Buderus Logano GC124 II/SP Quick guide

7 747 000 512 – 07/2006 US For installers
Please read carefully prior to installation and maintenance.
Installation and Service
Instructions
Gas boiler
Logano GC124 II/SP
CAUTION!
Before placing this boiler in operation
observe the safety instructions of this
installation and maintenance manual.
WARNING!
Installation, adjustment, modification,
operation or maintenance of the
heating system carried out by
unqualified personnel may result in
property damage, personal injury, and
loss of life.
The directions of this installation and
maintenance manual must be followed
precisely.
Contact a qualified service company,
service provider or the gas company if
support or additional information is
required.
CAUTION!
The operating manual is a component
of the technical documentation handed
over to the operator of the heating
system. Discuss the instructions in this
manual with the owner or operator of
the heating system and ensure that
they are familiar with all information
required for operation of the heating
system.
In the Commonwealth of
Massachusetts this boiler must be
installed by a licensed plumber or gas
fitter.
Keep this installation and maintenance manual available for future
reference.

Summary
2Installation and Service Instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
1 Safety considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Correct use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Observe the following symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Observe the following guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Tools, materials and accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Product Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Dimensions and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Moving the boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1 Moving the boiler with boiler cart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2 Lifting and carrying the boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6 Placing the boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1 Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.2 Leveling the boiler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7 Boiler installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1 Preparing for installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2 Connecting the heating system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.3 Electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.4 Fuel gas supply connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.5 Filling heating system and checking for leaks . . . . . . . . . . . . . . . . . . . . . . . . . 20
8 Check openings for combustion air supply and venting . . . . . . . . . . . . . 22
9 Requirements for connection to chimneys or venting systems . . . . . . . 23
10 Flue pipe installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
11 Placing the heating system in operation . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.1 Starting up the GC124 II and GC124 SP boilers . . . . . . . . . . . . . . . . . . . . . . . 29
12 Final start-up procedures for GC124 II models . . . . . . . . . . . . . . . . . . . . 30
13 Final start-up procedure for GC124 SP models . . . . . . . . . . . . . . . . . . . . 35
14 Start-up protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
14.1 Informing the owner/operator and handing over technical documentation . . . . . . . 41
15 Taking the heating system out of operation . . . . . . . . . . . . . . . . . . . . . . 42
15.1 Normal system shut-down. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
15.2 Emergency shut-down procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Summary
3
We reserve the right to make any changes due to technical modifications.
Installation and Service Instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
16 Boiler inspection and maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
16.1 Why is regular maintenance important? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
16.2 Testing the flue system, including combustion air, air inlets and
Ventilation openings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
16.3 Inspection of the boiler and burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
16.4 Preparing boiler for cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
16.5 Cleaning the boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
16.6 Cleaning the burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
16.7 Maintenance protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
16.8 Troubleshooting the GC124 II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
16.9 Troubleshooting the GC124 SP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
17 Parts lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
18 Technical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
19 Electrical circuit diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Safety considerations1
4Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
1 Safety considerations
Observe these instructions for your safety.
The burner and control must be correctly installed and
adjusted to ensure safe and economical operation of the
gas boiler.
Read this installation and maintenance manual carefully
and note the details on the boiler nameplate before
placing the boiler in operation.
1.1 Correct use
The Logano GC124 II/SP atmospheric gas boiler is
designed to heat water for a hot water heating system
for heating single or multiple occupancy buildings.
1.2 Observe the following symbols
Two levels of danger are identified and signified by the
following terms:
Additional symbols for identification of dangers and user
instructions:
1.3 Observe the following guidelines
1.3.1 National regulations
The heating system must comply with the relevant
regulations issued by national authorities, or the
regulations issued by the National Fuel Gas Code, ANSI
Z 223.1.
If specified by the local regulatory authorities the heating
system must comply with the regulations of the
"Standard for Controls and Safety Devices for
Automatically Fired Boilers," ANSI/ASME CSD-1.
Carbon monoxide detectors must be installed as
specified by the local regulations. The boiler must be
serviced annually (ÎChapter 16, page 43).
Boiler Operating Conditions
The hot water piping system must comply with the
current legislation and local regulations. If an existing
boiler is replaced, the complete hot water piping system
must be inspected to ensure that it is in perfect condition
to ensure safe operation.
WARNING!
RISK TO LIFE
Identifies possible dangers originating from
the product, which might lead to serious
injury or death if proper care is not taken.
CAUTION!
RISK OF INJURY
SYSTEM DAMAGE
Identifies potentially dangerous situations,
which might lead to medium or minor
injuries or to material losses if proper
caution is not followed.
WARNING!
RISK TO LIFE
from electrical shock.
USER NOTE
Guidelines for the optimum use and
setting of the control(s) plus other useful
information.
Maximum boiler temperature: 220 °F
Maximum operating pressure: 58 psi
WARNING!
RISK TO LIFE
due to neglecting your own safety in case
of emergency, such as with a fire.
zNever put yourself at risk. Your own
safety must always take priority.
WARNING!
RISK TO LIFE
from explosion of flammable gases.
If you smell gas there is a danger of
explosion.
zNever work on gas lines unless you are
licensed for this type of work.
zMake sure that a qualified company
installs the boiler, connects gas and
ventplaces the boiler in operation,
connects the electrical power, and
maintains and repairs the boiler.
zNo open flame! No smoking! Do not
use lighters
zPrevent spark formation. Do not
operate electrical switches, including
telephones, plugs or door bells.
zClose main gas valve.
zOpen doors and windows.
zWarn other occupants of the building,
but do not use door bells.
zCall gas company from outside the
building.
zIf gas can be heard escaping, leave the
building immediately, prevent other
people from entering, notify police and
fire departments from outside the
building.

Safety considerations 1
5
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
1.3.2 Installation notes
1.3.3 Information on the boiler room
CAUTION!
SYSTEM DAMAGE
due to incorrect installation.
zObserve all current standards and
guidelines applicable to the installation
and operation of the boiler heating
system as applicable in your state or
local jurisdiction.
WARNING!
RISK TO LIFE
from electrical shock.
zDisconnect the power supply to the
boiler heating system before
conducting any work on it, e.g. turn off
the heating system emergency switch
outside the boiler room.
zIt is not sufficient just to turn off the
control.
CAUTION!
SYSTEM DAMAGE
due to unsatisfactory cleaning and boiler
maintenance.
zClean and service the boiler system
once a year. Check that the complete
heating system operates correctly.
zImmediately correct all faults to prevent
system damage.
USER NOTE
Only use original Buderus spare parts.
Losses caused by the use of parts not
supplied by Buderus are excluded from the
Buderus warranty.
WARNING!
RISK TO LIFE
from explosion of flammable gases.
zNever work on gas lines unless you are
licensed for this type of work.
WARNING!
RISK TO LIFE
from electrical shock.
zDo not carry out electrical work unless
you are qualified for this type of work.
zBefore disconnect electrical power
completely and pad lock to prevent
accidental reconnection.
zObserve the local installation
regulations.
WARNING!
RISK TO LIFE
by poisoning.
Insufficient ventilation or combustion air
availability may cause dangerous flue gas
leaks or formation.
zMake sure that inlets and outlets are not
reduced in size or closed.
zIf faults are not corrected immediately,
the boiler must not be operated until all
faults have been corrected.
zInform the system operator and/or
owner of the fault and the danger in
writing.
WARNING!
RISK TO LIFE
by poisoning.
When working on the flue gas venting
equipment or vent damper leakage of flue
gases may endanger the lives of people.
zCarefully observe proper operation of
the vent damper. Do not start up the
boiler unless the vent damper is
operating properly.
zUse only original parts when replacing
parts.
zWhen replacing the vent damper, install
the new one in the specified position.
WARNING!
RISK TO LIFE
by poisoning by spillage of flue gases.
If the blocked vent switch, attached to the
open draft hood in the rear of the boiler
trips frequently, there may be a problem
with the chimney or the flue gas venting
system.
zIf the blocked vent switch trips
frequently the fault must be corrected
and proper operation of the blocked
vent switch test must be conducted.
WARNING!
RISK TO LIFE
by poisoning by leakage of flue gases.
zMake sure that the boiler is not
equipped with a thermally controlled
flue gas vent damper after the open
draft hood.

Safety considerations1
6Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
1.4 Tools, materials and accessories
You need standard tools for the installation and
maintenance of the boiler as used in boiler heating
system installation and oil, gas and water installations.
The following additional items will also be useful:
–Boiler cart with strap.
–Cleaning brushes and/or chemical cleaning agents
for wet cleaning of the cast iron heat exchanger.
1.5 Disposal
zDispose of the packaging material in an
environmentally prudent fashion.
zDispose of any components of the heating system
that require replacement in an environmentally
prudent fashion.
WARNING!
FIRE DANGER
due to flammable materials or liquids.
zMake sure that there are no flammable
materials or liquids in the immediate
vicinity of the boiler.
zMaintain a minimum distance of 15
inches from the boiler.

Product Description 2
7
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
2 Product Description
The boiler is a low temperature gas boiler.
The boiler consists of the following main components:
–Ignition module (GC124 II only) and adjustable
aquastat
–Boiler jacket and front door
–Boiler block with insulation
–Burner
The ignition module and adjustable aquastat monitor
and control all electrical and operational components of
the boiler.
The boiler jacket prevents energy loss and acts as
soundproofing.
The boiler block transfers the heat generated by the
burner to the heating water. The insulation reduces
energy loss.
Fig. 1 Logano GC124 II/SP gas boiler
1Boiler front door
2Aquastat (boiler temperature controller)
3Ignition module (GC124 II only)
4Boiler block with insulation
5Burner
6Boiler jacket
7 747 000 511-01.0K
6
1
5
3
4
2
GC124 II
GC124 SP
6
1
5
4
2

8Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications
Dimensions and Connections3
3 Dimensions and Connections
Tab. 1 Dimensions/specs for GC124 II and GC124 SP
Fig. 2 Back, side and front view, measurements in inches
* optional connection
2
3/8
RK 1¼"
VK 1¼"
GAS ½"
EL ¾"
(GAS ½")*
Connections (measurements see the following tables):
VK = Boiler supply
RK = Boiler return
EL = Boiler drain
GAS = Gas connection
Boiler
size
Boiler
input
A B Vent connection
II/SP
Min. relief valve
capacity
Number of
Orifices
Water
volume
Dry
weight
Btu/hr Inches Inches Inches lb/hr Qty. US Gal. lbs
18/3 74000 13 1/8" 8" 5" 62 2 2.4 228
25/4 103000 16 3/4" 8 2/3" 5" 86 32.9 287
32/5 132500 20 3/8" 9 1/2" 6" 110 4 3.4 349.5
Fig. 3 Pressure drop/boiler
USER NOTE
For the size and dimensions of the main
gas orifices, refer to ÎChapter 18,
page 79.

Scope of delivery 4
9
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
4 Scope of delivery
zCheck packaging upon receipt of delivery for dam-
age.
zCheck delivery for completeness.
Component Qty Packaging
method
Boiler, complete 11 palette
B-kit components:
- 1-1/4" supply manifold
- 30 psi relief valve
- long shank boiler drain (¾")
- ¼" pressure/temperature
gauge
- 90°-elbow (1¼" x 1" NPT)
- 90°-elbow (1¼" x 1¼" NPT)
- 90°-elbow (¾" NPT nipple)
- nipple1" NPT
- nipple 1¼" NPT
11 cardboard
box1
Vent damper 11 cardboard
box1
Circulator with whip 11 cardboard
box1
Technical documents 1 plastic pack-
age
Tab. 2 Scope of delivery
1On Palette
Accessory Qty
Cleaning Brush 1
Tab. 3 Scope of delivery

10 Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
Moving the boiler5
5 Moving the boiler
This chapter describes how to move the boiler safely
into place.
5.1 Moving the boiler with boiler cart
Move the boiler with packaging in tact and on its pallet
as much as possible.
zRemove packaging straps and cardboard box from
pallet.
zRemove screws that secure the boiler base to the
wood pallet.
zPick up boiler base from one side and slide to the
edge of the pallet. Place a steel pipe as roller under
the boiler base. Place additional steel pipes under
the boiler base and roll the boiler to its final destina-
tion.
CAUTION!
SYSTEM DAMAGE
Due to uneven and rough surfaces.
zObserve the transport diagrams on the
packaging to protect the sensitive com-
ponents from damage due to rough sur-
faces. Handle the product with care.
USER NOTE
zProtect all boiler connections from dirt if
the boiler is not installed immediately
following removal from packaging.
USER NOTE
Dispose of the packaging material in an
environmentally prudent fashion.
Fig. 4 Moving the boiler with rollers

Moving the boiler 5
11
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
zSet the boiler cart or dolley on the front side of the
boiler and put a piece of cardboard between the two
to prevent scratches.
zSecure boiler on the boiler cart.
zMove boiler to desired location.
zPlace the boiler at its final postion.
5.2 Lifting and carrying the boiler
The boiler can be picked up at the both long sides of the
boiler as shown.
Fig. 5 Moving the boiler with dolley or boiler cart.
1Additional card board for protection.
1
CAUTION!
RISK OF INJURY
due to improper securing of the boiler dur-
ing transport.
zUse a boiler coart or dolley and strap
for moving the boiler
zSecure boiler on the boiler cart.
zRemove the front door during lifting or
transport to prevent unintentional open-
ing.
Fig. 6 Lifting and carrying the boiler
7 747 000 511-04.0K
CAUTION!
RISK OF INJURY
due to carrying heavy loads.
zLift and carry the boiler with at least four
people at the designated side panel lo-
cations.

12 Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
Placing the boiler6
6 Placing the boiler
This chapter explains how to place the boiler and posi-
tion it in the boiler room.
The boiler is very heavy when filled with water. Check
that the floor can bear the weight before installation.
6.1 Clearances
The GC124 boiler is approved for closet installation.
The following minimum distances must then be main-
tained:
– front: 2",
– sides: 2",
– behind open draft hood: 6",
– above boiler top panel: 30".
A space of at least 33 inches is recommended in front of
the boiler with the door removed to allow sufficient ac-
cess space for operation and maintenance. When the
door is closed, a minimum clearance of 2 inches is re-
quired at the front and sides, 2 inches clearance is also
required for the flue pipe and 30 inches clearance to the
ceiling. The installation location and the base must be
smooth and horizontal.The boiler may be installed on
a flammable base, but not on carpet.
6.2 Leveling the boiler
Level the boiler in both horizontal directions.
zLevel the boiler using a level and place small wedges
(not supplied) for leveling purposes.
CAUTION!
SYSTEM DAMAGE
due to frost.
zPlace the boiler in a frost-free room.
Fig. 7 Required clearances in the boiler room
1Recommended service clearances
2Required minimum clearances
3Burner tray access door with combustion air opening as
required per ANSI Z.223.1
1
2
3

Boiler installation 7
13
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
7 Boiler installation
This chapter describes how to install the boiler. This in-
cludes the following tasks:
–Connecting the heating system
–Electrical connection
–Gas supply piping connection
7.1 Preparing for installation
zUnpack all boxes and containers and check all parts
against the packing lists to make sure that everything
has been supplied.
USER NOTE
Every boiler is carefully inspected and
tested before it leaves the factory. How-
ever, if you discover any damage or miss-
ing parts, please inform your supplier im-
mediately. Before disposing of packing
material, make sure that no parts are still
in it.
USER NOTE
For better access remove the front door.

14 Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
Boiler installation7
7.2 Connecting the heating system
Fig. 8 Low-water cut-off installation
1Boiler
2Radiator
3Heating system with low-water cut-of
4Heating system without low-water cut-off
1
2
2
12
2
2
2
3
4
CAUTION!
BOILER DAMAGE
Due to moisture.
zProtect the components of the gas igni-
tion system from moisture (dripping,
spray, rain) during installation of the
boiler, during operation and during
maintenance work (such as replacing
the pump, replacing the control, etc.).
CAUTION!
SYSTEM DAMAGE
Due to overheating as a result of a low wa-
ter condition.
zNote that a boiler installed above the
level of the heating system must be
equipped with a low-water cut-off. The
low-water cut-off must be installed dur-
ing installation of the boiler and placed
above the water level in the boiler with-
out any means of shutting the water off
between the boiler and low water
cut-off (ÎFig. 8).
CAUTION!
SYSTEM DAMAGE
Due to high temperature variations in the
heating system.
zIf the boiler is operated in connection
with a refrigeration system, make sure
that the pipes for the refrigerated liquid
are connected in parallel to the boiler
system with suitable valves to prevent
the refrigerated liquid from entering the
boiler.
zThe piping system of a boiler connect-
ed to the heating coils of hydro-air heat-
ing systems that may be exposed to the
circulation of cooled air must be
equipped with a flow-control valve or
some other automatic system for pre-
venting the boiler water from circulating
by gravity during the cooling cycle.

Boiler installation 7
15
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
Installation of B-kit
The relief valve and the pressure/temperature gauge are
mounted on the boiler supply manifold which is attached
to the VK (supply) connection of the boiler (included in
B-kit).
Installing boiler supply VK:
zRemove factory installed plastic inserts from boiler
supply (VK), boiler return (RK) and boiler drain (EL)
connections.
zInstall the 1¼"NPT nipple into boiler supply, the 1"
NPT nipple into boiler return and ¾" male NPT drain
valve into boiler drain connection.
zInstall 90° 1¼" x 1¼"NPT on 1¼" NPT supply nipple
and face upward and install 90° 1¼" x 1"NPT elbow
on return nipple and face in desired direction.
zInstall GC124 1¼" x 1¼"NPT supply manifold into
supply connection (VK) of the boiler. Do NOT place
on return connection of the boiler!
zInstall first 90° ¾" street elbow in upper ¾" NPT tap-
ping of GC124 1-1/4" supply manifold and install
pressure relief valve into this ¾" tapping. Make sure
to orient the discharge of the relief valve horizontally.
Install the temperature/pressure gauge in the lower
3/4" tapping of the supply manifold.
Fig. 9 Installation of B-kit
1Pressure relief valve ¾"
290° 3/4" street elbow
3GC124 1-1/4" supply manifold
4Pressure & temperature gauge
590° 1-1/4" NPT elbow
61-1/4" NPT nipple
7Boiler drain ¾" NPT (backside of boiler)
890° 1-1/4" x 1" NPT elbow
91" NPT nipple
1
2
4
5
8
VK
RK
6
9
EL
7
3
USER NOTE
Install the relief valve after the leak test.
(ÎChapter 7.5, page 20).
The relief valve must be installed in a ver-
tical position.
The relief valve must also be installed in
accordance with the requirements of the
ANSI/ASME Boiler and Pressure Vessel
Code, Section IV.
USER NOTE
We recommend installing a y-strainer (ac-
cessory) in the boiler return connection to
reduce build-up of debris on the water
side inside the boiler.
USER NOTE
Ensure compliance with all state and local
regulations pertaining to the installation of
boiler systems.

16 Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
Boiler installation7
7.3 Electrical connections
The electrical connections of the boiler must be made as
specified by the local codes and the current regulations
of the National Electrical Code, ANSI/NFPA–70.
The boiler must be grounded as specified by the regula-
tions of the relevant local authorities; otherwise follow
the regulations of the National Electrical Code,
ANSI/NFPA–70.
The boiler is fully functional with the factory installed
aquastat and the field installed vent damper and heating
system circulation pump.
Power supply connection.
Install incoming power to the boiler per local and state
codes.
zInstall an ON/OFF switch near the boiler per local
code requirements.
CAUTION!
FIRE DANGER
due to exposure to hot water pipes.
zMaintain a minimum clearance of two
inches between non-insulated pipes
carrying hot water and combustible
walls and surfaces in the boiler room.
A minimum of 1" high quality pipe insu-
lation is required to permit direct con-
tact with combustible surfaces.
USER NOTE
When making the electrical connections
please observe the following guidelines:
zPerform only electrical work, if you pos-
sess the required certification for such
work. When you do not have the re-
quired certification, have the electrical
work performed by a certified electri-
cian.
zObserve all local and state installation
regulations.
Fig. 10 ON/OFF switch (emergency shutoff switch)

Boiler installation 7
17
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
Description of field installed wiring connections
using factory supplied junction box.
zRemove two knock-outs from the left side of boiler
panel to route electrical feed and pump power into
junction box.
zRoute electrical power from the outside into junction
box.
zInstall a metal strain relief for the incoming power line
on outside of left boiler jacket panel. (ÎFig. 12).
zJust use supplied wiring nuts and double proper wir-
ing before powering up the boiler.
zCheck that the heating system functions correctly af-
ter any maintenance work.
Fig. 11 Electrical junction box
1Electrical junction box (Inside of jacket cabinet)
2Incoming line voltage wiring
3Furnished wiring nuts.
2
1
3
USER NOTE
When making the electrical connections
use only wires that are approved for elec-
trical use.
USER NOTE
Refer to the wiring diagrams on pages
Îpage 80 bis Îpage 82 for electrical
details.
Fig. 12 Strain relief for shielded electrical wiring
WARNING!
RISK TO LIFE
from electrical shock.
zWhen conducting maintenance work
label all cables before disconnecting
them.
zIf cables are connected incorrectly the
system may not operate correctly with
possibly dangerous consequences.
WARNING!
FIRE DANGER
Hot boiler components may damage elec-
trical wiring.
zMake sure that all cables are routed in
the ducts or on the boiler insulation.

18 Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
Boiler installation7
7.4 Fuel gas supply connection
7.4.1 Gas connections
For the gas pipe diameter required for the installation
please see ÎTab. 4 and ÎTab. 5. Make sure that the
pipe fitting has the correct thread size.
Make sure that a sediment trap is installed at the inlet for
the gas supply pipe to the boiler. A manual stop valve
must be installed outside the boiler jacket if required by
the local code. We recommend installing a manual
shut-off valve in the main gas pipe to the boiler. The gas
pipe must be fastened outside the boiler.
The local codes must be observed during installation of
the gas piping connections, otherwise the regulations of
the National Fuel Gas Code, ANSI Z 223.1 must be fol-
lowed.
zInstall gas piping without any undue stress on the
piping.
zThe Commonwealth of Massachusettes prohibits the
use of copper tubing for the gas line.
Gas carrying capacity (refer to technical manual ÎChapter 18, page 79)
Tab. 5 Gas pipe supply volume
1 Maximum gas supply volume in cubic feet per hour, based on
a specific gas weight of 0.60 and a gas pressure of 0.5 psi or less
and a pressure gradient corresponding to a water column of
0.3 inches.
Fig. 13 Gas piping connection to gas valve – right or left side
1Gas feed
2Manual shut-off valve
3Sediment trap
1
2
3
WARNING!
DANGER OF EXPLOSION
Leakage from the gas pipes and gas
connections may cause an explosion.
zUse soap solution to find leaks.
Nominal
diameter of
iron pipe
(inches)
Equivalent lengths for pipe fittings in
feet
Pipe fitting type
90°-
angle T-piece Shut-off valve
Gas
shut-off
Equivalent lengths in feet
1/2 1.4 2.7 0.3 0.80
3/4 2.1 4.1 0.5 1.25
1 2.6 5.2 0.6 1.6
1 1/4 3.5 6.9 0.8 2.15
1 1/2 4.0 8.0 0.9 2.50
Tab. 4 Equivalent lengths for pipe fittings
Length
of pipe
in feet
Gas pipe supply volume in cubic feet of gas
per hour1
1/2 3/4 11 1/4 1 1/2
10 132 278 520 1060 1600
20 92 190 350 730 1100
30 73 152 285 590 890
40 63 130 245 500 760
50 56 115 215 440 670
75 45 93 175 360 545
100 38 79 160 305 480
150 31 64 120 250 380

Boiler installation 7
19
We reserve the right to make any changes due to technical modifications.
Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
Disconnect the boiler with the manual shut-off valve and
physically separate the boiler from the gas piping if the
gas piping system is pressure tested with a test pressure
greater than 1/2 psi.
If the gas supply pipe system is pressure tested at a test
pressure of 1/2 psi or less, it is sufficient to disconnect
the boiler from the gas pipe system by closing the man-
ual shut-off valve.
Use only sealant that is resistant to corrosion by LPG for
pipe connection. Only a small amount of sealant must be
applied to the external thread of the pipe connections.
If you wish to convert the boiler to propane, please con-
tact Buderus for the required conversion components.
Do not attempt to convert the boiler without the ap-
proved Buderus propane conversion parts and the rele-
vant technical documentation. The technical documen-
tation is included with the propane conversion parts.
7.4.2 Installation at high altitudes
The boiler is designed for installation at altitudes below
8500 feet above sea level.
USER NOTE
If the installation location is over 8500 feet
above sea level, please contact Buderus
for another product option as the GC124
is not approved above 8500 feet opera-
tion.
CAUTION!
SYSTEM DAMAGE
due to dirt.
If the boiler is assembled and not in use,
note the following:
zProtect the boiler connections from dirt
by closing the connections.

20 Installation and maintenance instructions Gas Boiler Logano GC124 II/SP • Issue 07/2006
We reserve the right to make any changes due to technical modifications.
Boiler installation7
7.5 Filling heating system and checking
for leaks
The boiler is tested for leaks at the factory. Before plac-
ing the heating system into use, check the entire system
for soundness to avoid leaks occurring during operation.
Water treatment
Carry out the leak test at 1.5 times the normal operating
pressure and as specified by the local codes as follows:
USER NOTE
Have the water analyzed before filling the
heating system. The water may require
treatment as a result of the analysis.
Please consult the local water supply
company if the water is extremely hard or
has a pH level below 7.0.
CAUTION!
SYSTEM DAMAGE
due to overpressure during the leak test.
Pressure, control or safety components
may be damaged by high pressure.
zBefore conducting the leak test make
sure that no pressure, control or safety
components that cannot be disconnect-
ed from the water compartment of the
boiler are installed.
Maximum operating pressure Maximum test
pressure
30 psi (based on supplied re-
lief valve)
45 psi
58 psi (with special relief
valve)
75 psi
Tab. 6 Pressure Test