Watts Aerco Benchmark 750 User manual

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
Installation, Operation & Maintenance Manual
OMM-0119_0A AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 1of 170
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USER MANUAL
Installation, Operation and Maintenance
BENCHMARK
750 and 1000
Gas-Fired Boilers
Natural Gas Modulating
& Condensing Hot Water
Heating Boiler Models:
•BMK 750
•BMK 1000
THIS MANUAL APPLIES TO
CHINA LOW PRESSURE
(0.9 Bar) APPLICATIONS ONLY
Applicable to Serial Numbers:
G-16-0450 and Above
Latest Update: 11/03/2016

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
Installation, Operation & Maintenance Manual
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Technical Support
(Mon-Fri, 8am-5pm EST)
1-800-526-0288
www.aerco.com
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 these
materials.

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
Installation, Operation & Maintenance Manual
OMM-0119_0A AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 3of 170
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TABLE OF CONTENTS
FOREWORD ......................................................................................................................................... 7
CHAPTER 1. SAFETY PRECAUTIONS .........................................................................................11
1.1 WARNINGS & CAUTIONS ...................................................................................................................11
1.2 EMERGENCY SHUTDOWN.................................................................................................................12
1.3 PROLONGED SHUTDOWN.................................................................................................................12
CHAPTER 2. INSTALLATION ........................................................................................................13
2.1 INTRODUCTION...................................................................................................................................13
2.2 RECEIVING THE UNIT.........................................................................................................................13
2.3 UNPACKING.........................................................................................................................................13
2.4 SITE PREPARATION ...........................................................................................................................14
2.4.1 Installation Clearances....................................................................................................................................14
2.4.2 Setting the Unit...............................................................................................................................................15
2.5 SUPPLY AND RETURN PIPING..........................................................................................................16
2.6 PRESSURE RELIEF VALVE INSTALLATION .....................................................................................18
2.7 CONDENSATE DRAIN & PIPING ........................................................................................................19
2.8 GAS SUPPLY PIPING..........................................................................................................................21
2.8.1 Gas Supply Specifications ...............................................................................................................................21
2.8.2 Manual Gas Shutoff Valve ..............................................................................................................................21
2.8.3 External Gas Supply Regulator........................................................................................................................22
2.9 AC ELECTRICAL POWER WIRING.....................................................................................................22
2.9.1 Electrical Power Requirements.......................................................................................................................24
2.10 FIELD CONTROL WIRING.................................................................................................................25
2.10.1 Outdoor Air In (OUT) & Air Sensor Common (COM) ....................................................................................26
2.10.2 AIR TEMP SENSOR Terminals........................................................................................................................27
2.10.3 O2SENSOR Terminals (O2+ & O2-) ...............................................................................................................27
2.10.4 SPARK SIGNAL Terminals ..............................................................................................................................27
2.10.5 ANALOG IN Terminals...................................................................................................................................27
2.10.6 VALVE FEEDBACK Terminals .........................................................................................................................27
2.10.7 SHIELD Terminals (SHLD & SHLD) .................................................................................................................28
2.10.8 ANALOG OUT Terminals ...............................................................................................................................28
2.10.9 RS485 Comm (+, GND, & -) ...........................................................................................................................28
2.10.10 RS232 Comm (TxD & RxD) ..........................................................................................................................28
2.10.11 VFD/Blower (0-10 & AGND)........................................................................................................................28
2.10.12 Interlocks ....................................................................................................................................................28
2.10.13 Fault Relay (NC, COM, & NO)......................................................................................................................29
2.10.14 Auxiliary Relay Contacts (NC, COM, & NO).................................................................................................29
2.11 FLUE GAS VENT INSTALLATION.....................................................................................................29
2.12 COMBUSTION AIR.............................................................................................................................30
2.13 DUCTED COMBUSTION AIR.............................................................................................................30
2.14 SEQUENCING ISOLATION VALVE INSTALLATION........................................................................31
2.15 BENCHMARK PUMP RELAY.............................................................................................................32
CHAPTER 3. OPERATION ..............................................................................................................35
3.1 INTRODUCTION...................................................................................................................................35
3.2 CONTROL PANEL DESCRIPTION......................................................................................................35
3.3 CONTROL PANEL MENUS..................................................................................................................39
3.3.1 Menu Processing Procedure...........................................................................................................................39

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
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3.4 OPERATING MENU .............................................................................................................................41
3.5 SETUP MENU.......................................................................................................................................42
3.6 CONFIGURATION MENU ....................................................................................................................42
3.7 TUNING MENU.....................................................................................................................................45
3.8 COMBUSTION CAL MENU..................................................................................................................45
3.9 BST (BOILER SEQUENCING TECHNOLOGY) MENU.......................................................................46
3.10 START SEQUENCE...........................................................................................................................49
3.11 START/STOP LEVELS.......................................................................................................................53
CHAPTER 4. INITIAL START-UP..................................................................................................55
4.1 INITIAL START-UP REQUIREMENTS.................................................................................................55
4.2 TOOLS AND INSTRUMENTATION FOR COMBUSTION CALIBRATION..........................................55
4.2.1 Required Tools & Instrumentation .................................................................................................................56
4.2.2 Installing Gas Supply Manometer...................................................................................................................56
4.2.3 Accessing the Analyzer Probe Port .................................................................................................................57
4.3 NATURAL GAS COMBUSTION CALIBRATION..................................................................................58
4.4 REASSEMBLY......................................................................................................................................62
4.5 OVER-TEMPERATURE LIMIT SWITCHES.........................................................................................62
4.5.1 Digital Alarm Switch Checks and Adjustments ...............................................................................................63
CHAPTER 5. MODE OF OPERATION...........................................................................................65
5.1 INTRODUCTION...................................................................................................................................65
5.2 INDOOR/OUTDOOR RESET MODE ...................................................................................................65
5.2.1 Reset Ratio......................................................................................................................................................65
5.2.2 Building Reference Temperature....................................................................................................................65
5.2.3 Outdoor Air Temperature Sensor Installation ................................................................................................65
5.2.4 Indoor/Outdoor Startup .................................................................................................................................66
5.3 CONSTANT SETPOINT MODE ...........................................................................................................66
5.3.1 Setting the Setpoint ........................................................................................................................................67
5.4 REMOTE SETPOINT MODES .............................................................................................................67
5.4.1 Remote Setpoint Field Wiring.........................................................................................................................68
5.4.2 Remote Setpoint Startup ................................................................................................................................68
5.5 DIRECT DRIVE MODES.......................................................................................................................68
5.5.1 Direct Drive Field Wiring.................................................................................................................................69
5.5.2 Direct Drive Startup ........................................................................................................................................69
CHAPTER 6. SAFETY DEVICE TESTING.....................................................................................71
6.1 TESTING OF SAFETY DEVICES.........................................................................................................71
6.2 LOW GAS PRESSURE TEST..............................................................................................................72
6.3 HIGH GAS PRESSURE TEST .............................................................................................................73
6.4 LOW WATER LEVEL FAULT TEST.....................................................................................................74
6.5 WATER TEMPERATURE FAULT TEST..............................................................................................74
6.6 INTERLOCK TESTS.............................................................................................................................76
6.6.1 Remote Interlock Test.....................................................................................................................................76
6.6.2 Delayed Interlock Test ....................................................................................................................................76
6.7 FLAME FAULT TESTS.........................................................................................................................77
6.8 AIR FLOW FAULT TESTS....................................................................................................................79
6.8.1 Blower Proof Switch Test................................................................................................................................79
6.8.2 Blocked Inlet Switch Test ................................................................................................................................79
6.9 SSOV PROOF OF CLOSURE SWITCH...............................................................................................81
6.10 PURGE SWITCH OPEN DURING PURGE........................................................................................82

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
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6.11 IGNITION SWITCH OPEN DURING IGNITION.................................................................................82
6.1 SAFETY PRESSURE RELIEF VALVE TEST.......................................................................................84
CHAPTER 7. MAINTENANCE.........................................................................................................85
7.1 MAINTENANCE SCHEDULE ...............................................................................................................85
7.2 IGNITER-INJECTOR ............................................................................................................................86
7.3 FLAME DETECTOR .............................................................................................................................88
7.4 O2SENSOR..........................................................................................................................................89
7.5 SAFETY DEVICE TESTING.................................................................................................................89
7.6 BURNER ASSEMBLY INSPECTION ...................................................................................................90
7.7 CONDENSATE DRAIN TRAP ..............................................................................................................93
7.8 AIR FILTER CLEANING & REPLACEMENT........................................................................................94
7.9 WATER CUTOFF (LWCO) CAPACITOR INTEGRITY TEST...............................................................95
7.9.1 Low Water Cutoff (LWCO) - Capacitor Electrical Short Test ...........................................................................95
7.9.2 Low Water Cutoff (LWCO) - Standard C-More Test ........................................................................................97
7.10 SHUTTING THE HEATING BOILER DOWN FOR AN EXTENDED PERIOD OF TIME....................97
7.11 PLACING THE HEATING BOILER BACK IN SERVICE AFTER A PROLONGED SHUTDOWN......98
7.12 SPARK MONITOR (AC CURRENT TRANSDUCER).........................................................................98
CHAPTER 8. TROUBLESHOOTING GUIDE................................................................................99
8.1 INTRODUCTION...................................................................................................................................99
8.2 ADDITIONAL FAULTS WITHOUT SPECIFIC FAULT MESSAGES ..................................................111
CHAPTER 9. BOILER SEQUENCING TECHNOLOGY............................................................. 113
9.1 INTRODUCTION.................................................................................................................................113
9.1.1 Installation Notes..........................................................................................................................................114
9.2 AERCO BST QUICK START CHART.................................................................................................115
9.3 BST IMPLEMENTATION INSTRUCTION ..........................................................................................116
9.3.1 Option 1 - Constant Setpoint with DIRECT Wired Header Sensor ................................................................116
9.3.2 Option 2 - Constant Setpoint with MODBUS Wired Header Sensor.............................................................117
9.3.3 Option 3 - Outdoor Reset with DIRECT WIRED Header Sensor AND DIRECT WIRED Outdoor Sensor .........118
9.3.4 Option 4 - Outdoor Reset with MODBUS Header Sensor AND MODBUS Outdoor Sensor...........................120
9.3.5 Option 5 - Remote Setpoint with DIRECT WIRED Header Sensor AND 4-20ma Setpoint Drive ...................122
9.3.6 Option 6 - Remote Setpoint with DIRECT WIRED Header Sensor AND MODBUS Setpoint Drive.................124
9.3.7 Option 7 - Remote Setpoint with MODBUS Header Sensor AND 4-20ma Setpoint Drive ............................125
9.3.8 Option 8 - Remote Setpoint with MODBUS Header Sensor AND MODBUS Setpoint Drive .........................127
APPENDIX A: HEATING BOILER MENU ITEM DESCRIPTIONS.......................................... 129
TABLE A-1: OPERATING MENU ITEM DESCRIPTIONS .......................................................................129
TABLE A-2: SETUP MENU ITEM DESCRIPTIONS.................................................................................130
TABLE A-3: CONFIGURATION MENU ITEM DESCRIPTIONS ..............................................................131
TABLE A-4: TUNING MENU ITEM DESCRIPTIONS...............................................................................134
TABLE A-5: COMBUSTION CALIBRATION MENU ITEM DESCRIPTIONS...........................................135
APPENDIX B: STARTUP, STATUS & DISPLAY MESSAGES .................................................. 137
APPENDIX C: SENSOR RESISTANCE/VOLTAGE CHART...................................................... 141
APPENDIX D: RECOMMENDED PERIODIC TESTING ............................................................ 143
APPENDIX E: INDOOR/OUTDOOR RESET RATIO CHARTS ............................................... 145
APPENDIX F: DIMENSIONAL AND CLEARANCE DRAWINGS............................................. 149

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
Installation, Operation & Maintenance Manual
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APPENDIX G: PART LIST DRAWINGS ....................................................................................... 151
APPENDIX H: WIRING DIAGRAMS............................................................................................. 159
APPENDIX I: PIPING DRAWINGS .............................................................................................. 163
APPENDIX J: C-MORE CONTROL PANEL VIEWS................................................................... 165
APPENDIX K: RECOMMENDED SPARES................................................................................... 167
APPENDIX L: 220V TO 110V TRANSFORMER....................................................................... 169

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FOREWORD
The AERCO Benchmark (BMK) 750 MBH (220 kW) and 1000 MBH (293 kW) boilers are
modulating and condensing units. They represent 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 maximum turn down ratios for the BMK 1000 and BMK 750 are
20:1 and 15:1, respectively. These BMK models provide extremely high efficiency operation and
are ideally suited for modern low temperature, as well as, conventional heating systems.
The Benchmark Model BMK 750 and BMK 1000 boilers operate within the following input and
output ranges:
Benchmark
Model Input Range (BTU/hr.) Output Range (BTU/hr.)
Minimum
Maximum
Minimum
Maximum
BMK 750 50,000 (14.6 kW) 750,000 (220 kW) 47,750 (14 kW) 716,250 (210 kW)
BMK 1000 50,000 (14.6 kW) 1,000,000 (293 kW) 48,300 (14.15 kW) 968,000 (284 kW)
The output of the boiler is a function of the unit’s firing rate (valve position) and return water
temperature.
When installed and operated in accordance with this Instruction Manual, these boilers comply
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 BMK 750 and BMK 1000 boilers offer
the maximum venting flexibility with minimum installation space requirements. These boilers are
Category II and IV, positive pressure appliances. Single and/or multiple breeched units are
capable of operation in the following vent configurations:
Conventional, Vertical
Conventional, Sidewall
Conventional, Direct Vent, Vertical
Sealed, Direct Vent, Horizontal
These boilers are capable of being vented utilizing Polypropylene and AL29-4C vent systems.
The Benchmark's advanced electronics are available in several selectable modes of operation
offering the most efficient operating methods and energy management system integration.
IMPORTANT
Unless otherwise specified, all descriptions and procedures provided in this
Installation, Operation & Maintenance Manual apply to the Benchmark
series of boiler.

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Phrases, Abbreviations and Acronyms
Phrase, Abbreviation
or Acronym Meaning
A (Amp) Ampere
ACS AERCO Control System, AERCO’s boiler management systems
ADDR Address
AGND Analog Ground
ALRM Alarm
ANSI American National Standards Institute,
ASME American Society of Mechanical Engineers
AUX Auxiliary
BAS
Building Automation System, often used interchangeably with EMS
(see below)
Baud Rate Symbol rate, or simply the number of distinct symbol changes (signaling events) transmitted per second. It is not equal to bits per
second, unless each symbol is 1 bit long.
BMK (Benchmark) AERCO’s Benchmark series boilers
BMS or BMS II AERCO Boiler Management Systems
BLDG (Bldg) Building
BST AERCO on-board Boiler Sequencing Technology
BTU British Thermal Unit. A unit of energy approximately equal to the heat
required to raise 1 pound (0.45 kg) of water 1°F (0.55 °C)
BTU/HR BTUs per Hour (1 BTU/hr = 0.29 W)
CCP Combination Control Panel
C-More Controller
(or Control Box)
A control system developed by AERCO and currently used in all
Benchmark, Innovation and KC1000 Series product lines.
CFH Cubic Feet per Hour (1 CFH = 0.028 m3/hr)
CO Carbon Monoxide
COMM (Comm)
Communication
Cal.
Calibration
CNTL
Control
CPU Central Processing Unit
DIP Dual In-Line Package, a type of switch
ECU Electronic Control Unit (O2 sensor)
EMS Energy Management System; often used interchangeably with BAS
FM Factory Mutual. Used to define boiler gas trains.
GF-xxxx Gas Fired (an AERCO document numbering system)
GND Ground
HDR Header

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Phrase, Abbreviation
or Acronym
Meaning
Hex Hexadecimal Number (0 – 9, A – F)
HP Horse Power
HX Heat Exchanger
Hz Hertz (Cycles Per Second)
I.D. Inside Diameter
IGN Ignition
IGST Board Ignition/Stepper Board, contained in C-More Control Box
INTLK (INTL’K) Interlock
INCH, “ 英寸 (1英寸 = 2.54 cm)
I/O Input/Output
I/O Box Input/Output (I/O) Box currently used on Benchmark, Innovation and
KC1000 Series products
IP Internet Protocol
ISO International Organization for Standardization
Lbs.
Pounds (1 lb = 0.45 kg)
LED
Light Emitting Diode
LN
Low Nitrogen Oxide
MA (mA)
Milliampere (1 thousandth of an ampere)
MAX (Max) Maximum
MBH
1000 BTUs per Hour
（
1000 MBH = 293 kW
）
MIN (Min)
Minimum
Modbus® A serial, half-
duplex data transmission protocol developed by AEG
Modicon
NC (N.C.) Normally Closed
NO (N.O.) Normally Open
NOx Nitrogen Oxide
NPT National Pipe Thread
O
2
Oxygen
O.D. Outside Diameter
OMM & O&M Operation and Maintenance Manual
OnAER
AERCO’s on-line remote monitoring system
PCB
Printed Circuit Board
PMC Board
Primary Micro-Controller (PMC) board, contained in the C-More
P/N
Part Number
POC
Proof of Closure
PPM Parts per Million
PSI Pounds per Square Inch (1 PSI = 6.89 kPa)

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Phrase, Abbreviation
or Acronym
Meaning
PTP Point-to-Point (usually over RS232 networks)
P&T Pressure and Temperature
ProtoNode Hardware interface between BAS and a boiler or water heater
PVC Poly Vinyl Chloride, a common synthetic plastic
PWM Pulse Width Modulation
REF (Ref) Reference
RES. Resistive
RS232
(or EIA-232) A standard for serial, full-duplex (FDX) transmission of data based on the RS232 Standard
RS422
(or EIA-422)
A standard for serial, full-duplex (FDX) transmission of data based on
the RS422 Standard
RS485
(or EIA-485) A standard for serial, half-duplex (HDX) transmission of data based on the RS485 Standard
RTN (Rtn) Return
SETPT (Setpt) Setpoint Temperature
SHLD (Shld) Shield
SPDT Single Pole Double Throw, a type of switch
SSOV Safety Shut Off Valve
TEMP (Temp) Temperature
Terminating Resistor A resistor placed at each end of a daisy-chain or multi-drop network in
order to prevent reflections that may cause invalid data in the
communication
Tip-N-Tell
A device that indicates if a package was tipped during shipping
UL
A business that tests and validates products
VAC
Volts, Alternating Current
VDC
Volts, Direct Current
VFD Vacuum Fluorescent Display, also Variable Frequency Drive
W Watt
W.C. Water Column, a unit of pressure (1 W.C. = 249 Pa)
µA Micro amp (1 million
th
of an ampere)

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CHAPTER 1 – SAFETY PRECAUTIONS
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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)
for gas-fired boilers and ANSI/NFPASB for LP gas-fired boilers. 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! -
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.
--WARNING! -
Before attempting to perform 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
therefore must be completely sealed to prevent leakage of combustion
products into living spaces.
--WARNING! -
Electrical voltages up to 220 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.

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--WARNING! -
A 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.
--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.
NOTE
The Installer must identify and indicate the location of the
emergency shutdown manual gas valve to operating personnel.
Figure 1-1: Manual Gas Shutoff Valve
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.
VALVE OPEN VALVE CLOSED
MANUAL GAS SHUT-OFF VALVE

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CHAPTER 2 – INSTALLATION
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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 Model BMK 750 and BMK 1000 Heating Boiler.
2.2 RECEIVING THE UNIT
Each Benchmark Heating Boiler System is shipped as a single crated unit. The shipping weights
for the BMK 750 and BMK 1000 Models are approximately 1100 (499 kg) and 1200 pounds
(544 kg), respectively. 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
After unpacking, 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.
The following accessories come standard with each unit and are either packed separately within
the unit’s shipping container or are factory installed on the unit:
•Pressure/Temperature Gauge
•ASME Pressure Relief Valve
•Condensate Drain Trap (P/N 24441)
•1” Natural Gas Supply Shutoff Valve
When optional accessories are ordered, they may be packed within the unit’s shipping
container, factory installed on the unit, or packed and shipped in a separate container. Any
standard or optional accessories shipped loose should be identified and stored in a safe place
until ready for installation or use.

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CHAPTER 2 – INSTALLATION
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2.4 SITE PREPARATION
Ensure that the site selected for installation of the Benchmark 750/1000 Heating Boiler includes:
•Access to AC Input Power at 220 VAC, Single-Phase, 50 Hz @ 15 Amps
•Access to a Natural Gas line with a minimum pressure of 4 inches W.C. (1.00 kPa)
with the unit operating at maximum capacity.
2.4.1 Installation Clearances
The Benchmark Model 750 and 1000 are packaged in an enclosure having identical exterior
dimensions. The unit must be installed with the prescribed clearances for service as shown in
Figure 2-1a. 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 as follows:
•Sides: 24 inches (61 cm)
•Front: 24 inches (61 cm)
•Rear: 24 inches (61 cm)
•Top: 18 inches (45.7 cm)
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.
Figure 2-1a: Benchmark Heating Boiler Model 750/1000 Clearances
Housekeeping pad should not extend under the condensate assembly

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CHAPTER 2 – INSTALLATION
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--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 unit must be moved by pallet
jack or forklift from the FRONT ONLY.
2.4.2 Setting the Unit
The unit must be installed on a 4 to 6 inch (10 to 15 cm) thick housekeeping pad to ensure
proper condensate drainage. If anchoring the unit, refer to Figure 2-1b for anchor locations.
Figure 2-1b: Benchmark 750/1000 Anchor Bolt Locations
Remove the four (4) lag screws securing the unit to the shipping skid. The boiler can be lifted
and moved by inserting forklift tines in the front slots provided in the base of the unit, or it can be
lifted by attaching a lifting bar to the unit’s heat exchanger. A lifting bar (P/N 59174), with
attaching hardware, is supplied with each unit. When shipped, this bar is attached to the rear of
the unit as shown in Figure 2-2, View A. One (1) lifting tab is provided at the top of the unit’s
heat exchanger as shown. This tab is used to attach the lifting bar to the unit as follows:
--WARNING! -
•When lifting or moving the Heating Boiler, DO NOT attempt
to manipulate the Heating Boiler using the gas train or
blower.
•When using the lifting tab and bar, ensure there is no load
placed on the gas train or blower.

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Attachment of Lifting Bar
1. Remove the lifting bar from its shipping location at the rear of the unit (Figure 2-2, View
A). Retain the attaching hardware consisting of two (2) hex head cap screws, hex nuts
and flat washers.
2. Remove the top shroud from the boiler by grasping the handle on the top of the unit and
lifting straight up. Locate the lifting tab at the top-rear of the heat exchanger.
3. Refer to Figure 2-2, View B and attach the lifting bar to the heat exchanger lifting tab
using the hardware removed in step 1. The upper end of the lifting bar containing the oval
cutout should be positioned over the top of the heat exchanger as shown.
4. Using proper rigging equipment, capable of supporting 1000 to 1200 lbs. (435 – 544 kg),
lift the boiler and position it on the housekeeping pad.
5. After the boiler is properly set on the pad, detach the lifting bar and replace the shroud on
the top of the unit.
6. Retain the lifting bar for possible reuse at the installation site.
Figure 2-2: Heating Boiler Lifting Provisions
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.
2.5 SUPPLY AND RETURN PIPING
Benchmark 750 and 1000 Heating Boilers have 3” (7.62 cm) 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 E for
dimensional data.
When connecting the hot water outlet and cold water inlet to building piping, first make sure the
mating surfaces are thoroughly clean. AERCO recommends using Loctite ® 7649 to prime the
mating surfaces and then Loctite 567 as pipe dope. Do NOT use Teflon tape.
LIFTING BAR IN
LIFTING POSITION
LIFTING
BAR IN
SHIPPING
POSITION
LIFTING TAB
VIEW B - LIFTING POSITION
VIEW A - SHIPPING POSITION
1” (2.54 cm)
NATURAL
GAS INLET

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
CHAPTER 2 – INSTALLATION
OMM-0119_0A AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 17 of 170
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Figure 2-3: Supply and Return Locations
The dual inlet connections allow these units to be configured with a separate cooler return
temperature zone, rather than blending high and low return temperature zones. Utilizing the
dual return capability, these Heating Boilers can take further advantage of the condensing
capabilities. When configured with a lower return temperature zone or AERCO SmartPlates,
thermal efficiency can improve by up to 6% (Based on an 80°F (26.7°C) minimum return water
temperature at full fire. Lower return temperatures are possible which would yield even greater
efficiency gains. The maximum temperature differential across the Heating Boiler’s heat
exchanger is 100°F (55°C).
To use the secondary inlet, pipe the warmer return water to the secondary (upper) inlet and the
cooler return water to the primary (lower) inlet. . If the flow through both the primary and the
secondary return is constant, then the combined minimum flows must equal the specified
minimum flow of the Heating Boiler. If the flow through either of the inlet returns is intermittent,
then the minimum flow through one of the return connections must always equal the specified
minimum flow of the Heating Boiler.
If the secondary inlet is not utilized, it may serve as an inspection port. Contact your AERCO
representative for additional information.
1” (254 mm) NATURAL
GAS INLET
BOILER HOT
WATER OUTLET
(SUPPLY)
EXHAUST MANIFOLD
CONDENSATE
DRAIN PORT
AIR INLET
DRAIN VALVE
SECONDARY WATER INLET
(WARMER WATER RETURN)
PRIMARY WATER INLET
(
COOLER
WATER RETURN)

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2.6 PRESSURE RELIEF VALVE INSTALLATION
NOTE
Pressure relief valves are not required for low pressure applications, but
we recommend that they be installed as a safety measure to avoid the
build-up of pressure inside the device (although this rarely occurs).
An ASME Pressure Relief Valve rated 30 PSI (207 kPa) is supplied with each Benchmark
Boiler.
The relief valve is installed on the hot water outlet of the boiler as shown in Figure 2-4. A
suitable pipe joint compound should be used on the threaded connections. Any excess should
be wiped off to avoid getting any joint compound into the valve body. The relief valve must be
piped to within 12 inches (30.5 cm) of the floor to prevent injury in the event of a discharge.
No valves, restrictions, or other blockages are allowed in the discharge line. In multiple unit
installations the discharge lines must NOT be manifolded together. Each must be individually
run to a suitable discharge location.
Figure 2-4: P&T Relief Valve Location
See Diagram 1 in Appendix I for an example of a low-pressure piping scheme.
PRESSURE
RELIEF VALVE
3” HOT BOILER
WATER OUTLET
INSTALL TRIDICATOR
GAUGE HERE
(P/N 123675-TAB)

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OMM-0119_0A AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 19 of 170
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2.7 CONDENSATE DRAIN & PIPING
The Benchmark Heating 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 port located on the exhaust manifold (Figure 2-5) must be connected to
the condensate trap (P/N 24441) which is packed separately within the unit’s shipping container.
The condensate trap inlet features two integral O-rings and a thumbscrew to allow direct
connection of the drain port into the trap inlet. See the Condensate trap Installation instructions
and Figure 2-6.
Figure 2-5: Condensate Drain Connection Location
A sample condensate trap installation is shown in Figure 2-6. The following general guidelines
must be observed to ensure proper condensate drainage:
•The condensate trap inlet (Figure 2-6) must be level the exhaust manifold drain port.
•The base of the condensate trap must be supported to ensure that it is level (horizontal).
•The trap must be removable for routine maintenance.
While observing the above guidelines, install the condensate trap as follows:
Condensate Trap Installation
1. Connect the condensate trap inlet to the exhaust manifold drain connection by inserting
the drain port directly into the trap adaptor inlet, and then tightening the inlet thumbscrew,
as shown in Figure 2-6. The inlet features two integral O-rings to prevent leakage.
2. At the condensate trap outlet, install a 3/4” NPT nipple.
3. Connect a length of 1” (2.54 cm) diameter 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 10 gallons (37.8 liters) per hour. The
condensate drain trap, associated fittings and drain line must be removable for routine
maintenance.
DRAIN VALVE
CONDENSATE DRAIN PORT
1/4” ANALYZER
NPT PORT
EXHAUST
MANIFOLD
PRIMARY
WATER INLET

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WARNING!
Use PVC, stainless steel, aluminum or polypropylene for condensate
drain piping (Figure 2-6). Do NOT use carbon or copper components.
Figure 2-6: Sample Condensate Trap Installation (Right Side View)
EXHAUST
MANIFOLD
DRAIN PORT
COMBUSTION
ANALYZER
PROBE PORT
EXHAUST
MANIFOLD
3/4” NPT
NIPPLES
HOSE
CLAMP
T O
FLOOR
DRAIN
CONDENSATE
TRAP (P/N 24441)
TRAP INLET
INTEGRAL
ADAPTOR AND
THUMBSCREW
TOP
COVER
THUMB
SCREWS
(4 ea.)
1” (2.54cm)
DIAM.
NOTE
HOUSEKEEPING PAD MUST NOT EXTEND UNDER THE CONDENSATE ASSEMBLY.
4-6”
(10-15 cm)
THICK
4” (10cm)