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Read these instructions carefully before installation and operation of the heating system.

Installation Instructions

Stainless Steel Condensing Boiler

Buderus SB625WS/Buderus SB745WS

6 720 805 220-00.1T

DANGER!

The installation instructions included in this Manual are intended solely for 

use by a trained and certified installer, service company or the gas supply 
company. If the information in this manual is not followed, a fire or explosion 
may result causing property damage, personal injury, or death.



Have installation and service performed by a trained and certified 

installer or service company, or the gas supply company.



Bosch recommends signing a service and maintenance contract with a 

trained and certified installer or service company that covers annual 
servicing and condition-based maintenance. Proper maintenance is a 
fundamental requirement for safe and efficient operation and long 
service life.

The boiler must be serviced annually including the main burner, ignition 
burner, the entire venting system, and the combustion air supply. All 
parts that show any signs of damage or corrosion must be replaced.



Improper installation, adjustment, alteration, service, or maintenance 

can cause property damage, personal injury, or death. Refer to this 
manual and consult a trained and certified installer or service company, 
or the gas supply company before installation, service or maintenance.

The owner and operator is responsible for the operational safety and 

regulatory compliance of the heating system.

THIS MANUAL SHOULD BE HANDED TO THE OWNER AND OPERATOR OF 
THE APPLIANCE.

INSTALLER MUST REVIEW ALL SAFETY INSTRUCTIONS WITH THE 
OWNER AND OPERATOR.

UPON COMPLETION OF THE INSTALLATION THE INSTALLER MUST 
INSTRUCT THE OWNER AND OPERATOR ON THE FUNCTIONALITY AND 
THE PROPER OPERATION OF THE BOILER AND THE HEATING SYSTEM

Low temperature condensing boilers for gas/oil fired power burners

6 720 805 218 (201

3/

02

) en-us

Summary of Contents for Buderus SB625WS

Page 1: ...ent for safe and efficient operation and long service life The boilermustbeserviced annuallyincluding the mainburner ignition burner the entire venting system and the combustion air supply All parts that show any signs of damage or corrosion must be replaced Improper installation adjustment alteration service or maintenance can cause property damage personal injury or death Refer to this manualand...

Page 2: ...tion of door opening 20 5 3 2 Removing the hinge assembly B 23 5 4 Burners 23 5 5 Combustion gas exhaust 24 5 6 Venting Requirements 25 5 7 Code Required Vent Terminations 25 5 8 Combustion Air from outside the building 25 5 9 Combustion Air from an adjacent room 26 5 10 Condensate Removal 26 5 11 Condensate 26 5 11 1 Draining the condensate 26 5 11 2 Neutralizing the condensate 26 6 Commissioning...

Page 3: ...mpt to operate an appliance if any part of it is not in working order or is damaged Use only original spare parts The use of parts not supplied by the manufacturer may cause damage to the boiler other property and personal injury Also boiler damage caused by the use of unauthorized parts is not covered by the warranty DANGER Risk of fire when soldering and brazing Take appropriate protective measu...

Page 4: ...lectric shock Before removing the front panel disconnect the heating system from the electrical power supply by shutting off the emergency shutoff switch or the heating system circuit breaker It is not enough to switch off the control panel Power to the panel must be disconnected Ensure that the power is not restored unintentionally by following proper lock out tag out procedures Only qualified el...

Page 5: ...nd high temperature resistant stainless steel turbulators inside the tube bundle for maximum burner efficiency The boiler body is thoroughly insulated with a layer of high density glass wool The paint finished external paneling is also internally insulated with a layer of high density glass wool The boiler s front door and the flue gas chamber can be opened completely to facilitate the inspection ...

Page 6: ...before installation starts Where required by local regulations the system must comply with the AmericanSocietyofMechanicalEngineersSafetyCodeforControlsand Safety Devices for Automatically Fired Boilers ASME CSD 1 The local regulations regarding minimum pressure detectors and low water safety cutouts must be observed Installation and operation must comply with the device manufacturer s technical d...

Page 7: ... REQUIRED When the manufacturer of Product Approved side wall horizontally mounted gas equipment provides a venting system design or venting system components with the equipment the instructions provided by the manufacturer for the installation of the equipment and venting shall include Detailed instructions for the installation of the venting system or the venting system components and A complete...

Page 8: ...ipment For the installation and maintenance of the boiler standard tools are required as used for heating gas water and electrical installations 2 8 Data plate Serial number plate The serial number plate is located on the rear of the boiler block and specifies the serial number and model Data plate This lists the appliance s technical specifications and performance The data plate will be factory i...

Page 9: ...ar inch mm 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 1 9 16 40 F Flue connection depth inch mm 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 2 3 4 70 H Height of water fittings inch mm 52 3 4 1340 52 3 4 1340 57 1 16 1450 57 1 16 1450 66 3 4 1695 66 3 4 1695 75 1905 75 1905 80 5 16 2040 85 13 16 2180 H1 Boiler heigh...

Page 10: ...f flue gas side Ft3 dm3 8 93 253 9 78 277 14 58 413 17 02 482 26 03 737 30 37 860 45 55 1290 51 34 1454 62 25 1763 74 05 2097 Heat exchanger surface area Ft2 m2 65 65 6 1 94 72 8 8 139 93 13 0 175 45 16 3 234 65 21 8 310 00 28 8 426 25 39 6 500 52 46 5 604 93 56 2 670 37 62 2 Specific heat load MBH ft2 kw m2 8 28 26 18 8 04 25 40 7 07 22 32 7 29 23 01 6 99 22 08 7 06 22 29 6 42 20 26 7 29 23 01 7 ...

Page 11: ... inthe following table Fig 5 Water connections SB625WS 160 640 and SB745 800 1300 Fig 6 Water connections SB745WS 1550 M M 7 6 5 H A N B 8 F E D C 2 3 4 1 2 3 4 70 mm I G L O 8 6 720 805 218 18 1T M M 7 2 6 5 H I F G L O A N B E D C 2 8 3 4 1 6 720 805 218 19 1T P The choice of system components and the method of their installation are left up to the installer Installers must use their expertise t...

Page 12: ...ice fitting inch mm 11 1 4 285 11 1 4 285 11 13 16 300 17 3 4 450 23 5 8 600 27 9 16 700 29 1 2 750 33 1 2 850 33 1 2 850 33 1 2 850 E Distance between heating flow outlet and safety device fitting inch mm 15 3 4 400 15 3 4 400 17 3 4 450 21 1 16 535 21 11 16 550 23 13 16 605 27 9 16 700 33 1 2 850 39 3 8 1000 39 3 8 1000 F Distance between heating return 1 and flue gas outlet inch mm 10 5 8 270 1...

Page 13: ...1 Limescale deposits Limescale forms when the calcium and magnesium bicarbonates that are dissolved in the water at ambient temperature become chemically transformed when the water is heated Calcium bicarbonate forms calcium carbonate water and carbon dioxide while magnesium bicarbonate transforms into magnesium hydroxide and carbon dioxide Calcium bicarbonate Ca HCO3 2 when temperature is increas...

Page 14: ...signed to resist pressure from within but not to resist a vacuum within ensure that no part of the system is made from materials that are permeable to gases e g plastic pipes with no oxygen barrier used in floor heating systems The heating system should not need any further topping up once it is filled and bled of all air Any top ups need to be monitored bya meter treated and recorded in the heati...

Page 15: ...e designed and installed so that all gases can be vented quickly easily and effectively 3 6 Use of Antifreeze In areas where freezing may occur an antifreeze may be added to the system water as protection Please adhere to the specifications provided by the antifreeze manufacturer Use the anti freeze manufacturer s data to determine the anti freeze ratio for the desired freeze protection temperatur...

Page 16: ...d bearing Lift up very carefully Maintain less than a 45 degree angle with the vertical when lifting the boiler with chains or cables The rigging crane must be operated by trained personnel Fig 8 Transport WARNING Risk of injury from carrying heavy loads and inadequately securing loads for transport Use suitable means of transportation e g several pallet trucks a forklift truck crane or heavy duty...

Page 17: ...to facilitate draining of condensate to a neutralization system The boiler base must be flat and levelled The boiler condensate drain must be located above the height of the lid of the system s condensate neutralizer The gas supply pipe should be installed in such away that the boiler s paneling can be removed and the front door opened without having to remove the burner A1 B1 B2 B1 D B2 A2 6 720 ...

Page 18: ... 00 915 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 D inch mm 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 36 00 915 Minimum Service A1 inch mm 24 00 610 24 00 610 24 00 610 24 00 610 24 00 610 24 00 610 24 00 610 24 00 610 24 00 610 24 00 610 A2 inch mm 64 00 1626 64 00 1626 64 00 1626 64 00 1626 64 00 1626 64 00 1626 64 00 1626 64 00 1626 64 00 ...

Page 19: ...anel 7 Side panel 8 Front side panel 9 Front trim panel 10 Boiler frame 11 Front trim panel 12 Front side panel 13 Side panel 14 Rear side panel 15 Bottom rear bracket 16 Bottom rear panel 17 Top rear panel 18 Bottom rear panel 19 Top cross beams 1 2 3 4 5 8 7 6 9 11 12 13 14 15 16 17 19 10 10 18 6 720 805 218 32 1T ...

Page 20: ...nal requirements System A on the smaller sizes comes with a bracket and two hinge fixing nuts System B on the larger sizes comes with a hinge fixing plate a nut and an internal compression spring Fig 11 Door hinging systems 5 3 1 Changing the direction of door opening The boiler door hinges are factory fitted on the right of the door If you need to reverse the direction of opening remove the boile...

Page 21: ...door With the aid of a small hacksaw or a file remove the knockout on the side opposite the leading edge of the door both top and bottom Fig 16 Remove the knockout Seal the door by tightening the bolts 2 so that the door is self supported by compression against the packing Fig 17 Seal the door 1 Plug 2 Bolt Reverse the above steps to fit the door on the opposite side 6 720 805 218 48 1T 4 6 720 80...

Page 22: ...4 Remove the nuts 4 that secure the hinge plate 5 to the door Remove the plate Remount the hinge plate on the opposite side ensuring that the cylinder projecting above the nut 6 enters into its slot If necessary tighten the nut 6 to raise it Tighten the bolt 3 Fig 19 Changing the door opening system B 2 Bolt 3 Bolt 4 Nut 5 Hinge plate 6 Nut 6 720 805 218 49 1T 2 2 4 4 3 3 6 5 6 4 6 720 805 218 30 ...

Page 23: ...der to fit the burner blast tube The installer must cut the hole 3 8 larger than the blast tube diameter Thecombustionchamberdoormustbeopenedtoallowtheburnertobe mounted Fig 21 Burner A Ceramic insulation shipped loose L Minimum length Ø Diameter A 1 3 2 6 720 805 218 31 1T A pre drilled burner plate is included with the boiler vessel When you finish installing the burner fill the gap between the ...

Page 24: ...st be installed at a slope of at least 2 towards the boiler All condensate should be treated through a neutralization media before being eliminated to the floor drain Fig 22 Typical installation schematic H ø i 6 720 805 218 26 1T Description Symbol Unit SB625WS SB745WS 160 220 290 370 480 640 800 1050 1300 1550 Height of flue gas outlet H inch mm 19 7 8 505 19 7 8 505 21 1 2 545 21 1 2 545 25 3 8...

Page 25: ...ed areas corners or directly behind vegetation Vertical Terminations Roof penetrations should follow all appliance codes and the vent manufacturer sinstructions Theventshouldneverbeinstalledatless than the required clearances to combustible materials per UL NFPA and local codes Double wall or thimble assemblies are required when penetrating combustible walls and roofs Vertical discharges should ex...

Page 26: ...arge to the neutralization system Care should be taken to avoid kinks and from raising the drain line above the trap assembly 5 11 Condensate 5 11 1 Draining the condensate Condensing boilers produce a flow of condensate that varies according to operating conditions Themaximum hourly productionofcondensate is shown in the technical specifications table for each individual model Thecondensatedrains...

Page 27: ...oiler and flue gas stack together using a T union and connect the leg of the T to the inlet of the neutralization unit NOTICE The boiler room s condensate drain pit must be located at a lower level than the fitting on the neutralization unit NOTICE All connecting hoses must be kept as straight and as shortaspossible Any curves or sharp bends can lead to the hoses becoming clogged and can therefore...

Page 28: ...e adequate ventilation Never use or store chlorinated cleaning agents or halogenated hydrocarbons as contained in spray cans solvents or cleaning agents paints and adhesives for example in the boiler room A burner contaminated during building work must be cleaned before commissioning All cover plates enclosures clean out ports and guards must be in place at all times except during maintenance and ...

Page 29: ...nector 2 Restrictthewaterflowrateintheboilertoatemperaturedifferenceof at least 7 K between supply and return Size the pumps correctly Before connecting the boiler flush sludge and dirt out of the heating system Ensure that no oxygen enters the heating water during operation Only operate the boiler in sealed unvented systems 6 3 Hydraulic flow through boiler The SB Series does not require a minimu...

Page 30: ...tric shock Before opening the boiler isolate the heating system acrossalllifephasesandsecureagainstunintentional reconnection Carefully route the cables leads and capillary tubes Ensure that capillaries are never kinked Only carry out electrical work if you are a competent person If you are not suitably qualified arrange for a qualified electrician to make the electrical connections Observe local ...

Page 31: ...hing the heating system To prevent contamination in the boiler flush the heating system prior to commissioning Flush the system prior to connection to the boiler or Isolate the heating flow and return at the boiler Connect the heating flow to a water connection Connect hose to the heating return of the heating system Route hose from the heating return to a drain Open connected consumers e g radiat...

Page 32: ...k that the inspection aperture on the flue gas collector is closed Check that the combustion chamber door is securely closed Check that the safety equipment e g safety valve minimum and maximum pressure limiters high limit safety cut out is functioning correctly Check that the required operating pressure has been achieved Check the flange connections and other connections for tightness Check the c...

Page 33: ...tightness 8 Start the burner 9 Complete the burner test report regarding the individual output stages 10 Conduct a tightness test on the hot gas side After a short time in operation tighten the screws in the combustion chamber door to prevent leakage around the door as a result of the packing cord settling 11 Check the flange connections and fitting after the boiler has been heated up and retighte...

Page 34: ... through frost Whenthereisafrost theheatingsystemcanfreezeupif it is not operational e g because of a fault shutdown When there is a risk of frost protect your heating system against freezing up Ifyourheatingsystemhasbeenshutdownforseveral days due to a fault shutdown and there is a risk of frost drain the heating water at the drain fill valve Also leave the air vent valve at the highest point in ...

Page 35: ...e that the safety bolts 1 on the side of the boiler are tight Fig 32 Tighten safety bolts 1 Safety bolts System A and B Remove the main fixing bolts Fig 33 2 holding the door in place 8 2 2 Adjusting the door Make sure that the door presses uniformly all around the double seal to prevent dangerous fumes escaping into the air Proceed as follows to adjust the door seals System A Fitthedoorandtighten...

Page 36: ...er suitable tool to clean inside the combustion chamber and the flue gas pipes Fig 35 Clean the boiler 1 Door 2 Turbulator 3 Flue brush Open the inspection port 3 and clean out any deposits from inside the flue gas box If more thorough cleaning is required Remove the outer panels Unscrewthe eight fixingboltsand pull firmlyonthefluegasbox 1 to remove it from the boiler Check at regular intervals th...

Page 37: ...e installation engineer when the system was first commissioned 8 4 2 Sealed unvented systems Forsealedunventedsystems thepressuregaugeneedleshouldbenear themidpointofthegauge Theredneedleofthepressuregaugemustbe set to the pressure required for the heating system Check the heating system water pressure Top up with water via the filling valve in the heating system pipework Vent the heating system C...

Page 38: ...lace if required 6 Check and clean the burner Visual inspection and remove any contamination Check all safety equipment safety shutdown Function check Flue gas analysis with test report for each output stage See technical burner documentation 7 Check the flue for function and safety See flue manufacturer documentation 8 Check the hydraulic seal of the condensate siphon and replace if required 9 Ch...

Page 39: ...Inspection and maintenance 39 6 720 805 218 2013 02 SB625WS SB745WS Confirm professional inspection with signature date and company stamp Table 17 ...

Page 40: ... 11 Probe holder sump 7738003155 x x x 12 Probe holder sump 7738003156 x x x 13 Sump spring 7738003154 x x x 14 Gasket rear inspection door 7738003103 x x x 15 Flue collector gasket 7738003104 x x 15 Flue collector gasket 7738003105 x 16 Flue collector 7738003111 x x 16 Flue collector 7738003112 x 17 Flue gas outlet o ring 7738003117 x x 17 Flue gas outlet o ring 7738003118 x 18 Insulation blanket...

Page 41: ...Spare parts 41 6 720 805 218 2013 02 SB625WS SB745WS Fig 38 Spare parts SB625WS 160 220 290 6 720 805 218 54 1T 22 22 22 22 2 3 5 6 4 13 11 11 13 21 1 25 27 7 8 20 22 18 19 24 22 15 16 14 12 22 13 17 ...

Page 42: ... Sump spring 7738003154 x x x 14 Gasket rear inspection door 7738003103 x x x 15 Flue collector gasket 7738003105 x 15 Flue collector gasket 7738003106 x x 16 Flue collector 7738003112 x 16 Flue collector 7738003113 x x 17 Flue gas outlet o ring 7738003118 x 17 Flue gas outlet o ring 7738003119 x x 18 Insulation blanket 7738003125 x 18 Insulation blanket 7738003126 x 18 Insulation blanket 77380031...

Page 43: ...Spare parts 43 6 720 805 218 2013 02 SB625WS SB745WS Fig 39 Spare parts SB625WS 370 480 640 6 720 805 218 55 1T 5 6 4 11 21 1 25 27 7 8 20 18 24 15 16 13 17 22 22 22 22 22 22 2 3 11 13 1213 14 19 ...

Page 44: ... x x 14 Gasket rear inspection door 7738003164 x x x x 15 Flue collector gasket 7738003107 x x 15 Flue collector gasket 7738003109 x 15 Flue collector gasket 7738003110 x 16 Flue collector 7738003114 x x 16 Flue collector 7738003115 x 16 Flue collector 7738003116 x 17 Flue gas outlet o ring 7738003120 x x 17 Flue gas outlet o ring 7738003108 x 17 Flue gas outlet o ring 7738003122 x 18 Insulation b...

Page 45: ...are parts 45 6 720 805 218 2013 02 SB625WS SB745WS 26 Flue brush 7738003059 x x 28 Sealing rope 7738003166 x x x x Item no Article number 800 1050 1300 1550 Table 20 Spare parts SB745WS 800 1050 1300 1550 ...

Page 46: ...s SB625WS SB745WS 6 720 805 218 2013 02 Fig 40 Spare parts SB745WS 800 1050 1300 1550 6 720 805 218 56 1T 5 6 21 1 25 7 8 20 18 19 22 15 16 14 13 17 26 22 22 22 22 22 22 3 2 4 28 22 22 22 22 14 12 12 13 11 13 11 13 ...

Page 47: ...rcuit Check the vent valve The boiler has reached the set temperature but the radiators are still cold Air in the circuit Bleed the circuit Pump malfunctioning Check release the pump Problem with minimum temperature aquastat if present Check the temperature setting There is a smell of fumes Fumes are escaping into the air Check that the boiler body is clean Check that the flue pipes are clean Chec...

Page 48: ...hered to To protect the environment we use the best possible technology and materials taking into account economic points of view Packaging For the packaging we participate in the country specific recycling systems which guarantee optimal recycling All packaging materials used are environmentally friendly and recyclable Old appliances Old appliances contain resources that should be recycled The co...

Page 49: ...um total of all the calcium and magnesium salts dissolved in it The temporary hardness value expresses the sum total only of calcium and magnesium bicarbonates Hardness is expressed in mg kg of CaCO3 or in degrees French 1 fr 10 mg kg CaCO3 The use of hard water without suitable treatment can lead to the formation of limescale Alkalinity M alkalinityortotalalkalinityrepresentsthesumtotalofallalkal...

Page 50: ...mple of water for testing bleed the sampling system for 5 minutes to eliminate any oxides or other materials in suspension that might have accumulated in it The sample container must likewise by made from an inert material compatible with the sample collected e g glass or polyethylene Wash any containers thoroughly in the water to be sampled before actually taking the sample Ordinary analysis and ...

Page 51: ... 51 6 720 805 218 2013 02 SB625WS SB745WS Notes ...

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