Watts Aerco Benchmark OMM-0116 Installation and operation manual

Benchmark®Boilers
Natural Gas, Propane Gas and Dual Fuel Fired
Modulating & Condensing Boilers
Models 750 through 3000
Installation and Startup Manual
Other documents for this product include:
OMM-0116, GF-201 Operation-Service Manual
TAG-0019, GF-2070 Boiler Application Guide
TAG-0022, GF-2050 Vent-Combustion Air Guide
TAG-0047, GF-2030 Benchmark Gas Guide
TAG-0048, GF-2060 Benchmark Power Guide
Applies to serial numbers:
G-19-0001 and above
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, not for incidental or consequential
damages occurring in connection with the furnishing, performance, or use of
these materials
OMM-115_D •GF-200 •5/9/2019

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TABLE OF CONTENTS
FOREWORD ......................................................................................................5
SECTION 1: SAFETY PRECAUTIONS ...................................................................9
1.1 WARNINGS & CAUTIONS .....................................................................................................9
1.2 EMERGENCY SHUTDOWN.................................................................................................10
1.3 PROLONGED SHUTDOWN.................................................................................................10
1.4 IMPORTANT –FOR MASSACHUSETTS INSTALLATIONS ...............................................11
SECTION 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 ..............................................................................................................................17
2.5 LIFTING PROVISIONS.........................................................................................................19
2.5.1 BMK 750 –1000 lifting Provisions..................................................................................................19
2.5.2 BMK 1500 –3000 Lifting Provisions...............................................................................................20
2.6 SUPPLY AND RETURN PIPING..........................................................................................21
2.6.1 BMK 750 –1000 Supply and Return Piping....................................................................................21
2.6.2 BMK 1500 –3000 Supply and Return Piping..................................................................................21
2.6.3 Dual Inlet Return Piping .................................................................................................................22
2.7 PRESSURE RELIEF VALVE INSTALLATION .....................................................................23
2.8 CONDENSATE DRAIN AND PIPING...................................................................................24
2.9 GAS SUPPLY PIPING..........................................................................................................26
2.9.1 Gas Supply Specifications...............................................................................................................27
2.9.2 Manual Gas Shutoff Valve ..............................................................................................................27
2.9.3 External Gas Supply Regulator .......................................................................................................28
2.10 AC ELECTRICAL POWER WIRING...................................................................................30
2.10.1 Electrical Power Requirements ....................................................................................................30
2.10.2 Power Box Locations ....................................................................................................................31
2.10.3 Electrical Power Box Internal Components..................................................................................32
2.11 FIELD CONTROL WIRING.................................................................................................34
2.11.1 Outdoor Air & Air Sensor Common..............................................................................................35
2.11.2 AIR TEMP SENSOR ........................................................................................................................36
2.11.3 O2SENSOR (+ & –) ........................................................................................................................36
2.11.4 SPARK SIGNAL (+ & –)...................................................................................................................36
2.11.5 ANALOG IN ...................................................................................................................................36
2.11.6 VALVE FEEDBACK..........................................................................................................................37
2.11.7 SHIELD (SHLD & SHLD)..................................................................................................................37
2.11.8 ANALOG OUT................................................................................................................................37
2.11.9 RS485 Comm (+, GND, & -)...........................................................................................................37
2.11.10 RS232 Comm (TxD & RxD)..........................................................................................................37
2.11.11 VFD/Blower (0-10 & AGND) .......................................................................................................37
2.11.12 Interlocks....................................................................................................................................38
2.11.13 Fault Relay (NC, COM, & NO) .....................................................................................................38

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2.11.14 Auxiliary Relay Contacts (NC, COM, & NO) ................................................................................39
2.12 FLUE GAS VENT INSTALLATION.....................................................................................39
2.12.1 MASSACHUSETTS INSTALLATIONS ...............................................................................................39
2.13 COMBUSTION AIR.............................................................................................................40
2.13.1 DUCTED COMBUSTION AIR ..........................................................................................................40
2.14 BENCHMARK PUMP RELAY.............................................................................................41
2.15 SEQUENCING ISOLATION VALVE INSTALLATION.........................................................42
SECTION 3: START SEQUENCE ........................................................................45
3.1 INTRODUCTION ..................................................................................................................45
3.2 START SEQUENCE.............................................................................................................45
3.3 START/STOP LEVELS.........................................................................................................51
3.4 START/STOP LEVELS –AIR/FUEL & ENERGY INPUT .....................................................52
3.4.1 BMK 750/1000 Air/Fuel Valve Position and Energy Input .............................................................52
3.4.2 BMK 1500 Air/Fuel Valve Position and Energy Input .....................................................................53
3.4.3 BMK 2000 Air/Fuel Valve Position and Energy Input .....................................................................54
3.4.4 BMK 2500 Air/Fuel Valve Position and Energy Input .....................................................................55
3.4.5 BMK 3000 Air/Fuel Valve Position and Energy Input .....................................................................56
SECTION 4: INITIAL START-UP ........................................................................57
4.1 INITIAL START-UP REQUIREMENTS.................................................................................57
4.2 TOOLS & INSTRUMENTS FOR COMBUSTION CALIBRATION.........................................57
4.2.1 Required Tools & Instrumentation.................................................................................................57
4.2.2 Installing Gas Supply Manometer ..................................................................................................58
4.2.3 Accessing the Analyzer Probe Port.................................................................................................60
4.3 FUEL TYPES AND COMBUSTION CALIBRATION.............................................................61
4.4 COMBUSTION CALIBRATION.............................................................................................62
4.4.1 NATURAL GAS Combustion Calibration..........................................................................................63
4.4.2 PROPANE GAS COMBUSTION CALIBRATION..................................................................................67
4.5 REASSEMBLY......................................................................................................................71
4.6 DUAL FUEL SWITCHOVER.................................................................................................71
4.6.1 Switchover from NATURAL GAS to PROPANE ................................................................................72
4.6.2 Switchover from PROPANE to NATURAL GAS ................................................................................73
4.7 OVER-TEMPERATURE LIMIT SWITCHES .........................................................................74
4.7.1 Digital Alarm Switch Checks and Adjustments...............................................................................75
SECTION 5: SAFETY DEVICE TESTING ..............................................................77
5.1 TESTING OF SAFETY DEVICES.........................................................................................77
5.2 LOW GAS PRESSURE TEST ..............................................................................................78
5.2.1 LOW GAS PRESSURE TEST: BMK 750 –2500..................................................................................78
5.2.2 LOW GAS PRESSURE TEST: BMK 3000 Only....................................................................................80
5.3 HIGH GAS PRESSURE TEST .............................................................................................82
5.3.1 HIGH GAS PRESSURE TEST: BMK 750 –2500 .................................................................................82
5.3.2 HIGH GAS PRESSURE TEST: BMK 3000 Only...................................................................................84
5.4 LOW WATER LEVEL FAULT TEST.....................................................................................86
5.5 WATER TEMPERATURE FAULT TEST ..............................................................................87
5.6 INTERLOCK TESTS.............................................................................................................89
5.6.1 Remote Interlock Test ....................................................................................................................89

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5.6.2 Delayed Interlock Test....................................................................................................................89
5.7 FLAME FAULT TEST ...........................................................................................................90
5.8 AIR FLOW FAULT TESTS - BLOWER PROOF & BLOCKED INLET SWITCHES ..............91
5.8.1 Blower Proof Switch Test ...............................................................................................................91
5.8.2 Blocked Inlet Switch Test ...............................................................................................................93
5.9 SSOV PROOF OF CLOSURE SWITCH CHECK.................................................................94
5.10 PURGE SWITCH OPEN DURING PURGE........................................................................94
5.11 IGNITION SWITCH OPEN DURING IGNITION .................................................................97
5.12 SAFETY PRESSURE RELIEF VALVE TEST.....................................................................97
SECTION 6: BOILER SEQUENCING TECHNOLOGY ............................................99
6.1 INTRODUCTION ..................................................................................................................99
6.1.1 INSTALLATION NOTES...................................................................................................................100
6.2 AERCO BST QUICK START CHART.................................................................................100
6.3 BST IMPLEMENTATION INSTRUCTION ..........................................................................101
6.3.1 OPTION 1 - CONSTANT SETPOINT WITH DIRECT WIRED HEADER SENSOR..................................101
6.3.2 OPTION 2 - CONSTANT SETPOINT WITH MODBUS WIRED HEADER SENSOR ..............................102
6.3.3 OPTION 3 - OUTDOOR RESET WITH DIRECT WIRED HEADER SENSOR AND DIRECT WIRED
OUTDOOR SENSOR................................................................................................................................103
6.3.4 OPTION 4 - OUTDOOR RESET WITH MODBUS HEADER SENSOR AND MODBUS OUTDOOR SENSOR
...............................................................................................................................................................105
6.3.5 OPTION 5 - REMOTE SETPOINT WITH DIRECT WIRED HEADER SENSOR AND 4-20MA SETPOINT
DRIVE.....................................................................................................................................................107
6.3.6 OPTION 6 - REMOTE SETPOINT WITH DIRECT WIRED HEADER SENSOR AND MODBUS SETPOINT
DRIVE.....................................................................................................................................................109
6.3.7 OPTION 7 - REMOTE SETPOINT WITH MODBUS HEADER SENSOR AND 4-20MA SETPOINT DRIVE
...............................................................................................................................................................111
6.3.8 Option 8 - Remote Setpoint with MODBUS Header Sensor AND MODBUS Setpoint Drive.........113
SECTION 7: ONAER SETUP............................................................................115
7.1 INTRODUCTION ................................................................................................................115
7.1.1 Connecting the Ethernet Cable ....................................................................................................115
7.1.2 Confirming the Ethernet Connection...........................................................................................117
7.1.3 Confirm Ethernet DHCP Configuration.........................................................................................117
APPENDIX A: DIMENSIONAL AND CLEARANCE DRAWINGS .............................119

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FOREWORD
The AERCO Benchmark (BMK) 750, 1000, 1500, 2000, 2500, and 3000 natural gas and
propane fueled 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. These BMK models provide extremely high
efficiency operation and are ideally suited for modern low temperature, as well as, conventional
heating systems.
IMPORTANT!
Unless otherwise specified all descriptions provided in this document apply to the Benchmark
Series of boiler.
The Benchmark models operate within the input and output ranges listed below. All
measurements apply to both natural gas and propane models, unless otherwise specified.
Benchmark Boiler Intake and Output Ranges
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 (14.0 kW)
716,250 (210 kW)
BMK 1000
50,000 (14.6 kW)
1,000,000 (293 kW)
48,300 (14.2 kW)
968,000 (284 kW)
BMK 1500
75,000 (22 kW)
1,500,000 (440 kW)
64,500 (18.9 kW)
1,395,000 (409 kW)
BMK 2000
100,000 (29.3 kW)
2,000,000 (586 kW)
86,000 (25.2 kW)
1,860,000 (545 kW)
BMK 2500
167,000 (48.9 kW)
2,500,000 (732 kW)
144,000 (42.2 kW)
2,395,000 (702 kW)
BMK 3000
200,000 (58.6 kW)
3,000,000 (879 kW)
174,000 (51.0 kW)
2,874,000 (842 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, the BMK 750 –2000
and 5000 & 6000 comply with the NOxemission standards outlined in: South Coast Air Quality
Management District (SCAQMD), Rule 1146.2. In addition, the BMK 2500 –6000 comply with
the Bay Area Air Quality Management District regulation 9, Rule 7.
Whether used in singular or modular arrangements, the BMK 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:
•Room Combustion Air:
oVertical Discharge
oHorizontal Discharge
•Ducted Combustion Air:
oVertical Discharge
oHorizontal Discharge
These boilers are capable of being vented utilizing Polypropylene and AL29-4C vent systems. In
addition, the BMK 750 & 1000 models are also approved for PVC and CPVC, vent systems.

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The Benchmark's advanced electronics are available in several selectable modes of operation
offering the most efficient operating methods and energy management system integration.
AERCO Technical Terminology Meanings
TERMINOLOGY
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
CCS
Combination Control System
C-More Controller
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
DBB
Double Block and Bleed, a gas trains containing 2 Safety Shutoff
Valves (SSOVs) and a solenoid operated vent valve.
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.

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AERCO Technical Terminology Meanings
TERMINOLOGY
MEANING
GF-xxxx
Gas Fired (an AERCO document numbering system)
GND
Ground
HDR
Header
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 Controller
INTLK (INTL’K)
Interlock
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
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
O2
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
Controller
P/N
Part Number
POC
Proof of Closure

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AERCO Technical Terminology Meanings
TERMINOLOGY
MEANING
PPM
Parts per Million
PSI
Pounds per Square Inch (1 PSI = 6.89 kPa)
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 millionth of an ampere)

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SECTION 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.
See section 1.4 for important information regarding installation of units within the
Commonwealth of Massachusetts.
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.
•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.
•Before attempting to perform any maintenance on the unit, shut off all gas and electrical
inputs to the unit.
•The exhaust vent pipe of the unit may operate under a positive pressure and therefore must
be completely sealed to prevent leakage of combustion products into living spaces.
•Electrical voltages up to 120 VAC (BMK 750 –2000) and 208 or 460 VAC (BMK
2500/3000) 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.
•A single-pole (120 VAC units) or three-pole (220 VAC or higher units) 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.
•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.

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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
In addition, to ensure safety an emergency shutdown procedure that addresses the following
points should be designed and implement at the site:
•For automatically operated unattended boilers located in a boiler room, provide a
manually operated remote shutdown switch or circuit breaker located just inside or
outside each boiler room door. Design the system so activation of the emergency
shutdown switch or circuit breaker will immediately shut off the fuel supply to the unit(s).
•For automatically operated unattended boilers in a location other than a boiler room,
provide a manually operated remote shutdown switch or circuit breaker marked for easy
identification at a location readily accessible in the event of boiler mis-operation.
•Design the system so activation of the emergency shutdown switch or circuit breaker will
immediately shut off the fuel.
•For boilers monitored and/or operated from a continuously occupied control room,
provide an emergency shutdown switch in the control room that is hard-wired to
immediately shut off the fuel upon activation.
1.3 PROLONGED SHUTDOWN
If there is an emergency, turn off the electrical power supply to the unit and close the manual
gas valve located upstream the unit. The installer must identify the emergency shut-off device.
If the boiler needs to be shut down for a prolonged period, follow the instructions in Section
4.10:Shutting Boiler Down For Extended Period in the Benchmark 750-3000 Operation and
Maintenance Guide, OMM-0116 (GF-201).
After prolonged shutdown, it is recommended that the procedures in Section 4: Initial Startup
and Section 5: Safety Device Testing of this manual be performed to verify that all system-
operating parameters are correct.
VALVE
OPEN
VALVE
CLOSED

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1.4 IMPORTANT –FOR MASSACHUSETTS INSTALLATIONS
Requirements for Massachusetts Installations
Boiler Installations within the Commonwealth of Massachusetts must conform to the
following requirements:
•Boiler must be installed by a plumber or a gas fitter who is licensed within the
Commonwealth of Massachusetts.
•Prior to unit operation, the complete gas train and all connections must be leak
tested using a non-corrosive soap.
•The vent termination must be located a minimum of 4 feet above grade level. If
side-wall venting is used, the installation must conform to the following
requirements extracted from 248 CMR 5.08 (2):
(a) For all side wall horizontally vented gas fueled equipment installed in every dwelling,
building or structure used in whole or in part for residential purposes, including those owned or
operated by the Commonwealth and where the side wall exhaust vent termination is less than
seven (7) feet above finished grade in the area of the venting, including but not limited to decks
and porches, the following requirements shall be satisfied:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS: At the time of installation of the
side wall horizontal vented gas fueled equipment, the installing plumber or gasfitter shall
observe that a hard wired carbon monoxide detector with an alarm and battery back-up is
installed on the floor level where the gas equipment is to be installed. In addition, the
installing plumber or gasfitter shall observe that a battery operated or hard wired carbon
monoxide detector with an alarm is installed on each additional level of the dwelling,
building or structure served by the side wall horizontal vented gas fueled equipment. It shall
be the responsibility of the property owner to secure the services of qualified licensed
professionals for the installation of hard wired carbon monoxide detectors.
a. In the event that the side wall horizontally vented gas fueled equipment is installed in a
crawl space or an attic, the hard wired carbon monoxide detector with alarm and battery
back-up may be installed on the next adjacent floor level.
b. In the event that the requirements of this subdivision can not be met at the time of
completion of installation, the owner shall have a period of thirty (30) days to comply with
the above requirements; provided, however, that during said thirty (30) day period, a
battery operated carbon monoxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS: Each carbon monoxide detector as
required in accordance with the above provisions shall comply with NFPA 720 and be
ANSI/UL 2034 listed and IAS certified.
3. SIGNAGE: A metal or plastic identification plate shall be permanently mounted to the
exterior of the building at a minimum height of eight (8) feet above grade directly in line
with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or
equipment. The sign shall read, in print size no less than one-half (1/2) inch in size, "GAS
VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS". (Continued)

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Requirements for Massachusetts Installations
4. INSPECTION: The state or local gas inspector of the side wall horizontally vented gas
fueled equipment shall not approve the installation unless, upon inspection, the inspector
observes carbon monoxide detectors and signage installed in accordance with the
provisions of 248 CMR 5.08(2)(a)1 through 4.
(b) EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a)1 through 4:
1. The equipment listed in Section 10 entitled "Equipment Not Required To Be Vented" in
the most current edition of NFPA 54 as adopted by the Board; and
2. Product Approved side wall horizontally vented gas fueled equipment installed in a
room or structure separate from the dwelling, building or structure used in whole or in
part for residential purposes.
(c) MANUFACTURER REQUIREMENTS - GAS EQUIPMENT VENTING SYSTEM PROVIDED. When
the manufacturer of Product Approved side wall horizontally vented gas equipment provides a
venting system design or venting system components with the equipment, the instructions
provided by the manufacturer for installation of the equipment and the venting system shall
include:
1. Detailed instructions for the installation of the venting system design or the venting
system components; and
2. A complete parts list for the venting system design or venting system.
(d) MANUFACTURER REQUIREMENTS - GAS EQUIPMENT VENTING SYSTEM NOT PROVIDED.
When the manufacturer of a Product Approved side wall horizontally vented gas fueled
equipment does not provide the parts for venting the flue gases, but identifies "special venting
systems", the following requirements shall be satisfied by the manufacturer:
1. The referenced "special venting system" instructions shall be included with the appliance
or equipment installation instructions; and
2. The "special venting systems" shall be Product Approved by the Board, and the
instructions for that system shall include a parts list and detailed installation instructions.
(e) A copy of all installation instructions for all Product Approved side wall horizontally vented
gas fueled equipment, all venting instructions, all parts lists for venting instructions, and/or all
venting design instructions shall remain with the appliance or equipment at the completion of
the installation.
……………….[End of Extracted Information From 248 CMR 5.08 (2)]…………………

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SECTION 2: INSTALLATION
2.1 INTRODUCTION
This Section provides the descriptions and procedures necessary to unpack, inspect and install
the AERCO Benchmark Boilers, models 750, 1000, 1500, 2000, 2500 and 3000.
2.2 RECEIVING THE UNIT
Each Benchmark Boiler System is shipped as a single crated unit. The shipping weight for these
BMK models is approximately as follows:
•BMK 750: 1100 lbs. (499 kg)
•BMK 1000: 1200 lbs. (544 kg)
•BMK 1500/2000: 1800 lbs. (817 kg).
•BMK 2500/3000: 2200 lbs. (1000 kg)
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.
CAUTION!
While packaged in the shipping container, the unit must be moved by pallet jack or forklift from
the FRONT ONLY.
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, make a close inspection of the unit 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)
•A 1 “ or 2” Natural Gas Supply Shutoff Valve, and a Propane Shutoff Valve on Propane
and Dual Fuel units

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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.
2.4 SITE PREPARATION
Ensure that the site selected for installation of the Benchmark Boiler includes:
•Access to AC input power specified in Section 2.10.1.
•Access to natural gas or propane gas with minimum pressure specified in Section 2.9.1.
2.4.1 Installation Clearances
All Benchmark models are the same height, but vary in depth according to model pairs;
750/1000, 1500/2000, and 2500/3000. The unit must be installed with the prescribed clearances
for service as shown in Figure 2-1a, 2-1b and 2-1c. The minimum clearance dimensions,
required by AERCO, are listed below for all models. However, if Local Building Codes require
additional clearances, these codes shall supersede AERCO’s requirements. The 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.
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.
NOTE:
Benchmark 750 –3000 units may be installed with zero side clearances in pairs only. The
perimeter clearances still apply. See drawings in Appendix A: Dimensions and Clearance
Drawings.
If installing a Combination (CCP) system using an ACS panel, it is important to identify the
Combination Mode Boilers in advance and place them in the proper physical location. For
information on Combination Mode Boilers refer to Section 3.7 of the Benchmark 750 –3000
Boiler Operation and Maintenance Guide, OMM-0116 (GF-201).

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Figure 2-1a: BMK 750/1000 Clearances
Figure 2-1b: BMK 1500/2000 Clearances
NOTE:
Ensure that
condensate
assembly is
not located
over the
housekeeping
pad.
NOTE:
Ensure that
condensate
assembly is
not located
over the
housekeeping
pad.
4” High Pad

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Figure 2-1c: BMK 2500/3000 Clearances
WARNING!
Keep the unit area clear and free from all combustible materials and flammable vapors or
liquids.
FOR MASSACHUSETTS ONLY:
For Massachusetts installations, the unit must be installed by a plumber or gas-fitter licensed
within the Commonwealth of Massachusetts. In addition, the installation must comply with all
requirements specified in Section 1.4, above.
Housekeeping Pad.
FRONT
REAR
NOTE:
Ensure that
condensate
assembly is
not located
over the
housekeeping
pad.

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2.4.2 Setting the Unit
All Benchmark Boilers must be installed on a level housekeeping pad to ensure proper
condensate drainage. The pad thickness must be:
•BMK 750 –1000 –4 to 6 inch (10.2 to 15.2 cm)
•BMK 1500 –3000 –4 to 8 inch (10.2 to 20.3 cm)
If anchoring the unit, refer to the Figures below for anchor locations.
•All holes are flush with the bottom surface of the frame.
•All dimensions shown are in inches [millimeters]
Figure 2-2a: BMK 750/1000 Anchor Bolt Locations
Figure 2-2b: BMK 1500/2000 Anchor Bolt Locations

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NOTES:
•All holes are flush with the bottom surface of the frame
•All dimensions shown are in inches [millimeters]
Figure 2-2c: BMK 2500/3000 Anchor Bolt Locations
FRONT
REAR

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2.5 LIFTING PROVISIONS
WARNING!
When lifting or moving the boiler, DO NOT attempt to manipulate the boiler using the gas train
or blower.
2.5.1 BMK 750 –1000 lifting Provisions
Unpack and inspect the unit, then remove the four (4) lag screws securing the boiler to the
shipping pallet. 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 2-3a (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 described below.
WARNING!
When using the lifting tab and bar, ensure there is no load placed on the gas train or blower.
Attaching the Lifting Bar: BMK 750/1000 Instructions
1. Remove the lifting bar from its shipping location at the rear of the unit (Figure 2-3a, View
A). Retain the two (2) hex head cap screws, hex nuts and flat washers.
2. Remove the top shroud from the boiler and locate the lifting tab at the top-rear of the heat
exchanger.
3. Attach the lifting bar to the heat exchanger lifting tab using the hardware removed in step 1
(Fig. 2-3a, View B). 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 lifting 1200 lbs. (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, but retain the lifting bar for possible reuse at the installation site.
Figure 2-3a: BMK 750/1000 Boiler Lifting Provisions
LIFTING BAR
IN LIFTING
POSITION
LIFTING
BAR IN
SHIPPING
POSITION
LIFTING
TAB
VIEW B - LIFTING POSITION
VIEW A - SHIPPING POSITION

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2.5.2 BMK 1500 –3000 Lifting Provisions
Three lifting lugs are provided at the top of the primary heat exchanger as shown in Figure 2-3b.
Remove the front top panel from the unit to provide access to the lifting lugs. 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 8 inch (10.2 cm to 20.3 cm) housekeeping concrete pad (required)
in the desired location.
Figure 2-3b: Boiler Lifting Provisions –BMK 1500-3000 Shown
LIFTING LUGS (3 POSITIONS)
YELLOW ARROWS
2” NATURAL
GAS OR 1”
PROPANE GAS
INLET