AER MLX Series User guide

GF-115-P-H
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
PIPING APPLICATION GUIDE
Other manuals for this product include:
•GF-115-H MLX series Boiler Manual
•GF-115-C MLX E8 Controller/ BCM Manual
•GF-115-G MLX Gas Supply Guide
•GF-115-V MLX Venting Guide
•GF-115-E MLX Electrical Power Guide
Modulex MLX Series
(90psi High Pressure)
Gas Fired Boiler System
Modulating, Condensing,
Hot Water Boiler Models:
•MLX-303
•MLX-454
•MLX-606
•MLX-757
•MLX-909
•MLX-1060
Revised: 05/05/2011
High-Pressure Version

PR2: 03/01/13 Page 2of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
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

PR2: 03/01/13 Page 3of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Table of Contents
Table of Contents .......................................................................................................... 3
IMPORTANT!.................................................................................................................. 5
1. BOILER WATER QUALITY AND MAINTENANCE................................................. 6
1.1 Modulex Boiler Water Chemistry .......................................................................... 6
1.1.1 - Reaction of Metals to Water Chemistry ..................................................... 6
1.1.2 - Scale and Corrosion.................................................................................. 6
1.1.3 - Make-up or Feed Water Quality ................................................................ 6
1.1.4 - Treating Water to Prevent Freezing .......................................................... 6
1.1.5 - Water Treatment Certification.................................................................... 6
1.2 Testing and Maintenance of Water Quality.......................................................... 7
1.3 System Flushing, Treatment, and Cleansing ....................................................... 8
1.4 Water Quality Maintenance and Boiler Warranty................................................ 10
1.5 Water Treatment Certification............................................................................. 10
1.6 Water Treatment Analysis and Scheduling......................................................... 10
1.7 Hydronic System Water Testing and Treatment Resources............................... 10
2. MAXIMUM ALLOWABLE WORKING PRESSURE............................................... 11
3. BOILER LOOP DESIGN GUIDELINES ................................................................. 11
3.1 Primary Pump..................................................................................................... 15
3.2 Strainers ............................................................................................................. 16
3.3 Isolation Valves .................................................................................................. 16
3.4 Air Venting of the Heating System...................................................................... 16
4. CSD-1 MANIFOLD ASSEMBLY (SUPPLIED)....................................................... 17
5. CONNECTING SUPPLY AND RETURN PIPING .................................................. 21
5.1 Boiler Connections.............................................................................................. 21
5.2 Primary-Secondary Piping .................................................................................. 21
5.3 Additional Supply And Return Piping (PER ANSI Z21.13A) ............................... 21
5.4 Changing Left-Hand Connections to Right-Hand................................................ 22
6. SYSTEM FILLING AND DRAINING ...................................................................... 27
7. NOTES ON CONDENSATE DRAIN ...................................................................... 27
8. GAS MAINS AND CONNECTIONS....................................................................... 29
8.1 Gas Main Connection Notes............................................................................... 29

PR2: 03/01/13 Page 4of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
(This page left intentionally blank)

PR2: 03/01/13 Page 5of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
IMPORTANT!
•AERCO requires that the boiler loop to be de-coupled from the system loop. This can be achieved by
one of the following:
oEmploying primary-secondary piping.
oInstallation of a hydraulic separator between the boiler and the system loop.
oInstallation of a heat exchanger (for example, plate heat exchanger) between the boiler and the
system loop. If water treatment used in the system is not Aluminum compatible, the use of
a heat exchanger between the system and the boiler piping is MANDATORY.
•AERCO requires cleaning of the whole system and to fit a mandatory Y-strainer on the return pipe to
the boiler, equipped with isolation valves (See Figures 16 to 23 at the end of this document; see
Section 1.4for Flushing, Treatment, and Cleansing tips and guidelines).
•For boiler replacement installations, cleaning of the whole system is required before connecting the
Modulex boiler (See Section 1.4for Flushing, Treatment, and Cleansing tips and guidelines).
•Failure to clean a system will limit it from the full benefits offered by the high efficiency Modulex boiler.
•Boiler drain valve and condensate drain trap should be arranged to permit the fluids to drain freely, by
gravity, to a convenient floor drain.
•Relief valve must be installed vertically in the top, side, or to a valveless header connected to the
water supply outlet.
•Locate water supply and return fittings (i.e. unions, elbows, etc.) a minimum of 6 inches (from the
boiler fittings to prevent interference with the removal of the boiler panels and covers.
•All piping and electrical connections (i.e. service switches, conduit boxes, etc.) should be located at a
minimum of 6 inches from the boiler panels and covers.
•See Table 1 (Section 3) for sizing guidelines for the mandatory primary pump and boiler strainer.
A discharge pipe must be used and must not have an internal cross-sectional area less than the outlet of
the relief valve. The discharge pipe must be installed so that there will be no danger of scalding to the
boiler attendants. See Figure 1, below, for discharge pipe example on the Modulex boiler. The relief
valve point of discharge piping must have provisions for proper drainage.
Local codes and authorities should be consulted prior to installation.
Figure 1: Relief Valve
Point of Discharge
Example

PR2: 03/01/13 Page 6of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
1BOILER WATER QUALITY AND MAINTENANCE
1.1 Modulex Boiler Water Chemistry
1.1.1 - Reaction of Metals to Water Chemistry
Acidic condensates with a pH of 3.0 to 5.0 are commonly produced by the burning of natural gasses
within hydronic heating systems. It is very important to maintain a neutral chemistry of the water
because although the aluminum alloys used in the construction of Modulex boilers resist acidic
conditions, they are still vulnerable to highly alkaline environments (pH of 9.0 and above).
Metals, including aluminum, steel, iron, and copper used in hydronic heating systems are highly
reactive to acidic and alkaline chemical environments, so the water must be treated with protectants
and buffers to prevent corrosion of these metals. Because of this, most chemical water treatments
have been developed to protect an array of metals.
1.1.2 - Scale and Corrosion
Free oxygen can cause the formation of rust (iron oxides), which degrades metallic materials.
Magnetite is formed in un-inhibited water if there is electrolytic action in the presence of oxygen.
Sludge is formed when calcium compounds, primarily CaCO3, are heated. Rust and magnetite, when
combined with sludge, can form a very hard scale, which significantly reduces system efficiency and
life expectancy of the heating system. Scale reduces heat exchange due to its low heat conductivity
and so may cause very dangerous localized overheating. Waterside corrosion of all heating circuit
surfaces is also a major concern.
1.1.3 - Make-up or Feed Water Quality
Make-up or feed water is water added to a closed hydronic system to replenish water lost through
evaporation, maintenance, or leakage. The quality of make-up or feed water, which may contain
dissolved oxygen, minerals and other dissolved contaminants, is extremely important. Such introduced
water must be chemically treated or strictly limited when ensuring neutral chemical conditions in boiler
system water. Generally, any closed hydronic heating system should be restricted from receiving
untreated makeup water of no more than 5% of the total volume of system water per year.
1.1.4 - Treating Water to Prevent Freezing
When using anti-freeze solutions, their compatibility with the AERCO Modulex aluminum heat
exchanger and other components of the heating system must be determined prior to use. Traditional
HVAC propylene glycol is not suitable for aluminum heat exchangers: the pH of the glycol at various
dilutions is in excess of 9.5, whereas the pH must be within 6.5 and 8.0 for use with aluminum. There
are several suitable aluminum safe propylene glycols available that can provide the same levels of
burst, freeze and corrosion inhibiting protection as traditional propylene glycols. Consult your local
AERCO representative for recommendations on glycol solutions. If a glycol solution is used as anti-
freeze protection, a backflow preventer must be installed upstream of the fill/makeup valve.
Only virgin glycol should be used for systems requiring freeze protection, and it must be treated with
an inhibitor compatible with the particular chemical treatment being used in the system. Note that
glycol must be changed from time to time due to its limited useful life.
1.1.5 - Water Treatment Certification
When using chemical treatments in hydronic systems, it is necessary to ensure that the chosen
treatment is appropriate and certified by the manufacturer for such environments. The manufacturer
should also guarantee that the treatment, when applied according to the manufacturer’s
recommendations, will not cause harm to the boiler, pumps, piping, and other components of the
hydronic boiler system.

PR2: 03/01/13 Page 7of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
1.2Testing and Maintenance of Water Quality
Water in the installation should be checked, monitored, and treated for the following conditions and
characteristics:
•Hardness - High hardness of the available water is measured in grains of hardness and indicates the
quantity of minerals (mostly calcium and magnesium) which are dissolved in the water. Hardness
substantially contributes to the formation of scaling, which is highly undesirable. The total hardness
must be less than 200 ppm (11.7 grains/gallon)
•Artificial Softness – Do NOT use artificially softened water. Artificial softening agents generally use
salt, which creates a chloride water chemistry, a major contributor to the corrosion of the types of
metals used in hydronic systems. Elevated salt levels also contribute to higher conductivity levels,
another undesirable characteristic in hydronic systems.
•Chloride - Chlorides are salts resulting from the combination of the gas chlorine with a metal and are
instrumental in accelerating corrosion in the types of metals used in hydronic systems. Chlorides may
be introduced into the water naturally. Concentrations of chlorides in system water should be less
than 150 ppm.
•Conductivity – Dissolved metals and minerals increase the conductivity of water and indicate not
only the presence of undesired corrosive agents, but also contribute to the transfer and migration of
ions and charged particles in the water that contribute to fouling of sensors, valves, and other devices
used in the system. Additionally, high conductivity contributes to galvanic corrosion, in which one
metal will preferentially corrode when in contact with another type of metal, when both are in contact
with an electrolyte. Conductivity should be less than 3000 μS.
•pH - The pH, a measure of the acidic, neutrality, and alkalinity of the water, MUST always be within
6.5 and 8.0 for boilers using aluminum alloys, such as the Modulex boiler system.
•Oxygen - All precautions should be taken to avoid the formation and localization of oxygen in the
water of a heating system. Water that is low in minerals (soft water) absorbs oxygen much more
readily than mineralized (hard) water. For this reason it is necessary that in heating systems using
floor radiant heating, the plastic pipes used are impermeable to oxygen.
•Scale and Corrosion - The use of an inhibitor is advisable to treat feed and make-up water and to
protect heating systems against scale, corrosion and microbiologic growth. To prevent freezing, the
use of an anti-freezing agent together with the inhibitor is advisable. Qualified companies can also
provide boiler de-scaling.
•Total Solids - preferably less than 500 ppm, but a requirement of less than 1000 ppm
•Water treatment is also advisable in the following cases:
oVery large heating systems
oHigh quantities of replenished water due to leakages or maintenance works

PR2: 03/01/13 Page 8of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
1.3 System Flushing, Treatment, and Cleansing
Note that prior to cleaning the heating system, the boiler MUST be isolated from the piping to prevent
infusion of containments, including sludge, into the boiler. Instruction 1.3, below, shows
recommendations for flushing, cleaning, and treating the water used in the Modulex boiler system.
AERCO recommends the following cleaning solution, inhibitor, and antifreeze products. Visit
www.aerco.com for Product Fact sheet and Material Safety Data Sheets:
Cleaning solution — Sentinel X400 Liquid System Restorer
4 x 1 gallon case – part number 99155-2
5 gallon jug – part number 99155-1
Corrosion/Scale Inhibitor — Sentinel X100 Liquid Inhibitor
4 x 1 gallon case – part number 99153-2
5 gallon jug – part number 99153-1
Antifreeze — Sentinel X500 Liquid Inhibited Antifreeze
5 gallon jug – part number 99156-1
55 gallon jug – part number 99156-2
275 gallon tote – part number 99156-3
When cleaning, treating, and maintaining, a heating system, consult a qualified professional. The
following are AERCO’s tips/guidelines for cleaning a heating system – these do NOT take precedence
over detailed instructions from qualified professionals.
IMPORTANT!
Cleaning solution and inhibitors used must be compatible with heat exchanger material.
Corrosion/scale inhibitor will be ineffective if added to a dirty system; therefore, it is very
important to clean the system first.
Water treatments used must be compatible with EPDM gaskets used in the Modulex Boiler.
(EPDM = Ethylene Propylene Diene Manomer).
System Flushing Recommendations
Starts on the Next Page
INSTRUCTION 1.3

PR2: 03/01/13 Page 9of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
System Flushing Recommendations
•Make sure to use appropriate amount of cleaning solution,
carefully following the manufacturer’s instructions. Follow the
chemical manufacturer’s recommendations when introducing
cleaning agents into the system.
•Ensure that the cleaning solution is circulated thoroughly in the
system.
•Flush the system thoroughly to remove the maximum amount of
contaminants. When emptying the system, make sure it is done
as quickly as possible using all drain off points and ensuring all
low lying pipework is fully drained. Opening all bleed valves
ensures the system will be completely emptied.
•A reliable test to determine if a system is clean is if the Total
Dissolved Solids (TDS) of the water being drained is within 10% of
the make-up water TDS. This in
dicates that sufficient
contamination has been flushed from the system. If the
difference in TDS is more than 10%, it is recommended to repeat
the cleaning process until that is achieved. Turbidity test can be
used as an alternate way to determine if a system is clean.
•For boiler retrofit/replacement installation, it will be necessary to
repeat the cleaning process until the draining water appears to be
clear. Once clear, the above TDS comparison (or a turbidity test)
should be performed.
•If a flushing machine is used in the cleaning process, carefully
follow the manufacturer’s instructions. If the flushing machine is
designed to flush individual zones, the TDS comparison must be
made between each zone and the make-up water, or the turbidity
test performed for each zone.
•Add corrosion and scale inhibitor after the system has been
declared clean, using the appropriate amount recommended by
the manufacturer. Introduce the Multi-
Metal protector/scale
inhibitor to the system following the chemical treatment
manufacturer’s instructions. Adding inhibitor to a dirty system
reduces its effectiveness. It is better to add more inhibitor than
less – that is, it is better to exceed the recommended amount than
less.
•When refilling the system, ensure the boiler is not air-bound by
opening the pressure-relief valve located at the rear of the boiler.
Leave the relief valve open until a steady flow of water is
observed. Close the valve and finish filling the system.
INSTRUCTION 1.3
END

PR2: 03/01/13 Page 10 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
1.4 Water Quality Maintenance and Boiler Warranty
Heat exchanger failures due to improperly cleaned/treated and poorly maintained water are not covered
under warranty. Scheduled system/boiler water maintenance is required to maintain the heat exchanger
warranty. AERCO shall reserve the right to require maintenance records when evaluating warranty
claims.
1.5 Water Treatment Certification
When using chemical treatments in hydronic systems, it is necessary to ensure that the chosen treatment
is appropriate and certified by the manufacturer for such environments. The manufacturer should also
guarantee that the treatment, when applied according to the manufacturer’s recommendations, will not
cause harm to the boiler, pumps, piping, and other components of the hydronic boiler system.
1.6 Water Treatment Analysis and Scheduling
The proper mixture of water, chemical treatment and glycol (if used) should be ascertained based on a
sample of the system water and the make-up water. Your local water treatment company, or one of the
manufacturers listed below, may analyze your sample. Adjust the chemical composition of your system
water based on the analysis. After this initial analysis, the chemical composition of your system water
should be tested at the beginning of the heating season for boilers operated to provide comfort heat.
However, for boilers operating year round, this analysis should be made at least twice a year.
1.7 Hydronic System Water Testing and Treatment Resources
On the internet at www.awt.org, you may find a listing of water treatment firms and manufacturers of
chemical treatments developed for use in multi-metal hydronic systems. Click on the “Find a Water
Treater” button to access this list.
Below is a list of companies providing water treatment systems certified as safe for use in multi-metal
hydronic systems, including aluminum boilers. Contact any of the individuals listed for more information.
`
Fernox
Hydronic Agencies Ltd.
Sean Leonard
Edmonton, AB, CANADA
Phone: [phone]
Toll Free: (877) FERNOX4U
(877-337-6694)
Fax: [phone]
Email: [email protected]
www.hydronicagencies.com
Fernox USA
Cookson Electronics
Brian Conrad
Altoona PA
Phone: [phone]
Toll Free [phone]
Fax: [phone]
Email:
[email protected]
www.fernox.com
H-O-H Water Technology, Inc.
Steve Sadowski
Greendale, WI
Phone: [phone],
Toll Free: [phone]
Fax: [phone]
Email:
[email protected]
www.hohwatertechnology.com
Rhomar Water Management, Inc.
Dwight Hedgepeth
Springfield, MO
Phone: [phone],
Toll Free: [phone]
Fax: [phone]
Email: [email protected]
www.rhomarwater.com

PR2: 03/01/13 Page 11 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
2MAXIMUM ALLOWABLE WORKING PRESSURE
3BOILER LOOP DESIGN GUIDELINES
For proper and safe operation of the water tube Modulex boiler, the primary (boiler) loop piping and the
associated fittings and accessories must be designed/selected as discussed in the following sections.
Table 1 shows the required minimum flow rates at various system designed temperature rises. Also
shown are pressure drops through strainers typically needed in the boiler loop (see paragraph 4.2 for
strainer requirement details).
Table 1: Flow Rate and Pressure Drops
50
°
F Water Flow MLX-303 MLX-454 MLX-606 MLX-757 MLX-909 MLX-1060
Water Flow @ 50°F ∆T
G = Gallons per Min L =
Liters per Min
11 (G)
41.6 (L)
17 (G)
64.3 (L)
22 (G)
83.3 (L)
28 (G)
106.0 (L)
34 (G)
128.7 (L)
39 (G)
147.6(L)
Water Pressure Drop
(Ft. (m) of Hd.) @ Min.
Flow
1.2 Ft.
(.366 m)
1.5 Ft.
(.457 m)
1.4 Ft.
(.427 m)
1.6 Ft.
(.488 m)
1.7 Ft.
(.518 m)
1.7 Ft.
(.518 m)
Strainer ∆P (Ft. of Hd.) –
(‘Y’ Strainer, 20 mesh)
0.36 Ft
0.110 m
0.46 Ft
0.140 m
0.77 Ft
0.235 m
0.37 Ft
0.113 m
0.54 Ft
0.165 m
0.72 Ft
0.165 m
∆P (Ft. of Hd.) – (20’
SCH.40, 4 x 90°, 2 x
reducing couplings,
2 x Ball Valve)
1.09 Ft
0.332 m
0.81 Ft
0.247 m
1.47 Ft
0.448 m
0.65 Ft
0.198 m
0.96 Ft
0.293 m
1.23 Ft
0.375 m
Total Primary Loop ∆P (Ft.
of Hd.) @ ∆T of 50°F
2.64 Ft
0.805 m
2.77 Ft
0.844 m
3.65 Ft
1.11 m
2.62 Ft
0.799 m
3.21 Ft
0.978 m
3.64 Ft
1.109 m
Strainer, Pipes, Valves
and Fittings Sizes used
to estimate 
P fo r
above piping
configurations
1-1/4" 1-1/2" 1-1/2" 2" 2" 2"
Recommended AERCO
Pump+Circuit Setter Kit for
piping configurations not
exceeding the above
example
99127-1 99127-1 99127-1 99127-2 99127-2 99127-3
Kit includes: Pump Flange
Size
1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 2"
Kit includes: Circuit
Setter Size (NPT)
1-1/2” 1-1/2” 1-1/2” 2” 2” 2”
The Modulex boiler has a maximum allowable working pressure of 92 psi (345kPa, 3.5 bar),
and a minimum of 15 psi (103 kPa, 1 bar).

PR2: 03/01/13 Page 12 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Table 1: Flow Rate and Pressure Drops (Continued)
40
°
F Water Flow MLX-303 MLX-454 MLX-606 MLX-757 MLX-909 MLX-1060
Water Flow @ 40°F ∆T
G = Gallons per Min L
= Liters per Min
14 (G)
52.99 (L)
21 (G)
74.49 (L)
28 (G)
105.98 (L)
35 (G)
132.48 (L)
42 (G)
158.97 (L)
49 (G)
185.87 (L)
Water Pressure Drop (Ft.
of Hd.) across the Boiler
@ 40°F ∆T Flow
2.0 Ft
0.610 m
2.4 Ft
0.732 m
2.4 Ft
0.732 m
2.5 Ft
0.762 m
2.5 Ft
0.762 m
2.6 Ft
0.792 m
Strainer ∆P (Ft. of Hd.) –
(‘Y’ Strainer, 20 mesh)
0.58 Ft
0.177 m
0.70 Ft
0.213 m
0.37 Ft
0.113 m
0.58 Ft
0.177 m
0.83 Ft
0.293 m
1.13 Ft
0.314 m
∆P (Ft. of Hd.) – (20’
SCH.40, 4 x 90°, 2 x
reducing couplings, 2 x
Ball Valve)
1.63 Ft
0.497 m
1.30 Ft
0.396 m
0.65 Ft
0.198 m
1.01 Ft
0.308 m
1.49 Ft
0.454 m
1.89 Ft
0.576 m
Total Primary Loop ∆P
(Ft. of Hd.) @ ∆T of
40°F
4.21 Ft
1.283 m
4.41 Ft
1.344 m
3.42 Ft
1.042 m
4.09 Ft
1.247 m
4.82 Ft
1.469 m
5.62 Ft
1.713
Strainer, Pipes,
Valves and Fittings
Sizes used to
estimate 
P fo r
above piping
configurations
1-1/4" 1-1/2" 2" 2" 2" 2"
Recommended AERCO
Pump+Circuit Setter Kit
for piping configurations
not exceeding the above
example
99127-1 99127-1 99127-2 99127-2 99127-3 99127-3
Kit includes: Pump
Flange Size 1-1/2" 1-1/2" 1-1/2" 1-1/2" 2" 2"
Kit includes: Circuit
Setter Size (NPT) 1-1/2” 1-1/2” 2” 2” 2” 2”

PR2: 03/01/13 Page 13 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Table 1: Flow Rate and Pressure Drops (Continued)
30
°
F Water Flow MLX-303 MLX-454 MLX-606 MLX-757 MLX-909 MLX-1060
Water Flow @ 30°F ∆T
G = Gallons per Min L
= Liters per Min
19 (G)
71.9 (L)
28 (G)
106.0 (L)
37 (G)
140.0 (L)
46 (G)
174.1 (L)
56 (G)
212.0 (L)
65 (G)
246.0 (L)
Water Pressure Drop (Ft.
of Hd.) across the Boiler
@ 30°F ∆T Flow
3.8 Ft
1.16 m
4.2 Ft
1.28 m
4.2 Ft
1.28 m
4.3 Ft
1.31 m
4.5 Ft
1.37 m
4.5 Ft
1.37 m
Strainer ∆P (Ft. of Hd.) –
(‘Y’ Strainer, 20 mesh)
0.58 Ft
0.177 m
0.37 Ft
0.113 m
0.64 Ft
0.195 m
1.00 Ft
0.305 m
0.72 Ft
0.219 m
0.97 Ft
0.296 m
∆P (Ft. of Hd.) – (20’
SCH.40, 4 x 90°, 2 x
reducing couplings, 2
x Ball Valve)
NOTE: Reducing
coupling not applied
to
MLX-909 and MLX-
1060 because boiler
line size is already
2-1/2"
1.08 Ft
0.329 m
0.65 Ft
0.198 m
1.12 Ft
0.341 m
1.70 Ft
0.518 m
0.92 Ft
0.280 m
1.24 Ft
0.378 m
Total Primary Loop ∆P
(Ft. of Hd.) @ ∆T of
30°F
5.46 Ft
1.66
5.22 Ft
1.59 m
5.97 Ft
1.82 m
7.00 Ft
2.13 m
6.14 Ft
1.871 m
6.72 Ft
2.05 m
Strainer, Pipes,
Valves and Fittings
Sizes used to
estimate 
P fo r
above piping
configurations
1-1/2" 2" 2" 2" 2-1/2" 2-1/2"
Recommended AERCO
Pump+Circuit Setter Kit
for piping configurations
not exceeding the above
example
99127-1 99127-2 99127-3 99127-3 99127-4 99127-4
Kit includes: Pump
Flange Size 1-1/2" 1-1/2" 2" 2" 2" 2"
Kit includes: Circuit
Setter Size (NPT)
1-1/2” 2” 2” 2” 2-1/2” 2-1/2”

PR2: 03/01/13 Page 14 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Table 1: Flow Rate and Pressure Drops (Continued)
MLX-303 MLX-454 MLX-606 MLX-757 MLX-909 MLX-1060
Water Flow @ 20°F ∆T
G = Gallons per Min L
= Liters per Min
28 (G)
106.0 (L)
42 (G)
159.0 (L)
55 (G)
208.2 (L)
70 (G)
265.0 (L)
84 (G)
318.0 (L)
98 (G)
371.0 (L)
Water Pressure Drop (Ft.
of Hd.) across the Boiler
@ 20°F ∆T Flow
7.8 Ft
2.38 m
9.3 Ft
2.83 m
9.4 Ft
2.87 m
10 Ft
3.05 m
10.1 Ft
3.08 m
10.2 Ft
3.11 m
Strainer ∆P (Ft. of Hd.) –
(‘Y’ Strainer, 20 mesh)
0.37 Ft
0.113 m
0.83 Ft
0.253 m
0.70 Ft
0.213 m
1.13 Ft
0.344 m
1.63 Ft
0.497 m
2.22 Ft
0.677 m
∆P (Ft. of Hd.) – (20’
SCH.40, 4 x 90°, 2 x
reducing couplings, 2
x Ball Valve)
NOTE: Reducing
coupling not applied
to
MLX-606, 757, 909,
and 1060 because
boiler line size is
already
2-1/2"
0.65 Ft
0.198 m
1.49 Ft
0.494 m
0.91 Ft
0.277 m
1.49 Ft
0.494 m
2.14 Ft
0.652 m
2.71 Ft
0.826 m
Total Primary Loop ∆P
(Ft. of Hd.) @ ∆T of
20°F
8.82 Ft
2.69 m
11.62 Ft
3.54 m
11.00 Ft
3.35 m
12.62 Ft
3.85 m
13.87 Ft
4.23 m
15.13 Ft
4.61 m
Strainer, Pipes,
Valves and Fittings
Sizes used to
estimate 
P fo r
above piping
configurations
2" 2" 2-1/2" 2-1/2" 2-1/2" 2-1/2"
Recommended AERCO
Pump+Circuit Setter Kit
for piping configurations
not exceeding the above
example
99127-2 99127-3 99127-4 99127-4 99127-5 99127-5
Kit includes: Pump
Flange Size
1-1/2" 2" 2" 2" 1-1/2" 1-1/2"
Kit includes: Circuit
Setter Size (NPT) 2” 2” 2-1/2” 2-1/2” 2-1/2” 2-1/2”

PR2: 03/01/13 Page 15 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
3.1 Primary Pump
The primary pump shall have a discharge pressure able to assure the water flow rate in accordance
with the diagram shown in Figure 2. When selecting a pump, take into account the pressure drop
across the boiler, fittings, accessories and piping. See Table 1. The primary pump electrical connection
shall be made at terminals A10 and N as shown in Figure 3.
Pumps shall be calculated by installers or engineers according to boiler and system parameters. The
waterside resistance curve of the boiler is shown in Figure 2. The pump is not an integral part of the
boiler.
Figure 2: Water Side Pressure Loss Chart
NOTE
Select the pump flow rate so that the boiler water outlet temperature is 190°F (87.8°C) or
below.

PR2: 03/01/13 Page 16 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 3: Electrical Connection of Primary Pump
3.2 Strainers
AERCO requires the installation of a Y strainer to keep dirt out of the system and boiler. The valve
should be installed in the return piping with isolation valves to allow for cleaning as necessary. The Y
strainer shall have a 20 mesh or finer strainer. Such filter shall protect the boiler from the heating
system dirt. It should be regularly cleaned to prevent problems.
3.3 Isolation Valves
It is MANDATORY that ball or other type of valves be installed in the system supply and return piping to
isolate the boiler if necessary. In this case the boiler can be disconnected or drained without having to
drain the whole system.
3.4 Air Venting of the Heating System
The Modulex boiler comes standard with an air vent inside the boiler (see Figure 4). This vent is for
the boiler only and not the entire heating system. An effective air vent for air removal for the entire
heating system must be installed in the highest point of the system piping.
THERE IS 120 VAC BETWEEN TERMINALS A10 AND
NWHENEVER THE E8 BOILER CONTROLLER IS ON
ELECTRICAL CONNECTION OF PRIMARY PUMP
NO
NC
C
LINE
NEUTRAL
3-CONTACT RELAY
A10 N
4N
There is 120 VAC between terminals A10 and Nwhenever the E8 boiler controller is ON.
NEVER
bypass safety devices, such as safety valves and expansion vessels.

PR2: 03/01/13 Page 17 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
4CSD-1 MANIFOLD ASSEMBLY (SUPPLIED)
The installation of a low water cutoff, manual reset high limit aquastat and an ASME compliant safety
pressure relief valve designed for the boiler output capacity are required. These major components
along with a manifold and several others are supplied with the boiler and must be assembled and wired
when installing the boiler at the site. The manifold assembly components supplied are:
•3/4” Pressure Relief Valve
•Manifold Assembly [2-1/2” x 16” long (64 mm x 406 mm)]
•2-1/2” NPT Union
•Low Water Cut-Off Switch
•Aquastat
•Pressure/Temperature Gauge
The pressure relief valve and all other manifold components are shown in Figures 5 and 6for right-
hand and left-hand applications respectively.
FAN
GAS VALVE
BURNER
COVER
IGNITION
IONIZATION
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)
DRAINING TAP
CONDENSATE
DRAIN SIPHON
.98" [25 mm]*
BOILER
FRAME
ALUMINUM/
SILICON HEAT
EXCHANGER
AUTOMATIC
AIR VENT
CONDENSATE
COLLECTION
TRAY MANIFOLD
3.94"
[100 mm]
5.9" [150 mm]**
Figure 4: Modulex Main Components

PR2: 03/01/13 Page 18 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 5: CSD-1 Manifold Assembly and Components for Right-Hand Application
Figure 6: CSD-1 Manifold Assembly and Components for Left-Hand Application

PR2: 03/01/13 Page 19 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
To install the pressure relief valve and the other components shown, proceed as shown in Instruction
4.0, below.
OUTLET FLOW
CONNECTION
RETURN FLOW
CONNECTION
MANIFOLD WITH ALL
COMPONENTS
INSTALLED
GAS INLET
CONNECTION
Figure 7: Manifold Assembly and Components Installed on Right-Hand Side
Installing the Pressure Relief Valve and
Other Components
1. Attach 2-1/2” NPT union and manifold assembly to
the outlet supply connection on the boiler (Figure 7).
2. Connect the following components to the tapped
holes in the manifold assembly (Figure 5 or 6):
•Pressure Relief Valve
•Low Water Cut-Off Switch
•Aquastat
•Pressure/Temperature Gauge
•Check to ensure that all components are
securely tightened.
3. For electrical connections and wiring the CSD-1
manifold assembly in Figures 5 and 6, see the
separate CSD-1 wiring diagram included with the
manual package.
INSTRUCTION 4.0
NOTE
Use Teflon tape or a suitable pipe joint compound for component and piping connections
described in the following steps. Refer to Figure 5and 6for component identification.
END

PR2: 03/01/13 Page 20 of 38
GF-115-P-H
Modulex MLX Piping Guide
Technical Application Guide
TAG-0030_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
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