Watts AERCO Benchmark 2.0LN User manual

PR2: 04/22/13 Page 1of 158
Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
USER MANUAL
Modulating, Condensing,
Forced Draft, Hot Water Boiler
2,000,000 BTU/H Input
Applicable for Serial Numbers:
G-11-2402 and above.
Revised: 04/22/2013
Benchmark 2.0LN Low NOx Boiler
Installation, Operation, and Maintenance
Benchmark
2.0LN Dual-Fuel
Low NOx Boiler

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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
Disclaimer
The information contained in this manual is subject to change without notice from AERCO International,
Inc. AERCO makes no warranty of any kind with respect to this material, including but not limited to
implied warranties of merchantability and fitness for a particular application. AERCO International is not
liable for errors appearing in this manual. Nor for incidental or consequential damages occurring in
connection with the furnishing, performance, or use of this material.
Technical Support:
(Mon–Fri, 8am-5pm EST)
1-800-526-0288
www.aerco.com

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Table of Contents
CHAPTER 1: SAFETY PRECAUTIONS.................................................................................. 9
1.1 WARNINGS & CAUTIONS....................................................................................9
1.2 EMERGENCY SHUTDOWN ...............................................................................10
1.3 PROLONGED SHUTDOWN................................................................................10
CHAPTER 2: INSTALLATION.............................................................................................. 11
2.1 INTRODUCTION.................................................................................................11
2.2 RECEIVING THE UNIT .......................................................................................11
2.3 UNPACKING .......................................................................................................11
2.4 SITE PREPARATION..........................................................................................11
Installation Clearances............................................................................................. 122.4.1 Setting the Unit........................................................................................................ 122.4.2
2.5 SUPPLY AND RETURN PIPING.........................................................................13
2.6 CONDENSATE DRAIN AND PIPING..................................................................14
Exhaust Manifold Condensate Drain....................................................................... 152.6.1
2.7 GAS SUPPLY PIPING.........................................................................................16
Gas Supply Specifications. ...................................................................................... 172.7.1 Manual Gas Shutoff Valve....................................................................................... 172.7.2 IRI Gas Train Kit ..................................................................................................... 172.7.3
2.8 AC ELECTRICAL POWER WIRING....................................................................18
Electrical Power Requirements................................................................................ 182.8.1
2.9 MODES OF OPERATION AND FIELD CONTROL WIRING...............................19
Constant Setpoint Mode........................................................................................... 192.9.1 Indoor/Outdoor Reset Mode.................................................................................... 202.9.2 Boiler Management System Mode........................................................................... 202.9.3 Remote Setpoint and Direct Drive Modes............................................................... 202.9.4 Combination Mode .................................................................................................. 202.9.5
2.10 I/O BOX CONNECTIONS..................................................................................21
Outdoor Sensor In (1).......................................................................................... 212.10.1
Air Temp. Sensor (2)........................................................................................... 222.10.2
Analog In (3)........................................................................................................ 222.10.3
B.M.S. (PWM) In (4) .......................................................................................... 222.10.4
Shield (5).............................................................................................................. 232.10.5
mA Out (6)........................................................................................................... 232.10.6
RS-485 Comm (7)................................................................................................ 232.10.7
TxD, RxD (8)....................................................................................................... 232.10.8
VFD/Blower (9)................................................................................................... 232.10.9
Exhaust Switch In (11)...................................................................................... 232.10.10

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
Interlocks (10, 12)........................................................................................... 232.10.11
Fault Relay (13).................................................................................................. 242.10.12
Auxiliary Relay Contacts (14) ........................................................................... 242.10.13
2.11 FLUE GAS VENT INSTALLATION....................................................................24
2.12 COMBUSTION AIR ...........................................................................................24
Combustion Air From Outside the Building.......................................................... 252.12.1 Combustion Air From Inside The Building........................................................... 252.12.2 Sealed Combustion ................................................................................................ 252.12.3 Temporary Combustion Air Filtering During Construction.................................. 252.12.4
2.13 BENCHMARK PUMP RELAY OPTION.............................................................25
CHAPTER 3: CONTROL PANEL OPERATION................................................................. 27
3.1 INTRODUCTION.................................................................................................27
3.2 CONTROL PANEL DESCRIPTION.....................................................................27
3.3 CONTROL PANEL MENUS ................................................................................31
Menu Processing Procedure..................................................................................... 313.3.1
3.4 OPERATING MENU............................................................................................32
3.5 SETUP MENU.....................................................................................................33
3.6 CONFIGURATION MENU...................................................................................34
3.7 TUNING MENU ...................................................................................................35
3.8 COMBUSTION CAL MENU.................................................................................35
3.9 START SEQUENCE............................................................................................36
3.10 START/STOP LEVELS......................................................................................39
CHAPTER 4: INITIAL START-UP........................................................................................ 41
4.1 INITIAL START-UP REQUIREMENTS................................................................41
4.2 TOOLS AND INSTRUMENTATION FOR COMBUSTION CALIBRATION..........41
Required Tools & Instrumentation .......................................................................... 424.2.1 Installing Gas Supply Manometer ........................................................................... 424.2.2 Accessing the Analyzer Probe Port.......................................................................... 434.2.3
4.3 NATURAL GAS COMBUSTION CALIBRATION.................................................44
4.4 PROPANE COMBUSTION CALIBRATION.........................................................49
4.5 UNIT REASSEMBLY...........................................................................................53
4.6 OVER-TEMPERATURE LIMIT SWITCHES........................................................53
Digital Alarm Switch Checks and Adjustments...................................................... 544.6.1
CHAPTER 5: MODE OF OPERATION ................................................................................ 56
5.1 INTRODUCTION.................................................................................................56
5.2 INDOOR/OUTDOOR RESET MODE ..................................................................56
Reset Ratio............................................................................................................... 565.2.1 Building Reference Temperature............................................................................. 565.2.2 Outdoor Air Temperature Sensor Installation.......................................................... 565.2.3 Indoor/ Outdoor Startup........................................................................................... 565.2.4

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
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5.3 CONSTANT SETPOINT MODE..........................................................................57
Setting the Setpoint.................................................................................................. 575.3.1
5.4 REMOTE SETPOINT MODES............................................................................58
Remote Setpoint Field Wiring................................................................................. 585.4.1 Remote Setpoint Startup.......................................................................................... 595.4.2
5.5 DIRECT DRIVE MODES.....................................................................................59
Direct Drive Field Wiring........................................................................................ 605.5.1 Direct Drive Startup................................................................................................. 605.5.2
5.6 BOILER MANAGEMENT SYSTEM (BMS)..........................................................60
BMS External Field Wiring..................................................................................... 605.6.1 BMS Setup and Startup............................................................................................ 615.6.2
5.7 COMBINATION CONTROL SYSTEM (CCS)......................................................61
Combination Control System Field Wiring............................................................. 615.7.1 Combination Control System Setup and Startup..................................................... 625.7.2
CHAPTER 6: SAFETY DEVICE TESTING ......................................................................... 63
6.1 TESTING OF SAFETY DEVICES........................................................................63
6.2 NATURAL GAS LOW GAS PRESSURE FAULT TEST.......................................63
6.3 PROPANE LOW GAS PRESSURE FAULT TEST..............................................64
6.4 NATURAL GAS HIGH GAS PRESSURE TEST..................................................65
6.5 PROPANE HIGH GAS PRESSURE TEST..........................................................65
6.6 LOW WATER LEVEL FAULT TEST....................................................................66
6.7 WATER TEMPERATURE FAULT TEST.............................................................66
6.8 INTERLOCK TESTS............................................................................................67
REMOTE INTERLOCK ......................................................................................... 676.8.1 DELAYED INTERLOCK....................................................................................... 686.8.2
6.9 FLAME FAULT TESTS........................................................................................68
6.10 AIR FLOW FAULT TESTS ................................................................................69
6.11 SSOV PROOF OF CLOSURE SWITCH............................................................70
6.12 IGNITION SWITCH OPEN DURING IGNITION ................................................71
6.13 PURGE SWITCH OPEN DURING PURGE.......................................................71
6.14 SAFETY PRESSURE RELIEF VALVE TEST....................................................72
CHAPTER 7: MAINTENANCE.............................................................................................. 73
7.1 MAINTENANCE SCHEDULE..............................................................................73
7.2 IGNITER-INJECTOR...........................................................................................74
7.3 FLAME DETECTOR............................................................................................76
7.4 COMBUSTION CALIBRATION ...........................................................................77
7.5 SAFETY DEVICE TESTING................................................................................77
7.6 BURNER ASSEMBLY INSPECTION ..................................................................77
7.7 CONDENSATE DRAIN TRAP.............................................................................80

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
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7.8 SHUTTING THE BOILER DOWN FOR AN EXTENDED PERIOD OF TIME.......81
7.9 PLACING THE BOILER BACK IN SERVICE AFTER A PROLONGED
SHUTDOWN .............................................................................................................81
CHAPTER 8: TROUBLESHOOTING GUIDE..................................................................... 83
8.1 INTRODUCTION..............................................................................................83
8.2 ADDITIONAL FAULTS WITHOUT SPECIFIC FAULT MESSAGES ................93
CHAPTER 9: RS232 COMMUNICATION............................................................................ 97
9.1 INTRODUCTION.................................................................................................97
Aquiring the PuTTY Application ............................................................................ 979.1.1 Logging on to a Remote Machine Using PuTTY.................................................... 979.1.2 Running a Command on a Remote Machine Using PuTTY.................................... 989.1.3
9.2 RS232 COMMUNICATION SETUP.....................................................................99
9.3 MENU PROCESSING UTILIZING RS232 COMMUNICATION...........................99
9.4 DATA LOGGING...............................................................................................100
Fault Log................................................................................................................ 1009.4.1 Operation Time Log............................................................................................... 1009.4.2 Sensor Log............................................................................................................. 1019.4.3
APPENDIX A: MENU ITEM DESCRIPTIONS................................................................ 103
APPENDIX B: STARTUP, STATUS AND FAULT MESSAGES..................................... 109
APPENDIX C: SENSOR TEMPERATURE RESISTANCE............................................. 113
APPENDIX D: INDOOR/OUTDOOR RESET RATIO CHARTS................................... 115
APPENDIX E: BOILER DEFAULT SETTINGS............................................................... 119
APPENDIX F: PART AND DIMENSIONAL DRAWINGS.............................................. 121
APPENDIX G: PIPING DRAWINGS................................................................................. 137
APPENDIX H: WIRING SCHEMATICS........................................................................... 143
APPENDIX I: RECOMMENDED PERIODIC TESTING CHECK LIST....................... 149
APPENDIX J: BENCHMARK CONTROL PANEL FEATURES..................................... 151
APPENDIX K: BMK 2.0 DUAL-FUEL SWITCHOVER INSTRUCTIONS.................... 153
SWITCHOVER FROM NATURAL GAS TO PROPANE..........................................153
SWITCHOVER FROM PROPANE TO NATURAL GAS..........................................156
APPENDIX L: RECOMMENDED SPARE PARTS LISTS.............................................. 157

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Operation and Maintenance Manual
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Foreword
The AERCO Benchmark 2.0LN Dual-Fuel Low NOx (LN) Boiler is a modulating unit. It
represents a true industry advance that meets the needs of today's energy and environmental
concerns. Designed for application in any closed loop hydronic system, the Benchmark's
modulating capability relates energy input directly to fluctuating system loads. The Benchmark
2.0LN, with its 20:1 turn down ratio and condensing capability, provides extremely high
efficiencies and makes it ideally suited for modern low temperature, as well as, conventional
heating systems.
The boiler operates at inputs ranging from 100,000 BTU/hr. to 2,000,000 BTU/hr. The output of
the boiler is a function of the unit’s firing rate and return water temperature. Output ranges from
99,000 BTU/hr. to 1,933,000 BTU/hr., depending on operating conditions.
When installed and operated on natural gas in accordance with this Instruction Manual, the
Benchmark 2.0LN Boiler complies with the NOx emission standards outlined in:
South Coast Air Quality Management District (SCAQMD), Rule 1146.2
Whether used in singular or modular arrangements, the Benchmark 2.0LN offers the maximum
flexibility in venting with minimum installation space requirements. The Benchmark's advanced
electronics are available in several selectable modes of operation offering the most efficient
operating methods and energy management system integration.
For service or parts, contact your local sales representative or AERCO INTERNATIONAL.
NAME:
ORGANIZATION:
ADDRESS:
TELEPHONE:
INSTALLATION DATE: _____________________________________________

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
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CHAPTER 1: SAFETY PRECAUTIONS
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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
CHAPTER 1: SAFETY PRECAUTIONS
1.1 WARNINGS & CAUTIONS
Installers and operating personnel MUST, at all times, observe all safety regulations. The
following warnings and cautions are general and must be given the same attention as specific
precautions included in these instructions. In addition to all the requirements included in this
AERCO Instruction Manual, the installation of units MUST conform with local building codes, or,
in the absence of local codes, ANSI Z223.1 (National Fuel Gas Code Publication No. NFPA-54).
Where ASME CSD-1 is required by local jurisdiction, the installation must conform to CSD-1.
Where applicable, the equipment shall be installed in accordance with the current Installation
Code for Gas Burning Appliances and Equipment, CSA B149.1, and applicable Provincial
regulations for the class; which should be carefully followed in all cases. Authorities having
jurisdiction should be consulted before installations are made.
IMPORTANT
This Instruction Manual is an integral part of the product and must
be maintained in legible condition. It must be given to the user by
the installer and kept in a safe place for future reference.
WARNING
WARNINGS MUST BE OBSERVED TO PREVENT SERIOUS
INJURY. WARNING
BEFORE ATTEMPTING TO PER-FORM ANY MAINTENANCE
ON THE UNIT, SHUT OFF ALL GAS AND ELECTRICAL INPUTS
TO THE UNIT. WARNING
THE EXHAUST VENT PIPE OF THE UNIT OPERATES UNDER
A POSITIVE PRESSURE AND THERE-FORE MUST BE
COMPLETELY SEALED TO PREVENT LEAKAGE OF
COMBUSTION PRODUCTS INTO LIVING SPACES.
WARNING
A DOUBLE-POLE SWITCH MUST BE INSTALLED ON THE
ELECTRICAL SUPPLY LINE OF THE UNIT. THE SWITCH MUST
BE INSTALLED IN AN EASILY ACCESSIBLE POSITION TO
QUICKLY AND SAFELY DISCONNECT ELECTRICAL SERVICE.
DO NOT AFFIX SWITCH TO UNIT SHEET METAL
ENCLOSURES. WARNING
DO NOT USE MATCHES, CANDLES, FLAMES, OR OTHER
SOURCES OF IGNITION TO CHECK FOR GAS LEAKS.
WARNING
FLUIDS UNDER PRESSURE MAY CAUSE INJURY TO
PERSONNEL OR DAMAGE TO EQUIPMENT WHEN
RELEASED. BE SURE TO SHUT OFF ALL INCOMING AND
OUTGOING WATER SHUTOFF VALVES. CAREFULLY
DECREASE ALL TRAPPED PRESSURES TO ZERO BEFORE
PERFORMING MAINTENANCE.

CHAPTER 1: SAFETY PRECAUTIONS
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
WARNING
electrical voltages up to 120 vac may be used in this equipment.
Therefore the cover on the unit’s power box (located behind the
front panel door) must be installed at all times, except during
maintenance and servicing.
CAUTIONS
Must be observed to prevent equipment damage or loss of
operating effectiveness. CAUTION
Many soaps used for gas pipe leak testing are corrosive to metals.
The piping must be rinsed thoroughly with clean water after leak
checks have been completed.
CAUTION!
DO NOT use this boiler if any part has been under water. Call a
qualified service technician to inspect and replace any part that
has been under water.
1.2 EMERGENCY SHUTDOWN
If overheating occurs or the gas supply fails to shut off, close the manual gas shutoff valve (Figure 1-1)
located external to the unit. IMPORTANT
The Installer must identify and indicate the location of the
emergency shutdown manual gas valve to operating personnel.
1.3 PROLONGED SHUTDOWN
After prolonged shutdown, it is recommended that the startup procedures in Chapter 4 and the safety
device test procedures in Chapter 6 of this manual be performed, to verify all system-operating
parameters. If there is an emergency, turn off the electrical power supply to the AERCO boiler and close
the manual gas valve located upstream the unit. The installer must identify the emergency shut-off
device.
Figure 1-1: Manual Gas Shutoff Valve

CHAPTER 2: INSTALLATION
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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
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CHAPTER 2: INSTALLATION
2.1 INTRODUCTION
This Chapter provides the descriptions and procedures necessary to unpack, inspect and install
the AERCO Benchmark 2.0LN Dual-Fuel Boiler. Brief descriptions are also provided for each
available mode of operation. Detailed procedures for implementing these modes are provided in
Chapter 5.
2.2 RECEIVING THE UNIT
Each Benchmark 2.0LN System is shipped as a single crated unit. The shipping weight is
approximately 1600 pounds. The unit must be moved with the proper rigging equipment for
safety and to avoid equipment damage. The unit should be completely inspected for evidence of
shipping damage and shipment completeness at the time of receipt from the carrier and before
the bill of lading is signed.
NOTE
AERCO is not responsible for lost or damaged freight.
Each unit has a Tip-N-Tell indicator on the outside of the crate. This indicates if the unit has
been turned on its side during shipment. If the Tip-N-Tell indicator is tripped, do not sign for the
shipment. Note the information on the carrier’s paperwork and request a freight claim and
inspection by a claims adjuster before proceeding. Any other visual damage to the packaging
materials should also be made clear to the delivering carrier.
2.3 UNPACKING
Carefully unpack the unit taking care not to damage the unit enclosure when cutting away
packaging materials
A close inspection of the unit should be made to ensure that there is no evidence of damage not
indicated by the Tip-N-Tell indicator. The freight carrier should be notified immediately if any
damage is detected.
IMPORTANT
After unpacking, take off the unit top panel and remove the strap
and packing material at the top of the heat exchanger. The
packing material is located in the area of the igniter-injector and
staged ignition solenoid on the burner assembly.
The following accessories come standard with each unit and are either packed separately within
the unit’s packing container or are factory installed on the boiler:
•Pressure/Temperature Gauge
•ASME Pressure Relief Valve
•Condensate Drain Trap
•2” Gas Supply Shutoff Valve
When ordered, optional accessories may be packed separately, packed within the boiler
shipping container, or may be installed on the boiler. Any standard or optional accessories
shipped loose should be identified and stored in a safe place until ready for installation or use.
2.4 SITE PREPARATION
Ensure that the site selected for installation of the Benchmark 2.0LN Boiler includes:

CHAPTER 2: INSTALLATION
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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
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•Access to AC Input Power at 120 VAC, Single-Phase, 60 Hz @ 20 Amps
•Access to Natural Gas line at a minimum supply gas pressure of 8.5" W.C.
•Access to Propane line at a minimum supply gas pressure of 8.5” W.C.
Installation Clearances2.4.1
The unit must be installed with the prescribed clearances for service as shown in Figure 2-1.
The minimum clearance dimensions, required by AERCO, are listed below. However, if Local
Building Codes require additional clearances, these codes shall supersede AERCO’s
requirements. Minimum acceptable clearances required are:
•Sides: 24 inches
•Front : 24 inches
•Rear: 30 inches
•Top: 18 inches
All gas piping, water piping and electrical conduit or cable must be arranged so that they do not
interfere with the removal of any panels, or inhibit service or maintenance of the unit.
44.5" 18"
79"
101"
4" HIGH PAD
24"
24"
30"24"
REAR FRONT
Figure 2-1: Benchmark 2.0LN Boiler Clearances
WARNING
KEEP THE UNIT AREA CLEAR AND FREE FROM ALL
COMBUSTIBLE MATERIALS AND FLAMMABLE VAPORS OR
LIQUIDS. CAUTION
While packaged in the shipping container, the boiler must be
moved by pallet jack or forklift from the FRONT ONLY.
Setting the Unit2.4.2
The unit must be installed on a 4 inch to 6 inch housekeeping pad to ensure proper condensate
drainage. If anchoring the unit, refer to the dimensional drawings in Appendix F for anchor

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locations. Two lifting tabs are provided at the top of the heat exchanger. Figure 2-2 shows the
location of the tab on the top-left side. The second tab is located on the top-right side of the heat
exchanger. USE THESE TWO TABS TO LIFT AND MOVE THE UNIT. Remove the top panel
from the unit to provide access to the lifting tabs. Remove the four (4) lag screws securing the
unit to the shipping skid. Lift the unit off the shipping skid and position it on the 4 inch to 6 inch
housekeeping concrete pad (required) in the desired location.
WARNING
WHEN LIFTING OR MOVING THE BOILER:
•DO NOT MANIPULATE THE BOILER USING THE GAS TRAIN OR
BLOWER
•WHEN USING THE LIFTING TABS, ENSURE THERE IS NO LOAD
PLACED ON THE GAS TRAIN OR BLOWER
LIFTING
TABS (2)
Figure 2-2: Partial Top View Showing Lifting Tab Location
In multiple unit installations, it is important to plan the position of each unit in advance. Sufficient
space for piping connections and future service/maintenance requirements must also be taken
into consideration. All piping must include ample provisions for expansion.
If installing a Combination Control Panel (CCP) system, it is important to identify the
Combination Mode Boilers in advance and place them in the proper physical location. Refer to
Chapter 5 for information on Combination Mode Boilers.
2.5 SUPPLY AND RETURN PIPING
The Benchmark 2.0LN Boiler utilizes 4” 150# flanges for the water system supply and return piping
connections. The physical location of the supply and return piping connections are on the rear of the unit
as shown in Figure 2-3. Refer to Appendix F, Drawing AP-A-798 for additional dimensional data.

CHAPTER 2: INSTALLATION
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Figure 2-3: Supply and Return Locations
2.6 CONDENSATE DRAIN AND PIPING
The Benchmark 2.0LN Boiler is designed to condense water vapor from the flue products.
Therefore, the installation must have provisions for suitable condensate drainage or collection.
The condensate drain pipe located on the exhaust manifold (Figure 2-4) must be connected to a
condensate trap which is packed separately within the unit’s shipping container.
The procedure to install and connect the condensate drain is provided in paragraph 2.6.1.

CHAPTER 2: INSTALLATION
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EXHAUST
MANIFOLD
1/2” NPT
CONDENSATE
DRAIN
CONNECTION
HOUSE-
KEEPING
PAD
BOILER
RETURN
Figure 2-4: Condensate Drain Connection Location
Exhaust Manifold Condensate Drain2.6.1 NOTE
There are two slightly different types of condensate traps
that may be used in your configuration; an older style
without built-in adapter, and a newer style with a built-in
adapter (see Figure 2-5). Installation is the same (1/4”
threads are inside built-in adapter on newer style).
A condensate drain trap (part no. 24060) is shipped loose and must be installed at the rear of
the unit. The trap inlet and outlet contain tapped 3/4” NPT ports. The actual installation details
for the condensate trap will depend on the available clearances, housekeeping pad
height/dimensions and other prevailing conditions at the site. However, the following guidelines
must be observed to ensure proper condensate trap operation:
•The condensate trap inlet (Figure 2-5) must be level with, or lower than the exhaust manifold
drain port.
•The condensate trap must be supported to ensure that its base is level (horizontal).
•The trap must be removable for routine maintenance. AERCO recommends that a union be
utilized between the exhaust manifold condensate drain port and the trap inlet port.
1. While observing the above guidelines, connect the condensate trap inlet to the exhaust
manifold drain connection using the appropriate piping components (nipples, reducers,
elbows, etc.) for the boiler installation site.
2. At the condensate trap outlet, install a 3/4” NPT nipple.
3. Connect a length of 1” I.D polypropylene hose to the trap outlet and secure with a hose
clamp.
4. Route the hose on the trap outlet to a nearby floor drain.
If a floor drain is not available, a condensate pump can be used to remove the condensate to
drain. The maximum condensate flow rate is 20 GPH. The condensate drain trap, associated
fittings and drain line must be removable for routine maintenance.

CHAPTER 2: INSTALLATION
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Figure 2-5: Condensate Trap Installation: Older (left) and Newer (right) Style
2.7 GAS SUPPLY PIPING
The AERCO Benchmark 2.0LN Gas Components and Supply Design Guide, GF-2030 must be
consulted prior to designing or installing any gas supply piping.
WARNING
NEVER USE MATCHES, CANDLES, FLAMES OR OTHER
SOURCES OF IGNITION TO CHECK FOR GAS LEAKS.
WARNING
Many soaps used for gas pipe leak testing are corrosive to metals.
There-fore, piping must be rinsed thoroughly with clean water after
leak checks have been completed.
NOTE
All gas piping must be arranged so that it does not interfere with
removal of any covers, inhibit service/maintenance, or restrict
access between the unit and walls, or another unit.
Benchmark 2.0LN Dual-Fuel units contain two 2 inch gas inlet connections on the rear of the
unit as shown in Figure 2-3.
Prior to installation, all pipes should be de-burred and internally cleared of any scale, metal
chips or other foreign particles. Do Not install any flexible connectors or unapproved gas
fittings. Piping must be supported from the floor, ceiling or walls only and must not be supported
by the unit.
A suitable piping compound, approved for use with natural gas, should be used. Any excess
must be wiped off to prevent clogging of components.
To avoid unit damage when pressure testing gas piping, isolate the unit from the gas supply
piping. At no time should the gas pressure applied to the unit exceed 14” W.C. Leak test all
external piping thoroughly using a soap and water solution or suitable equivalent. The gas
piping used must meet all applicable codes.

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Gas Supply Specifications.2.7.1
The maximum static pressure to the unit must not exceed 14” W.C. The specifications for
natural gas and propane are as follows:
Natural Gas:
The gas supply pressure to the unit must be of sufficient capacity to provide 2000 cfh while
maintaining the gas pressure at 4.0" W.C. for FM or 5.0" W.C. for IRI gas trains.
Propane:
The gas supply pressure to the unit must be of sufficient capacity to provide 800 cfh while
maintaining the gas pressure at 4.0" W.C. for FM or 5.0" W.C. for IRI gas trains.
The maximum static pressure to the unit must not exceed 14” W.C.. The minimum operating
gas pressure for natural gas and propane is 8.5 inches W.C. for both FM and IRI gas trains
when the unit is firing at maximum input.
Manual Gas Shutoff Valve2.7.2
A manual shut-off valve must be installed in the gas supply line upstream of the Boiler as shown
in Figure 2-6. Maximum allowable gas pressure to the Boiler is 14” W.C.
Figure 2-6: Manual Gas Shut-Off Valve Location
IRI Gas Train Kit2.7.3
The IRI gas train is an optional gas train configuration which is required in some areas for code

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
compliance or for insurance purposes. The IRI gas train is factory pre-piped and wired. See
Appendix F, Drawing AP-A-843 for details.
2.8 AC ELECTRICAL POWER WIRING
The AERCO Benchmark 2.0LN Electrical Power Wiring Guide, GF-2060LN, must be consulted
prior to connecting any AC power wiring to the unit. External AC power connections are made
to the unit inside the Power Box on the front panel of the unit. Remove the front door of the unit
to access the Power Box mounted directly above the Control Box. Loosen the four Power Box
cover screws and remove cover to access the AC terminal connections inside the Power Box
(Figure 2-7).
NOTE
All electrical conduit and hardware must be installed so that it
does not interfere with the removal of any unit covers, inhibit
service/maintenance, or prevent access between the unit and
walls or another unit.
UPPER RIGHT CORNER OF FRONT PANEL
TERMINAL BLOCK
Figure 2-7: AC Input Terminal Block Location
Electrical Power Requirements2.8.1
The AERCO Benchmark 2.0LN Boiler accepts 120 VAC, single-phase, 60 Hz @ 20A. The
Power Box contains a terminal block as shown in Figure 2-8. In addition, a wiring diagram
showing the required AC power connections is provided on the front cover of the Power Box.
Each Boiler must be connected to a dedicated electrical circuit. NO OTHER DEVICES
SHOULD BE ON THE SAME ELECTRICAL CIRCUIT AS THE BOILER.
A double-pole switch must be installed on the electrical supply line in an easily accessible
location to quickly and safely disconnect electrical service. DO NOT attach the switch to sheet
metal enclosures of the unit.
After placing the boiler in service, the ignition safety shutoff device must be tested. If an external
electrical power source is used, the installed boiler must be electrically bonded to ground in
accordance with the requirements of the authority having jurisdiction. In the absence of such
requirements, the installation shall conform to National Electrical Code (NEC), ANSI/NFPA 70
and/or the Canadian Electrical Code (CEC) Part I, CSA C22.1 Electrical Code.
For electrical power wiring diagrams, see the AERCO Benchmark 2.0LN Electrical Power Wiring
Guide, (GF-2060LN).

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GND
NEU
L1
120 VAC, 1 PHASE
Figure 2-8: AC Terminal Block Configurations
2.9 MODES OF OPERATION AND FIELD CONTROL WIRING
The Benchmark 2.0 Boiler is available in several different modes of operation. While each unit
is factory configured and wired for its intended mode, some additional field wiring may be
required to complete the installation. This wiring is typically connected to the Input/Output (I/O)
Box located on the lower portion of the unit front panel (Figure 2-9) behind the removable front
door.
To access the I/O Box terminal strips shown in Figure 2-9, loosen the four cover screws and
remove the cover. All field wiring is installed from the rear of the panel by routing the wires
through one of the four bushings provided.
Refer to the wiring diagram provided on the cover of the I/O Box when making all wiring
connections.
Brief descriptions of each mode of operation, and their wiring requirements, are provided in the
following paragraphs. Additional information concerning field wiring is provided in paragraphs
2.10.1 through 2.10.13. Refer to Chapter 5 for detailed information on the available modes of
operation.
Figure 2-9: Input/Output (I/O) Box Location
Constant Setpoint Mode2.9.1
The Constant Setpoint Mode is used when it is desired to have a fixed setpoint that does not
deviate. No wiring connections, other than AC electrical power connections, are required for
this mode. However, if desired, fault monitoring or enable/disable interlock wiring can be

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Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
utilized (see paragraphs 2.10.11.1 and 2.10.11.2).
Indoor/Outdoor Reset Mode2.9.2
This mode of operation increases supply water temperature as outdoor temperatures decrease.
An outside air temperature sensor (AERCO Part No. 122790) is required. The sensor MUST
BE wired to the I/O Box wiring terminals (see Figure 2-10). Refer to paragraph 2.10.1 for
additional information on outside air temperature sensor installation.
Boiler Management System Mode2.9.3
NOTE
BMS Model 168 can utilize either pulse width modulation (PWM)
or RS485 Modbus signaling to the Boiler. BMS II Model 5R5-384
and the AERCO Control System (ACS) can utilize only RS485
signaling to the Boiler.
When using an AERCO BMS, BMS II, or ACS (AERCO Control System), the field wiring is
connected between the BMS/BMS II/ACS Panel and each Boiler’s I/O Box terminal strip (Figure
2-10). Twisted shielded pair wire from 18 to 22 AWG must be utilized for the connections. The
BMS Mode can utilize either pulse width modulation (PWM) signaling, or RS485 Modbus
signaling. For PWM signaling, connections are made from the AERCO Boiler Management
System to the B.M.S. (PWM) IN terminals on the I/O Box terminal strip. For RS485 Modus
signaling, connections are made from the BMS/BMS II/ACS to the RS485 COMM terminals on
the I/O Box terminal strip. Polarity must be maintained and the shield must be connected only at
the AERCO BMS/BMS II/ACS. The boiler end of the shield must be left floating.
For additional instructions, refer to Chapter 5, paragraph 5.6 in this manual. Also, refer to GF-
108M (BMS), GF-124 (BMS II Model 5R5-384), and GF-131 (ACS) operation manuals.
Remote Setpoint and Direct Drive Modes2.9.4
The boiler can accept several types of signal formats from an Energy Management System
(EMS), Building Automation System (BAS) or other source, to control either the setpoint
(Remote Setpoint Mode) or air/fuel valve position (Direct Drive Mode) of the Boiler. These
formats are:
•4 to 20 mA/1 to 5 VDC
•0 to 20 mA/0 to 5 VDC
•PWM – (Pulse Width Modulated signal. See para. 2.10.4)
•Network (RS485 Modbus. See para. 2.10.7)
While it is possible to control a boiler or boilers using one of the previously described
modes of operation, it may not be the method best suited for the application. Prior to
selecting one of these modes of operation, it is recommended that you consult with your
local AERCO representative or the factory for the mode of operation that will work best with
your application. For more information on wiring the 4 to 20 mA / 1to 5VDC or the 0 to 20
mA / 0 to 5 VDC, see paragraph 2.10.3.
Combination Mode2.9.5
NOTE
Only BMS Model 168 and ACS can be utilized for the Combination
Mode, not the BMS II (Model 5R5-384).
With a Combination Mode unit, field wiring is between the unit’s I/O Box wiring terminals, the