Strebel S-FX Installation, Operating & Maintenance Manual

Brand: Strebel

Model: S-FX

Type: Installation, Operating & Maintenance Manual

STREBEL

S-FX Boiler Range

Models 70 – 125 – 220 - 320

Floor Standing High Efficiency Condensing Boiler

Installation, Operating & Maintenance Manual

Please read and understand before commencing installation and leave the manual with the customer for future reference.

2021-09-01 v2

TABLE OF CONTENTS

1 INTRODUCTION .................................................................................................................................. 6

2 SAFETY GUIDELINES ......................................................................................................................... 6

3 TECHNICAL DATA for S-FX BOILERS .............................................................................................. 8

3.1 FUNCTIONAL INTRODUCTION ...................................................................................................... 8

3.1.1 Technical specifications datasheet ............................................................................... 9

3.2 ERP SPECIFICATIONS DATASHEET ........................................................................................... 10

4 BOILER DIMENSIONS ....................................................................................................................... 11

4.1 S-FX 70 ................................................................................................................................. 11

4.2 S-FX 125 ............................................................................................................................... 11

4.3 S-FX 220 ............................................................................................................................... 12

4.4 S-FX 320 ............................................................................................................................... 12

5 INSTALLATION OF THE S-FX BOILERS ......................................................................................... 13

5.1 GENERAL NOTES .................................................................................................................... 13

5.2 BOILER ROOM ......................................................................................................................... 13

5.2.1 General ....................................................................................................................... 13

5.2.2 Boiler room ................................................................................................................. 13

6 CONNECTIONS ................................................................................................................................. 14

6.1 BOILER CONNECTIONS ............................................................................................................. 14

6.2 GAS CONNECTION................................................................................................................... 15

6.3 FLOW & RETURN CONNECTIONS .............................................................................................. 16

6.4 WATER QUALITY ...................................................................................................................... 17

6.5 CHEMICAL WATER TREATMENT ................................................................................................. 17

6.6 CONDENSATE DRAIN ............................................................................................................... 17

6.7 EXPANSION VESSEL ................................................................................................................ 18

6.8 PRESSURE RELIEF VALVE......................................................................................................... 18

6.9 NON-RETURN VALVES. ........................................................................................................... 18

6.10 BYPASS .................................................................................................................................. 18

6.11 FROST PROTECTION ................................................................................................................ 18

6.12 AUTOMATIC FILLING SYSTEM / PRESSURISATION UNITS. ........................................................... 18

6.13 WATER PRESSURE .................................................................................................................. 18

6.14 INSTALLING A STRAINER AND/OR DIRT SEPARATOR .................................................................... 19

6.15 PLASTIC PIPING IN THE HEATING SYSTEM .................................................................................. 19

7 BOILER SHUNT PUMP ...................................................................................................................... 20

7.1 S-FX 70 & 125 HYDRAULIC GRAPH .......................................................................................... 20

7.2 S-FX 220 & 320 HYDRAULIC GRAPH ........................................................................................ 20

8 FLUE GAS AND AIR SUPPLY SYSTEM .......................................................................................... 21

8.1 GENERAL ................................................................................................................................ 21

8.2 S-FX EXHAUST FLUE CONNECTION ......................................................................................... 22

8.3 PLANTROOM COMBUSTION AIR ................................................................................................ 23

8.3.1 Air contamination ........................................................................................................ 23

8.4 BOILER CATEGORIES - TYPES OF FLUE GAS SYSTEMS. ............................................................... 24

8.5 FLUE TERMINAL & COMMON FLUES / DUCTS ............................................................................ 24

8.5.1 Horizontal Flue Terminal Positioning.......................................................................... 24

8.5.2 Vertical Flue Terminal Positioning .............................................................................. 24

8.5.3 Common Flue / Ducts ................................................................................................. 24

8.6 HORIZONTAL FLUE TERMINAL RISK ASSESSMENT ..................................................................... 25

8.6.1 Figure 12 – line G ....................................................................................................... 25

8.6.2 Figure 7 – line Y ......................................................................................................... 25

8.7 OTHER FLUE TERMINAL MINIMUM DISTANCES .......................................................................... 26

9 ELECTRICAL INSTALLATION .......................................................................................................... 27

9.1 GENERAL ................................................................................................................................ 27

9.2 CONNECTION MAINS SUPPLY .................................................................................................... 27

9.3 ELECTRICAL CONNECTIONS ..................................................................................................... 27

9.4 ELECTRICAL SCHEMATICS ....................................................................................................... 28

9.5 DRAWING NUMBER LEGEND .................................................................................................... 31

9.6 SCHEMATIC & WIRING EXAMPLES ............................................................................................ 32

9.6.1 2 x Direct heating circuits ........................................................................................... 32

9.6.2 1 x Direct heating circuit & 1 x dhw primary circuit with pump ................................... 33

9.6.3 1 x Direct heating circuit & 1 x dhw primary circuit with three way valve ................... 34

9.6.4 3 x S-FX in cascade: 1 x Direct heating circuit & 1 x dhw primary circuit with pump . 35

9.6.5 Remote on / off control, remote reset & bms outputs per S-FX boiler ........................ 37

10 BURNER CONTROLLER AND DISPLAY. ........................................................................................ 38

10.1 DISPLAY AND BUTTONS ............................................................................................................ 38

10.1.1 Display icons ............................................................................................................... 38

10.2 POWERING UP & DOWN ........................................................................................................... 39

10.2.1 Turning on the s-fx boiler for the first time .................................................................. 39

10.2.2 Changing the contrast ................................................................................................. 39

10.2.3 Turning off the boiler display ....................................................................................... 39

10.2.4 Powering down the complete boiler ............................................................................ 39

10.3 USER MENU STRUCTURE ......................................................................................................... 40

10.3.1 Heating Parameter ...................................................................................................... 41

10.3.2 DHW Parameter .......................................................................................................... 43

10.3.3 Time Programming ..................................................................................................... 43

10.3.4 Holiday Function ......................................................................................................... 44

10.3.5 Setting Date & Time .................................................................................................... 44

10.4 TECHNICAL MENU STRUCTURE ................................................................................................. 45

10.4.1 To Access the Parameters.......................................................................................... 45

10.4.2 To Access the Configuration, Transparent & System Parameters ............................. 45

10.4.3 Configuration Parameter - b........................................................................................ 46

10.4.4 Transparent Parameter – P ........................................................................................ 47

10.4.5 System Parameter – P. ............................................................................................... 48

10.4.6 S-FX Information Menu ............................................................................................... 49

11 S-FX CASCADING ............................................................................................................................. 50

11.1 SYSTEM SETUP ........................................................................................................................ 50

11.2 BOILER CASCADE COMMUNICATION SETUP. ............................................................................... 50

12 NATURAL GAS TO LPG CONVERSION .......................................................................................... 51

12.1 PART 1 – FITTING THE LPG CONVERSION KIT ........................................................................... 51

12.2 PART 2 – SOFTWARE CHANGE ................................................................................................. 51

13 COMMISSIONING THE BOILER........................................................................................................ 52

13.1 FIRST: FLUSHING THE BOILER WITH WATER .............................................................................. 52

13.2 SECOND: FILLING & VENTING THE BOILER AND THE SYSTEM ...................................................... 52

13.3 THIRD: CHECK THE WATER FLOW ............................................................................................. 52

13.4 MOUNTING CONDENSATE TRAP ................................................................................................ 52

13.5 CHECKING GAS PRESSURE ...................................................................................................... 52

14 ADJUSTING AND SETTING THE BOILER ....................................................................................... 53

14.1 INTRODUCTION ........................................................................................................................ 53

14.1.1 Combustion table ........................................................................................................ 53

14.1.2 Adjustment Values ...................................................................................................... 54

14.2 PUTTING THE BURNER INTO HIGH & LOW FIRE .......................................................................... 56

14.3 HIGH & LOW FIRE ADJUSTMENT ............................................................................................... 56

14.3.1 Adjusting The Burner At High Fire .............................................................................. 56

14.3.2 Adjusting The Burner At Low Fire ............................................................................... 56

14.3.3 Location Of Adjustment Screws .................................................................................. 57

14.4 HEATING CAPACITY ADJUSTMENT (RANGE RATED) ................................................................... 57

14.5 CASCADE TEST MODE ............................................................................................................. 58

14.6 START UP CHECKLIST .............................................................................................................. 59

15 INSPECTION, MAINTENANCE AND SERVICE. ............................................................................... 61

15.1 GENERAL ................................................................................................................................ 61

15.2 INSPECTION, MAINTENANCE AND SERVICE. ................................................................................ 61

15.3 MAINTENANCE CHECKLIST ....................................................................................................... 65

16 FAULT CODES / TROUBLESHOOTING ........................................................................................... 66

16.1 LIST OF FAULT CODES ............................................................................................................. 66

16.1.1 Lock Out Faults – A Codes (Requires Resetting) ....................................................... 66

16.1.2 Temporary Faults – F Codes (Automatically Reset) ................................................... 67

17 USER INSTRUCTIONS ...................................................................................................................... 68

18 USER’S PART. ................................................................................................................................... 68

18.1 SAFETY GUIDELINES. ............................................................................................................... 68

18.2 TO TURN OFF GAS TO THE APPLIANCE ....................................................................................... 68

18.3 MAINTENANCE AND INSPECTION ............................................................................................... 68

1 INTRODUCTION

This manual is written for:

▪ The Installer.

▪ System Design Engineer.

▪ The Service Engineer.

▪ The User.

Strebel Ltd are not accountable for any damage caused by incorrect following these instructions. For service and

repair purposes use only original Strebel Ltd spare parts.

All documentation produced by the manufacturer is subject to copyright law

2 SAFETY GUIDELINES

Carefully read all the instructions before commencing installation.

Keep these instructions near the boiler for quick reference.

The appliance should be installed by a skilled installer such as GAS SAFE registered person, electrical work

carried out by a qualified person, all according to national and regional standards.

Failure to comply with these regulations could deem the warranty invalid.

This appliance must be installed in accordance with the rules that apply and only be used in an adequately

ventilated space conforming to standards in place.

Without written approval of the manufacturer the internals of the boiler may not be changed. When changes are

executed without approval, the boiler certification becomes invalid.

Commissioning, maintenance and repair must be done by a skilled installer/engineer, according to all applicable

standards and regulations.

A. This appliance does not have a pilot. It is equipped with an ignition device which automatically lights the

burner. Do not try to light the burner by hand.”

B. BEFORE OPERATING smell all around the appliance area for gas. Be sure to smell next to the floor because

some gas is heavier than air and will settle on the floor.”

C. Do not use this appliance if any part has been under water. Immediately call a qualified service technician to

inspect the appliance and to replace any part of the control system and any gas control which has been

under water.”

What to do if you smell gas:

▪ Do not use any electrical equipment.

▪ Do not press any switches.

▪ Close the gas supply.

▪ Ventilate the room (open the windows and/or outdoor water heater room doors).

▪ Immediately warn the installer.

The manufacturer/supplier is not liable for any damage caused by inaccurately following of these

mounting instructions. Only original parts may be used when carrying out any repair or service

works.

This appliance can be used by children aged from 8 years and above and persons with reduced

physical, sensory or mental capabilities or lack of experience and knowledge if they have been given

supervision or instruction concerning use of the appliance in a safe way and understand the hazards

involved.

“WARNING: Improper installation, adjustment, alteration, service or maintenance can cause property

damage, personal injury (exposure to hazardous materials) * or loss of life. Installation and service must be

performed by a qualified installer, service agency or the gas supplier (who must read and follow the supplied

instructions before installing, servicing, or removing this water heater.

These instructions are written for the installer of Strebel products and contain all necessary information on

the installation and adjustment of S-FX ranges of boilers. Please read these instructions fully before

installation to ensure that all work is carried out correctly.

We suggest that you keep a copy of these instructions near the boiler.

These instructions together with those in any supplemental instruction booklet cover the basic principles

to ensure the satisfactory installation of the boiler, although detail may need slight modification to suit

particular local site conditions.

It is the law that all gas appliances and fittings are installed by a competent person (such as a Gas Safe

registered installer) and in accordance with The Gas Safety (installation and Use) Regulations.

The relevant British standards for installation, codes of practice or rules in force and in accordance with

the Manufactures’ instructions.

The installation must be carried out in accordance with the following regulations plus relevant codes &

standards:

- Due consideration must be given to current Health & Safety Legislation while this product is being

installed.

- Key Approved Documents to the Building Regulations, in the region of the United Kingdom that

this product is being installed.

- The Local Building Regulations and Local water by-laws, the gas services area and the Local

Authority recommendations.

- The appropriate British & European Standards for the type of installation and fuel used, including

but not exclusively the following standards: -

o BS 5440: Part 2 (Flues and Ventilation).

o BS 6644: Installation of gas-fired hot water boilers of rated inputs between 70kW & 1.8MW

- The clean air act as defined by the local authority.

- The appropriate documents as produced by the Institution of Gas Engineers and Managers

Documents (IGEM) for the type of installation and fuel used, including but not exclusively the

following documents: -

o IGE/UP/1.

o IGE/UP/2.

o IGE/UP/4.

o IGEM/UP/10 Edition 4.

- If the product is being fuelled with LPG then the appropriate UKLPG Codes of Practice (CoP)

should be referred to.

- Wiring to the appliance must be in accordance with the IEE (BS 7671) Wiring Regulations the

Health and Safety Document No 635 “The Electricity at Work Regulations 1989” and any local

regulations that apply.

- CP 342: Part 2, 1994. Code of practice for centralised hot water supply – buildings other than

individual dwellings.

- CIBSE, Guides A, B and C.

Adhere to all regulations that are in force at the time of installation or service.

3 TECHNICAL DATA FOR S-FX BOILERS

3.1 Functional introduction

The S-FX boilers is a high efficiency, low emissions premix condensing heat generator for heating, running on

natural gas or LPG and equipped with a microprocessor control system.

The boiler body consists of a patented stainless-steel helical tube heat exchanger and a premix burner in stainless

steel, equipped with electronic ignition with ionisation flame control, modulating fan and modulating gas valve.

The S-FX is a heat generator arranged to operate alone or in cascade.

The S-FX boiler is standard set for Natural Gas (G20).

Boiler control includes:

▪ Cascade control for up to six boilers.

▪ Remote operation and heat demand indication from each boiler.

▪ Weather compensation control.

▪ Calorifier control.

Connections for:

▪ On/Off thermostat.

▪ 0-10 VDC remote flow temperature (set point)

control.

▪ 0-10 VDC remote burner input control.

▪ Outdoor temperature sensor.

▪ External calorifier pump or diverter valve.

▪ Boiler pump.

▪ System pump.

▪ External flow switch or external safety device.

▪ External system sensor.

▪ DHW indirect sensor or DHW control thermostat.

Cascade control

When using the integrated cascade control, a maximum of six boilers can be controlled in a cascade

configuration. Using an appropriate external control, this number may be increased at will.

0-10 VDC connection available

The boiler flow temperature or power input can be controlled by an external 0-10 VDC signal. When a number of

boilers are cascaded, and controlled by the integrated cascade control, the signal should be directed to the master

boiler only. If an alternative control is used, more than one boiler may be controlled by a 0-10 VDC signal.

Time program

For both central heating and hot water function of the boiler, time programs with six programmable periods per day

are available. These time programs are set and activated by entering the desired settings directly at the boiler

control panel.

3.1.1 TECHNICAL SPECIFICATIONS DATASHEET

GENERAL

Product identification number:

CE 0085CL0441

Gas Appliance Type

B23

Boiler Model

S-FX 70

S-FX 125

S-FX 220

S-FX 320

Classification

II2H3P

Water Content

litre

166

265

386

530

Weight (empty)

180

280

400

500

Flow Connection

inch / F

R 1 ¼”

R 2”

DN65 PN16

Return Connection

inch / F

R 1 ¼”

R 2”

DN65 PN16

Gas Connection

inch

R ¾”

R 1”

Flue Exhaust Connection

100

160

200

HEATING Values min-max:

Nominal Input (net)

14.0 - 65.5

23.0 - 116.0

41.0 - 207.0

62.0 - 299.0

Nominal Input (gross)

15.5 - 72.7

25.5 - 128.7

45.5 - 229.7

68.8 - 331.8

Nominal Output 80/60 °C

13.7 - 64.4

22.5 - 113.5

40.2 - 203.7

60.8 - 294.4

Nominal Output 50/30 °C

15.1 - 70.0

24.8 - 123.9

44.2 - 221.1

66.8 - 319.3

BOILER EFFICIENCY

Efficiency – Full Load 100% NCV

98.30

97.90

98.40

Efficiency – Full Load 30% NCV

109.70

109.50

109.70

Seasonal Efficiency (Part L) GV

96.76

96.77

96.70

96.88

GAS CONSUMPTION Values min-max:

Natural gas (G20)

m3/h

1.48 - 6.93

2.43 - 12.28

4.34 - 21.90

6.56 - 31.64

Propane (G31) 1

kg/h

1.09 - 5.09

1.79 - 9.01

3.19 - 16.08

4.82 - 23.23

Gas supply pressure

nominal 2

G20

mbar

G31

mbar

EMISSION Values min-max:

CO2 flue gas 3

G20

8.8 - 9.3

8.7 - 9.3

8.5 - 9.0

G31

9.8 - 10.3

9.5 - 10.5

NOx class

Flue gas temperature at combustion air

temperature = 20 °C

°C

Mass flow flue gas (min/max)

g/s

7.0 - 30.0

11.0 - 53.0

20.0 - 94.0

30.0 -

140.0

Available pressure for the flue system 4

200

INSTALLATION

Resistance boiler

T = 11 K

kPa

2.3

5.0

2.3

3.2

T = 20 K

kPa

1.2

2.3

1.4

Pressure boiler min-max.

bar

0.8 – 6.0

Max. flow temperature

°C

ELECTRIC

Maximum power consumption 5

105

200

260

330

Power supply

V/Hz

230 / 50

Protection class

IPX0D

NOTES

1 Using propane (LPG), LPG conversion kit to be fitted and parameter change required

2 Min. and max. gas supply pressures.

p nominal [mbar]

p min [mbar]

p max [mbar]

G20

G31

3 The CO2 requirement of the unit – 0.1% tolerance either way

4 Maximum allowed combined resistance of flue gas piping at high fire

5 Power consumption is measured without circulation pump

3.2 ErP Specifications Datasheet

Technical parameters according to the European ERP (Energy Related Products) legislation:

Boiler Model:

S-FX 70

S-FX 125

S-FX 220

S-FX 320

Condensing boiler:

Yes

Low temperature boiler:

Yes

B11 boiler:

Cogeneration space heater:

Combination heater:

Unit:

Value

Rated heat output

114

204

294

P-rated (P4) at 60-80 ⁰C

64.4

113.5

203.7

294.4

Heat output (P1) 30% at 30-37 ⁰C

12.8

24.2

41.6

60.6

Seasonal space heating energy

efficiency (ɳs).

94.0

Energy efficiency (ɳ4) at 60-80 ⁰C

88.5

88.1

88.6

88.7

Energy efficiency (ɳ1) at 30-37 ⁰C

98.7

98.8

98.6

98.8

Auxiliary electricity consumption

At full load (elmax).

0.105

0.200

0.260

0.330

At part load (elmin)

0.019

0.025

0.037

0.043

In standby mode (Psb)

0.003

Other

Standby heat loss (Pstby)

0.190

0.300

0.350

0.400

Ignition burner power consumption (Pign)

0.000

Emissions (NOx) of nitrogen oxides

(EN15502-1:2012+A1:2015)1

mg/kWh

18.0

17.0

22.0

20.0

Sound power level, indoors

(EN 15036-1:2006)

58.0

62.0

72.0

76.0

1 These numbers are used to assign credits according to the BREEAM standards

4 BOILER DIMENSIONS

4.1 S-FX 70

4.2 S-FX 125

4.3 S-FX 220

4.4 S-FX 320

5 INSTALLATION OF THE S-FX BOILERS

5.1 General Notes

The S-FX boiler is mounted on a pallet with a wooden “support” frame around it. The boiler is wrapped in shrink

warp before the wooden support frame is mounted. After the frame is placed the whole pallet, boiler and frame

package is shrink wrapped again.

Only remove this packaging when the boiler has been positioned at the place where it will be installed. After

removing the wrapping and the frame, the boiler can be taken off the pallet using a forklift or another suitable lifting

device.

Final Positioning

Each S-FX boiler comes with four heavy duty wheels (black

arrow) fitted as standard to the base of the boiler to allow easy

movement within the plantroom. Once the boiler is in its final

position, use the adjustable feet (red arrow) next to each wheel

to level the boiler and secure it into position.

5.2 Boiler Room

5.2.1 GENERAL

The S-FX range must be installed in a suitable room with ventilation openings direct to outside air in conformity

with the current regulations. If there are several other heat generators that can work together in the same room,

the ventilation openings must be sized to allow all heat generators to operate simultanously.

The place of installation must be free of flammable materials or objects, corrosive gases, powders or voltile

substances. The installation room must be dry and not exposed to rain, snow or frost.

5.2.2 BOILER ROOM

For the installation of the boiler(s) the following demands regarding the boiler room should be considered:

1. The radiation losses of the unit are low.

2. The boiler has a built-in fan that will generate noise, depending on the heat demand. The sound emissions

are quite low from the boiler but be aware that some noise is produced.

3. You need a power supply of at least 230V-50 Hz with an earth connection and may need a supply of 400V-

50Hz depending on the pump. We advise to install a separate “safe working switch on which all poles are

switched” externally so one can work on the boiler while having all the wiring free of supply voltage.

4. The air supply of the boiler will be drawn in from the boiler room.

Other considerations related to the boiler location.

• The ventilation of the boiler room must meet all applicable standards and regulations, regardless of the

selected supply of fresh air to the boiler location.

• The flue gas tube must be connected to an outside wall or roof duct. The air supply is required to come

from outside into the plant room via correctly sized vents / ducts.

• The installation area must be dry and frost-free.

• There must be sufficient lighting available in the boiler room to work safely on the boiler.

• Mind the positioning of electrical components in relation to the temperature sensitivity.

• Make sure there is an open connection with the sewer to drain the condensate. This connection should

be lower than the condensate drain level of the boiler.

• Ensure that the correct space is provided when positioning the boiler for maintenance and replacement of

parts. The recommended minimum clearance is:

- Side clearance: 50 mm

- Front clearance: 500 mm

- Rear clearance: 500 mm

- Above clearance 200 mm

• Make sure that the floor on which the boiler is placed can hold the weight of the boiler.

The S-FX range is strictley prohibited to be installed outdoors, unless adequately protected against

atmospheric agents.

6 CONNECTIONS

6.1 Boiler connections

S-FX

S-FX 70

S-FX 125

S-FX 220

S-FX 320

Flow Connection Size

1 ¼" Threaded

2" Threaded

DN65 Flanged PN16

Primary Return Connection Size

1 ¼" Threaded

2" Threaded

DN65 Flanged PN16

Gas Connection

3/4”

1”

6.2 Gas Connection

Before making the connection, make sure the S-FX applaince can operate with the type of fuel

available. Clean all the pipes of the gas system to remove any residues that could affect correct

functioning of the boiler.

Connection of the S-FX appliance to the fuel supply must comply with current installation standards.

To allow easy opening of the burner door during annual service / maintenance, the last section of the gas pipe must

be considered. See chapter 15.2 which shows how the burner door is opened and closed.

As per the above picture, the red arrow shows where the gas connection to the boiler is located. The burner door

hinge is located directly below thus the gas connection on the S-FX boiler is attached to the fan which is attached to

the burner door that is a moveable part. For the burner door to be opened, the gas pipe connecting into the gas

connection on the boiler will need to be removed. Therefore it is suggested that either:

• The last section is a stainless steel hose with an isolation valve fitted – gas pipe example above.

• The last section of gas pipe work has breakable unions with an isolation valve fitted.

S-FX

S-FX 70

S-FX 125

S-FX 220

S-FX 320

Gas Supply Connection Size

¾"

Make sure that all gas connections are tight. The capacity of the gas meter must be sufficient for the simultaneous

use of all units connected to it. The diameter of the gas pipe leaving the boiler is not decisive for choosing the

diameter of the pipe between the S-FX unit and the gas meter. It must be chosen according to its length and

pressure drop, in conformity with the current regulations.

Do not use the gas pipes to earth eletrical appliances.

In case of connection in cascade, make sure to install a fuel shut off valve externally with respect to

the modules.

6.3 Flow & Return Connections

Before making the connection, carefully flush all the pipes of the system to remove residues or

impurties that could affect the operation of the unit. See “water quailty” and “chemical water

treament” chapters.

S-FX

S-FX 70

S-FX 125

S-FX 220

S-FX 320

Flow Connection Size

1 ¼" Threaded

2" Threaded

DN65 Flanged PN16

Return Connection Size

1 ¼" Threaded

2" Threaded

DN65 Flanged PN16

The hydraulic connections are:

• Connection A = Supply / Flow Connection.

• Connection B = Return Connection.

Each hydraulic connection has a premade pocket for the flow & return sensors to be inserted.

6.4 Water quality

The system water must be checked periodically (at least twice a year during the seasons of use, as required by

UNI8065) and possibly have a clear appearance and must be within the following parameters:

• Water PH: From 7 to 8.5.

• Copper Cu (mg/l): < 0.5 mg/l.

• Iron Fe (mg/l): < 0.5 mg/l.

• Chlorides (mg/l): < 50 mg/l.

• Conductivity (µS/cm): < 200µS/cm.

• Sulfates < 100 mg/l.

• Nitrates < 100 mg/l.

6.5 Chemical water treatment

The chemical compatibility of several products for treatment of the central heating equipment has been tested on

the heat exchangers and the boilers. See below for the list with the corrosion inhibitors in preventative and curative

treatment for gas fired central heating boilers. If water treatment is required when filling the system or preforming

maintenance an inhibitor should be used. Follow the instructions provided by the inhibitor manufacturer when

adding it to the system.

The following is a list of approved chemical treatments.

Corrosion-/ Scale inhibitors and recommended suppliers

Product Types

Fernox

Sentinel

Inhibitors

Protector F1 / Alphi 11

X100, X500

Noise reducer

X200

Universal cleaner

Restorer

X300

Sludge remover

Protector F1, Cleaner F3

X400

Antifreeze

Alphi 11

X500

Tightness

Leaker Sealer F4

6.6 Condensate Drain

The condense drain is supplied loose within the S-FX boiler casing on delivery, please connect before operating

the boiler.

The condensate drain is placed at the centre and at the bottom of

the boiler and has a hose discharge. Connect this flexible hose to

the sewer system.

Use only plastic parts with the condensate drain. Metal lines are

not allowed.

Blockage of this drain might damage the boiler. The drain

connection is correct when the condensate can be seen flowing

away, e.g. using a funnel. Any damage that might occur, when the

drain is not installed correctly, is not covered by the warranty of the

boiler.

There should be an open connection of the condensate hose into

the sewage system. A possible vacuum in the sewage system

must never give the opportunity to suck on the boiler’s condensate

drain hose.

Maximum condensate flow per S-FX model:

S-FX 70

S-FX 125

S-FX 220

S-FX 320

8.3 litres per hour

14.9 litres per hour

26.7 litres per hour

39 litres per hour

When mounting the bottom part of the condensate trap, before commissioning the boiler and/or after

maintenance, the condensate trap must ALWAYS be completely filled with water.

This is a safety measure: the water in the condensate trap keeps the flue gases from leaking

out of the heat exchanger via the condensate drain.

6.7 Expansion Vessel

The capacity of the expansion vessel must be selected and based on the capacity of the central heating system

and the static pressure. Suggest to fit the expansion vessel in the return pipe of the central heating system.

6.8 Pressure relief valve

The S-FX boiler has no internal pressure relief valve, it is required to be installed as close to the boiler on the flow

pipe of the heating system. When having cascaded boilers, each boiler requires to have its own pressure relief

valve. It is recommended to install isolation valves on the flow and return pipework, so the boiler can be isolated

from the heating system, when needed. Make sure that the pressure relief valve is mounted between the boiler

and the isolation valves.

Alternatively, there is a connection on the S-FX boilers flow pipe just before it connects to the system which is

plugged off. This is primarily used for any BMS temperature sensor require but can be used to connect a safety

valve. But due to the size of the connection, NABIC FIG 500 high lift valves will be required:

- S-FX 70 & 125 = ½” FBSP Connection.

- S-FX 220 = ¾” FBSP Connection.

- S-FX 320 = 1” FBSP Connection.

The specifications and size of the relief valve should be determined by the installer and must comply with all

applicable regulations and boiler capacity.

6.9 NON-Return Valves.

All S-FX boilers have a non-return valve installed on the air pipe just before the internal combustion fan. These

valves are certified to give protection of up to 30 pascals when installed on a pressurised flue system.

6.10 Bypass

The boiler has no internal bypass. When many thermostatic valves are being used, the system should have a by-

pass to allow an adequate flow when all thermostatic valves are closed.

Instead of a bypass also a low-loss header or a SMH Boiler Guard can be used for this function.

The boiler flow will also be influenced when a pipe of the heating system is frozen / blocked. Make sure all heating

pipes are free from the risk of frost. If there is the risk of freezing of the heating system, all the pipe section must

be insulated and/or protected with the help of a tracing.

6.11 Frost protection

The boiler has a built-in frost protection that is automatically activating the S-FX boiler and connected heating

pumps when the boiler supply / flow (water) temperature drops below 6 °C.

This frost protection function will not fire up the boiler if the power supply or gas supply has been turned off. If

necessary, for system protection use a suitable antifreeze liquid as listed within chapter 6.5.

NOTICE: A boiler damaged by frost is not covered under warranty.

6.12 Automatic Filling System / Pressurisation Units.

When using an automatic water refill system some precautions should be taken (fresh water is bringing fresh

oxygen into the system), like installing a water meter to measure and evaluate the total water volume that is added

to the system. This to detect and eliminate any water leakage as soon as possible. When an automatic water refill

system is used, some form of logging should take place to prevent continuously filling of the system with large

amounts of oxygenated fresh water. This can happen when a leak in the system is not detected and the total

added water amount is not being logged.

6.13 Water pressure

The installation should be designed and built to conform to all applicable regulations and standards, including the

right safety valves. IMPORTANT: Always keep the pressure in the boiler lower than the value at which its safety

relief valve opens.

Switch

A water pressure switch has been built into the boiler. With this switch, the minimum water pressure in the boiler

is 0.8 bar. The normal water pressure is supposed to be between 1.5 and 2.0 bar.

The pressure sensor will stop the boiler from firing when the water pressure drops below 0.8 bar, and start the

boiler firing again when the water pressure reaches above 1.0 bar.

6.14 Installing a strainer and/or dirt separator

Always install a strainer (water filter)

and/or a dirt separator in the return pipe

of the boiler; in such a way that the water

going to the boiler is free of any

debris/particles.

When using a water filter always check

a week after installation to determine the

strainer cleaning interval. Advice is to

mount valves before and after the

strainer, including an air bleed valve, so

the strainer can be isolated from the

heating circuit for service operations.

Clean water is very important, blocked

and/or polluted heat exchangers,

including failures and/or damages

caused by this blockage are not covered

by the warranty.

6.15 Plastic piping in the heating system

When plastic pipes with no oxygen barrier e.g. under-floor heating system, are used in the central heating system,

these should be separated from the boiler system by using a plate heat exchanger. Diffusion (through the plastic)

can cause air to enter the heating system. This could damage the boiler, pumps and other components in the

system. Be aware that plastic piping is often used in under floor heating systems. When no measures have been

taken to prevent the entrance of air into the boiler system, the warranty of the boiler and any boiler part may be

deemed invalid.

SYSTEM WITH DIRT SEPARATOR

SYSTEM WITH STRAINER

SYSTEM WITH STRAINER AND DIRT SEPARATOR

DIRT SEPARATOR

DIRT SE-

PARATOR

WATER

RETURN FROM

SYSTEM

WATER

RETURN

FROM

SYSTEM

WATER

RETURN

FROM

SYSTEM

WATER FLOW TO

BOILER(S)

WATER FLOW TO

BOILER(S)

WATER

FLOW TO

BOILER(S)

DIRT

BLEED

VALVE

DIRT

BLEED

VALVE

AIR

BLEED

VALVE

AIR

BLEED

VALVE

STRAINER

(WATER FILTER)

STRAINER

(WATER FILTER)

7 BOILER SHUNT PUMP

The S-FX boilers do not have an internal shunt pump therefore using the following graphs, select a pump that is

compatible with the hydraulic resistance of the boiler and the system against the required flow rate.

7.1 S-FX 70 & 125 Hydraulic graph

7.2 S-FX 220 & 320 Hydraulic graph

It is recommended to observe the water flow rates in the table and as specified below.

DESCRIPTION

S-FX 70

S-FX 125

S-FX 220

S-FX 320

Water flow rate ΔT 10

5.52

9.73

17.46

25.23

m3/h

Water flow rate ΔT 20

2.76

4.86

8.73

12.62

m3/h

Water flow rate ΔT 40

1.38

2.43

4.37

6.31

m3/h

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Strebel S-FX Installation, Operating & Maintenance Manual

Strebel S-FX Installation, Operating & Maintenance Manual

Strebel S-FX Installation, Operating & Maintenance Manual

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