
The Strata 3 boilers are designed to operate on a flow to return temperature drop of 20K (∆t 20°C).
Systems must be sealed and pressurised and operate within the range 0.5 bar to 5.3 bar. The system design
should incorporate a pressure gauge, visible from the filling point to indicate the system water pressure.
Table 3 - Boiler hydraulic resistance
Model 220 330
Design Flow Rate at 80/60 Flow/Return Temperatures 2.38 l/s 3.57 l/s
Hydraulic Resistance at 80/60 Flow/Return Temperatures 65.0 kPa 62.5 kPa
Design Flow Rate at 50/30 Flow/Return Temperatures 2.62 l/s 3.95 l/s
Hydraulic Resistance at 50/30 Flow/Return Temperatures 82.5 kPa 74.0 kPa
The Signal to start the boiler pump is provided by the boiler, and where the pump motor rating does
not exceed 600 Watt 230V single phase, the pump may be driven directly from power available from the
boiler inbuilt controls.
All systems must be thoroughly cleansed prior to the connection of the boiler. The
system water should be treated to prevent general system corrosion and the
deposition of scale or sludge in the boiler waterways. If installing the boiler onto an old
system, it is recommended to install a spirotech or similar dirt arrester/filter. Failure
to cleanse and water treat the system will render the appliance guarantee void.
If plastic pipes are used for the flow and return pipes, for radiators or under floor
heating, a plate exchanger should be considered between the system water and the
boiler water. If such a separator is not used, the MHS guarantee on all boiler parts will
become null and void, unless it can be proved that the plastic pipes used have a vapour
tight layer.
The connection of the flow and return are located at the top rear of the unit. With regard to servicing,
it is a requirement that isolation valves are installed.
For specialist advice and water treatment product, contact:
Betz Dearborn Fernox Fry Technology
Widnes, Tamden House, Marlow Way,
Cheshire Beddington Farm Road,
WA8 8UD Croydon CR0 4XS
Tel: [phone] Tel: [phone]
BLR Pump
recommended system design
typical single Strata 3 boiler installation
Expansion Vessel
AAV
AAV
AAV
Return Header
Flow Header
Pumps
DOC
DOC
DOC LSV
IV
IV
IV
IV
DOC
SV
Strainer
IV IV
Strata 3 Boiler
Heating Load
IV
IV
IV
IV
IV
IV
HWS
Load
Vertical Low
Velocity Mixing
Header
Vmax 0.5m/s
Fill Point*
Fig 4.5a
* Fill Point. In accordance with BS6644, automatic
pressurisation unit must be installed

10
STRATA3
4.5 hydraulic system design (contd)
recommended system design
typical multiple Strata 3 boiler installation
Expansion Vessel
AAV
AAV
Return Header
Flow Header
Pumps
DOC
DOC
LSV
IV
IV
IV
IV
NRV
IV
DOC DOC
SV
Strainer
Strata 3 Boiler
Strata 3 Boiler
Heating Load
IV
IV
IV
IV
IV
IV
IV IV
HWS
Load
Vertical Low
Velocity Mixing
Header
Vmax 0.5m/s
BLR Pump
IV IV
NRV
BLR Pump
SV
Fill Point*
Fig 4.5b
Boiler Power kW Diameter based upon ∆t 20°C
220 100mm
330 125mm
440 125mm
660 150mm
880 175mm
990 175mm
1100 200mm
1320 200mm
1650 225mm
Table 4 - Low velocity vertical mixing header diameter sizing guide
Tube diameters refer to medium grade or large steel tubes and are calculated using data from CIBSE guide C4
AAV
* Fill Point. In accordance with BS6644, automatic
pressurisation unit must be installed
The initial filling of a sealed heating system, and
subsequent refilling, must be by a method that has
been approved by the Water Regulation Advisory
Scheme (WRAS) for that type of heating system.
ie. Non Domestic (Other than in-House) Fluid
Category 4 (C-4). For Category 4 systems, the
approved method of filling must comprise of the
following components in the arrangement shown;
●Control valve
●Strainer
●Verifiable backflow device with reduced
pressure zone (RPZ Valve). Incorporating a
'Type BA' air gap.
●Tundish
●Control valve
Further more, in accordance with BS6644, for
boiler/s with an input greater than 60kW, an
automatic pressurisation unit must be installed to
automatically replenish any lost or evpourated water.
The pressurisation unit must comprise of the
following components;
●A cistern fitted with a float operated valve
incorporating either a 'Type AG' (C-3), or
'Type AF' (C-4) air gap.
●A presssure booster pump fitted with a single
check valve
●A pressure reducing valve
●A pressure switch
For information on a comprehensive range of
pressurisation units please contact MHS Sales.
4.6 filling the system
MCWS
CV CV
Strainer
Heating System
Tundish
RPZ

11
STRATA3
4.8 electrical supply
A 240 Volt single phase supply must be present at the proposed boiler location. Wiring external to the
appliance must be in accordance with BS 7671 (the current IEE Wiring Regulations) for electrical installation
and any local regulations which apply.
Wire used for the outdoor sensor, the room unit and the domestic hot water temperature sensor must
have the following minimum cross section, depending upon the cable length.
4.7 gas supply
The Strata 3 boiler is designed and delivered ready for Natural Gas group G20. For operation with
LPG. The LPG conversion kit must be ordered and installed and the multifunctional gas valve adjusted as
necessary. (See section 5.4). The Gas Supplier should be consulted at the installation planning stage in
order to establish the availability of an adequate supply of gas. An existing service pipe MUST NOT be used
without prior consultation with the gas supplier. An existing meter and/or pipework should be of sufficient
size to carry the maximum boiler input plus the demand of any other installed appliance. (BS 6891:1988).
The governor at the meter must give a constant outlet pressure of 20 mbar (8 in. wg) when the
appliance is running on natural gas (G20) or 37 mbar at the regulator when using LPG (G31). The gas supply
should be purged in accordance with IGE/UP/1. WARNING: Before purging open all doors and windows,
also extinguish any cigarettes, pipes and any other naked lights.
The mains cable must be PVC insulated to BS 6500 table 16.
WARNING: THIS APPLIANCE MUST BE EARTHED. (Failure to provide a satisfactory Earth connection
would be a safety hazard and may also result in appliance malfunction).
The method of connection to the mains supply must facilitate complete electrical isolation of the
appliance. A fused double pole switch having a 3mm contact separation in both poles and serving only the
boiler (and its external controls) may be used.
Length m Minimum Cross Section mm2
Up to 25 0.25
25 ... 50 0.5
70 ... 140 1
Table 5
5.0 installation
instructions
5.1 unpacking the boiler
The boiler is delivered in a fully paletted crate containing the boiler and associated fittings, plus any
other optional ancillary control components in separate cartons.
The boiler crate contains:
●Strata 3 220/330 boiler.
●Assembly, commissioning and maintenance manual.
●External temperature sensor with screws and plugs.
Built into each unit are the following:
●Siphon for condensation discharge integrated
in exhaust gas collector.
●Flow temperature sensor.
●Thermometer with LCD display.
●Manometer with LCD display.
●SPIRANOX condensing heat exchanger in
austentic (316L) stainless steel.
●ECONOX premix radiant burner,
RPM-controlled.
●Gas control valve, gas/air pressure ratio 1:1.
●Boiler water temperature control.
●Fully automatic ignition.
●Ionisation monitoring.
●Weather-dependent (compensated) control.

12
STRATA3
5.1 unpacking the boiler (contd)
The unit must be inspected immediately after delivery. Any damage to the consignment must be
reported within 3 days.
Firstly move the packaged appliance to the desired location. To unpack the boiler, carefully remove
the outer crate and cut away the outer packaging. By holding the steel base only, lift the boiler and remove
the palette.
5.2 positioning the boiler
The appliance should be moved to the desired location prior to unpacking, making sure that all
clearance dimensions as stated in section 4.2 are adhered to.
Level the appliance in a horizontal position by turning the adjustable feet underneath the base of the
unit. Check that the appliance is in a true horizontal position by using a spirit level.
Once the appliance is in a true horizontal position, the adjustable feet must be secured by the
locking nuts.
5.3 gas connection
The gas connection is located on the upper left hand side of the appliance (viewed from the front) (see
section 3.2). The gas supply should be sized, installed, tested and purged in accordance with IGE/UP/1&2.
The connection to the appliance must include a suitable method of disconnection and a gas control
cock must be installed adjacent to the appliance for isolation purposes.
The gas pipe used to supply the appliance must not allow a pressure drop of greater than 1 mbar from
the meter to the appliance. The nominal inlet working gas pressure measured at the appliance should be
20.0 mbar for natural gas (G20) or 37 mbar (G31) for propane (LPG). The installer should install a pressure
test point adjacent to the gas inlet connection.
The gas supply line should be purged in accordance with IGE/UP/1. WARNING: Before purging open
all doors and windows, also extinguish any cigarettes, pipes and any other naked lights.
5.4 LPG conversion instructions
The Strata 3 is supplied suitable for use with natural gas. For conversion to LPG, the natural gas injector
must be replaced with the LPG injector (accessed from inside the air inlet duct). The LPG injector is
included in the LPG conversion kit, part No. 96.00044-0404.
Injector Size
Natural Gas (G20)
L.P.G (G31)
220
10.8mmØ
7.5mmØ
330
13.0mmØ
9.7mmØ
5.5 water connections
Strata 3 boilers must only be installed on sealed and pressurised systems. All systems must be
thoroughly cleansed prior to the connection of the boiler. The system water must be treated to prevent
general system corrosion and the deposition of scale or sludge in the boiler waterways. If installing the
boiler onto an old system, it is recommended to install a diamante, spirotech or similar dirt arrester/filter.
See section 4.5 for water treatment product stockists. The central heating flow and return connections
are flanged fittings –DN40 PN6 for the Strata 3 220 and DN50 PN6 for the Strata 3 330. The flow and
return connections are located at the upper rear of the appliance.
A suitable safety valve must be installed onto the boiler flow pipe between the boiler and any
isolation valve. The boiler flow and return pipes must include a method of disconnection and must include
isolation valves.
The low pressure gas cut off switch will need to be adjusted from approx. 15mbar (G20) to
approx. 27 mbar (G31).

13
STRATA3
5.6 condensate waste connections
The condensate waste connection is located at the lower rear of the appliance. During the operation
of the Strata 3 boiler, because of the low exhaust gas temperatures in both the heating boiler itself and in
the exhaust gas system, a slightly acidic condensation water (pH value between 3.5 and 5) is deposited.
The condensate waste connection is a 40mm plastic tube located at the rear of the appliance. Only
plastic components must be used for the condensation discharge. Metal pipes are not acceptable due to
the acidic nature of the condensate.
The built in siphon allows the unit to be connected directly to a drain system. A level control device is
built into the siphon. In the event of a blockage in the condensate line, the burner is automatically switched
off before any damage is done to the appliance.
The siphon drain point is located behind the rear casing panel, next to the condensate water
connection. This must be opened annually in order to flush the condense system and to remove any debris.
If any part of the condensate waste pipe is to be run external to the building or is at risk of freezing,
then the pipe must be suitably insulated to protect it from freezing.
If a suitable drain for accepting the condensate waste is not available nearby to, and below the boiler
(e.g. if the boiler is installed in a basement below ground level), an (optional extra) condensate receptacle
and pump (available from MHS) can be installed adjacent to the appliance. This will collect and remove
condensate to a remote drain up to 5 metres height above the receptacle position. Note that blockage of
the waste discharge will cause the unit to switch off by means of a built in level control device.
It is recommended that the condensate waste pipework should include a method of disconnection and
cleaning points.
5.7 electrical connections –general
To remove the control panel:-
●Unfasten the screw which secures the front panel.
●Pull the panel out and away from the appliance.
●From inside the casing, remove the 2 fixing screws on the underside, upper return edge of the
2 side panels.
●Slide the entire control panel/box away from the appliance.
●Hang the panel, using the turned up brackets, on to the appliance cross member for easy access.
Note: All electrical connection cables must be fed through from the rear of the boiler. Do not pass cables
through or fix to the casing panels.
Fig 5.7a
One Screw
One Screw
Casing
Cross
Member

14
STRATA3
5.7 electrical connections –general (contd)
L1 PE
A1 A2 R2
R1 NL1 PE
R3
NNPE L1 L2 NPE
L1
Fig 5.7b
5.7.1 connecting power supply
The mains electrical connection on the Strata 3 is made via plus No (1) (see fig 5.7b) with a conductor
cross section of 3 x 1.5mm2.
Wire used for the outdoor sensor, the room unit and the domestic hot water temperature sensor must
have the minimum cross section, depending upon the cable length stated in table 5, section 4.7.
5.7.2 fuses
The Strata 3 boilers have 3 electrical fuses in the boiler control panel. (fig 5.7b).
1
2
3x2
Fig 5.7c
location of fuses
64 321
64 321
5
Control Panel Rear Side
location of electrical points
Permanent Supply
(L1 + PE + N)
Outside Air Sensor (A1 + A2)
RE2132 Room Unit (R1 + R2 + R3)
KKM2 Cascade Manager (R2 + R3)
0-10V via an adapter '+' R2 '-' R1
0-3V '+' R2 '-' R1
HWS Sensor
or Thermostat HWS Diverter Valve or HWS Primary Pump
(N + PE + L1)
Terminal
Block
External Gas Safety
Shut Off Valve - LPG
Only (if reqd)
(N + PE + L1)
Room
Thermostat/Volt
Free Switch
(L2 + L1)
PR01 / MR03
(N + PE + L1)
weiland plug / socket functions
Phase and Neutral Protection (230 V AC) 5A Fuse 24 V AC 5A Fuse
1 2 3
4
5
6

15
STRATA3
5.7.2 fuses (contd)
Fuses 1 and 2 protect the power supply phase and neutral. Fuse 3 protects the entire 24V AC circuit.
The 24V AC power supply is rectified in the boiler control panel and controls the fan and supplies the room
unit(s) with voltage. The supply voltage of the sensors is not accessibly fused in the boiler control panel.
This applies also for the protection of the ignition transformer. In the case of a fault in these areas, the
boiler control panel must be replaced.
5.7.3 connecting a boiler (transport) pump
It is recommended that the boiler pump be electrically connected to the boiler. The pump will start as
dictated by the boiler, will overrun when necessary and will run when commanded by the boiler's own frost
protection programme.
The signal to start the pump is provided via plug x 33 and where the pump motor does not exceed 600
watts, 230V 1 phase, the pump may be driven directly from power available from the boiler inbuilt controls,
plug x 33 is located on a flying lead and may be found in the top area of the boiler approximately half way
along the length of the boiler. Where the pump motor exceeds 600watts an auxillary relay must be used.
5.7.4 external temperature sensor
Where weather variable/direct on boiler weather compensation control is required, the external
temperature sensor must be installed. The external sensor should be mounted on the North or Northeast
side of the buildings, at approximately 2/3 of façade height.
The external temperature sensor should not be mounted above windows or below eaves. Under no
circumstances may the sensor be exposed to direct sunlight. The external temperature sensor should be
connected via two cores on plug No 4 –see fig 5.7b.
5.7.5 room unit RE 2132
Where room temperature influence, or
remote adjustment is required, a room unit will
need to be installed. This is available as an
additional accessory (see fig 5.7d).
If the room temperature sensor of the room
unit is used, no thermostat/radiator/convector
valves should be installed in the room with the
room unit.
The room unit must not be directly influenced
by insulation or heat sources, such as heat emitters
or direct sunlight. The room unit should be
connected via three cores on plug No 4 –
see fig 5.7b.
5.7.6 external on/off control
Where this is required a 230V AC volt-free contact must be installed. With the contact open, the
boiler control is switched to the frost protection function, whilst with the contact closed, depending on the
DIP switch configuration of the boiler control, the boiler will operate.
The external on/off control should be connected via two cores on plug (3), terminals L1 and L2, fig
5.7b. Only one of the aforementioned control systems can be utilised at one time.
Fig 5.7d
Remote tamper
proof temperature
sensors are
available to allow
the controller to
be installed in a
non heated area
Sensor ID
= QAW44

16
STRATA3
5.7.7 cascade controller KKM2
The KKM2 Cascade Manager is available as an accessory (see fig 5.7f). The cascade controller can
operate up to 5 units. On a load dependant basis, it controls the modulation of the burners, and the
switching of the appliance(s). It includes all necessary sensors and an external temperature control which
adjusts the flow temperature of the cascade system as a function of the outside air temperature and/or
the sensed room temperature via the RE 2132 (if required) or 0-3 or 0-10v input. The KKM2 may also be
set to give a constant flow temperature and can also control a domestic hot water circuit.
Fig 5.7f
Other types of cascade controllers with a continuous 0 to 3V, or 0 to 10V signal can also be connected.
An optional adapter is required, for 0 to 10V. See Fig 5.7e (Below)
A1 A2
0v
Nr: 4
V+
R1 R2 R3
0 - 10v adaptor
Welland Plug
To Boiler Socket Nr: 4
Welland Connection Plug Nr: 4
0-10 volt Adaptor
0-3 volt control direct to boiler plug
Nr: 4 without adaptor.
0-10 volt control via 0-10 volt adaptor
(optional extra) Fig 5.7e

17
STRATA3
246810
1357 9
12
S1LN
N
LE N
LE
ES4S5S6
D5D2D1
14 16 18 20 22 24 26 28 30 32 34 36 38
23 25 27 29 31 33 35 37
11 13 15 17 19 21
RS232
R2
R3
R2
R3
R2
R3
R2
R3
R2
R3
Fig 5.7g
5.7.8 domestic hot water temperature sensor (TF)
(if required)
For domestic hot water priority, a KTY 81-210 sensor or a volt free contact thermostat can be used.
Connections are provided at connector No 5 –see fig 5.7b.
5.7.9 LPG operation
For use with LPG, an external gas solenoid valve (if required) may be installed in the gas supply line
outside the building. This interrupts the gas distribution if there is no heat demand or a fault. Connections
for an external solenoid (if required) are provided at plug No 2 –see fig 5.7b.
5.7.10 connecting the DHW primary pump
(if required)
A domestic hot water primary pump can be connected directly to the boiler. The connection should
be made via a 3 core cable to plug No 6 –see fig 5.7b. Max load 2A. Where the pump motor exceeds
2Amps a proprietry relay must be used.
5.7.7 cascade controller KKM2 (contd)
HWS Primary Pump 230V ac
Heating Pump 230V ac
230Vac Supply
Flow Sensor
Return Sensor
HWS Sensor
Outside Air Sensor
RE 2132 Room Unit
or
External On/Off Controls
Boiler Control Connections
For Strata 3 Control
Connect to Plug 4 R2 & R3
KKM2 sequence controller wiring details
Further information can be found in the operating manual of the KKM cascade manager.
B1
B2
B3
B4
B5

18
STRATA3
5.7.11 circuit diagram
S1
B
S
B S
B S
B S
S
1
3 2
20 10
10
5
16
8
9
1
6
21
43
1
6
FUSE 24V
FUSE 230 VAC
2 (X)
VOLT FREE ALARM CONTACT
Gas Valve 230 VAC
Fan
HWS D/Valve HWS Pump
R/Stat PRO 1 PRO 3
LPG Solenoid
Supply 230 VAC
Boiler Pump
3
12
4
1
11 1
RS232
4 1
212
VTE
Transformer
Flow Temperature Sensor
Return Temperature Sensor
Water
Pressure Sensor
Gas Pressure Switch
Limit thermostat water
12 VDC Primary Boiler
Limit thermostats Condensers 12 VDC
Model
330 Only
Fluegas Limit Thermostat 12 VDC
Outside Sensor
Room unit
Cascade Manager
0-10V (via special adaptor)
KO = White
K2 = Brown
K3 = Green
K4 = Gray
K5 = Orange
K6 = Blue
K7 = Red
K8 = Black
X10
X12
K5
K5
K6
K6
K7
K2
K3
K8
K0
K12 K18
K18
K17
K4
K18
K12
K19
K17
K20
K20
X17
B S
B S
X19
K0
K6
K0
K7
K9
K9
K9
K9
K9
K13
K2
X16
1
2
3
4
PE
4 5 6
1 2 3
5
6
6
5
4
3
J6 J5
2
1
RTE
S4
X1 X2 X3
MRO3
PRO1
X4 X5 X6 X7 X8
X32
X33
X43 X42 X41
X26
F FHSP TOP
Fuse (2x) 230 VAC
Ignition/Ionisation
FURIMAT 762
X9
F
Q-P
K9 = Violet
K12 = Yellow/White
K13 = Braun/White
K14 = Green/White
K17 = Blue/White
K18 = Red/White
K19 = Black/White
K20 = Violet/White
1
1
6 5 4
3 2 1
2 3
4 5 6
R3R2R1A1 A2
234
X15 RTE
D1
HWS Sensor/ Volt Free stat
= Weiland Plugs
X45 X44
X63
X61
X62
K8
Q-P Q-P
X21
B S
B
N
LIN
PE
PE
LL N
LP
PRO 1
PRO 2
RE2
L
N L
L1 PE N
N N
N
EL
IO PE
PE L
L
L
L2
N
PE
L1
N
PE
PE
L
N
PE
L
N
L
PE
N
L
L2
N
PE
L1
PE N
L
PE
N
N
L
PE
PE
N
B S
B S
B S
B S
N
L
L
L
PE
PE
N
L
L
L
PE
PE
N
N
N
1 3 2
N
L
N
LL
LP N
L
PE
N
B
S
A1A2
230V DC
230V DC
230V DC
A1A2 RE1
PE
N
L S
S
X22
Q-P
X20
B S
X18
X18
Q-P Q-P
12346
54
6
3 2 1
Fig 5.7h
circuit diagram Strata 3 220/330

19
STRATA3
5.8 Add on Modules
5.8.1 Pump module PR 01
The PR 01 pump control serves to control an additional heating circuit pump (pump 2).
Mounting
●Remove the 4 screws on the front of the
pump control.
●Remove the cover.
●Mount the unit in the space provided inside the
boiler casing.
●Refer to the instructions supplied with the unit.
140
60
115
Technical Information
●Supply Voltage –230V 50Hz
(mains from Strata 3 appliance)
●Maximum contact load –2A
●Maximum contact rating –120W
NOTE: The DIP switch of the Strata 3 must be
adjusted so that only one direct heating circuit is
controlled (DIP 1 = OFF).
If the power consumption of pump 2 is more
than 120W, an auxiliary relay is to be installed.
Fig 5.7j
Fig 5.7k
Fig 5.7L
PR01
Control
Module
PR01
Control
Module

20
STRATA3
LN
NETZ NL PUMPE 2
L1 PE N L2
X16X3
65
4321
X3
X2
Fig 5.8a
5.8.1 Pump module PR 01 (contd)
Pump 2
System
heating
pump
PR 01
Power Supply
Weiland
Plug 3
Control Panel Wiring
Cable sets are supplied, labeled, and approximately 140cm in length