Miura LXW-50 User manual

Revised: November 10, 2015
The Best Partner of
Energy, Water & Environment
LXW HOT WATER BOILER
Installation & Operation Manual
Standard Pressure:
LXW-50 LXW-100 LXW-150 LXW-200
High Pressure:
LXWH-100
INFORMATION IN THIS MANUAL MAY BE CHANGED AT ANY TIME WITHOUT ANY NOTICE.
> Please ensure that installation & operation manual is read and observed in full by all persons working with the hot water
boiler.
> Please also ensure that it is stored in a location where it may be easily accessed.
Issued Date: 11/10/2015

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TABLE OF CONTENTS
SECTION 1 Introduction ___________________________________________________ 1
1.1 Definitions and Symbols______________________________________________________ 1
1.2 Guarantee _________________________________________________________________ 1
1.3 Introduction _______________________________________________________________ 2
1.4 Features___________________________________________________________________ 2
1.5 Specifications _______________________________________ Error! Bookmark not defined.
SECTION 2 Acts & Regulations _____________________________________________ 12
2.1 Acts & Regulations _________________________________________________________ 12
2.2 National Regulatory Organizations ____________________________________________ 13
SECTION 3 Installation ___________________________________________________ 14
3.1 Unloading ________________________________________________________________ 14
3.2 Assembling _______________________________________________________________ 15
3.3 Recommended Piping_______________________________________________________ 15
3.4 Water Piping ______________________________________________________________ 16
3.5 Fuel Piping________________________________________________________________ 18
3.6 Clearances and Ventilation___________________________________________________ 20
3.7 Stacks and Breeching Installation _____________________________________________ 21
3.8 Electrical Installation _______________________________________________________ 23
SECTION 4 Operation & Maintenance_______________________________________ 24
4.1 Preparation before Start-up __________________________________________________ 24
4.2 Start-up __________________________________________________________________ 25
4.3 Shut-down________________________________________________________________ 25
4.4 Cautions During Operation___________________________________________________ 26
4.5 Safety Attachments ________________________________________________________ 27
4.6 Water Treatment __________________________________________________________ 30
SECTION 5 Maintenance _________________________________________________ 32
5.1 Maintenance & Cleaning Schedule ____________________________________________ 32
5.2 Spare parts _______________________________________________________________ 33
5.3 Troubleshooting ___________________________________________________________ 34
5.4 Flow Chart of LXW Sequence Operation ________________________________________ 36

SECTION 1 INTRODUCTION
1.1 DEFINITIONS AND SYMBOLS
Note, Caution and Danger are used throughout this manual with the following definitions and
symbols.
NOTE:Indicates an area or subject of special merit, emphasizing either the product
capabilities or common errors in installation, operation or maintenance.
CAUTION:Indicates possible damage to equipment. It also indicates any condition or practice,
which, if not observed or remedied, could result in damage or destruction of equipment.
DANGER:Indicates any condition or practice, which, if not observed, could result in personal
injury or possible death.
1.2 GUARANTEE
Refer to warranty documents for specific details.
ONE YEAR Standard warranty for parts from boiler commissioning date or 18 months from
shipping date whichever occurs first. Express shipping cost for overnight or next day delivery
of parts is not included. Damage to the boiler or parts of the boiler after leaving the factory
are not covered. Parts replaced under this warranty must be returned to MIURA. If the failed
part is not returned, the customer will be charged for the new item.
SEVEN-YEAR limited factory warranty on pressure vessel against material or workmanship
defects.

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1.3 INTRODUCTION
Miura Canada Co., Ltd. began North American activities in 1988, when the manufacturing plant
in Brantford, Ontario, was established. Their engineering department developed procedures to
meet ASME codes and listing approval from UL, CSA. The United States corporate sales office,
Miura Boiler, Inc., was established and has developed relationships with national, state and city
inspectors and agencies.
The North American network consists of branches in Chicago, Los Angeles, New York, Atlanta
and Ontario. The parent Company, Miura Boiler Ltd. in Japan, is the leading manufacturer of
boilers and other thermal equipment in the Pacific Rim holding more than 55% of the market.
With factories in five countries, production now exceeds 14,000 units per year.
As a result of design necessities in Japan, such as limited space and total dependence on
foreign energy, the MIURA BOILER has been engineered as a highly efficient, vertical water
tube, once-through, forced-flow design. The MIURA Boiler features a compact unit with a low-
water content and is designed to run with a minimum amount of maintenance with simple
push-button controls. Operation is quiet, radiant heat losses are minimal. Miura Boilers are
often installed in a multiple boiler network. The high efficiency Miura Boiler has won
numerous awards from Engineering Societies and Gas Associations because it is a compact,
safe, cost-effective boiler.
1.4 FEATURES
The MIURA BOILER is a low water content, water tube design, which provides full output within 5
minutes. In addition, it is a compact, safe, cost saving boiler. Such features contribute to the
success of the boiler obtaining more than 50% of the market share in Japan, Korea and Taiwan.
Based on these features, Miura has developed the new Low NOxBoiler by using the most
advanced technical engineering and innovative designs. The flat shaped burner and the boiler
vessel are uniquely designed for the LXW/LXWH.
It is known that the temperature of combustion flames should be less than 3,272°F (1,800C) to
prevent NOxgeneration. Generally, combustion flames will have some high temperature areas
generating NOx. Miura engineers have calculated the temperature distribution in the combustion
and heat exchanging areas. From theoretical analysis and rigorous testing the designed
temperature distribution is homogeneously less than 3,272°F (1,800C). The burner surface is
made as large as possible and the furnace volume as small as possible to optimize the
combustion process. As a result, the LXW has NOxemissions of less than 20 PPM at 3% converted
O2based on Natural gas combustion.
In addition, the LXW has a very narrow design. No need to destroy any doors or knock down any
walls during installation; the LXW fits through a standard door opening.

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The completely packaged LXW has the following items as standard equipment:
Boiler design is c-UL-us approved and labelled (FM available)
High-Low Gas pressure switch
Low Air pressure switch
Control water temperature by thermocouple with water temperature switch controls
ASME safety relief valve
Main gas line & Pilot line regulators
Dual pilot gas solenoid valves
Dual main gas fluid actuator valves and plugged leak test port (vent valve available)
Forced draft blower and motor
Completely enclosed, heavy gauge casing
ASME stamped Pressure Vessel including inspection ports
An independent high temperature limit and high temperature control
Low-water fuel cutoff with manual reset
Digital water temperature display with back up thermometer gauge
Pressure gauge
User friendly digital display
Communication interface capability
Display of hours of operation and record of five most recent faults
Remote monitoring of boiler performance and trouble shooting by modem link with Miura
factory is available.
CAUTION:All systems require continuous proper water treatment. This treatment is
mandatory from the time your MIURA BOILER is installed. Failure to follow the
recommended water treatment and maintenance procedures could shorten the life (as well
ALL NOx CONCENTRATIONS CONVERTED TO 3% EXCESS OXYGEN
(MEASURED BY AN AUTHORIZED LAB)

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as the efficiency) of your boiler and could affect the warranty.

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1.5 SPECIFICATIONS
1.5.1 SPECIFICATION FOR LXW-50
ITEM
UNITS
LXW-50
Boiler type
Multiple water tubes
Boiler Horsepower Rating
BHP
50
Maximum working pressure
PSIG (Kg/cm²)
160 (11.25)
Max. working temperature
F (C)
250 (121)
Heat input
Btu/Hr
(Kcal/Hr)
2,041,000 (514,500)
Heat output
1,674,000 (421,800)
Efficiency
%
82
Heating surface area
Ft² (m²)
177 (16.4)
Full water content
Gal (L)
44 (166)
Operational Weight
Lb (Kg)
3,200 (1,450)
Shipping Weight
3,000 (1,360)
Combustion control
Step modulation: Hi-Low-Off
Combustion system
Forced draft, Pre-mixed burner
Ignition system
Automatic Pilot burner
Spark system (15,000V)
High voltage electrical spark
Power Supply
208,230,460,575 volt, 3 phase, 60 Hz
Max. Electric Consumption
KVA
3.8
Blower Motor Output
HP (KW)
3 (2.25)
Fuel Type
Natural Gas or Propane Gas
Fuel Supply Pressure
PSIG
3 - 5
Fuel consumption
SCFH (Nm3/Hr)
2,030 (54.5) *
Flue Gas Volume (Wet)
27,200 (730) *
Flue Gas Volume (Dry)
23,200 (620) *
Flue Gas Velocity
Ft/s (m/s)
16.3 (5.0) *
Flue Gas Temperature
F (C)
420 (216)
Main Water Inlet
Inches
3
Main Water Outlet
3
Safety Valve Outlet
1
Fuel Gas Inlet
1½
Drain
1½
Chimney Diameter
12
Flame Detector
Ultraviolet Flame eye
Overheating Protection
Low water cutoff, Flow switch & Thermocouple
NOTE:
i. Fuel consumption is based on Natural Gas with a High heating value of 1,004 Btu/SCF.
ii. Efficiency is based on high heating values of fuels & operating at 140°F.

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1.5.2 SPECIFICATION FOR LXW-100
ITEM
UNITS
LXW-100
Boiler type
Multiple water tubes
Boiler Horsepower Rating
BHP
100
Maximum working pressure
PSIG (Kg/cm²)
160 (11.25)
Max. working temperature
F (C)
250 (121)
Heat input
Btu/Hr
(Kcal/Hr)
4,083,000 (1,029,000)
Heat output
3,348,000 (843,600)
Efficiency
%
82
Heating surface area
Ft² (m²)
247 (22.9)
Full water content
Gal (L)
64 (240)
Operational Weight
Lb (Kg)
4,650 (2,100)
Shipping Weight
4,100 (1,860)
Combustion control
Step modulation: Hi-Low-Off
Combustion system
Forced draft, Pre-mixed burner
Ignition system
Automatic Pilot burner
Spark system (15,000V)
High voltage electrical spark
Power Supply
208,230,460,575 volt, 3 phase, 60 Hz
Max. Electric Consumption
KVA
10.4
Blower Motor Output
HP (KW)
10 (7.5)
Fuel Type
Natural Gas or Propane Gas
Fuel Supply Pressure
PSIG
3 –5
Fuel consumption
SCFH (Nm3/Hr)
4,070 (109) *
Flue Gas Volume (Wet)
54,500 (1,460) *
Flue Gas Volume (Dry)
46,600 (1,250) *
Flue Gas Velocity
Ft/s (m/s)
24 (7.3) *
Flue Gas Temperature
F (C)
420 (216)
Main Water Inlet
Inches
4
Main Water Outlet
4
Safety Valve Outlet
1
Fuel Gas Inlet
2
Drain
1½
Chimney Diameter
14
Flame Detector
Ultraviolet Flame eye
Overheating Protection
Low water cutoff, Flow switch & Thermocouple
NOTE:
i. Fuel consumption is based on Natural Gas with a High heating value of 1,004 Btu/SCF.
ii. Efficiency is based on high heating values of fuels & operating at 140°F.

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1.5.3 SPECIFICATION FOR LXWH-100
ITEM
UNITS
LXWH-100
Boiler type
Multiple water tubes
Boiler Horsepower Rating
BHP
100
Maximum working pressure
PSIG (Kg/cm²)
300 (21.1)
Max. working temperature
F (C)
350 (177)
Heat input
Btu/Hr (Kcal/Hr)
4,083,000 (1,029,000)
Heat output
3,348,000 (843,600)
Efficiency
%
82
Heating surface area
Ft² (m²)
377 (35)
Full water content
Gal (L)
74 (280)
Operational Weight
Lb (Kg)
5,070 (2,300)
Shipping Weight
4,170 (2,020)
Combustion control
Step modulation: Hi-Low-Off
Combustion system
Forced draft, Pre-mixed burner
Ignition system
Automatic Pilot burner
Spark system (15,000V)
High voltage electrical spark
Power Supply
208,230,460,575 volt, 3 phase, 60 Hz
Max. Electric Consumption
KVA
10.4
Blower Motor Output
HP (KW)
10 (7.5)
Fuel Type
Natural Gas or Propane Gas
Fuel Supply Pressure
PSIG
3-5
Fuel consumption
SCFH (Nm3/Hr)
4,070 (109) *
Flue Gas Volume (Wet)
54,500 (1,460) *
Flue Gas Volume (Dry)
46,600 (1,250) *
Flue Gas Velocity
Ft/s (m/s)
24 (7.3) *
Flue Gas Temperature
F (C)
420 (216)
Main Water Inlet
Inches
4
Main Water Outlet
4
Safety Valve Outlet
3
Fuel Gas Inlet
2
Drain
1½
Chimney Diameter
14
Flame Detector
Ultraviolet Flame eye
Overheating Protection
Low water cutoff & Thermocouple
NOTE:
i. Fuel consumption is based on Natural Gas with a High heating value of 1,004 Btu/SCF.
ii. Efficiency is based on high heating values of fuels & operating at 140°F.

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1.5.4 SPECIFICATION FOR LXW-150
ITEM
UNITS
LXW-150
Boiler type
Multiple water tubes
Boiler Horsepower Rating
BHP
150
Maximum working pressure
PSIG (Kg/cm²)
160 (11.25)
Max. working temperature
F (C)
250 (121)
Heat input
Btu/Hr (Kcal/Hr)
6,124,000 (1,582,000)
Heat output
5,022,000 (1,265,000)
Efficiency
%
82
Heating surface area
Ft² (m²)
404 (37.5)
Full water content
Gal (L)
90 (340)
Operational Weight
Lb (Kg)
5,800 (2,630)
Shipping Weight
5,000 (2,270)
Combustion control
Step modulation: Hi-Low-Off
Combustion system
Forced draft, Pre-mixed burner
Ignition system
Automatic Pilot burner
Spark system (15,000V)
High voltage electrical spark
Power Supply
208,230,460,575 volt, 3 phase, 60 Hz
Max. Electric Consumption
KVA
14.4
Blower Motor Output
HP (KW)
15 (11.25)
Fuel Type
Natural Gas or Propane Gas
Fuel Supply Pressure
PSIG
3 –5
Fuel consumption
SCFH (Nm3/Hr)
6,100 (163) *
Flue Gas Volume (Wet)
81,700 (2,190) *
Flue Gas Volume (Dry)
69,800 (1,870) *
Flue Gas Velocity
Ft/s (m/s)
36 (11) *
Flue Gas Temperature
F (C)
420 (216)
Main Water Inlet
Inches
6
Main Water Outlet
6
Safety Valve Outlet
1½
Fuel Gas Inlet
2
Drain
1½
Chimney Diameter
14
Flame Detector
Ultraviolet Flame eye
Overheating Protection
Low water cutoff, Flow switch & Thermocouple
NOTE:
iii. Fuel consumption is based on Natural Gas with a High heating value of 1,004 Btu/SCF.
iv. Efficiency is based on high heating values of fuels & operating at 140°F.

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1.5.5 SPECIFICATION FOR LXW-175
ITEM
UNITS
LXW-175
Boiler type
Multiple water tubes
Boiler Horsepower Rating
BHP
175
Maximum working pressure
PSIG (Kg/cm²)
160 (11.25)
Max. working temperature
F (C)
250 (121)
Heat input
Btu/Hr (Kcal/Hr)
7,145,000 (1,800,700)
Heat output
5,859,000 (1,476,000)
Efficiency
%
82
Heating surface area
Ft² (m²)
404 (37.5)
Full water content
Gal (L)
90 (340)
Operational Weight
Lb (Kg)
5,800 (2,630)
Shipping Weight
5,000 (2,270)
Combustion control
Step modulation: Hi-Low-Off
Combustion system
Forced draft, Pre-mixed burner
Ignition system
Automatic Pilot burner
Spark system (15,000V)
High voltage electrical spark
Power Supply
208,230,460,575 volt, 3 phase, 60 Hz
Max. Electric Consumption
KVA
14.4
Blower Motor Output
HP
15
Fuel Type
Natural Gas or Propane Gas
Fuel Supply Pressure
PSIG
3 –5
Fuel consumption
SCFH (Nm3/Hr)
7,120 (190) *
Flue Gas Volume (Wet)
95,400 (2,560) *
Flue Gas Volume (Dry)
81,500 (2,180) *
Flue Gas Velocity
Ft/s (m/s)
20.6 (6.3) *
Flue Gas Temperature
F (C)
420 (216)
Main Water Inlet
Inches
6
Main Water Outlet
6
Safety Valve Outlet
2
Fuel Gas Inlet
2
Drain
1½
Chimney Diameter
20
Flame Detector
Ultraviolet Flame eye
Overheating Protection
Low water cutoff, Flow switch & Thermocouple
NOTE:
i. Fuel consumption is based on Natural Gas with a High heating value of 1,004 Btu/SCF.
ii. Efficiency is based on high heating values of fuels & operating at 140°F.

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1.5.6 SPECIFICATION FOR LXW-200
ITEM
UNITS
LXW-200
Boiler type
Multiple water tubes
Boiler Horsepower Rating
BHP
200
Maximum working pressure
PSIG (Kg/cm²)
160 (11.25)
Max. working temperature
F (C)
250 (121)
Heat input
Btu/Hr (Kcal/Hr)
8,370,000 (2,109,000)
Heat output
6,696,000 (1,687,000)
Efficiency
%
80
Heating surface area
Ft² (m²)
404 (37.5)
Full water content
Gal (L)
90 (340)
Operational Weight
Lb (Kg)
5,800 (2,630)
Shipping Weight
5,000 (2,270)
Combustion control
Step modulation: Hi-Low-Off
Combustion system
Forced draft, Pre-mixed burner
Ignition system
Automatic Pilot burner
Spark system (15,000V)
High voltage electrical spark
Power Supply
208,230,460,575 volt, 3 phase, 60 Hz
Max. Electric Consumption
KVA
14.4
Blower Motor Output
HP
15
Fuel Type
Natural Gas or Propane Gas
Fuel Supply Pressure
PSIG
3 –5
Fuel consumption
SCFH (Nm3/Hr)
8,340 (223) *
Flue Gas Volume (Wet)
111,700 (2,990) *
Flue Gas Volume (Dry)
95,500 (2,560) *
Flue Gas Velocity
Ft/s (m/s)
25.4 (7.7) *
Flue Gas Temperature
F (C)
470 (243)
Main Water Inlet
Inches
6
Main Water Outlet
6
Safety Valve Outlet
2
Fuel Gas Inlet
2
Drain
1½
Chimney Diameter
20
Flame Detector
Ultraviolet Flame eye
Overheating Protection
Low water cutoff, Flow switch & Thermocouple
NOTE:
i. Fuel consumption is based on Natural Gas with a High heating value of 1,004 Btu/SCF.
ii. Efficiency is based on high heating values of fuels & operating at 140°F.

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SECTION 2 ACTS & REGULATIONS
2.1 ACTS &REGULATIONS
There are a number of codes, standards, laws and regulations for boilers and related equipment
that should be considered. Regulatory requirements are dictated by a variety of sources and are
focused primarily on safety. The equipment shall be installed in accordance with the current
regulations, codes and specifications of the applicable City, Country, Provincial/State and Federal
agencies. Authorities having jurisdiction should be consulted before installations are made. For
more information on how the various rules affect boiler selection and operation, you may want
to contact your local MIURA authorized representative or the engineering firm designing the
boiler installation. Here are some essential rules to consider:
a) The boiler industry is tightly regulated by the American Society of Mechanical Engineers
(ASME) and ASME Codes, which controls boiler design, inspection, and quality assurance. All
boilers’ pressure vessels and other pressure vessels should have an ASME stamp.
b) All pressure vessels should be inspected and registered with the National Board.
c) In Canada, the design of all boilers, pressure vessels, fittings, and piping must be registered
with local province as required in CSA B51.
d) The insurance company insuring the facility or boiler may dictate additional requirements.
Miura can provide special boiler trim according to the requirements of major insurance
companies such as FM. Special boiler trim items usually pertain to added safety controls.
Some industries, such as food processing, brewing, or pharmaceuticals may also have
additional regulations that have an impact on the boiler and boiler room.
e) c-UL-us approval may be required to verify boiler safety performance.
f) A full time boiler operator may be required. Operator requirements depend on the boiler’s
size, pressure, heating surface area and/or volume of water. Boilers can be selected to
minimize the boiler operator requirements; either by choosing a boiler that is exempt from
the rules or by installing special equipment that gives the operator more freedom in the
facility. Contact the local boiler inspector for details.
g) Most state/province or local authorities require a permit to install and operate a boiler.
Additional restrictions may apply in non-attainment areas where air quality does not meet
the national ambient air quality standards and emission regulations are more stringent. Be
sure to investigate these requirements before buying a boiler.
h) Most states/provinces require an annual boiler inspection. There may be other requirements
on piping as well.
i) For all new boilers with inputs over 10 million Btu/Hr, U.S. Federal emission standards apply
including permitting and reporting procedures.
j) Ratings of boilers are based on sea level operation. For operation at elevations above 2,000
feet (600m), equipment ratings shall be reduced at the rate of 4 percent for each 1,000 feet
(300m) above sea level.

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2.2 NATIONAL REGULATORY ORGANIZATIONS
MIURA recommends contacting your actual insurance provider as well as the utility companies
for assistance in identifying and complying with codes and regulations.
A partial list of agencies having jurisdiction over boiler installation and operation is given
below. This list is comprehensive but by no means all-inclusive.
UNDERWRITERS LABORATORIES
333 Pfingsten Rd.
Northbrook, IL
60062-2096
[phone]
NATIONAL BOARD
1055 Crupper Ave.
Columbus, OH
43229-1183
[phone]
A.S.M.E.
The Park Avenue
New York, NY 10016-5990
[phone]
AMERICAN GAS ASSOCIATION
400 North Capitol Street NW, Suite 450
Washington, DC 20001
[phone]
CSA INTERNATIONAL
178 Rexdale Blvd.
Etobicoke, Ontario
M9W 1R3
[phone]
T.S.S.A.
3300 Bloor St., West
14th Floor, Centre Tower
Toronto, Ontario M8X 2X4
[phone]
N.F.P.A.
1 Batterymarch Park
Quincy, MA 02169-7471
[phone]
FACTORY MUTUAL RESEARCH CORPORATION
1151 Boston-Providence Turnpike,
Norwood, MA 02062
[phone]
AMERICAN NATIONAL STANDARD INSTITUTE
25 West 43rd Street,
New York, NY 10036
[phone]
ENVIRONMENT PROTECTION AGENCY
LOCAL BUILDING &CONSTRUCTION INSP.
FOOD &DRUG ADMINISTRATION
OCCUPATIONAL SAFETY &HEALTH ADM.
LOCAL FIRE MARSHALL
LOCAL BOILER INSPECTION

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SECTION 3 INSTALLATION
NOTE:The installation of the equipment shall be in accordance with the regulations of the
authorities having jurisdiction.
CAUTION: All boiler prices are F.O.B. the factory at Brantford, Ontario. This means that
MIURA is not responsible for damage to the boiler occurring during shipping. We strongly
recommend a complete inspection of all boiler shipments at place and time of delivery. This
inspection should include photographs of the boiler and ancillary equipment packing crates.
If any damage is found, do not release the driver or unload the equipment until a satisfactory
arrangement is made with shipping company to cover the damage. MIURA makes
reasonable effort to ensure that no vibration or shock damage will occur. However, if such
damage occurs and is not discovered and noted at the time of delivery, MIURA is not
responsible to pay for the cost of repairs and any damaged parts will not be under warranty.
NOTE:It is the customer’s responsibility to confirm utility availability before ordering the
boiler and follow all local regulations.
3.1 UNLOADING
For transportation the LXW/LXWH boiler may be disassembled and shipped in separate
components as follows:
Boiler vessel with burner and control box (blower assembly may be shipped separated if
required by customer)
Optional parts such as silencer, filter box, valves etc.
NOTE:Some small parts, such as bolts and nuts etc. may be shipped inside associated control
box for the boiler.
The LXW series boiler may be unloaded from the transport truck using a forklift. However, if a
forklift is used, precautions should be taken to ensure that the boiler does not tip over. The
boiler is top heavy and the weight is not centered. Because of the many variables involved
such as model, size of forklift and size of the loading dock, MIURA is not able to recommend a
specific method of unloading the boiler. As a general starting point, the boiler center of gravity
will be the midpoint of the two lifting lugs. Securing the top of the boiler to the forklift with a
chain or similar methods is strongly recommended.

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3.2 ASSEMBLING
CAUTION:This is a completely shop tested, assembled and fully packaged boiler. Each unit and
assembly has been well adjusted in the factory. It is very important not to make any
adjustments without first consulting your nearest authorized MIURA dealer. Field reassemble
is customer’s responsibility.
3.2.1 BLOWER ASSEMBLY
Line up the blower outlet flange with the windbox inlet flange. Place the supplied rubber gasket
between the two flanges. Tighten all bolts.
NOTE:Prior to installing pump, softener, and other equipment, review applicable instruction
books.
3.2.2 FOUNDATION &ANCHORING
The recommended foundation is a 6” concrete slab. Reinforcement of slab is not necessary if
the floor is solid. After positioning, anchor the boiler to the foundation using 5/8” anchor bolts
(not supplied by MIURA).
NOTE:Installer and operator must identify emergency shut-off device, which includes power
switch, main fuel, and water cock.
3.3 RECOMMENDED PIPING
3.3.1 CLOSED SYSTEM
A closed system should operate with little or no make-up. Consequently, very little water needs
to be added over the years of servicing. Liming or scale build-up should be negligible unless the
make-up is too great. The most common cause of problems due to excessive make-up is leaks in
the system, automatic vent not valved off after start-up, improper air elimination and faulty
pressure reducing valve. It is important to realize that air elimination is a continuous process in
a properly designed system.
Simply venting off excessive air during start-up will not satisfy this requirement. The expansion
tank provides the air cushion to accommodate the expansion and contraction of the system
water. This tank should be sized to approximately 3/4 full when the system is at maximum
operating temperature and ¼ full when at ambient temperature. Therefore, ½ of the tank
capacity must accommodate the expansion of the entire system. This would include the water
content of the heater system piping and all heat users or loops.

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When the expansion tank has little or no air in it, it is referred to as being "water logged" which
means that air has either escaped or migrated to some other part of the system instead of being
properly returned to the expansion tank. Greater amounts of air occurring in the tank, in spite of
attempts to bleed down, indicates that air is being drawn into the system at some point where
there is a leak and the system pressure is below that of the atmosphere. The cause for a water
logged expansion tank must be quickly found and corrective action taken, otherwise there will be
a constant loss of water from the relief valve, constant make-up of water which will result in the
liming of a system that was intended to be closed.
NOTE:
Dirt and scale from the entire system will tend to collect in the boiler and should be
washed out until the system is clean.
Periodic water analysis should be performed to see if additional treatment is needed.
3.4 WATER PIPING
Boiler Model
LXW-50
LXW-100
LXW-150
LXW-175
LXW-200
LXWH-100
Water Inlet
3”
4”
6”
6”
6”
4”
Water Outlet
3”
4”
6”
6”
6”
4”
Inlet/Outlet Connection
150# flg
150# flg
150# flg
150# flg
150# flg
300# flg
Drain Outlet (npt)
1½”
1½”
1½”
1½”
1½”
1½”
Safety Valve Outlet (npt)
1”
1”
1½”
2”
2”
3”
Please Contact your nearest MIURA representative or Distributor about accessories.
Before the boiler is fired for the first time after installation is completed, flush all piping.
MIURA is not responsible for damage as a result of debris in piping such as a stuck open check
valve.
Practical experience has proven that even though hot water boilers generally operate on
closed systems, water losses and entrance of air may lead to pitting, corrosion and formation
of sludge or scale. It is therefore essential to obtain suitable water treatment
recommendations from specialists and to apply them rigidly. A water meter is
recommended to know the amount of make-up water used.
DRAIN

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To avoid condensation in the boiler and the chimney, do not operate boiler for extended
periods of time at boiler outlet temperatures lower than 180F(minimum heating return
temperature should be above 130°F). If the boiler is maintained at lower temperatures, the
moisture in the flue gases will condense on the boiler tubes or chimney and form acidic
water. The net result is that corrosion occurs on the combustion side of the flues and in the
vent stub and chimney. If lower water temperatures are required, mixing valves should be
used.
The maximum GPM circulating rate in relation to full boiler output and system temperature
drop may be determined from the following formula:
)(500 )/( FperatureDroSystemTemp HrBtuutBoilerOutp
GPM  
Main hot water piping should slope upward. If the slope is downward, it must be properly
vented to remove air.
Relief valve discharge outlet must be piped toward the drain, leaving the pipe open so as to
enable observation of water flow, when active.
Follow all local regulations.
NOTE: In multiple installations of hot water boilers, the equalization of water flow to the boilers
is an important consideration. This can be accomplished by using individual circulating pumps
for the boilers with symmetrical piping to the boilers, or by using balancing valves or orifice
plates and gauges in the piping to the individual boilers. If balancing valves or orifice plates are
used, there must be a significant pressure drop across the balancing devices. If care is not
taken to ensure equal flow, the unequal flow will cause an unequal-firing rate. The net result
would be that the common header outlet water temperature would not be up to the desired
temperature.

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18
3.5 FUEL PIPING
FUEL TYPE: Natural & Propane Gas
SUPPLY PRESSURE: 3 - 5 PSIG *
NOTE:3 –5 PSIG is the setting range, NOT the allowable fluctuation range. Maintain steady, set
gas supply pressure within 0.2 PSIG but NEVER below 3 PSIG during operation. This pressure
must be at the regulator supplied with MIURA Boiler gas piping. If necessary, use larger pipe
for long piping runs. Failure to maintain required gas flow rate pressure will result in frequent
boiler misfire!
NOTE:Do not use any gas piping with a diameter smaller than the gas inlet piping to boiler.
All main gas train piping to the burner is included with the packaged LXW (except for
individual regulator and pressure switch vents).
CAUTION:Do not attempt to change any part of this gas train without first consulting the
nearest authorized MIURA representative.
Boiler HP
50
100
150
175
200
Gas Inlet (NPT)
1½”
2”
2”
2”
2”
Main Gas Regulator Vent (NPT)
1”
1”
1”
1”
1”
Pilot Gas Regulator Vent (NPT)
⅛”
⅛”
⅛”
⅛”
⅛”
Pressure Switches Vent (NPT)
⅛”
⅛”
⅛”
⅛”
⅛”
Automatic Vent, optional (NPT)
¾”
1”
1”
1”
1”
*See specification tables for fuel consumption.
Supply pressure of 3 to 5 PSIG is required at boiler
regulator inlet at full firing rate and when boiler
combustion is stopped. Installation of a pressure
gauge to monitor gas supply pressure is
recommended. If the boiler is operated with
propane fuel, MIURA STRONGLY recommends the
use of a vaporizer. Collecting the propane gas from
the top of the tank is possible, but not
recommended due to variations in vapor space
pressure depending on ambient air temperature.
Also, ensure the vaporizer is sized for full boiler
capacity even if the normal load is less than the
maximum capacity of the boiler. This
recommendation is based on the boiler operating at
full rated fuel flow during the startup period.
To out doors
Union
Fitting
Main Gas Regulator
1'' NPT
Use
drip leg
& rain
cap on
vent
line