Buderus SB735 Series User manual

6302 2319 – 10/2003 US/CA For the user
Please read carefully before use.
Operating Instructions
Condensing Gas Boiler SB735
Series

Preamble
2
We reserve the right to make any changes due to technical modifications.
Operating Instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
To these instructions
These operating instructions contain important
information for the safe and correct operation and
maintenance of the condensing gas boiler SB735.
Subject to technical modifications.
Constant development may lead to minor deviations of
illustrations, functional steps and specifications from
those described/shown.
Updating your documentation
Pleaseletusknowifyouwouldliketo make suggestions
to improve our documentation, or if you have noticed
any errors.
Correct fuel
This system requires the correct fuel to ensure a proper
operation. During commissioning, your system installer
will enter the correct type of fuel, which your system
requires, into the table below.
This device meets all basic requirements of
relevant standards and guidelines.
Its conformity has been verified. All
associated documents and the original
Declaration of Conformity are available
from the manufacturer.
CAUTION
SYSTEM DAMAGE
through incorrect fuel.
zOnly use the correct fuel identified for
your system.
USER NOTE
We recommend you seek the advice of
your system installer if you intend
changing the fuel for your system.
Use the following fuel:
company stamp/date/signature

Index
3
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
1 For your safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.1 Correct use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.2 Notes structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.3 Please observe these safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.3.1 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.3.2 Working on the heating system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2 Product description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3 Using correct fill and make-up water . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.1 Water description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.2 Water quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4 System start-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
4.1 Making the system operational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
4.2 Commissioning the control device and the burner. . . . . . . . . . . . . . . . . . . . . . . .9
5 System shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1 Shutting down the control device and burner. . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2 Shutting down the system in an emergency . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Correcting burner faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 System maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1 Why is regular maintenance important? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.2 Checking and correcting the water pressure . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2.1 When do you need to check the water pressure in your heating system? . . . . . . . . . . . . 13
7.2.2 Open systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.2.3 Sealed systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

For your safety1
4
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
1 For your safety
TheSB735,condensing gas boiler,has been developed
and built employing the latest technologies and safety
regulations.
Ease of operation was given particularly high priority.
Please observe the safety and operator’s instructions to
ensure optimum safe, economical and environmentally-
friendly utilisation of your system.
1.1 Correct use
The SB735 condensing gas-fired boiler was designed
for heating domestic hot water and, for example, the
central heating of multi-occupancy buildings, as well as
public and commercial buildings.
1.2 Notes structure
Two levels of danger are identified and signified by
symbols:
1.3 Please observe these safety
instructions
Incorrect operation of SB 735 boilers may lead to
material losses.
zOnly operate the boiler as intended and when it is in
perfect condition.
zLet a heating contractor install and maintain your
heating system.
zLet your local heating contractor train you properly in
the use of this system.
zPlease read these operating instructions carefully.
WARNING!
DANGER TO LIFE
Identifies possible dangers emanating
froma product, which might lead to serious
injury or death, if appropriate care is not
taken.
CAUTION!
DANGER OF INJURY/
SYSTEM DAMAGE
Points to a potentially dangerous
situation, which might lead to medium or
slight injuries or to material losses.
USER NOTE
User tips for the optimum utilisation and
setting of the equipment plus useful
information.
WARNING!
DANGER TO LIFE
through the explosion of volatile gases.
There is a risk of explosion if you can smell
gas.
zKeep open flames away. Do not
smoke. Do not use lighters.
zAvoid sparks!
Do not operate electrical switches, incl.
telephone, plugs or door-bells.
zClose the main gas shut-off valve.
zOpen windows and doors.
zWarn all occupants, but do not use
doorbells.
zLeave the building.
zCall your gas supplier and your local
heating engineer from outside the
building.
zIf necessary, notify police or fire
services.
zImmediately leave the danger zone if
you hear gas streaming out.

For your safety 1
5
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
1.3.1 Location 1.3.2 Working on the heating system
WARNING!
Danger to life
through poisoning.
Insufficient ventilation can lead to
dangerous flue gas leaks.
zEnsure that the ventilation and exhaust
air openings are neither restricted nor
closed.
zTheboilermustnotbeoperated,unless
you immediately remedy the fault.
WARNING!
Risk of fire
through flammable material or liquids.
zNever store flammable materials or
liquids in the immediate vicinity of the
heat generator.
CAUTION!
Boiler damage
through contaminated combustion air.
zNever use chlorinated cleaning agents
or halogenated hydrocarbons (as, for
example, contained in spray cans,
solvents or cleaning agents, paints and
adhesives).
zAvoid frequent very dusty
atmospheres.
zNever hang laundry to dry in the boiler
room.
CAUTION!
System damage
through frost.
zEnsure that the boiler room is always
free from frost.
WARNING!
Danger to life
through the explosion of volatile gases.
zEnsurethattheinstallation,thegasand
flue gas connections, the initial start-
up,thepowerconnection,maintenance
and repair work are only carried out by
competent specialists.
zEnsure that work on parts of the gas
installation are only carried out by a
licensed specialist.
CAUTION!
System damage
through inadequate cleaning and
maintenance.
zHave your system inspected, cleaned
andmaintainedannuallyby a specialist
contractor.
zWe recommend you enter into a
contract covering an annual inspection
and maintenance on a "as-required-
basis".

6
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
Product description2
2 Product description
The following are components of the SB735,
condensing gas-fired boiler (Fig. 1):
–Boiler block (Fig. 1, item 5) incl. thermal insulation
and burner door (Fig. 1, item 4).
The boiler block transfers the heat generated by the
burner to the heating water. The burner door is
designed to carry the burner and to close the
combustion chamber.
–Boiler jacket (Fig. 1, item 3), thermal insulation and
boiler front walls (Fig. 1, item 1).
The boiler shell and thermal insulation prevent
energy loss.
–Control device (Fig. 1, item 2) (Optional).
Thecontroldeviceisdesigned to monitor and control
all electrical components of the SB735.
Fig. 1 SB735, condensing gas-fired boiler
Item 1: Boiler front walls
Item 2: Control device
Item 3: Boiler jacket panel
Item 4: Burner door
Item 5: Boiler block
2
3
1
4
1
3
5

Using correct fill and make-up water 3
7
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
3 Using correct fill and make-up water
This chapter contains general information about the
water in your heating system.
Observe the basic, system-specific requirements for
water quality in Chapter 3.2 "Water quality".
3.1 Water description
In your heating system, water is used as heat transfer
medium.Waterisgivendifferentdescriptionsdepending
on its purpose.
–Heating water:
Water contained within your heating system.
–Fill water:
Water used for the first filling of your system before
commissioning.
–Make-up water:
Water used for the re-filling your system in case of
water losses.

8
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
Using correct fill and make-up water3
3.2 Water quality
All water contains substances, e. g. Ca (HCO3)2
(calcium hydrogen-carbonate), which may influence the
function of your heating system. These may lead to
corrosion, scaling and other deposits.
Regularly check your water consistency and, if
necessary, treat your fill and make-up water, to ensure
that your heating system remains economic, functional,
operationally reliable and energy efficient.
Observe the following table regarding the correct use
and treatment of the fill and make-up water.
This table is an extract from the Code of Practice K8
"Water treatment for hot water heating systems" and the
VDI 2035 "Water treatment guideline".
CAUTION!
SYSTEM DAMAGE
through corrosion and scaling because of
fill and make-up water, which does not
comply with system-specific requirements.
zCheck with your local heating
contractor or your water supply
company regarding the Ca (HCO3)2
concentration (calcium hydrogen-
carbonate) in your area.
zYou should treat the fill and make-up
water,if it does notcomply with system-
specific requirements. In such cases
contact your local heating contractor.
Total rated boiler
output in MBH Ca (HCO3)2 concentration in mol/m³ Maximum fill and make-up water volume Vmax in m³ Heating water pH value
300 < Q ≤ 1600 ≤ 2.0 V max = three times the system volume 8.2–9.5
1601 < Q ≤ 3500 ≤ 1.5
300 < Q ≤ 1600 > 2.0 8.2–9.5
1601 < Q ≤ 3500 > 1.5
Table. 1 Requirements of filling, make-up and heating water
Vmax 0 0313 QkW()
Ca HCO3
()
2mol
m3
----------
⎝⎠
⎛⎞
-------------------------------------------------
⋅,=

System start-up 4
9
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
4 System start-up
This chapter explains how you prepare the system for
operationand howto commission the control device and
the burner.
4.1 Making the system operational
Youshouldcheckthefollowingto preparethesystem for
operation:
zthe system water pressure see Chapter 7.2
"Checking and correcting the water pressure",
page 13),
zwhether the main fuel supply shut-off valve is open,
zwhether the heating system emergency stop switch
has been activated or the boiler room fuse is
inserted.
Let your specialist show you where the fill valve is
located in the pipework of your system (return).
4.2 Commissioning the control device
and the burner
Start up your boiler via the control device (in this
example(Fig. 2):2000seriesLogamaticcontroldevice).
By commissioning the control device, you also
automatically commission the burner. The burner can
then be started via the control device. For further details
in this connection, see the operating instructions of the
relevant control device or burner.
zSwitch the boiler water thermostat (Fig. 2, item 1) to
"AUT".
zSet the On/Off switch (Fig. 2, item 2) to "I" (ON).
Fig. 2 2000 series Logamatic control device
Item 1: Boiler water thermostat
Item 2: On/Off switch
12
USER NOTE
zPlease observe the operating
instructions of the control device.

System shutdown5
10
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 102003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
5 System shutdown
This chapter explains, how you shut down your boiler,
the control device and burner. Furthermore, you will find
explanations as to how you can shut down your system
in emergencies.
zShutoff the fuel supply atthe main fuel shut-off valve.
5.1 Shutting down the control device and
burner
Shut down your boiler via the control device. The burner
is automatically shut down when the control device is
shut down.
zSet the On/Off switch (Fig. 2, page 9) to "0" (OFF).
5.2 Shutting down the system in an
emergency
In other dangerous circumstances, isolate the main fuel
shut-off valve and the electrical power supply of the
system via the boiler room main fuse or the emergency
stop switch for the boiler room (see Chapter 1.3 "Please
observe these safety instructions", page 4).
CAUTION!
SYSTEM DAMAGE
through frost.
The system can freeze up if it is out of use,
e.g. through a shut-down because of
fault(s).
zProtect your heating system against
frost damage, where temperatures
below freezing are expected.
zDrain the heating water at the lowest
point in the system, using the boiler
drain. To do this, open the air vent
valve at the highest point in the system.
USER NOTE
For further details in this connection, see
the operating instructions of the relevant
control device.
USER NOTE
zOnly in an emergency, shut off the
system via the boiler room fuse or
heating system emergency stop switch.

Correcting burner faults 6
11
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
6 Correcting burner faults
Heating system faults are indicated in the control device
display(Fig. 3, item 2). You willfinddetailed information
regarding fault displays in the operating instructions of
the respective control device. In addition, if the burner
develops a fault, a fault lamp on the burner and an
indicator on the (Fig. 3, item 1) control device may
illuminate.
zPress the burner reset button (see burner operating
instructions).
See the technical burner documentation for information
regardingthe resettingoftheburner, iftheburnerwillnot
start after three attempts.
Fig. 3 Burner fault indication
Item 1: Indicator lamp
Item 2: Display
21
CAUTION!
SYSTEM DAMAGE
through frost.
The system can freeze up if it is out of use,
e.g. through a shut-down because of
fault(s).
zYou should drain the heating water via
theboiler drain atthelowest pointinthe
system, to protect it against freezing, if
the system remains switched off for
several days because of a fault shut
down.
CAUTION!
SYSTEM DAMAGE
through too frequent activation of the reset
button.
The burner ignition transformer may be
damaged, if you press the reset button
more than three times in succession, after
the burner refuses to start.
zDo not attempt to clear a fault more
thanthreetimesinsuccessionbyusing
the reset button.

12
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
System maintenance7
7 System maintenance
This chapter explains, why regular maintenance is
important for your system. It will also indicate to you,
how you can check and regulate the water pressure.
Observe the separate maintenance instructions for
maintenance work on the neutralising system. Only
specialists should carry out work on the neutralising
system.
7.1 Why is regular maintenance
important?
You should have your system regularly serviced for the
following reasons:
–to maintain the highest level of efficiency and to
operate the system economically (low fuel
consumption),
–to achieve a high level of operational reliability,
–to maintain the highest level of environmentally
responsible combustion.
CAUTION!
SYSTEM DAMAGE
through inadequate cleaning and
maintenance.
zHave your system inspected, cleaned
andmaintainedannually by a specialist
contractor.
zWe recommend you enter into a
contract covering an annual inspection
and maintenance on an "as-required-
basis".

System maintenance 7
13
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
7.2 Checking and correcting the water pressure
Your heating system must contain sufficient water to
ensure the safe and correct function of your system.
Fill make-up water into your system, if the system
pressure is too low (see Chapter 3 "Using correct fill and
make-up water", page 7).
7.2.1 When do you need to check the water
pressure in your heating system?
–Recently filled in make-up water loses much of its
volume in the first few days because it releases
gases. With new systems therefore check the water
pressure in your heating system initially on a daily
basis, and then after increasing intervals.
–Check the water pressure monthly, if the heating
system still loses volume.
CAUTION!
SYSTEM DAMAGE
through frequent re-filling.
The system may be damaged, depending
on water quality, by corrosion or scaling, if
you frequently need to re-fill your system
with make-up water.
zEnquire from your local heating
contractor whether you can use your
public water untreated or whether you
need to treat it before filling your
system.
zNotify your local heating contractor if
you need to regularly add make-up
water to your system.
USER NOTE
Air pockets may form through the fill or
make-up water releasing gases.
zVentthe system viatheradiatorsand,if
required, replenish the system with
make-up water.

14
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
System maintenance7
Systems are generally designated as open or sealed
systems. Open systems are now rarely installed.
Therefore, a sealed system is used as an example of
how you can check the water pressure.
The specialist will have carried out all initial settings
during commissioning.
7.2.2 Open systems
On open systems the pressure gauge needle (Fig. 4,
item 1) must be within the red range (Fig. 4, item 3).
7.2.3 Sealed systems
On sealed systems the pressure gauge needle (Fig. 5,
item 2) must be within the green range (Fig. 5, item 3).
Set the red needle (Fig. 5, item 1) on the pressure
gauge to the required system pressure.
zCheck the system water pressure.
zThe water pressure in the system is too low, if the
pressure gauge needle falls below (Fig. 5, item 2)
the green range (Fig. 5, item 3). Re-fill the heating
system with make-up water (see Chapter 3 "Using
correct fill and make-up water", page 7).
zFill make-up water through the fill cock in the heating
system pipework (return).
zVent the heating system.
zRe-check the water pressure.
Fig. 4 Pressure gauge for open systems
Item 1: Pressure gauge needle
Item 2: Green needle
Item 3: Red marking
1
2
3
Fig. 5 Pressure gauge for sealed systems (in bars)
Item 1: Red needle
Item 2: Pressure gauge needle
Item 3: Green marking
3
1
2
CAUTION!
SYSTEM DAMAGE
through frequent re-filling.
The system may be damaged, depending
on water quality, by corrosion or scaling, if
you frequently need to re-fill your system
with make-up water.
zEnsure that your heating system is
adequately vented.
zCheckthe heatingsystemforleaks and
the function of the expansion vessel.

Notes
15
We reserve the right to make any changes due to technical modifications.
Operating instructions condensing gas boiler Logano plus SB735 • Issue 10/2003
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de

BBT North America Corporation
50 Wentworth Avenue
Londonderry, NH 03053
Tel: [phone] ● Fax: [phone]
www.buderus.net
BBT North America Corporation reserves the right to make changes without notice
due to continuing engineering and technological advances.
Heating Contractor:
PRODUCTS MANUFACTURED BY
BBT Thermotechnik GmbH
35573 Wetzlar
www.buderus.de