HydroTherm MG Series Manual

MG2-605
42-9158
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IN UNITED STATES: 260 NORTH ELM ST., WESTFIELD, MA 01085 • [phone]/FAX [phone]
IN CANADA: 5211 CREEKBANK ROAD,MISSISSAUGA, ONT L4W 1R3 • [phone]/FAX [phone]
MG SERIES
INSTALLATION MANUAL
AND REPLACEMENT
PARTS LIST
Modular Power Gas Cast
Iron Water Heating Plants
770,000 to 2,310,000
Btuh Input
SECTION 1: INTRODUCTION
Heating Plant Design............................................ 2
Code Compliance................................................. 2
Heating Plant Shipment........................................ 2
Heating Plant Dimensions..................................... 3
SECTION 2: INSTALLING MODULES
Step 1: Planning Ahead......................................... 4
Step 2: Arranging Heating Plant............................ 5
Step 3: Setting & Aligning Modules....................... 5
SECTION 3: INSTALLING WATER PIPING
Step 1: Planning Ahead......................................... 6
Step 2: MC Heat Exchangers................................ 6
Step 3: Supply & ReturnHeaders.......................... 6
Step 4: Hydronic Components............................... 7
Step 5: Hydrotesting The System.......................... 8
SECTION 4: VENTING THE HEATING PLANT
Step 1: Planning Ahead........................................ 11
Step 2: Draft Regulators, Vent Connectors
&Slip Joints............................................. 12
Step 3: Breeching Runs....................................... 13
SECTION 5: INSTALLING JACKETS
Jacket Assembly................................................... 14
SECTION 6: INSTALLING BURNER
Burner Requirements........................................... 15
SECTION 7: INSTALLING GAS PIPING
Step 1: Gas Main & Gas Headers........................ 15
Step 2: Test Gas Piping........................................ 16
SECTION 8: WIRING THE HEATING PLANT
Wiring Requirements............................................ 16
SECTION 9: HEATING PLANT START-UP
Step 1: Planning Ahead........................................ 17
Step 2: Start-Up & Adjustments............................ 17
APPENDICES
A: Breeching/ChimneySizing............................... 18
B: Gas Pipe Sizing................................................ 20
C: Control Guidelines............................................ 22
REPLACEMENT PARTS 27
NOTE: If shop drawings have not been provided, refer to the Appendices at the rear of this manual for sizing
(breeching, chimney&gas piping) and control system data.
Applicable For Larger Heating
Plants Using Boiler Banks
Of 6-Modules Or Less

2
HEATING PLANT DESIGN
Multi-Temp heating plants are comprised of individual
cast iron modules that are piped to common headers to
provide large hot water heating capacities. They are de-
signed and intended for use for a central space heating
system, for volume water heating, or for combination
space heating/volume water heating. Each module is
self-contained with its own set of controls and can oper-
ate independent of the other modules. Multi-Temp mod-
ules can be arranged to fit just about any available area.
Products of combustion are vented through each mod-
ule’s vent connector, connected to a manifold (breeching)
for joining individual connectors. Breeching is connected
to a chimney which provides the necessary draft.
The objective of a Multi-Temp heating plant control sys-
tem is to relate plant output to the actual heating load by
automatic step-firing. This means that more or fewer
modules are operated in response to an increase or de-
crease in actual heating load. Hydrotherm has develop-
ed three basic methods (levels) of control which meet
most operating requirements encountered. Typical wir-
ing diagrams for these basic methods are provided in the
appendices at the rear of this manual. Special control
system designs can be developed through the Hy-
drothermapplications engineering group.
CODE COMPLIANCE
Installations must conformto requirements of the au-
thority having jurisdiction. Where required by the author-
ity having jurisdiction, the installation must also conform
to Standard for Controls and Safety Devices for
Automatically Fired Boilers, ANSI/ASME CSD-1.
All electrical wiring must be in accordance with the re-
quirements of the authority having jurisdiction or, in
absence of such requirements, with National Electrical
Code NFPA-70-latest edition. If an external electrical
source is utilized, installed module must be electrically
grounded in accordance with the requirements of the
authority having jurisdiction or, in the absence of such
requirements, with the National Electrical Code NFPA-
70-latest edition. UL listed power limited circuit cable is
almost universally approved for safety controls on heat-
ing equipment, either internally or externally, without pro-
tection of conduits or raceway.
For Canada, installations must be in accordance with
Standard C.S.A. C22.1 Canadian Electrical Code, Part 1
and Part 2, and/or local codes.
HEATING PLANT SHIPMENT
Heating plant packing list (attached to one of the pack-
ages) clearly lists the number of packages and their con-
tents. Check this list against all material on the job site for
completeness.
Heating Modules: Each module is shipped unjacketed in
its own carton and weighs 623 lbs. (maximum for MG-
385 module).
Draft Regulators: One for each module is shipped in car-
ton with module.
Jackets: There are twojacket sizes- “A" jacket to en-close
twoheating modules and “B” jacket to enclose three
heating modules. The correct combination of “A” and “B”
jackets are furnished to form a complete enclosure for
the entire heating plant.
Burners: When ordered, one Midco DS-45 power gas
burner for each module is shipped in a separate carton.
Optional Header Sets: When ordered, each header set
includes supply and return headers, pipe nipples, union
and self-aligning couplings. There are two header set
sizes -”A” headers for joining two heating modules and
“B” headers for joining three heating modules. The cor-
DANGER: Indicates an imminently hazardous situ-
ation which, if not avoided, will result in death,
serious injury or substantial property damage.
WARNING: Indicates a imminentlyhazardous situ-
ation which, if not avoided, could result in death,
serious injuryor substantial property damage.
CAUTION: Indicates a imminently hazardous situa-
tion which, if not avoided, may result in minor
injury or property damage.
The following terms are used throughout this manual to bring attention to the presence of potential hazards
or to important information concerning the product:
SECTION 1: INTRODUCTION
NOTE: Used to notify of special instructions on
installation, operation or maintenance which are
important to equipment but not related to personal
injury hazards.

rect combination of “A” and “B” headers are furnished to
manifold the complete heating plant.
Optional Heat Exchanger: When ordered, each heat
exchanger is shipped with the pipe and fittings required
for installation. There are two types of heat exchangers
for volume water heating - “MC2” for two heating modules
and “MC3” for three heating modules.
Control Equipment: When ordered, controls such as mo-
torized valves, modulating aquastats, step controllers,
thermostats, etc., are furnished in separate cartons.
3
3' 7"
5' 4"
7' 1"
8' 10"
10' 7"
LENGTH
"L"
MG-770
MG-1155
MG-1540
MG-1925
MG-2310
BOILER
MODEL
(TYPICAL)
21"10-1/2"
23-7/8"
9" 26" 20"
PRESS. RELIEF VALVES
2" SUPPLY
& RETURN
TAPPINGS
14"
57-1/2"
48-1/2"
TEMP./PRESS. INDICATORS
"L"
HI-LIMITS
*
9-1/2"
13"
21"
8" DRAFT REGULATOR
TEE ASS'Y.
DRAIN
VALVE
*
OPTIONAL: FACTORY-SUPPLIED SUPPLY & RETURN HEADERS 
MIDCO
DS-45
POWER
GAS
BURNER 
MODEL MG HEATING PLANT DIMENSIONS

4
SECTION 2: INSTALLING MODULES
STEP 1: PLANNING AHEAD
IMPORTANT TO NOTE
1. Observe minimum clearances to combustibles.
2. Observe proper combustion air requirements.
3. Provide a firm, level and fireproof foundation (modules
must be installed on non-combustible floor).
MINIMUM CLEARANCES TO COMBUSTIBLES: The
following must be observed: 18” from jackets to front and
rear; 6" each side; and 38” from jacket tops to ceilings.
Local requirements may specify greater clearances and
must be adhered to.
COMBUSTION AIR REQUIREMENTS: Provisions for
combustion air must be in accordance with applicable
local codes.
If the heating plant is installed in an unconfined space,
adequate air will be available via normal infiltration.
If the heating plant is installed in a confined space (a
space with a volume of less than 50 cubic feet per 1000
Btu/hr of input for all fuel burning equipment) or building
construction is unusually tight, adequate air for combus-
tion must be provided by two openings: one located about
6” below the ceiling, the other about 6” above the floor.
Each opening must have a minimum free area as fol-
lows:
1. One square inch per 4000 Btu/hr of input when com-
municating directly with the outside or through a verti-
cal duct.
2. One square inch per 2000 Btu/hr of input when com-
municating through horizontal ducts to outside.
3. One square inch per 1000 Btu/hr of input when ven-
tilation air is provided by openings in doors, etc. to
adjoining spaces having adequate infiltration.
NOTE: Modules employ atmospheric combustion.
Combustion air must not be contaminated with halo-
genated hydrocarbon vapors, cleaning fluid vapors,
aerosol propellants, freon or other corrosive chemi-
cals. Otherwise, module heat exchangers will be sub-
ject to corrosion, reducing module life.
HEATING PLANT FOUNDATION: Concrete base pad is
preferred. Loading is 195 lbs. per square foot; special
reinforcements not required. If the floor is of combustible
material and where permitted by local codes, fabricate a
fireproof base as shown in Figure 2.1. Local codes may
require different construction.
22 GAUGE
SHEET METAL
6"
FLOOR
6" OVERHANG
OF BLOCK AND
SHEET METAL
ALL AROUND
4" HOLLOW CLAY TILE (TWO COURSES). OPENINGS THRU
BLOCKS IN TOP COURSE TO BE AT 90 ANGLE TO OPENINGS
THRU BOTTOM COURSE
0
FIGURE 2.1
WARNING: Never install heating plant on com-
bustible flooring without fireproof base or on car-
peting as heat damage and/or fire may result.
WARNING: The boiler must be supplied with com-
bustion air in accordance with Section 5.3, Air for
Combustion & Ventilation, of the latest revision of
the National Fuel Gas Code, ANSI Z223.1 and all
applicable local building codes. Failure to provide
adequate combustion air for this appliance can
result in excessive levels of carbon monoxide which
can result in severe personal injury or death!

1. Snap a chalk line on foundation where rear of modules
will be located. Modules must be spaced 21" center to
center.
2. Remove cartons from modules; move with skids to a
position alongside final module location. Rockmodule off
skid into proper location on foundation - rear of burner
base on the chalk line and left of burner base at the inter-
val mark.
3. Ensure that supply and return tappings on rear of each
module are spaced at 21" intervals. If more than 1/8" of
vertical discrepancy exists, shim under module base to
bring the supply tappings in line.
4. Level each module front-to-rear and side-to-side by
shimming under base as necessary.
CAUTION: Do not loosen tie rods on module absorption unit. They accommodate thermal expansion. Loss of
module’s structural integrity & water leaks/damage may result.
STEP 3: SETTING & ALIGNING MODULES
21"
REAR
FRONT
CHALK LINE
OUTLINE OF
MODULE BASE
FIGURE 2.3
5
1. Locate heating plant as close to the chimney as possi-
ble so breeching length to chimney is kept to a minimum.
Only 6" is required between the first module and the
chimney.
2. Modules employing MC heat exchangers (if any) must
belocated closest to the chimney to assure adequate
draft for summertime operation.
3. Arrange heating plant in multiple banks of six modules
or less (unless otherwise specified on factory-approved
specially-designed venting systems). NO MORE THAN
SIX MODULES MAY BE CONNECTED DIRECTLY
WITH FACTORY-SUPPLIED HEADERS. Several exam-
ples of typical arrangements are shown here.
Recommended clearances (which are more than clear-
ances to combustibles) allow for servicing, system instal-
lation & connections.
4. Make sure that any connecting breeching runs will not
oppose or face each other, but rather, mix together in the
same general direction (specifically "Y" together rather
than "tee" together).
STEP 2: ARRANGING HEATING PLANT
IN-LINE GROUPING
36"
TO WALL
OR NEXT
BANK 
6 MODS
36" 
26" 
56" 
36"
TO WALL
OR NEXT
BANK 
36" 
5 MODS
6 MODS
FACE-TO-FACE GROUPING
36" 
36" 
26" 
26" 
76" 
36" 
56" 
36" 
36" 
6 MODS
6 MODS
BACK-TO-BACK GROUPING
26" 
29" 
26" 
56" 

6
STEP 3: SUPPLY & RETURN HEADERS
1. Whether installing factory-supplied headers or field-
fabricated headers, WATER PIPING MUST BE IN-
STALLED TOPROVIDE REVERSE RETURN FLOW
(see Figure 3.1). This piping arrangement ensures ad-
equate flow to every heating plant module.
2. For installation of factory-supplied supply and return
headers, refer to Hydrotherm Supply & Return Header
Installation Guide (H2) packaged with the header sets. All
external piping must be supported byhangers,not bythe
boilers or their accessories. NO MORE THAN SIX MOD-
ULES MAYBE DIRECTL
YCONNECTED WITH FACTO-
RY-SUPPLIED HEADERS.
RETURN HEADER
SUPPLY HEADER
FIGURE 3.1
STEP 2: MC HEATEXCHANGERS
For installation of factory-supplied MC/MCI heat exchangers, refer to Hydrotherm MC & MCI Installation Guide (MC2) pack-
aged with the heat exchanger. All external piping must be supported by hangers, not by the boilers or their accessories.
STEP 1: PLANNING AHEAD
IMPORTANT TO NOTE
1. Field-fabricated headers must have correct number of
tappings to accept all water piping accessories; locations
of tappings must be in accordance with guidelines pro-
vided in Step 4 in this section.
2. If system anti-freeze will be used, the system must be
designed to accommodate the necessary changes in
heat transfer, pump head, flow rate and expansion.
3. Water treatment is recommended in areas where water
quality is a problem; it must be used in hard water areas
and on very large volume heating systems.
FIELD-SUPPLIED COMPONENTS: Some of the follow-
ing may not have been supplied by Hydrotherm, depend-
ing on how the heating plant was ordered, but are
required for installation: air separator, air eliminator,
expansion tank, low water cut-off, manual reset hi-limit,
pressure reducing fill valve, pump(s), shut-off valves, and
motorized valve (for combination space/ volume water
heating). Optional: flowcheck valve, flow meter, strainer
and backflow preventer.
FREEZE PROTECTION: Where it's absolutely neces-
sary, system anti-freeze can be utilized, but it must be
compatible with hydronic heating systems. For more
information, consult The Hydronics Institute Technical
Topics Number 2A publication.
NOTE: Never use an RV type anti-freeze protection
solution nor an automotive type anti-freeze as dam-
age to modules and other system components may
result.
WATER TREATMENT: Alocal water treatment company
should be consulted to determine the requirements for
your particular system and locality through thorough
chemical analysis of your system water.
CAUTION: Modules are not for use in systems where
water is replenished. Minerals in the water can build
up on heat transfer surfaces and cause overheating
and subsequent failure of the cast iron sections. If
piping exists where water leakage would not be visi-
ble, awater meter should be installed to record intro-
duction of boiler feed water.
SECTION 3: INSTALLING WATER PIPING

STEP 4: HYDRONIC COMPONENTS
The diagrams in Figures 3.4 through 3.7 show typical
locations of various hydronic components required for
Multi-Temp heating plants. In all cases, installation
should be in accordance with component manufactur-
er’s recommendations (literature, if applicable, is pack-
aged with component). In addition, the following guide-
lines should be followed.
PRESSURE RELIEF VALVES: One supplied for each
module. Install relief valves with spindle in the vertical
position (i.e., valve discharge in horizontal) with cou-
pling and nipple in 3/4" tapping at top of modules. In-
stall field-supplied valve discharge piping (Figure 3.3).
CAUTION: Piping must be installed from the relief
valve discharge so there will be no danger of
scalding personnel.
TEMPERATURE/PRESSURE INDICATORS: One
temperature/pressure indicator supplied for each mod-
ule. INSTALL AFTER ASSEMBLING JACKET.
DRAIN VALVES: One supplied for each module. In-
stall below return connection.
PRESSURE REDUCING (FILL) VALVE: Follow manu-
facturer’sinstallation instructions.
AIR SEPARATOR(1):Locate in the supply line between
boiler and system pump (where it will protect all mod-
ules under all operating conditions). Followmanufac-
turer’s installation instructions.
AIR ELIMINATOR(1):Install on air separator (where it
will protect all modules under all operating conditions).
(1) For heating plants providing volume water heating only (instantaneous recovery or with storage tank), see Figures 3.6
and 3.7 on page 10 for installation guidelines.
RELIEF VALVE
DISCHARGE
PIPING
MUST
TERMINATE
6" ABOVE
FLOOR
SAME SIZE
OR LARGER
THAN OUTLET
NIPPLE
COUPLING
PRESSURE
RELIEF VALVE
(VERTICAL)
FIGURE 3.3
7
STEP 3: SUPPLY & RETURN HEADERS (CONTINUED)
EXAMPLES
OF TYPICAL
SUPPLY & RE-
TURN WATER
PIPING FOR
HEADERS.
NO MORE
THAN SIX
MODULES
MAY BE
DIRECTLY
CONNECTED!
IN-LINE - 6 MODULES OR LESS
BACK TO BACK
MORE THAN 6 MODULES
IN-LINE - MORE THAN 6 MODULES
SUPPLY
RETURN
SUPPLY
RETURN
SUPPLY
RETURN
WARNING: Never install any type of valve between
the pressure relief valve and the heating plant mod-
ules! Failure to comply with this warning can result
in a heating plant explosion causing extensive
property damage,severe personal injury or death!

Follow manufacturer’s installation instructions.
EXPANSION TANK(1):Locate on suction side of pump
(where it will protect all modules under all operating
conditions). Follow manufacturer’s instructions.
MANUAL RESET HI-LIMIT(1):Locate in supply piping
downstream of connection of the last module.
LOW WATER CUTOFF(1):(Electronic type or float
type) Locate in supply header. Follow manufacturer’s
installation instructions. If heating plant is to be
installed above level of radiation, a low water cutoff
must be installed to protect plant from dry fire.
CAUTION: To prevent accidental dry fire, do not
install isolation valves between low water cutoff
and the module.
CAUTION: Do not install any low water cutoff in a
location where water will not freelydrain awayfrom
the float or probe (i.e., in a pipe tree or loop) should
alow water condition develop in the module.
For electronic probes,vertical installation (where all
water can freely drain awayfrom probe) is preferred
over horizontal. Do not install in small diameter pipe
nipples or bushings, as insufficient clearance to probe
mayresult in corrosion and/or erroneous readings.
SYSTEM PUMP(1) Locate in the heating plant supply
piping, downstream of the modules. Followmanufac-
turer's installation instructions.
NOTE: Heating plants must not be used without
forced system circulation, as overheating/failure of
cast iron sections may result.
MOTORIZED VALVE: Commonly used on combination
space/volume water heating systems to ensure a pri-
ority for domestic hot water over space heating. (2"
globe valve with motor for MC2 heat exchanger) (2-
1/2" butterfly valve with motor and linkage for MC-3
heat exchangers) See Figure 3.5 for location. Follow
manufacturer’s instructions.
FLOW CHECK VALVE (Optional): Important to con-
trol direction of flow and prevent gravity circulation.
Locate where it cannot cause isolation of any particu-
lar loop or zone from the main system. Follow manu-
facturer’s installation instructions.
FLOW METER (Optional): Will help determine total
system water volume for purposes of system water
treatment, as well as aid in identification of a system
leak. Follow manufacturer’s installation instructions.
STRAINER (Optional): For retrofit or steam conver-
sion systems,basket-type strainer will trap loose sys-
tem scale. Locate in return water line. Follow manufac-
turer’s installation instructions.
BACKFLOW PREVENTER (Optional): Used as a
means of isolation (space heating system from main
water supply) to safeguard against potential hazard of
fill valve connection allowing migration of water treat-
ment chemicals into potable water supply. Follow man-
ufacturer’s installation instructions.
OTHER COMPONENTS: Install all other waterside
components such as shut-off valves, mixing valves,
thermometers and supply water temperature sensors;
install sensors or probes in a location that will sense
supply water temperature from all modules. Follow
manufacturer's installation instructions.
STEP 4: HYDRONIC COMPONENTS (CONTINUED)
(1) For heating plants providing volume water heating only (instantaneous recovery or with storage tank), see Figures 3.6
and 3.7 on page 10 for installation guidelines.
8
STEP 5: HYDROTESTING THE SYSTEM
It is recommended that hydrotesting of the entire heat-
ing system be performed before installing jackets and
controls or wiring the system. Fill the entire system
with water and pressurize. All fittings and components
should then be inspected for visible signs of leakage. If
no pressure drop is detected for a two-hour period
under pressure, the heating system may be considered
water tight.

9
LOW WATER
CUTOFF
BASKET TYPE
STRAINER
System
Return
MANUAL RESET
HI-LIMIT
SHUT-OFF
VALVE
RETURN HEADER
SUPPLY HEADER
AIR
SEPARATOR
CIRCULATOR
EXPANSION
TANK
PRESSURE
REDUCING
(FILL) VALVE
AIR ELIMINATOR
(AIR VENT)
FLOW CHECK
VALVE
BACKFLOW
PREVENTER
To Potable
Water
System
FILL
System
Supply
City
Water
Supply
TYPICAL PIPING FOR SPACE HEATING SYSTEM
FRONT OF BOILER
MOUNT DRAIN VALVE BELOW
RETURN CONNECTION
RETURN
INLET
MAKE-UP
WATER METER
TYPICAL PIPING FOR COMBINATION SPACE/VOLUME WATER
HEATING SYSTEM
NOTE: WHEN A HOLBY MIXING VALVE IS USED
THERE MUST BE A 27" DROP BELOW THE COIL
COLD WATER TERMINAL IN THE COLD WATER
LINE BEFORE ENTERING THE COIL
To Potable
Water
System
City
Water
Supply
MIXING
VALVE
LOW WATER
CUTOFF
HEAT EXCHANGER
MOTORIZED
VALVE
Service
Hot Water
Supply
Service
Recirculating
Hot Water
BRONZE
CIRCULATOR
*
*
BASKET TYPE
STRAINER
System
Return
SHUT-OFF
VALVE
MANUAL RESET HI-LIMIT
EXPANSION
TANK
AIR SEPARATOR
AIR ELIMINATOR (AIR VENT)
CIRCULATOR
FLOW CHECK VALVE
Supply
FLOW CHECK VALVE
PRESSURE
REDUCING
(FILL) VALVE
FRONT OF BOILER
MOUNT DRAIN VALVE BELOW
RETURN CONNECTION
RETURN
INLET
BACKFLOW
PREVENTER
MAKE-UP
WATER METER
TYPICAL PIPING FOR
SPACE HEATING SYSTEM
Figure 3.4
TYPICAL PIPING FOR
COMBINATION SPACE/VOLUME
WATER HEATING SYSTEM
Figure 3.5

TYPICAL PIPING FOR VOLUME WATER HEATING ONLY
(INSTANTANEOUS RECOVERY)
TYPICAL PIPING FOR VOLUME WATER HEATING ONLY
(WITH STORAGE TANK)
NOTE: WHEN A HOLBY MIXING VALVE IS USED THERE MUST BE A 27" DROP BELOW THE COIL COLD WATER TERMINAL IN THE COLD WATER
LINE BEFORE ENTERING THE COIL
*
SHUT-OFF VALVE
City
Water
Supply
Service Hot
Water Supply
Service
Recirculating
Hot Water
BRONZE CIRCULATOR FLOW CHECK VALVE
EXPANSION
TANK
AIR ELIMINATOR (AIR VENT)
BACKFLOW PREVENTER
MIXING VALVE
*
PRESSURE
REDUCING
(FILL) VALVE
LOW WATER
CUTOFF
MANUAL RESET
HI-LIMIT
THERMOMETER
MAKE-UP WATER METER
FIGURE 3.6
INSTALL MANUAL RESET HI-LIMIT, LOW WATER CUTOFF, AIR ELIMINATOR (ONE OR MORE), EXPANSION
TANK AND BRONZE CIRCULATOR IN LOCATIONS SHOWN. AIR SEPARATOR NOT REQUIRED.
City
Water
Supply
Service
Recirculating
Hot Water
Service
Hot Water
Supply
PRESSURE
REDUCING
(FILL) VALVE
BACKFLOW PREVENTER
BRONZE CIRCULATOR
FLOW CHECK VALVE
SHUT-OFF VALVE
PRESS RELIEF VALVE
STORAGE TANK
AIR ELIMINATOR (AIR VENT)
LOW WATER
CUTOFF
MANUAL RESET HI-LIMIT
EXPANSION
TANK MAKE-UP
WATER METER
FIGURE 3.7
10
COMBINATION HEATING
& COOLING INSTALLATIONS
If hot water module is installed in connection with water chiller,
chilled water must be piped in parallel with module, using appropri-
ate valves to prevent chilled medium from entering module. When
modules are connected to heating coils in air handling units, where
they may be exposed to refrigerated air circulation, module piping
system shall be equipped with flow-control valves or other automatic
means to prevent gravity circulation of module water during cooling
NOTE: VALVES "H" OPENED ON HEATING WITH "C" VALVES
CLOSED REVERSE PROCEDURE ON COOLING.
EXP. TANK VENT ROOM
UNIT
DRAIN
CHILLER
BOILER
H
C
PUMP
RELIEF
VALVE
FILL
VALVE
DRAIN
C
H
BOILER
FIGURE 3.8

11
IMPORTANT TO NOTE
1. Breaching runs must be as short as possible.
2. No more than six modules may be served by one
breaching run to assure adequate draft (unless otherwise
specified on factory-approved specially-designed venting
systems).
3. Observe breaching construction requirements.
4. Observe proper chimney requirements.
5. Flues from other gas-burning appliances must not be
connected into heating plant breaching; otherwise, inad-
equate draft may result.
6. Natural draft equipment (heating plants without
mechanical draft components) must not be connected into
any portion of a mechanical draft or power vent system
operating under positive pressure, including the chimney.
7. If shop drawings with approved breaching and chimney
sizes are not available, you can use the sizing guidelines
recommended in Appendix A at the rear of this manual.
MULTI-TEMP HEATING PLANT VENTING SYSTEM:
Consists of draft regulators (factory-supplied), vent con-
nectors,breaching and chimneyor vent pipe (see Figure
4.1). Draft regulators are installed between the modules’s
flue outlet and vent connector. Breaching is the horizon-
tal manifold for connecting each module’s vent connector
to the chimney. Venting system components must be
installed in accordance with requirements of the local
authority having jurisdiction.
BREACHING CONSTRUCTION REQUIREMENTS:
Round breaching is preferred to maximize flue gas flow.
Rectangular breaching is the only acceptable alternative;
the larger dimension of the rectangle must be in the
vertical. Breaching should be constructed of sheet metal
with smooth interior surfaces. Figure 4.2 provides mini-
mum sheet metal gauges (adhere to local requirements
for sheet metal thickness). All joints must be tight to pre-
vent leakage, by sufficient joint overlap, rolled joints or
welding.
CHIMNEY REQUIREMENTS: Lined masonry chimneys
or Type B metal vent systems, constructed in accordance
with national codes, are suitable. Chimney construction
materials must be compatible with the fuel being used.
Chimney condition is of paramount importance for a safe
and efficient installation. For existing chimneys, all instal-
lations must include a chimneyinspection by a qualified
individual or agency. Particular attention should be paid
on oil-to-gas conversions. Soot may have accumulated in
the chimneyand/or degraded the chimney liner. Most util-
ities require the installation of a newliner, safety spill
switches or other chimney upgrades. Check with the local
utility for the required safety precautions.
MECHANICAL DRAFT REQUIREMENTS: When pro-
per venting of the Multi-T
emp heating plant cannot be
accomplished bynatural means,mechanical draft induc-
ers or power venters may be used, properly sized and
properly installed, following the recommendations of their
manufacturers. A fan prove switch must be used in the
control system and wired such that the heating plant will
not fire (prevent flow of gas) until inducer or power venter
fan operation is proved.
VENT
CONNECTORS
DRAFT
REGULATORS
BREECHING
POWER GAS HEATING PLANT
C
H
I
M
NE
Y
FIGURE 4.1
MINIMUM SHEET METAL GAUGE
FOR ROUND AND RECTANGULAR BREECHING
DIAMETER
IN INCHES
6TO 10
10 TO 12
SHEET
METAL
GAUGE
24
22
20
16
14 TO 16
OVER 16
GREATER
DIMENSION
IN INCHES
10 TO 13
14 TO 18
19 TO 20
OVER 20
ROUND RECTANGULAR
FIGURE 4.2
STEP 1: PLANNING AHEAD
SECTION 4: VENTING THE HEATING PLANT
DANGER: A chimney which does not meet modern
safety standards will result in a fire or deadly carbon
monoxide poising of the building residents.

12
1. Mount each module’s factory-supplied draft regulator
over module flue outlet opening, with barometric draft
control facing to the front.
2. Install a vent connector between each module’s draft
regulator and the breaching. Vent connector diameter
should be the same as draft regulator; IT MUST
NEVER BE SMALLER.
3. Where possible, vent connector height should use all
SLIP JOINT
OR DRAW
BAND
BREECHING
VENT
CONNECTOR 1-FT. MINIMUM RISE
FLOW
45
ELBOW
0
DRAFT
REGULATOR
FIGURE 4.3
STEP 2: DRAFT REGULATORS, VENT CONNECTORS & SLIP JOINTS
available head room. Minimum vertical height of vent
connector is 1-foot.
4. Vent connector should connect to breaching with a
straight 900connection. For improved flue gas flow,
connectors may be installed with 450rounded type
elbow; angled toward chimney (see right diagram).
5. For ease of servicing, install a slip joint or a draw
band between the draft regulator and vent connector.
6. Where it may be necessary to vent two banks of
boilers into a common breaching, the vent con-
nectors must be angled at 450sand theymust
enter the breaching at the lowest point possible to
minimize the ineffective area of the breaching. The
450elbows must be the rounded type,and the 1-
foot minimum height must be maintained.
This arrangement applies for a maximum of three
boilers per bank (unless otherwise specified on
factory-approved specially-designed venting sys-
tems). For larger banks of boilers, use individual
breaching for each bank.
1-FT. MINIMUM RISE
BREECHING
VENT
CONNECTOR
ROUNDED
45 ELBOW
0
INEFFECTIVE
BREECHING
AREA
FIGURE 4.4
DANGER: Flue outlet and draft regulator as supplied must not be altered as proper module operation
would be jeopardized. Fire or carbon monoxide poisoning will result.

13
STEP 3: BREACHING RUNS
1. Breaching can be full size for an entire bank of boil-
ers (Figure 4.5 left) or may be tapered (Figure 4.5
right), using one tapered division within a bank of six
modules.
2. For tapered breaching, the smallest sized breaching
division is always the furthest from the chimney with
transition to the larger division leading toward the chim-
ney(see Figure 4.5 right). All increaser fittings must be
tapered to assure proper flue gas flow.
3. Remember, for rectangular breaching, the larger di-
mension of the rectangle must be in the vertical.
4. ALL BREACHING RUNS MUST BE PITCHED 1/4”
PER FOOT OF LENGTH UPWARDS TOWARD THE
CHIMNEY.
5. Where breaching runs connect into another breach-
ing run, they must be connected so the flow-streams
from each breaching run do not face or oppose each
other,but rather, mix together in the same general di-
rection (see Figure 4.6). Construction involves using
Wye-fittings and rounded 450elbows angled towards
the chimney to assure proper flue gas flow.
TAPERED
PITCH 1/4" PER RUNNING FOOT
UPWARD TOWARD CHIMNEY
C
H
I
M
N
E
Y
C
H
I
M
N
E
Y
FULLSIZE
PITCH 1/4" PER RUNNING FOOT
UPWARD TOWARD CHIMNEY
FIGURE 4.5
PREFERRED
DOUBLE WYE FITTING WYE FITTING
45 ELBOW
0
ACCEPTABLE
FIGURE 4.6
6. Where two or more breaching runs connect into the
same chimney,make sure the openings into the chim-
neydo not face or oppose each other.
7. At the breaching-chimneyconnection, breaching
must be flush with the inside of the chimneyliner and
sealed.
CHIMNEY
BREECHING
RUN
BREECHING
RUN
FIGURE 4.7

14
6. Temperature/Pressure Indicators: Install in top
holes in front panels; one per module.
7. Hi-Limits: Install through knockouts in front panels;
one per module. (Well is factory installed.)
HI-LIMIT AQUASTATS
(FOR EACH MODULE)
TEMPERATURE/PRESSURE
INDICATORS
(FOR EACH MODULE)
FIGURE 5.3
FIGURE 5.2
NOTE: Remember, “A” jacket sets are for enclosing
two modules and “B” jacket sets are for enclosing
three modules.
1. Join upper and lower rear panels with screws pro-
vided.
2. Place front and rear panels along heating plant, and
attach side panel on the right with screws provided.
3. Any number of “A” or “B” jackets may be joined to-
gether in one continuous line; just omit one side panel
(left panel) in between jacket sets. Fasten front and
rear panels to remaining side panel(s) with screws pro-
vided; when assembling, overlap bends as shown.
4. Install top panels starting with left top panel. Lock
each panel into the preceding panel and secure with
the screws provided.
5. Attach rating plate, lighting instructions label and lit-
erature pak where indicated by stencils.
CENTER TOP PANEL LEFT TOP PANEL
LOWER REAR PANEL
SIDE PANEL
FRONT PANEL
SIDE PANEL
RIGHT TOP PANEL
SIDE PANEL
FRONT PANEL
FRONT PANEL
UPPER REAR PANEL
FIGURE 5.1
SECTION 5: INSTALLING JACKETS

SECTION 7: INSTALLING GAS PIPING
15
STEP 1: GAS MAIN & GAS HEADERS
1. Gas main and gas headers must be sized to provide a
total maximum pressure drop of 0.3" W.C. (natural gas) or
0.5" W.C. (propane) between gas meter and each mod-
ule’s power gas burner. If shop drawings with approved
pipe sizes are not available, use sizing guidelines recom-
mended in Appendix B at the rear of this manual.
2. Gas main from meter to gas headers must have a
non-restrictive lubricated plug valve close to the mod-
ules as well as a full-sized sediment trap at the low
point in the gas main. Use a vertical rise sediment trap
that is a minimum of three times the gas main pipe
diameter.
3. The gas header is the manifold to
which each module’s burner is con-
nected; the connection at each bur-
ner inlet requires a ground joint union.
If total equivalent pipe length, straight
pipe plus fittings,from burner inlet to
header is 5-ft or less, use a pipe diam-
eter that matches burner inlet; over 5-
ft, calculate diameter.
4. All piping must be supported with
floor supports or byhangers, not by
boilers or accessories. Always follow
good piping practices. Pipe joint com-
pound must be compatible with gas
being used. Check local codes and
utilities for any special requirements.
SECTION 6: INSTALLING BURNER
Install each module’s burner, following manufacturer’s installation instructions packaged with the burner.
FROM
METER
LUBRICATED
PLUG VALVE
GAS HEADER
GROUND JOINT UNION
SUPPORT
GAS MAIN
SEDIMENT
TRAP
SUPPORT

16
STEP 2: TEST GAS PIPING
DANGER: Before placing gas piping into service, carefully test it to assure every joint is gas tight. Bubble
test all joints with a soap solution. NEVER TEST WITH AN OPEN FLAME AS FIRE OR EXPLOSION WILL
RESULT.
For any pressure testing in excess of 1/2 psi, the module
and its individual shutoff valve must be isolated from the
piping system by disconnecting them and capping the
outlet(s). For any pressure testing equal to or less than
1/2 psi, module must be isolated from the piping system
by closing its manual shutoff valve.
Minimum pressure required at the gas burner inlet is 5"
W.C. (natural gas) and 11" W.C. (propane). Maximum
pressure allowable at the burner inlet is 14" W.C. If the
gas pressure is above these limits, a pressure regulator
must be installed. If the gas pressure is below these lim-
its, contact the local utility.
WHEN TESTING IS COMPLETED, CLOSE MAIN GAS SHUT-OFF VALVE
&SET POWER GAS BURNERS IN “OFF” POSITION
SECTION 8: WIRING THE HEATING PLANT
CAUTION: Label all wires prior to disconnection
when servicing controls. Wiring errors can cause
improper and dangerous operation. Verify proper
operation after servicing.
If shop drawings with approved control selection and
wiring diagrams are not available, you can use the con-
trol and wiring guidelines recommended in Appendix C at
the rear of this manual.
All electrical wiring must be in accordance with require-
ments of the authority having jurisdiction or, in absence
of such requirements, with National Electrical Code
NFPA-70-latest edition. If an external electrical source is
utilized, module must be electrically grounded in accor-
dance with requirements of the authority having jurisdic-
tion or, in the absence of such requirements, with the
National Electrical Code NFP
A-70-latest edition. UL listed
power limited circuit cable is almost universally approved
for safety controls on heating equipment, either internally
or externally, without protection of conduits or raceway.
For Canada, installations must be in accordance with
Standard C.S.A. C22.1 Canadian Electrical Code, Part 1
and Part 2, and/or local codes.
Safety devices (such as low water cut-offs and manual
reset high limits) must be wired so they shut down all
modules protected by those devices. Switch ratings on
safety or control devices must not be exceeded; this may
require the use of relays for larger heating plants.
Air and water temperature sensor wiring must not be run
in the same conduit as power wiring; use shielded wiring
in runs over 25 feet long.
NOTE: If any of the original wire supplied with mod-
ule must be replaced, use similar wire of 105 C rating.
Otherwise,insulation maymelt or degrade, exposing
bare wire.
NOTE: Module transformers must not be used to
power external accessories (i.e. zone valves, relays,
etc.). Otherwise, transformers will be overloaded and
burn out.
POWER REQUIREMENTS PER MODULE
3amps,115v/60Hz
DANGER:Turn off electrical power supply before ser-
vicing. Contact with live electric components can
cause shock or death.

SECTION 9: HEATING PLANT START-UP
17
STEP 1: PLANNING AHEAD
1. Check flow direction arrows imprinted on water system
components are pointing in the proper direction.
2. If system was not previously hydrotested, fill system.
Check all temperature/pressure indicators to assure there
is at least the desired cold fill pressure in the system.
3. Check all fittings and components for visible signs of
leakage, including each module's (and header's) supply
and return water connections.
4. Check that system pump(s) are interlocked with the
heating plant's operating controls so modules cannot fire
without pump(s) running.
NOTE:Do not drawwater from heating system for
cleaning. Minerals in the water can build up on heat
transfer surface and cause overheating and subse-
quent failure of the cast iron sections.
1. Thoroughly purge system following standard purging
practices. Remember,every loop in the system must be
properly purged.
2. Check air elimination equipment for proper operation to
be certain there is no air in the water system.
3. With main gas valve OFF, turn on power to modules.
Open all zones individually; let system pump(s) run until
all air is purged from each zone (sound of air bubbles
flowing in piping has been eliminated).
4. Then operate system pump(s) with all zones open;
continue for the minimum time required to pass entire
system volume through separation point until sound of air
bubbles flowing in piping has been eliminated.
5. Open main gas valve, allowing gas to flow through gas
piping system. Open each burner's gas inlet.
6. Set operating control(s) to call for heat and follow start-
up instructions packaged with burners.
7. Allow system water temperature to rise slowly to about
30° F above fill temperature; shut down modules but
allow system pump(s) to run continuously. When all
sounds of air bubbles are eliminated, increase system
temperature another 30° F. Repeat procedure until maxi-
mum system design temperature is reached.
8. Start and stop burners several times by raising and
lowering the controls settings.
9. Check all safety and operating controls to be sure they
are operating in accordance with manufacturer's recom-
mendations.
a. Hi-Limit Aquastat: Mounted on each module, it cuts
off gas supply to the module when module wa-ter tem-
perature exceeds setting. Check high limit is set at 220°
F. To verify aquastat operation, with a small screwdriv-
er, reduce high limit setting to 100° F. Fire module until
water temperature reaches or exceeds 100° F, at which
time the burner should shut off. If for any reason burn-
er does not shut off, or allows the water temperature to
exceed 120° F, replace aquastat. If no replacement is
necessary,returnsetting to 220° F.
b. Manual Reset High Limit: Mounted in supply head-
er,it shuts off all module burners if system operating
water temperature exceeds setting. Checkthat setting
is 250° F. To verify operation, with a small screwdriver,
reduce setting while heating plant is firing. All module
burners should shut off,as operating water tempera-
ture exceeds the reduced setting. If module burners do
not shut off,checkhigh limit electrical wiring. If O.K.,
replace high limit.
c. Checkthat low water cutoff(s) actually shut down
heating plant as intended.
10. Before leaving the job, make sure heating plant
installation has been inspected and approved bylocal
authorities having jurisdiction over the installation.
STEP 2: START-UP & ADJUSTMENTS
DANGER: To avoid fire or explosion hazards: Do not
store anything against modules or allow dirt or
debris to accumulate in area immediately surround-
ing modules. Keep heating plant area clear and free
from combustible materials, gasoline and other
flammable vaporsand liquids. Lint, paper or rags
must not be allowed to accumulate near burners. Do
not place clothing on module casings to dry.

APPENDIX A: BREECHING/CHIMNEY SIZING
DRAFT REQUIREMENT: For MG heating plants, the
chimney-breeching system should produce -06" to -08"
W.C. (as measured with draft gauge) in vent connector
and -01" to -03" W.C. in combustion chamber.
BREECHING LENGTH
Maximum breeching length (from the furthest module to
the chimney) for each bank of boilers is limited by the
chimney height. As a general rule, maximum breeching
length should not exceed 75% of chimney height; this can
be superseded by specially engineered venting systems.
For power gas heating plants, chimney height is mea-
sured from base on which the module sits. Therefore, it is
important to locate the heating plant as close to the chim-
neyas possible. To minimize breeching length and corre-
sponding chimney height requirement only 6" required
between chimney and first module.
Example: Let’sassume a MG-1925A heating plant has
been specified and the chimneyheight is limited to 21-
feet due to building constraints (see Figure A1). The
breeching length for the heating plant should not exceed
15.75 feet. Using the chartin Figure A2, an MG-1925A
heating plant requires approximately 9-feet in length plus
a 6" minimum clearance between the first module and the
chimney; thus,breeching length is compatible with the
allowable chimney height.
Breeching Length Formula: For your installation.
1. _________ ft. x 75% = _____________ft.
(Chimney Ht.) (Max. Breech Lg.)
2. _______ft. + __________ft. = _____________ft.
(Plant Lg.) (From 1st Mod (Req. Breech Lg.)
To Chimney)
3. If required length is equal to or less than maximum
length, application is O.K. If required length exceeds
maximum length, then you would have to consider ap-
propriately dividing the heating plant or bank of boilers.
BREECHING DIAMETER
1. Determine if one full size breeching, which is preferred,
or a tapered transition to a smaller diameter will be used
in the breeching run to serve the particular heating plant
or bank of boilers.
2. Determine the number of vent connectors being ac-
commodated by each section of the breeching (one vent
connector per module).
3. Treating each section separately, determine the correct
breeching size from sizing table in Figure A2. (Size is
based on heating plant operating at sea level; first module
6" from chimney; breeching full size and insulated from top
of draft regulator to chimneyentrance; and 1-ft minimum
vent connector height. The recommendations in Figure A3
are not to be used for any other configuration; for non-stan-
dard configurations,consult Hydrotherm factorydirectly.)
Example: Let’s assume a MG-2310A heating plant.
1. Breeching will be circular with a tapered transition,
identified as Section A and Section B (see Figure A3).
2. The number of vent connectors feeding into Section A
is 6 (all of the vent connectors in the heating plant). The
number of vent connectors feeding into Section B is 3.
3. For Section A size, under the heading “No. of Modules”
in Figure A2, go down to 6 and read across to the col-
umn, “Breeching Sizing,” where you’ll find that Section A
MG-1925 HEATING PLANT
SHOULD NOT EXCEED
(75% x 21 FT) = 15.75 FT
21 FEET
9 FEET 6"
FIGURE A1
18
Boiler
Model Length
3' 7"
5' 4"
7' 1"
8' 10"
10' 7"
MG-770
MG-1155
MG-1540
MG-1925
MG-2310
No. of
Modules
Breeching Sizing (Minimum)
Circular
Dia. In. I.D.
Rectangular
Sq. In. I.D.
2
3
4
5
6
10
12
13
14
15
86
124
146
169
194
FIGURE A2
SECTION A
6 CONNECTORS
(15" DIAMETER)
SECTION B
3 CONNECTORS
(12" DIAMETER)
MG-2310 HEATING PLANT
FIGURE A3

19
must be 15" in diameter. For Section B size, go down to
3modules, where you’ll find that Section B must be 12"
in diameter. Where the two breeching sections are con-
nected, a 12" to 15" tapered increaser must be used.
Rectangular Breeching: Where necessary to use rec-
tangular instead of circular breeching, the larger dimen-
sion of the rectangle must be in the vertical, as shown in
Figure A4, MG-2310A heating plant example. For the
breeching division sizes from Figure A2, Section A is 194
square inches and Section B is 124 square inches. Size
of the rectangles will be about 15" high by 13" wide for
Section A and 12" high by 11" wide for Section B.
CHIMNEY SIZING
As a reminder, if the existing chimney will be used for the
new heating plant, it cannot be assumed that chimney
size is adequate. Chimney size must be based on the
chimney’s capacity, which involves several factors, the
first of which is the chimney’s capability to handle the
heating plant Btuh input capacity that is to be vented into
it. For example, a six-module MG-2310A heating plant
has a Btuh input of 2,382,000; therefore, the chimney
must be sized to handle a minimum of 2,382,000 Btuh.
However, if the installation has two MG-2310A heating
plants vented into the same chimney, then the chimney
capacity must be 4,764,000 Btuh input.
Chimneycapacity is directly related to what’sconnected
to it - the chimney does not function on its own, but op-
erates in conjunction with the breeching and equipment
connected to it. Another important factor is draft loss;
equipment and breeching must be located as close as
possible to chimney to minimize draft loss. Equipment
located further away from the chimney will have greater
draft loss, necessitating a chimney with a greater capac-
ity to accommodate the greater draft loss.
Chimney capacity also varies with its height and inside
diameter. The higher the chimney, the greater its capaci-
ty; the larger the inside diameter, the greater its capacity.
Any two different size chimneys can have equal ca-paci-
ty; that is, a short chimney with a larger inside diameter
can have the same capacity as a higher chimney with a
smaller inside diameter.
Chimney height determines the total draft which can be
developed and is generally governed by the building
height/design and boiler room location. Chimney inside
diameter determines the restriction to flow with the larger
diameter having less restriction. Generally, the inside
diameter should never be smaller than the diameter of
the breeching connecting into it.
Figure A5 shows minimum chimney sizes for Multi-Temp
power gas heating plants. (Sizes based on first module
located 6" from chimneyand proper breeching size, as
determined from Appendix A. If first module is located
more than 6" from chimney or breeching is non-standard
configuration, then proper chimney height and diameter,
for a specific heating plant Btuh input capacity & breech-
ing, can be determined from ASHRAE guidelines.)
SECTION A
194 sq. in.
15" x 13"
SECTION B
124 sq. ft.
12" x 11"
MG-2310 HEATING PLANT
15
"
11
"
FIGURE A4
Boiler
Model
Rectangular
Linear x Ht.
(In. x In. x Ft.)
13 x 18 x 22
18 x 18 x 23
20 x 20 x 25
20 x 24 x 25
24 x 24 x 25
Circular
Dia. x Ht.
(In. x Ft.)
14 x 22
16 x 23
18 x 25
20 x 25
22 x 25
CHIMNEY SIZING (MINIMUM)
MG-770
MG-1155
MG-1540
MG-1925
MG-2310
FIGURE A5

20
APPENDIX B: GAS PIPE SIZING
For accurate gas pipe sizing, be sure to use total equiv-
alent pipe length: Add the equivalent foot-length of all fit-
tings, such as elbows, tees and valves, used in the gas
pipe run to the straight length of pipe. This can be deter-
mined from National Fuel Gas Code tables. For the initial
determination only, add 20% for the fittings to the straight
length of piping to get a total equivalent length. However,
once a diameter has been selected, total equivalent
length must be verified.
You need to know:
1. Total Btuh input of all modules in the heating plant.
2. Heating value, Btu per cubic foot, of the natural gas
which can be obtained from the local gas utility.
3. Total equivalent lengths of the gas main and the gas
headers which must be sized separately.
Tables B1 and B2 are pipe sizing tables for natural gas
and propane gas piping. They apply for sizing black iron
pipe only and are based on total equivalent pipe length
and maximum capacity of the pipe, in cubic feet of gas
per hour for natural gas or in thousands of Btu per hour
for propane. Natural gas sizing table assumes a 1000
Btu/cu.ft. heating value for natural gas.
Gas Headers (Natural Gas)
1. Determine cubic feet of gas per hour for each bank of
modules, using the following formula:
Module Bank Btuh Input =Cubic Feet Per Hour
NG Heating Value
2. Determine length of the header, which is typically de-
pendent on length of the bank of modules which it serv-
es. Use the “Length” column in Figure A2. In most cases,
the header is straight pipe only.
3. In Table B1, find appropriate pipe length in upper por-
tion of table under "Length of Pipe, Feet" heading.
4. Move down the column; match the cubic feet per hour
from Step 1. Higher capacity selection is acceptable.
5. Move across to the left-hand column "Nominal Iron
Pipe Size, Inches" and read required pipe size.
Gas Main (Natural Gas)
1. Determine the cubic feet of gas per hour for the total
heating plant, using the following formula:
Heating Plant Btuh Input =Cubic Feet Per Hour
NG Heating Value
2. Determine total equivalent length of gas main. Re-
member, if exact number/type of fittings are not known,
for initial determination only, add 20% for fittings to the
straight length of piping to get a total equivalent length.
3. In Table B1, find appropriate pipe length in upper por-
tion of table under "Length of Pipe, Feet" heading.
4. Move down the column; match the cubic feet per hour
from Step 1. Higher capacity selection is acceptable.
5. Moveacross to the left-hand column "Nominal Iron
Pipe Size,Inches" and read required pipe size.
6. Once a diameter has been selected, verify the total
equivalent length.
Maximum Capacity of Pipe in Cubic Feet of Natural Gas per Hour for Gas Pressures of
0.5 Psig or Less and a Pressure Drop of 0.3 Inch Water Column
(Based on a 0.60 Specific Gravity Gas)
Nominal
Iron Pipe
Size,
Inches
Internal
Diameter,
Inches
Length of Pipe, Feet
10
32
72
132
278
520
1,050
1,600
3,050
4,800
8,500
17,500
20
22
49
92
190
350
730
1,100
2,100
3,300
5,900
12,000
30
18
40
73
152
285
590
890
1,650
2,700
4,700
9,700
40
15
34
63
130
245
500
760
1,450
2,300
4,100
8,300
50
14
30
56
115
215
440
670
1,270
2,000
3,600
7,400
60
12
27
50
105
195
400
600
1,150
1,850
3,250
6,800
70
11
25
46
96
180
370
560
1,500
1,700
3,000
6,200
80
11
23
43
90
170
350
530
990
1,600
2,800
5,800
90
10
22
40
84
160
320
490
930
1,500
2,600
5,400
100
9
21
38
79
150
305
460
870
1,400
2,500
5,100
125
8
18
34
72
130
275
410
780
1,250
2,200
4,500
150
8
17
31
64
120
250
380
710
1,130
2,000
4,100
175
7
15
28
59
110
225
350
650
1,050
1,850
3,800
200
6
14
26
55
100
210
320
610
980
1,700
3,500
1/4"
3/8"
1/2"
3/4"
1"
1-1/4"
1-1/2"
2"
2-1/2"
3"
4"
.326
.493
.622
.824
1.049
1.380
1.610
2.067
2.469
3.026
4.026
TABLE B1