AER Modulex MLX-303 User manual

MC2: 10/03/12 Page 1of 90
GF-115-H
TAG-0083_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
USER MANUAL
Revised: 10/03/2012
Modulating, Condensing,
Hot Water Boiler Models:
•MLX-303
•MLX-454
•MLX-606
•MLX-757
•MLX-909
•MLX-1060
Modulex MLX Series Boiler
Other manuals for this product include:
•GF-115-C MLX E8 Controller/BCM Manual
•GF-115-E MLX Electrical Power Guide
•GF-115-P-H MLX Piping Guide
•GF-115-V MLX Venting Guide
•GF-115-G MLX Gas Supply Guide
Installation, Operation, and Maintenance
Modulex MLX Series
Gas Fired Boiler

MC2: 10/03/12 Page 2of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
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

MC2: 10/03/12 Page 3of 90
GF-115-H
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
TABLE OF CONTENTS
TABLE OF CONTENTS.................................................................................................................... 3
CHAPTER 1: SAFETY PRECAUTIONS.................................................................................. 7
Important – For Massachusetts Installations .............................................................................. 8
CHAPTER 2: GENERAL DESCRIPTION............................................................................. 11
2.1 Introduction To Technical Features ............................................................................... 11
2.2 Code and Standards Approvals...................................................................................... 12
2.3 Installation Flexibility.................................................................................................... 12
2.4 Dimensions and Weights................................................................................................ 13
2.5 Technical Data................................................................................................................ 15
2.6 Modulex Main Components – Side View...................................................................... 16
2.7 Boiler Freeze Protection................................................................................................. 17
CHAPTER 3: INSTALLATION............................................................................................... 19
3.1 Introduction to Installation............................................................................................. 19
3.2 Installation Instructions.................................................................................................. 19
3.2.1 Unpacking the Boiler .......................................................................................... 19
3.2.2 Boiler Location.................................................................................................... 21
3.2.3 Pad Height for Boiler .......................................................................................... 21
3.2.4 Boiler Connections.............................................................................................. 22
3.3 Data Plate ....................................................................................................................... 23
CHAPTER 4: GENERAL INFORMATION FOR VENTING.............................................. 25
4.1 Vent Pipe Connection..................................................................................................... 25
4.2 Gas Vent Categories....................................................................................................... 25
4.3 Installation And Sizing................................................................................................... 25
4.4 Existing Boiler Removal From Common Venting System............................................ 26
CHAPTER 5: PIPING................................................................................................................ 27
5.1 Makeup Water Quality................................................................................................... 27
5.2 Maximum Allowable Working Pressure...................................................................... 27
5.3 Boiler Loop Design Guidelines...................................................................................... 27
5.4 CSD-1 Manifold Assembly (Supplied).......................................................................... 27
5.5 Connecting Supply And Return Piping (Per ANSI Z21.13a) ........................................ 27
5.6 System Filling and Draining .......................................................................................... 28
5.7 Notes On Condensate Drain........................................................................................... 28
5.8 Gas Mains and Connections........................................................................................... 28
CHAPTER 6: ELECTRICAL................................................................................................... 29
6.1 Electrical Connections.................................................................................................... 29

MC2: 10/03/12 Page 4of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
6.2 DHW (Domestic Hot Water) Storage Tank................................................................... 31
6.3 Enable / Disable ............................................................................................................. 31
6.4 Installation Of Sensors................................................................................................... 31
CHAPTER 7: BOILER OPERATION..................................................................................... 33
7.1 Introduction to Boiler Operation.................................................................................... 33
7.2 Modulation Theory......................................................................................................... 33
7.3 Ignition Sequence........................................................................................................... 33
7.4 Modes of Operation........................................................................................................ 34
7.4.1 Indoor/Outdoor Reset.......................................................................................... 34
7.4.2 0 To 10 Volt Remote Set-Point........................................................................... 34
7.4.3 Constant Set-Point............................................................................................... 34
7.4.4 Boiler Operation for Troubleshooting (Manual Mode)....................................... 34
7.5 Modulex Boiler Initial Startup ....................................................................................... 34
7.5.1 Tools & Instruments Required For Combustion Calibration.............................. 35
7.5.2 Installing the Supply Gas Manometer................................................................. 35
7.5.3 Preparing The Flue For Use With The Combustion Analyser............................ 36
7.5.4 Supply Gas Pressure Check & Adjustment......................................................... 36
7.5.5 Combustion Calibration. ..................................................................................... 38
7.6 Unit Reassembly ............................................................................................................ 40
CHAPTER 8: SAFETY DEVICE TESTING .......................................................................... 41
8.1 Testing of Safety Devices .............................................................................................. 41
8.2 Processing and Clearing Fault Codes............................................................................. 41
8.3 LOW GAS PRESSURE FAULT TEST......................................................................... 42
8.4 LOW WATER LEVEL FAULT TEST ......................................................................... 43
8.5 WATER TEMPERATURE FAULT TEST................................................................... 44
8.6 FLAME FAULT TESTS................................................................................................ 45
8.7 SAFETY PRESSURE RELIEF VALVE TEST ............................................................ 46
CHAPTER 9: MAINTENANCE............................................................................................... 47
9.1 Modulex Preventative Maintenance Kits....................................................................... 47
9.1.1 Annual Maintenance Kit ..................................................................................... 47
9.1.2 Fireside Inspection Kit........................................................................................ 47
9.2 Annual Maintenance Instructions................................................................................... 48
9.2.1 REQUIRED Tasks: ............................................................................................. 48
9.2.2 RECOMMENDED Tasks:.................................................................................. 48
9.2.3 Tools Required.................................................................................................... 48
9.2.4 Replacing the Spark Igniters and Flame Detectors............................................. 50
9.2.5 Testing the Flame Detection Circuitry................................................................ 50
9.3 Fireside Inspection Instructions ..................................................................................... 50

MC2: 10/03/12 Page 5of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
9.3.1 Unit Disassembly for a Fireside Inspection........................................................ 51
9.3.2 Removing The Burner Modules.......................................................................... 55
9.3.3 Maintenance of Burner Modules and Combustion Chamber.............................. 56
9.3.4 Reassembly After Burner Mainentance .............................................................. 57
9.3.5 Testing the Flame Detection Circuitry................................................................ 57
9.3.6 Disassembly, Inspection, and Maintenance for the Flue Collector..................... 57
9.4 Burner Section Replacement Instructions...................................................................... 59
9.4.1 Disassembly For Burner Section Replacement................................................... 60
9.4.2 Replacement of Burner Sections......................................................................... 61
9.4.3 Replacing the Condensate Tray Top Gasket....................................................... 62
9.4.4 Re-Assembly After Burner Section Replacement............................................... 64
9.5 Final Testing and Return To Service.............................................................................. 64
CHAPTER 10: TROUBLE SHOOTING GUIDE................................................................... 65
10.1 Introduction ................................................................................................................ 65
CHAPTER 11: TEMPERATURE SENSOR RESISTANCE CHART.................................. 77
CHAPTER 12: MODULEX PARTS DRAWING AND LIST................................................ 78
CHAPTER 13: BOILER WATER QUALITY AND MAINTENANCE............................... 83
13.1 Modulex Boiler Water Chemistry .............................................................................. 84
13.1.1 Reaction of Metals to Water Chemistry.......................................................... 84
13.1.2 Scale and Corrosion......................................................................................... 84
13.1.3 Make-up or Feed Water Quality...................................................................... 84
13.1.4 Treating Water to Prevent Freezing................................................................. 84
13.1.5 Water Treatment Certification......................................................................... 85
13.2 Testing and Maintenance of Water Quality................................................................ 85
13.3 System Flushing, Treatment, and Cleansing.............................................................. 86
13.4 Water Quality Maintenance and Boiler Warranty...................................................... 87
13.5 Water Treatment Certification.................................................................................... 87
13.6 Water Treatment Analysis and Scheduling ................................................................ 87
13.7 Hydronic Water Testing and Treatment Resources................................................... 88

MC2: 10/03/12 Page 6of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
CHAPTER 1: SAFETY PRECAUTIONS
The following defined symbols are used throughout this manual to notify the reader of potential hazards of
varying risk levels.
Indicates an imminently hazardous situation, which if not avoided, WILL
result in death or serious injury.
Indicates a potentially hazardous situation, which if not avoided, MAY
result in death or serious injury.
Indicates a potential hazardous situation, which if not avoided, COULD
result in minor or moderate injury. Also may caution against unsafe
practices.
Note that all hazard notifications and notes are presented enclosed in a rectangle with filleted (round)
corners, as shown below, in order to differentiate them from the main text.
It is of utmost importance to observe all CAUTIONS and WARNINGS presented in this manual to avoid
injury, death, and damage to the equipment. Failure to properly heed safety warnings and cautions may
result in the voiding of applicable warranties.
NEVER USE FLAMES TO DETECT GAS LEAKS!
What to do if you smell gas:
•Do NOT try to light or turn on any appliance.
•Do NOT touch any electric switch or open switched doors.
•Do NOT use any phone or intercom device in your building.
•Do NOT touch metal doorknobs or any grounded device or surface without using insulated
gloves or other insulated material if you suspect static charge buildup.
•Immediately call your gas supplier from a neighbor’s phone or, if you are outside, your cell
phone. Follow the gas supplier’s instructions.
•If you cannot reach your gas supplier, call the fire department.
This boiler has been built for installation in the country indicated on the
technical data plate. Installation in any other country may be a source
of danger for people, animals and property.
NOTE
Carefully read the warranty conditions and clauses on the warranty
certificate attached to the boiler.
WARNING
!
!
WARNING
!
!
WARNING
!
!
DANGER
!
!
CAUTION
!
!

MC2: 10/03/12 Page 8of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Important – 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.
•If a glycol solution is used as anti-freeze protection, a backflow preventer must be installed
upstream of the Fill/Makeup Valve.
•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".
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.
(Continued on Next Page)
Chap 1: Safety
Precautions

MC2: 10/03/12 Page 9of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
Important - For Massachusetts Installations
(Continued from Previous Page)
B. EXEMPTIONS:The following equipment is exempt from 248 CMR 5.08(2)(a)1 to 4:
1. The equipment listed in Chapter 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 identification of each "special venting system" shall include the listing of either the
website, phone number or manufacturer’s address where the venting system installation
instructions can be obtained; and
2. The "special venting systems" shall be Product Approved by the Board, and the
instructions provided with the system shall include a parts list and detailed installation
instructions.
E. A copy of all installation instructions for the 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)]
Chap 1: Safety
Precautions

MC2: 10/03/12 Page 10 of 90
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
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AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
CHAPTER 2: GENERAL DESCRIPTION
Each AERCO Modulex Boiler is shipped as either a Natural Gas Only
Boiler OR a Propane Gas Only Boiler. It is NOT a Dual-Fuel Boiler.
Ensure that the correct fuel and f
\
2.1 Introduction To Technical Features
Modulex is a compact, modular, gas fired, Low NOx, condensing boiler. The boiler body is comprised of
sections of cast aluminum/magnesium/silicon alloy. The boiler is designed to recover the latent heat of
the combustion gases, thereby allowing it to attain a thermal efficiency of 92% as tested by the
Hydronics Institute, a Division of GAMA. These cast aluminum sections make up modules referred to
as the heat modules. Each module can deliver an output between a maximum of 152 MBH and a
minimum of 45 MBH and are composed of a pre mix combustion chamber, metallic mesh radiant
burner, modulating fan with control pressure switch, gas valve, ignition device, flame detection, NTC
sensor for local temperature control and a safety thermostat.
The heat modules are housed in a single enclosure and are connected to a single exhaust manifold.
These modules are independent of each other and are sequentially staged, a technique known as
cascading, which produces reliable and stable heat at high efficiencies. Each heat module has its own
printed circuit (PC) board that controls and monitors combustion as well as the temperature of each
heat module, providing operational reliability and safety. The entire boiler is controlled by a single
microprocessor. This microprocessor is responsible for the staging and modulation of the heat
modules, monitoring supply and return water temperatures as well as heating and domestic hot water
(DHW) zones. Other features include:
•The heating load is shared with as many boiler modules as possible running at a minimum output to
ensure the maximum efficiency at partial load operation.
•Access to all testing/programming parameters of each module: operation test, operation time, boiler
freeze protection from 45°F (7°C), pump’s anti seize program.
•Lead-lag burner operation based on burner operating hours. The boiler module with the least burner
operating hours is the first to start and the burner with the most operating hours is the first to stop.
•D.H.W. production by a priority sensor, with control capability of a dedicated pump or a 3-way
diverting valve for storage tank temperature control.
•A service mode for manual operation of individual heat modules capability for troubleshooting or
combustion calibration
•Diagnostics including relay and sensor testing.
Reliability is improved by the modular design of the Modulex since each heat module is independent of
the other, having its own ignition and combustion safeguard system. If one of the boiler’s heat modules
stops functioning, the remaining module(s) continue to operate.
The Modulex boiler can be comprised of from 2 to 7 modules and 3 to 8 cast aluminum sections. The
input to each heat module is 151.5 MBTU/Hr. The smallest Modulex 303, comprised of two heat
modules, has a combined total input of 303,000 BTU/Hr (2 x 151.5 = 303 MBTU) while the largest, the
1060 comprised of 7 heat modules has a total input of 1060 MBTU’s (See Table 2-1).
For one Modulex 303 boiler consisting of two modules, the output modulates from 15% to 100%. For a
Modulex 1060 boiler consisting of seven modules, the output modulates from 4.3% and 100%. If a
system comprised of two boilers is installed, then the modulation range for each boiler increases to 7.5%
to 100% for the Modulex 303 and 2.2% to 100% for the Modulex 1060.
CAUTION
!
!

MC2: 10/03/12 Page 12 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
2.2 Code and Standards Approvals
MODULEX has been reviewed for compliance with the applicable sections of the following North
American Standards:
•Z21.13: Gas fired low pressure steam and hot water boilers.
•ASME SECTION IV: Boiler and pressure vessel code rules for construction of heating
boilers.
•BTS 2000:Testing standard method to determine efficiency of commercial space heating
boilers.
•SCAQMD Rule 1146.2: NOx emissions from water heaters and small boilers.
•CSD-1-2004: Controls and safety devices for automatically fired boilers.
Table 2-1: Modulex Boiler Output Range, Turn-Down Ratio & Condensate Production
Heat
Modules Model Output Range MBH1
(KW) Turn
Down
Ratio
Condensate Production [gph (l/h)]
Min. Max. Min. Max.
2
MLX-303
41(12)
279 (82)
6:1
1.3 (5)
3.4 (13)
3
MLX-454
41(12)
418 (122)
10:1
1.9 (7.3)
5.3 (20)
4
MLX-606
41(12)
558 (163)
13:1
2.7 (10.1)
7.1 (27)
5
MLX-757
41(12)
696 (204)
16:1
3.3 (12.6)
9.0 (34)
6
MLX-909
41(12)
835 (245)
20:1
4.0 (15.1)
10.6 (40)
7
MLX-1060
41(12)
975 (286)
23:1
4.6 (17.6)
12.4 (47)
1MBH = 1000 Btu/hr
2.3 Installation Flexibility
The Modulex boiler allows for installation flexibility, i.e. it is suitable to be connected with the water
supply and return and the gas connections on the Right Hand (right-hand) side (standard delivery
condition) or on the Left Hand (left-hand) side. This is accomplished by reversing the gas and water
manifolds utilizing the instructions supplied with the boiler. The same is true for the vent pipe
connection, which at the installation, can be moved from the right-hand side (standard delivery condition)
to the left-hand side or to the rear of the boiler. The installation flexibility features include the following:
•Two or more Modulex boilers may be installed in a multiple boiler system with gas connecting pipes,
supply/return water pipes arranged for connection to either the left or right-hand side of each unit.
The unit is shipped with all connections on the right hand side as viewed from the front of the unit.
•The vent pipe may be installed on the right, the left, or behind the heating system.
NOTE
Installation of the vent behind the unit will require accommodations for
the easy removal of the venting in order to provide service that requires
removal of the rear panel.

MC2: 10/03/12 Page 13 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
2.4 Dimensions and Weights
The dimensions and weights for each Modulex Model are shown in Diagram 1 and 2 of Figure 2-1 and
Table 2-2.
4.33” (110 mm)
12.40”
(315 mm)
4.33” (110 mm)
16.73”
(425 mm)
8.78”
(223 mm)
13.39”
(340 mm)
L
8.78”
(223 mm)
13.39”
(340 mm)
FRONT VIEW
S
10.55” (268 mm)
Ø
13.78”
(350 mm)
13.58
(345 mm)
B
C
TOP VIEW
H
D
B
A
Figure 2-1: Modulex Dimensions and Weights (Diagram 1 of 2)

MC2: 10/03/12 Page 14 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
20.94”
(532 mm)
8.66”
(220 mm)
4.17”
(106 mm) 17.80” (452 mm)
8.35”
(212 mm)
LEFT HAND SIDE VIEW
M
R
G
11.86”
(301 mm)
15.47”
(393 mm)
8.66”
(220 mm)
10.43”
(265 mm)
36.50”
(927 mm)
4.96”
(126 mm) 8.35”
(212 mm)
5.39
17.92” (455 mm)
27.36” (695 mm)
6.90”
(175 mm)
41.46”
(1053 mm)
G
M
R
RIGHT HAND SIDE VIEW
Figure 2-1: Modulex Dimensions and Weights (Diagram 2 of 2)
Table 2-2: Modulex Models Dimensions and Weights
(2 MODULES)
HEIGHT 41.46 (1053)
IN (MM)
WIDTH "L" NET 27.36 (695)
WIDTH W/PACKAGING 30.32 (770)
DEPTH "C" 37.09 (942)
DEPTH "A" 27.36 (695)
DEPTH "B" 32.28 (820)
DEPTH W/PACKAGING 30.71 (780)
NET WEIGHT LB (KG) 331 (150)
GROSS WEIGHT LB (KG) 386 (175)
CONNECTION
GAS 1-1/2 (38)
WATER OUTLET (SUPPLY) M 2 (50)
WATER INLET (RETURN) R 2 (50)
EXH. VENT CONNECTION "D" 4 (102)
EXH. VENT WIDTH "H" 9.45 (240)
CONDENSATE DRAIN DIA. 1.57 (40)
27.36 (695)
30.32 (770)
27.36 (695)
32.28 (820)
30.71 (780)
408 (185)
463 (210)
1-1/2 (38)
2 (50)
2 (50)
4 (102)
9.45 (240)
1.57 (40)
32.83 (834) 38.11 (968)
35.7 (908) 41.0 (1042)
37.09 (942)
27.36 (695) 27.36 (695)
32.28 (820) 32.28 (820)
30.71 (780) 30.71 (780)
496 (225) 573 (260)
551 (250) 639 (290)
1-1/2 (38) 1-1/2 (38)
2 (50) 2 (50)
2 (50) 2 (50)
4 (102) 6 (152)
9.45 (240) 9.45 (240)
1.57 (40) 1.57 (40)
43.39 (1102) 48.66 (1236)
46.3 (1176 51.6/1310
27.36 (695) 27.36 (695)
32.28 (820) 32.28 (820)
30.71 (780) 30.71 (780)
672 (305) 761 (345)
739 (335) 827 (375)
1-1/2 (38) 1-1/2 (38)
2 (50) 2 (50)
2 (50) 2 (50)
6 (152) 6 (152)
9.45 (240) 9.45 (240)
1.57 (40) 1.57 (40)
DIMENSIONS
MODULEX MODELS
MLX-303
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
IN (MM)
(3 MODULES) (4 MODULES) (5 MODULES) (6 MODULES) (7 MODULES)
41.46 (1053) 41.46 (1053) 41.46 (1053) 41.46 (1053) 41.46 (1053)
MLX-454 MLX-606 MLX-757 MLX-909 MLX-1060
37.09 (942) 37.09 (942) 37.09 (942) 37.09 (942)

MC2: 10/03/12 Page 15 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
2.5 Technical Data
(The Name Plate is placed under the front jacket next to the control panel.)
MIN/MAX INPUT AND OUTPUT:
Model Number Min Input Max Input Max Output* Net IBR Rating
MLX-303
45,500
303,000
260,000-279,000
237,000
MLX-454
45,500 454,000 390,000-418,000 355,000
MLX-606 45,500 606,000 521,000-558,000 474,000
MLX-757 45,500 757,000 651,000-696,000 592,000
MLX-909 45,500 909,000 835,000-836,000 710,000
MLX-1060 45,500 1,060,000 912,000-975,000 829,000
DIMENSIONS:
Model Number
Height
Width
Depth
Weight
MLX-303
42” (1067 mm)
28” (711 mm)
27” (686 mm)
405 lbs. (183.7 kg)
MLX-454
42” (1067 mm)
28” (711 mm
27” (686 mm)
484 lbs. (219.6 kg)
MLX-606
42” (1067 mm)
33” (838 mm)
27” (686 mm)
575 lbs. (260.8 kg)
MLX-757
42” (1067 mm)
38” (965 mm)
27” (686 mm)
673 lbs. (305.2 kg)
MLX-909
42” (1067 mm)
44” (112 mm)
27” (686 mm)
765 lbs. (346.8 kg)
MLX-1060
42” (1067 mm)
49” (1245 mm)
27” (686 mm)
869 lbs. (394.0 kg)
SPECIFICATIONS:
Model Number
MLX-303
MLX-454
MLX-606
MLX-757
MLX-909
MLX-1060
Boiler Category
IV
IV
IV
IV
IV
IV
Type of Gas Natural Gas
(MLX-303B)
or Propane
(MLX-303BP)
Natural Gas
(MLX-454B)
or Propane
(MLX-454BP)
Natural Gas
(MLX-606B)
or Propane
(MLX-606BP)
Natural Gas
(MLX-757B)
or Propane
(MLX-757BP)
Natural Gas
(MLX-909B)
or Propane
(MLX-909BP)
Natural Gas
(MLX-1060B)
or Propane
(MLX-
1060BP)
Gas Connections (NPT)
1.5”
1.5”
1.5”
1.5”
1.5”
1.5”
Max. Gas Pressure
14” W.C.
(34.8 mbar)
14” W.C.
(34.8 mbar)
14” W.C.
(34.8 mbar)
14” W.C.
(34.8 mbar)
14” W.C.
(34.8 mbar)
14” W.C.
(34.8 mbar)
Optimal Gas Pressure
7” W.C.
(17.4 mbar)
7” W.C.
(17.4 mbar)
7” W.C.
(17.4 mbar)
7” W.C.
(17.4 mbar)
7” W.C.
(17.4 mbar)
7” W.C.
(17.4 mbar)
Min. Gas Pressure
4”
(10 mbar)
4”
(10 mbar)
4”
(10 mbar)
4”
(10 mbar)
4”
(10 mbar)
4”
(10 mbar)
Max. Allowed Working
Pressure
92 psi
(634 kPa)
92 psi
(634 kPa)
92 psi
(634 kPa)
92 psi
(634 kPa)
92 psi
(634 kPa)
92 psi
(634 kPa)
Electrical Req:
120V 15 Amp. Max.
1.2 FLA 1.8 FLA 2.4 FLA 3.0 FLA 3.6 FLA 4.2 FLA
Water Connections
(NPT)
2-1/2” 2-1/2” 2-1/2” 2-1/2” 2-1/2” 2-1/2”
Min. Water Flow (GPM)
11
17
22
28
38
39
Max. Water Flow (GPM)
28
42
55
70
84
98
Water Pressure Drop
@ Max. Flow (Ft. of
Head)
7.8 9.3 9.4 10.0 10.1 10.2

MC2: 10/03/12 Page 16 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
SPECIFICATIONS (Continued):
Model Number
MLX-303
MLX-454
MLX-606
MLX-757
MLX-909
MLX-1060
Water Volume: Gallons 2.8 3.8 4.9 5.9 6.9 8.0
Water Volume: Liters 10.4 14.4 18.4 22.3 26.9 30.2
Thermal Modules 2 3 4 5 6 7
Turn-Down Ratio 6:1 10:1 13:1 16:1 20:1 23:1
Vent Size 4” (102 mm) 4” (102 mm) 4” (102 mm) 6” (152mm) 6” (152mm) 6” (152mm)
Vent Materials (per
local code) Can support PVC, ABS, CPVC, or AL29-4C venting materials.
Temperature Control
Range All units can be applied to deliver 50°F to 185°F (10°C to 85°C) supply water.
Maximum Noise Level All units deliver <50 dBA when operating at or below full fire.
NOx Emissions
Certification All units have been certified by SCAQMD and TCEQ for <30 ppm NOx.
Standard Listings &
Approvals All units have been certified by CSA and Standard for Controls and Safety Devices for Automatically Fired Boilers, ANSI/ASME CSD-1.
2.6 Modulex Main Components – Side View
Figure 2-2 illustrates the Main Components included in each Modulex Boiler model. In addition, an
exploded view parts list drawing is included in Appendix B.
FAN
GAS VALVE
BURNER
COVER
IGNITION
FLAME
DETECTOR
LOCAL NTC
SENSOR
H.L.
THERMOSTAT
BURNER
FILLING-UP
ELBOW
GAS PIPE
AIR INTAKE
CONNECTION
GLOBAL FLOW
NTC TEMPERATURE
SENSOR
HOT WATER
OUTLET (SUPPLY)
1/4" CONNECTION
WITH PLUG
GLOBAL RETURN
NTC TEMPERATURE
SENSOR
COLD WATER INLET
(RETURN)
WATER DRAIN
VALVE
CONDENSATE
DRAIN TRAP
1" [25 mm]
BOILER
FRAME
ALUMINUM/
SILICON HEAT
EXCHANGER
AUTOMATIC
AIR VENT
CONDENSATE
COLLECTION
TRAY MANIFOLD
4"
[100 mm]
5.9" [150 mm]
Figure 2-2: Modulex Main Components

MC2: 10/03/12 Page 17 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
2.7 Boiler Freeze Protection
Should the boiler water outlet temperature decrease to less than 44.6°F (7°C), the system pump will start.
Should temperature decrease to less than 37.4°F (3°C), all heat modules will start at minimum output until
the return temperature reaches 50°F (10°C). Such a protection device is exclusively for the boiler. For the
protection of the whole system, a second freeze protection thermostat is necessary to switch on the
heating system pump.
NOTE
If glycol is used as antifreeze in the boiler, a back flow preventer must be
installed in the make-up/fill line.

MC2: 10/03/12 Page 18 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 2: General
Description
(This page left intentionally blank)

MC2: 10/03/12 Page 19 of 90
GF-115-H
TAG-0083_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
CHAPTER 3: INSTALLATION
3.1 Introduction to Installation
The Modulex Boiler is intended to be installed as a Category IV vent installation and must be installed
in compliance with all applicable laws and regulations including the ones below. See Sub-section 4.2
for category descriptions.
To ensure proper boiler installation, complete ALL instructions in
Section 3.2.
The installation must conform to the requirements of the authority having jurisdiction or, in the absence
of such requirements, to one of the following:
UNITED STATES: Installation must conform to the requirements of the National Fuel Gas Code, ANSI
Z223.1 installation Codes.
CANADA: Installation must conform to the requirements of CAN/CGA CSA B149.1 installation codes.
Where required by the authority having jurisdiction, the installation must conform to the Standard for
Controls and Safety Devices for Automatically Fired Boilers, ANSI/ASME CSD-1.
IMPORTANT NOTE!
Installers must follow local regulations with respect to installation of
Carbon Monoxide (CO) Detectors. Also, follow the maintenance
recommendations in this manual.
For Massachusetts Installations:
The boiler must be installed by a plumber or gas fitter licensed within the
Commonwealth of Massachusetts. For installations in buildings used for
residential purposes, if a side-wall vent termination is less than 7 feet
above grade, an NFPA 720 compliant, ANSI/UL 2034 listed and IAS
certified carbon monoxide detector must be installed on the floor level
where the boiler is installed and on each level of the building served by
the boiler.
3.2 Installation Instructions
The following information in this section provides the instructions to unpack and install the Modulex Boiler.
3.2.1 Unpacking the Boiler
The Modulex Boiler is delivered assembled and protected by a plastic bag inside a rugged
cardboard box, which is fixed on a pallet (see Figure 3-1). The pallet allows the boiler to be handled
by a forklift or pallet jack. The boiler, with the packaging, can fit through a doorway of 32 in. (81 cm),
whereas, without packaging, it can fit through a doorway of 28 in. (71 cm). To unpack the Modulex,
remove both straps and then the cardboard box from above. Check to ensure that the product is
intact.
The packing elements (cardboard box, straps, plastic bags, etc…)
should be kept away from small children as these pose a risk of
suffocation and/or choking.
WARNING
!
!
WARNING
!
!

MC2: 10/03/12 Page 20 of 90
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 •Ph: 800-526-0288
GF-115-H
OMM-0083_0B
Modulex MLX Series Gas Fired Boiler System
Operation and Maintenance Manual
Chap 3:
Installation
Figure 3-1: Packaged Modulex Boiler
Packed inside the boiler packing you will find:
Painted steel panels:
•The front one connected to the back panel by a shrink wrap film
•The right hand side panel connected to the left hand panel by shrink wrap
On the front of the boiler:
•Flue collector, with exhaust connector screwed to the pallet:
1. 4 inch for models 303 to 606.
2. 6 inch for models 757 to 1060.
Use these items only when the specified flue pipe size is increased to 4” (for models
303 to 606) and 6” (for models 757 to 1060). Otherwise, use the exhaust connector
“shipped in the separate carton” described below (4” for models 303 to 606, 6” for
models 757 to 1060).
•A plastic bag containing 3 gaskets (1 rectangular for condensate tray and flue collector, 1
square for exhaust connector.
•Three (3) surface-mount strap-on sensors.
•Screws necessary for accessory installation.
•Piping for 1 ½” condensate drain, including one tee and two 90 degree elbows.
On the back of the boiler:
•Plastic condensate drainpipe, 38.5 inches (1meter) long, placed under the casing rear
panel.
•Outside air sensor with 49 feet, 2.5 inches (15 m) cable.
•Manual Gas Shutoff Valve.
Shipped in a separate carton are the following:
Accessory kit that includes a CSD-1 installation kit for Models 303 through 606 and Models 754
through 1060 as follows:
•Kit P/N 29073: For Models 303-606 with 50 psig Relief Valve
•Kit P/N 29074: For Models 707-1060 with 50 psig Relief Valve
•Kit P/N 29075: For Models 303-606 with 90 psig Relief Valve
•Kit P/N 29076: For Models 707-1060 with 90 psig Relief Valve
See the packing list shipped in this manual package for a complete listing of accessories. See
paragraph 5.4 for more information about the CSD-1 kits.