Watts Aerco Modulex EXT Series User guide

Technical Application Guide
Modulex EXT Series
Piping Application Guide
Modulating and Condensing Boilers
Applies to the following
Modulex EXT Series models:
•MLX EXT 450 2S
•MLX EXT 600 2S
•MLX EXT 800 2S
•MLX EXT 1100 2S
•MLX EXT 1500 2S
•MLX EXT 2300 2S
•MLX EXT 2600 2S
•MLX EXT 3000 2S
TAG-0099 • 10/7/2021
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 or for incidental or consequential
damages occurring in connection with the furnishing, performance, or use of
these materials.
Heating and Hot Water Solutions
AERCO International, Inc. • 100 Oritani Drive • Blauvelt, NY 10913
USA: T: [phone] • Toll Free: [phone] • AERCO.com
Technical Support • [phone] • Mon-Fri, 8 am - 5 pm EST
© 2021 AERCO

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Modulex EXT Series Piping Application Guide
MANDATORY REQUIREMENTS
Contents
SECTION 1: MANDATORY REQUIREMENTS 3
SECTION 2: BOILER QUALITY AND MAINTENANCE 5
2.1. BOILER WATER CHEMISTRY................................................................................................5
2.1.1. Reaction of Metals to Water Chemistry.........................................................................5
2.1.2. Scale and Corrosion......................................................................................................5
2.1.3. Make-up or Feed Water Quality ....................................................................................5
2.1.4. Treating Water to Prevent Freezing ..............................................................................5
2.1.5. Water Treatment Certification .......................................................................................5
2.2. TESTING AND MAINTENANCE OF WATER QUALITY..........................................................6
2.3. SYSTEM FLUSHING, TREATMENT, AND CLEANSING ........................................................7
2.3.1. System Flushing Recommendations.............................................................................7
2.3.2. Water Quality Maintenance and Boiler Warranty...........................................................8
2.3.3. Water Treatment Certification .......................................................................................8
2.3.4. Water Treatment Analysis and Scheduling....................................................................8
2.3.5. Hydronic System Water Testing and Treatment Resources..........................................8
SECTION 3: BOILER LOOP DESIGN GUIDELINES 10
3.1. Flow Rate & Pressure Drops: Models EXT 450 2S, 600 2S, 800 2S & 1100 2S .................10
3.2. Flow Rate & Pressure Drops: Models EXT 1500 2S, 2300 2S, 2600 2S & 3000 2S............12
3.3. PRIMARY PUMP....................................................................................................................15
3.4. STRAINERS...........................................................................................................................16
3.5. ISOLATION VALVES.............................................................................................................16
3.6. AIR VENTING OF THE HEATING SYSTEM..........................................................................17
SECTION 4: CSD-1 MANIFOLD ASSEMBLY (SUPPLIED) 19
4.1. Installing the Pressure Relief Valve and Other Components ............................................20
SECTION 5: CONNECTING SUPPLY & RETURN PIPING 22
5.1. BOILER CONNECTIONS.......................................................................................................22
5.2. PRIMARY-SECONDARY PIPING..........................................................................................22
5.3. ADDITIONAL SUPPLY AND RETURN PIPING.....................................................................22
5.4. CHANGING RIGHT-HAND CONNECTIONS TO LEFT-HAND ..............................................22
5.4.1. Modulex Light Commercial Models EXT 450 2S, 600 2S, 800 2S & 1100 2S..............22
5.4.2. Modulex Commercial Models EXT 1500 2S, 2300 2S, 2600 2S & 3000 2S ................23
5.4.3. Reversing Gas Manifold Connections (EXT 450 2S - 1100 2S)...................................24
5.4.4. Reversing Cold/Hot Water Flow & Return Connections (EXT 450 2S - 1100 2S)........24
5.4.5. Reversing Flow & Return Temperature Sensors.........................................................26
5.4.6. Reversing the Boiler Sensor KF and Automatic Air Vent.............................................26
SECTION 6: SYSTEM FILLING AND DRAINING 27
SECTION 7: CONDENSATE DRAIN 28
SECTION 8: PIPING DIAGRAMS 30

Modulex EXT Series Piping Application Guide
MANDATORY REQUIREMENTS
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 3of 37
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SECTION 1: MANDATORY REQUIREMENTS
The following actions are mandatory to ensure proper piping and drainage of the Modulex EXT system.
CAUTION!
Local codes and authorities must be consulted prior to installation.
•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.
oInstalling a hydraulic separator between the boiler and the system loop.
oInstalling a heat exchanger (e.g. 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 Figure 13 through 20 at the end of this document).
•For boiler replacement installations, cleaning of the whole system is required before connecting the
Modulex boiler (See Section 2.3 for 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.
•For units installed in environments likely to experience freezing temperatures, it is necessary to ensure
that the condensate line and exhaust manifold are equipped with suitable freeze protection, such as a
heat trace line.
•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.
•For all outdoor applications, electrical connections must either be NEMA4 rated or protected by a
suitable outdoor enclosure.
•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 a discharge pipe example on the Modulex boiler.
•The relief valve point of discharge piping must have provisions for proper drainage.

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Modulex EXT Series Piping Application Guide
MANDATORY REQUIREMENTS
Figure 1: Relief Valve Point of Discharge Example
RELIEF VALVE
PIPED TO POINT OF
DISCHARGE
RELIEF VALVE DISCHARGE PIPING

Modulex EXT Series Piping Application Guide
BOILER QUALITY AND MAINTENANCE
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SECTION 2: BOILER QUALITY AND MAINTENANCE
2.1. BOILER WATER CHEMISTRY
2.1.1. Reaction of Metals to Water Chemistry
A neutral water pH must be maintained because, although the aluminum alloys used in the construction of
Modulex EXT boilers resist acidic conditions, they are still vulnerable to highly alkaline environments (pH of
9.0 and above). THE WATERSIDE pH MUST BE MAINTAINED BETWEEN 6.5 and 8.0.
Metals such as aluminum, steel, iron, and copper used in hydronic heating systems are highly reactive to
acidic and alkaline environments; the water must be treated with protectants and buffers to prevent
corrosion. Most chemical water treatments have been developed to protect an array of metals.
2.1.2. Scale and Corrosion
Free oxygen can cause the formation of rust (iron oxides), which degrade 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.
2.1.3. 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. Reverse osmosis, deionized, distilled or
mineral treated water should not be used.
2.1.4. 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 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
Section 2.3 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.
2.1.5. 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

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Modulex EXT Series Piping Application Guide
BOILER QUALITY AND MAINTENANCE
cause harm to the boiler, pumps, piping, and other components of the hydronic boiler system.
2.2. TESTING AND MAINTENANCE OF WATER QUALITY
Water in the installation should be checked, monitored, and treated for the following:
•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 –Chloride salts result from the combination of chlorine gas 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 be 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, an
anti-freezing agent 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 work

Modulex EXT Series Piping Application Guide
BOILER QUALITY AND MAINTENANCE
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 7of 37
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2.3. 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. Section 2.3 provides recommendations for
flushing, cleaning, and treating the water used in the Modulex EXT boiler system.
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).
AERCO recommends the following cleaning solution, inhibitor, and antifreeze products. Visit
www.aerco.com for Product Fact sheet and Material Safety Data Sheets:
•Water Quality Testing —X100 Quick Test Kit
Part number 99152-1
•Corrosion/Scale Inhibitor —Sentinel X100 Liquid Inhibitor
4 x 1 gallon case –part number 99153-2
5 gallon jug –part number 99153-1
•Boiler Noise Reducer —Sentinel X200 Liquid Noise Inhibitor
4 x 1 gallon case –part number 99154-2
5 gallon jug –part number 99154-1
•System Cleaner —Sentinel X300 Liquid System Cleaner
4 x 1 gallon case –part number 99199-2
5 gallon jug –part number 99199-1
•Cleaning solution —Sentinel X400 Liquid System Restorer
4 x 1 gallon case –part number 99155-2
5 gallon jug –part number 99155-1
•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.
2.3.1. System Flushing Recommendations
•Use an appropriate amount of cleaning solution, carefully following the manufacturer’s instructions.
Follow the 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.

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BOILER QUALITY AND MAINTENANCE
•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 indicates that sufficient contamination has been
flushed from the system. If the difference in TDS is more than 10%, repeat the cleaning process until
that is achieved. A turbidity test can be used as an alternate way to determine if a system is clean.
•For boiler retrofit/replacement installation, repeat the cleaning process until the draining water is 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 manufacturer’s instructions. Adding inhibitor to a dirty system reduces its
effectiveness. It is better to add more inhibitor (exceed the recommended amount) than less.
When refilling the system, ensure the boiler is not air-bound by opening the pressure-relief valve on 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.
2.3.2. 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.
2.3.3. 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.
2.3.4. 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 each heating season. For boilers operating year round, this analysis should
be made at least twice a year.
2.3.5. 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.

Modulex EXT Series Piping Application Guide
BOILER QUALITY AND MAINTENANCE
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 9of 37
Phone: [phone].2021
Fernox
Hydronic Agencies Ltd.
Sean Leonard
Edmonton, AB, CANADA
Phone: [phone]
Toll Free: (877) FERNOX4U
(877-337-6694)
Fax: [phone]
[e-mail]
www.hydronicagencies.com
H-O-H Water Technology, Inc.
Steve Sadowski
Greendale, WI
Phone: [phone],
Toll Free: [phone]
Fax: [phone]
[e-mail]
www.hohwatertechnology.com
Fernox USA
Cookson Electronics
Brian Conrad
Altoona PA
Phone: [phone]
Toll Free [phone]
Fax: [phone]
[e-mail]
www.fernox.com
Rhomar Water Management, Inc.
Dwight Hedgepeth
Springfield, MO
Phone: [phone],
Toll Free: [phone]
Fax: [phone]
[e-mail]
www.rhomarwater.com

AERCO International, Inc. •100 Oritani Dr. Blauvelt, NY 10913
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BOILER LOOP DESIGN GUIDELINES
SECTION 3: BOILER 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).
The following primary/secondary piping design guidelines should be used for AERCO Modulex Boiler
installations. The data was calculated based upon systems with Return Water Temperatures above 80F.
A 20 mesh strainer (or finer) is required at each boiler inlet. Water flow rates and pressure drops shown
below are for the boiler loop. Boiler water flow rates vary with system design parameters. The boiler
loop fittings and strainer pressure drops shown below are examples only –actual pressure drops
will vary depending on actual piping layout and strainer size/type used.
3.1. Flow Rate & Pressure Drops: Models EXT 450 2S, 600 2S, 800 2S & 1100 2S
TABLE 1.1: Light Commercial: 50F∆T Water Flow
50°F ΔT Water Flow
EXT 450 2S
EXT 600 2S
EXT 800 2S
EXT 1100 2S
WaterFlow(GPM)@Max. ∆T of 50F
18
24
30
41
WaterPressureDrop(Ft.ofHd.)acrossBoiler@50F
∆T Flow
2.1
1.7
1.6
1.8
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.50
0.89
0.41
0.80
∆P (Ft. of Hd.) – (20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2xBallValve)
0.81
1.47
0.65
1.23
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 50F
3.44
4.09
2.67
3.82
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
1-1/2"
1-1/2"
2"
2"
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-1
99127-1
99127-2
99127-3
Kitincludes:PumpFlangeSize
1-1/2"
1-1/2"
1-1/2"
2"
Kit includes:Circuit SetterSize (NPT)
1-1/2”
1-1/2”
2”
2”

Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 11 of 37
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TABLE 1.2: Light Commercial: 40F∆T Water Flow
40°F ΔT Water Flow
EXT 450 2S
EXT 600 2S
EXT 800 2S
EXT 1100 2S
WaterFlow@40°F ΔT
G=GallonsperMin
22
30
37
52
WaterPressureDrop(Ft.ofHd.)acrossBoiler@40F
∆T Flow
3.3
2.6
2.6
2.7
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.78
0.41
0.64
1.26
∆P (Ft. of Hd.) – (20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2xBallValve)
1.30
0.65
1.01
1.89
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 40F
5.35
3.69
4.22
5.89
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
1-1/2"
2"
2"
2"
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-1
99127-2
99127-2
99127-3
Kitincludes:PumpFlangeSize
1-1/2"
1-1/2"
1-1/2"
2"
Kit includes:Circuit SetterSize (NPT)
1-1/2”
1-1/2”
2”
2”
TABLE 1.3: Light Commercial: 30F∆T Water Flow
30°F ΔT Water Flow
EXT 450 2S
EXT 600 2S
EXT 800 2S
EXT 1100 2S
WaterFlow(GPM)@30F ∆T
30
39
49
69
WaterPressureDrop(Ft.ofHd.)acrossBoiler@30°F
ΔT Flow
5.7
4.6
4.6
4.8
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.41
0.73
1.14
1.09
ΔP (Ft.ofHd.)–(20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2x BallValve).NOTE:Reducingcouplingnot
appliedtoMLX-909 and MLX-1060 because boiler line
sizeisalready2-1/2"
0.65
1.12
1.70
1.24
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 30F
6.8
6.43
7.47
7.10
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
2"
2"
2"
2-1/2"
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-2
99127-3
99127-3
99127-4
Kitincludes:PumpFlangeSize
1-1/2"
2"
2"
2"
Kit includes:Circuit SetterSize (NPT)
2"
2"
2”
2-1/2”

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Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
TABLE 1.4: Light Commercial: 20F∆T Water Flow
20°F ΔT Water Flow
EXT 450 2S
EXT 600 2S
EXT 800 2S
EXT 1100 2S
WaterFlow(GPM)@Min. ΔT of 20°F
42
56
71
99
WaterPressureDrop(Ft.ofHd.)acrossBoiler@ 20°F
ΔT Flow
11.8
9.2
9.7
9.5
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.92
0.80
1.26
2.46
ΔP (Ft. of Hd.) – (20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2x BallValve).NOTE:Reducingcouplingnot
appliedtoMLX-909 and MLX-1060 because boiler line
sizeisalready2-1/2"
1.49
0.91
1.49
2.71
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 20F
14.19
10.91
12.41
14.71
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
2"
2-1/2"
2-1/2"
2-1/2"
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-3
99127-4
99127-4
99127-5
Kitincludes:PumpFlangeSize
2”
2"
2"
1-1/2"
Kit includes:Circuit SetterSize (NPT)
2"
2-1/2”
2-1/2”
2-1/2”
3.2. Flow Rate & Pressure Drops: Models EXT 1500 2S, 2300 2S, 2600 2S & 3000 2S
TABLE 2.1: Commercial: 50F∆T Water Flow
50°F ΔT Water Flow
EXT 1500 2S
EXT 2300 2S
EXT 2600 2S
EXT 3000 2S
WaterFlow(GPM)@Max. ΔT of 50°F
56
84
99
113
WaterPressureDrop(Ft.ofHd.)acrossBoiler@ 50°F
ΔT Flow
2.6
3.3
3.6
3.0
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.29
0.64
0.29
0.37
ΔP (Ft. of Hd.) – (20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2xBallValve)
0.41
0.91
0.33
0.433
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 50F
3.32
4.83
4.22
3.75
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
3”
3”
4”
4”
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-6
99127-7
99127-7
99127-7
Kitincludes:PumpFlangeSize
2”
3"
3"
3"
Kit includes:Circuit SetterSize (NPT)
2-1/2”
3"
3"
3"

Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 13 of 37
Phone: [phone].2021
TABLE 2.2: Commercial: 40F∆T Water Flow
40°F ΔT Water Flow
EXT 1500 2S
EXT 2300 2S
EXT 2600 2S
EXT 3000 2S
WaterFlow(GPM)@Max. ΔT of 40°F
70
106
123
141
WaterPressureDrop(Ft.ofHd.)acrossBoiler@ 40°F
ΔT Flow
3.6
4.9
5.2
4.6
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.45
1.00
0.45
0.58
ΔP (Ft. of Hd.)–(20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2xBallValve)
0.63
1.42
0.50
0.66
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 40F
4.69
7.35
6.20
5.83
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
3”
3”
4”
4”
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-7
99127-7
99208-3
99208-3
Kitincludes:PumpFlangeSize
3”
3"
3"
3"
Kit includes:Circuit SetterSize (NPT)
3”
3"
3"
3"
TABLE 2.3: Commercial: 30F∆T WaterFlow
30°F ΔT Water Flow
EXT 1500 2S
EXT 2300 2S
EXT 2600 2S
EXT 3000 2S
WaterFlow(GPM)@Max. ΔT of 30°F
94
141
164
188
WaterPressureDrop(Ft.ofHd.)acrossBoiler@30°F
ΔT Flow
5.2
9.5
9.8
8.5
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
0.79
1.79
0.79
1.04
ΔP (Ft. of Hd.) – (20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2xBallValve)
1.12
3.81
0.88
1.15
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 40F
7.17
15.11
11.52
10.72
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
3”
3”
4”
4”
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99127-7
99208-5
99208-5
99208-6
Kitincludes:PumpFlangeSize
3”
3"
3"
3"
Kit includes:Circuit SetterSize (NPT)
3”
3"
3"
3"

AERCO International, Inc. •100 Oritani Dr. Blauvelt, NY 10913
Phone: [phone]
Page 14 of 37
10.07.2010
TAG-0099
Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
TABLE 2.4: Commercial: 25F∆T Water Flow
25°F ΔT Water Flow
EXT 1500 2S
EXT 2300 2S
EXT 2600 2S
EXT 3000 2S
WaterFlow(GPM)@Max. ΔT of 25°F
113
169
197
225
WaterPressureDrop(Ft.ofHd.)acrossBoiler@20°F
ΔT Flow
7.9
16.4
17.7
13.1
Strainer ∆P (Ft. of Hd.) – (‘Y’ Strainer, 20 mesh)
1.14
2.57
1.14
1.49
ΔP (Ft. ofHd.)–(20’ SCH.40, 4 x 90°, 2 x reducing
couplings,2xBallValve)
2.27
4.97
1.79
2.31
Total Primary Loop ∆P (Ft. of Hd.) @ ∆T of 25F
11.28
23.95
20.65
16.92
Strainer, Pipes, Valves and Fittings Sizes used to
estimate ∆P for above piping configurations
3”
3”
4”
4”
RecommendedAERCO Pump+CircuitSetterKitfor
pipingconfigurationsnotexceedingtheaboveexample
99208-4
99208-7
99208-7
99208-7
Kitincludes:PumpFlangeSize
3”
3"
3"
3"
Kit includes:Circuit SetterSize (NPT)
3”
3"
3"
3"

Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 15 of 37
Phone: [phone].2021
3.3. PRIMARY PUMP
The primary pump shall have a discharge pressure able to assure the designed water flow rate, taking
into account pressure drop losses as shown in Figure 2. When selecting a pump, take into account the
pressure drop across the boiler, fittings, accessories and piping. 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.
NOTE: Select the pump flow rate so that the boiler water outlet temperature is 190°F (87.8°C) or below.
Figure 2: Water Side Pressure Loss Charts

AERCO International, Inc. •100 Oritani Dr. Blauvelt, NY 10913
Phone: [phone]
Page 16 of 37
10.07.2010
TAG-0099
Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
Figure 3: Electrical Connection of Primary Pump
WARNING!
There is 120 VAC between terminals Y4-1 and Y4-2 whenever the boiler is ON.
3.4. STRAINERS
AERCO requires the installation of a Y strainer to keep dirt out of the system and boiler. The strainer 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 heating system dirt. It should be
regularly cleaned to prevent problems.
3.5. ISOLATION VALVES
It is MANDATORY that ball or other type of shut-off valves be installed in the system supply and return
piping to isolatethe boiler if necessary. In this casethe boiler can be disconnected or drained without having
to drain the whole system.
WARNING!
NEVER bypass safety devices, such as safety valves and expansion vessels.

Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 17 of 37
Phone: [phone].2021
3.6. AIR VENTING OF THE HEATING SYSTEM
The Modulex boiler comes standard with an automatic air vent inside the boiler (see Figure4a and 4b). This
vent is for the boiler onlyand 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.
Figure 4a: MODULEX EXT Main Components (Right Side View)
(EXT 450 2S - 1100 2S))

AERCO International, Inc. •100 Oritani Dr. Blauvelt, NY 10913
Phone: [phone]
Page 18 of 37
10.07.2010
TAG-0099
Modulex EXT Series Piping Application Guide
BOILER LOOP DESIGN GUIDELINES
Figure 4b: MODULEX EXT Main Components (Left Side View)
(EXT 1500 2S - 3000 2S)

Modulex EXT Series Piping Application Guide
CSD-1 MANIFOLD ASSEMBLY (SUPPLIED)
TAG-0099 AERCO International, Inc. •100 Oritani Dr. •Blauvelt, NY 10913 Page 19 of 37
Phone: [phone].2021
SECTION 4: CSD-1 MANIFOLD ASSEMBLY (SUPPLIED)
The installation of a flow switch, pressure/temperature gauge, and an ASME compliant safety pressure
relief valve designed for the boiler output capacity is required. These major components are supplied with
the boiler and must be assembled and wired when installing the boiler at the site. The manifold assembly
components supplied are:
•Pressure Relief Valve (3/4” for EXT 450 2S –1100 2S, 1-1/2” for EXT 1500 2S –3000 2S)
•Flow Switch
•Pressure/Temperature Gauge
NOTE: Units ship with an 80 psi relief valve. For higher or lower system pressure, a different rated relief
valve must be field supplied.
Full instructions for installing these components are included in the Modulex EXT Installation, Operation &
Maintenance Guides.
Figure 5: Input/Output Box and Flow Switch Connection

AERCO International, Inc. •100 Oritani Dr. Blauvelt, NY 10913
Phone: [phone]
Page 20 of 37
10.07.2010
TAG-0099
Modulex EXT Series Piping Application Guide
CSD-1 MANIFOLD ASSEMBLY (SUPPLIED)
The pressure relief valve and all other manifold components are shown in Figures 5 and 6.
Figure 6: Manifold Assembly and Components for EXT 450 2S, 600 2S, 800 2S & 1100 2S
Figure 7: Manifold Assembly and Components for EXT 1500 2S, 2300 2S, 2600 2S & 3000 2S
To install the pressure relief valve and the other components shown, complete the instructions below.
NOTE: Use Teflon tape or a suitable pipe joint compound for component and piping connections
described in the following steps. Refer to Figure 5 and 6, above, for component identification.
4.1. Installing the Pressure Relief Valve and Other Components
1. Attach manifold to the outlet supply connection on the boiler via the flanged connections.
2. Cut the flow switch paddle. For EXT models 450 2S to 1100 2S, cut for 2-1/2” pipe, and for EXT
models 1500 2S to 3000 2S, cut for 4” pipe as directed in the flow switch paddle packaging. For
installations expecting less than a 10 gpm flow, adjust switch as follows:
a) With no flow, turn adjustment screw on the switch counter-clockwise until the switch trips.
b) Then turn screw 1/2 turn clock-wise and continue installation.
Flow Switch
Pressure/Temperature
Gauge
3/4” Pressure
Relief Valve
Flow Switch
1-1/2” Pressure Relief Valve
Pressure/Temperature Gauge