A.O. Smith Burkay HW-300 User manual

GAS FIRED COMMERCIAL COPPER BOILERS
Instruction Manual
PRINTED 0213 321078-002
Thank you for buying this energy efcient boiler.
We appreciate your condence in our products.
MODELS: HW
300, 399, 420, 520, 670
FOR HYDRONIC HEATING AND
HOT WATER SUPPLY
UP - FLOW MODELS
INSTALLATION - OPERATION
MAINTENANCE - LIMITED WARRANTY
INDOOR ONLY
25589, Highway 1
McBee, SC 29101
WARNING: If the information in these
instructions is not followed exactly, a fire
or explosion may result causing property
damage, personal injury or death.
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS:
Do not try to light any appliance.
Do not touch any electrical switch; do
not use any phone in your building.
Immediately call your gas supplier
from a neighbor’s phone. Follow the
gas supplier’s instructions.
If you cannot reach your gas supplier,
call the fire department.
Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.
•
•
•
•
H

2
System Connections ........................................................................ 16
Air Requirements ............................................................................. 16
Unconned Space ........................................................................... 16
Fresh Air Openings for Conned Spaces ........................................ 17
VENTING .............................................................................................. 21
Standard Venting ............................................................................. 21
Sidewall Venting .............................................................................. 22
Venting System ................................................................................ 22
GAS SUPPLY CONNECTIONS ........................................................... 24
Gas Manifold Pressure Regulators .................................................. 25
BOILER START UP AND OPERATIONS ............................................. 26
Filling the System ............................................................................ 26
Precautions ...................................................................................... 26
Pilot and Main Burner ...................................................................... 26
Checking and Adjusting Input .......................................................... 28
TROUBLESHOOTING ......................................................................... 32
GENERAL MAINTENANCE ................................................................. 40
Manual Reset High Limit Switch Continuity Test ............................. 40
Pressure Relief Valve Test ............................................................... 40
Cleaning and Flushing Instructions ................................................. 40
Venting Maintenance ....................................................................... 41
WIRING ................................................................................................ 42
Wiring Connections ......................................................................... 42
PIPING DIAGRAMS ............................................................................. 47
LIMITED WARRANTY .......................................................................... 61
TABLE OF CONTENTS
TABLE OF CONTENTS .......................................................................... 2
SAFE INSTALLATION, USE AND SERVICE.......................................... 3
GENERAL SAFETY................................................................................ 4
INTRODUCTION .................................................................................... 5
Abbreviations Used ........................................................................... 5
Qualications ..................................................................................... 5
DIMENSIONS AND CAPACITY DATA .................................................... 6
CONTROL COMPONENTS ................................................................... 8
BOILER INSTALLATION CONSIDERATIONS ..................................... 12
Hydronic System ............................................................................. 12
Hot Water Supply Boiler System - General Water Line Connections
......................................................................................................... 12
Closed Water Systems .................................................................... 13
Thermal Expansion .......................................................................... 13
Vent Valves ...................................................................................... 13
Manifold Headers ............................................................................ 13
Cooling Piping ................................................................................. 13
Circulating Pump ............................................................................. 13
GENERAL REQUIREMENTS .............................................................. 15
Required Ability ................................................................................ 15
Location ........................................................................................... 15
Replacing Existing Common Vented Boiler ..................................... 15
Chemical Vapor Corrosion ............................................................... 16
Installation Clearances .................................................................... 16
Leveling ........................................................................................... 16

3
The proper installation, use and servicing of this boiler is extremely important to your safety and the safety of others.
Many safety-related messages and instructions have been provided in this manual and on your boiler to warn you and others of
a potential injury hazard. Read and obey all safety messages and instructions throughout this manual. It is very important that the
meaning of each safety message is understood by you and others who install, use, or service this boiler.
DANGER indicates an imminently
hazardous situation which, if not avoided,
will result in injury or death.
This is the safety alert symbol. It is used to alert you to
potential personal injury hazards. Obey all safety
messages that follow this symbol to avoid possible
injury or death.
WARNING indicates a potentially hazardous
situation which, if not avoided, could result
in injury or death.
CAUTION indicates a potentially hazardous
situation which, if not avoided, could result in
minor or moderate injury.
CAUTION used without the safety alert
symbol indicates a potentially hazardous
situation which, if not avoided, could result in
property damage.
WARNING
CAUTION
CAUTION
DANGER
All safety messages will generally tell you about the type of hazard, what can happen if you do not follow the safety message, and
how to avoid the risk of injury.
The California Safe Drinking Water and Toxic Enforcement Act requires the Governor of California to publish a list of substances
known to the State of California to cause cancer, birth defects, or other reproductive harm, and requires businesses to warn of
potential exposure to such substances.
WARNING: This product contains a chemical known to the State of California to cause cancer, birth defects, or other reproductive
harm. This boiler can cause low level exposure to some of the substances listed in the Act.
IMPORTANT DEFINITIONS
Gas Supplier: The Natural Gas or Propane Utility or service who supplies gas for utilization by the gas burning appliances within
this application. The gas supplier typically has responsibility for the inspection and code approval of gas piping up to and including
the Natural Gas meter or Propane storage tank of a building. Many gas suppliers also offer service and inspection of appliances
within the building.
SAFE INSTALLATION, USE AND SERVICE
APPROVALS
H

4
GROUNDING INSTRUCTIONS
This boiler must be grounded in accordance with the National
Electrical Code, Canadian Electrical Code and/or local codes.
Boiler is polarity sensitive; correct wiring is imperative for proper
operation.
This boiler must be connected to a grounded metal, permanent
wiring system, or an equipment grounding conductor must be
run with the circuit conductors and connected to the equipment
grounding terminal or lead on the boiler.
CORRECT GAS
Make sure the gas on which the boiler will operate is the same as
that speci ed on the boiler rating plate. Do not install the boiler if
equipped for a different type of gas; con sult your supplier.
PRECAUTIONS
If the unit is exposed to the following, do not operate until
all corrective steps have been made by a qualied service
technician:
1. Exposure to re.
2. If damaged.
3. Firing without water.
4. Sooting.
If the boiler has been exposed to ooding, it must be replaced.
PROPANE OR LIQUEFIED PETROLEUM (LP) GAS
MODELS
Boilers for propane (LP) gas are different from natural gas models.
A natural gas boiler will not function safely on propane (LP) gas
and no attempt should be made to convert a boiler from natural
gas to propane (LP) gas.
Propane (LP) gas must be used with great caution. It is highly
explosive and heavier than air. It collects rst in the low areas
making its odor difcult to detect at nose level. If propane (LP)
gas is present or even suspected, do not attempt to nd the cause
yourself. Leave the building, leaving doors open to ventilate, then
call your gas supplier or service agent. Keep area clear until a
service call has been made.
At times you may not be able to smell an propane (LP) gas
leak. One cause is odor fade, which is a loss of the chemical
odorant that gives propane (LP) gas its distinctive smell. Another
cause can be your physical condition, such as having a cold or
diminishing sense of smell with age. For these reasons, the use
of a propane gas detector is recommended.
If you experience an out of gas situation, do not try to relight
boilers yourself. Call your local service agent. Only trained propane
(LP) professionals should conduct the required safety checks in
accordance with industry standards.
HIGH ALTITUDE INSTALLATIONS
Rated inputs are suitable up to 2000 feet (610 m) elevation.
Consult the factory for installation at altitudes over 2000 feet
(610 m).
GENERAL SAFETY

5
This design complies with the current edition of the ANSI Z21.13
low-pressure boiler standard.
Compliance under this standard implies that when the boiler
underwent test, the gas manifold and control assembly pro vided
on the boiler met safe lighting and other performance criteria.
Detailed installation diagrams are found in this manual. These
diagrams will serve to provide the installer a reference for the
materials and methods of piping necessary. It is essential that
all water, gas piping and wiring be installed as shown on the
diagrams. You should thoroughly read and understand this
manual before installation and/or operation of this boiler.
The factory warranty will be void if the boiler(s) have been
improperly installed or operated.
In addition to these instructions, the boiler(s) shall be installed
in accordance with those installation regulations in force in the
local area where the installation is to be made. These shall be
carefully followed in all cases. Authorities having jurisdiction
should be consulted before installations are made.
In the absence of local codes, the installation must comply
withthe current editions, as follows:
In the United States:
The National Fuel Gas Code, ANSI Z223.1/NFPA 54 and the
National Electric Code, NFPA 70.
In Canada:
Installation Code CAN/CSA B149.1 and Canadian Electrical
Code, CSA C22.1.
Thank you for purchasing this boiler. Properly installed and
maintained, it should give you years of trouble free service.
ABBREVIATIONS USED
Abbreviations found in this Instruction Manual include :
• ANSI - American National Standards Institute
• ASME - American Society of Mechanical Engineers
• NEC - National Electrical Code
• NFPA - National Fire Protection Association
• UL - Underwriters Laboratory
• CSA - Canadian Standards Association
INTRODUCTION
QUALIFICATIONS
QUALIFIED INSTALLER OR SERVICE AGENCY
Installation and service of this boiler requires ability equivalent
to that of a Qualied Agency, as dened by ANSI below. In the
eld involved. Installation skills such as plumbing, air supply,
venting, gas supply and electrical supply are required in addition
to electrical testing skills when performing service.
ANSI Z21.13 - CSA 4.9: “Qualied Agency” - “Any individual,
rm, corporation or company that either in person or through
a representative is engaged in and is responsible for (a) the
installation, testing or replacement of gas piping or (b) the
connection, installation, testing, repair or servicing of appliances
and equipment; that is experienced in such work; that is familiar
with all precautions required; and that has complied with all the
requirements of the authority having jurisdiction.”
If you are not qualied (as dened by ANSI above) and licensed
or certied as required by the authority having jurisdiction
to perform a given task do not attempt to perform any of the
procedures described in this manual. If you do not understand
the instructions given in this manual do not attempt to perform
any procedures outlined in this manual.

6
DIMENSIONS AND CAPACITY DATA
EXTRA OPENING
FOR THERMOMETER
AND PRESSURE
RELIEF VALVE
HW-520 AND
HW--670
DIMENSIONS IN INCHES
MODELS
HW-300 HW-399 HW-420 HW-520 HW-670
AOverall height 65 (1651) 57-1/8 (1451) 57-1/8 (1451) 68-5/16 (1735) 67-1/2 (1715)
BHeight to Top of Jacket 43-1/4 (1099) 45-1/8 (1146) 45-1/8 (1146) 56-1/4 (1429) 56-1/4 (1429)
CFloor to Center Line Water Inlet 36 (914) 38-3/4 (984) 38-3/4 (984) 46 (1168) 46 (1168)
DDiameter of Jacket 25-1/4 (641) 27 (686) 27 (686) 27 (686) 27 (686)
EFloor to Center Line Water Outlet 12 (305) 12 (305) 12 (305) 12 (305) 12 (305)
FDraft Diverter Outlet Diameter 8 (203) 10 (254) 10 (254) 10 (254) 12 (305)
GFloor to Center Line Gas Inlet 16-1/2 (419) 16-3/4 (425) 16-3/4 (425) 18 (457) 18 (457)
HOverall Depth 29-5/8 (753) 31-1/2 (800) 31-1/2 (800) 36-1/2 (927) 36-1/2 (927)
JSupport Height 9 (229) 9 (229) 9 (229) 9 (229) 9 (229)
KWidth of Control String (approx.) 14 (356) 14 (356) 14 (356) 11 (279) 11 (279)
LPipe Size of Water Inlet (NPT) 1-1/4 1-1/2 1-1/2 2 2
MPipe Size of Water Outlet (NPT) 1-1/4 1-1/2 1-1/2 2 2
NPipe Size of Gas Inlet (NPT) 3/4 3/4 111
PControl String Plus 1/2 Jacket Diameter (approx.) 26-5/8 (676) 27-1/2 (699) 27-1/2 (699) 24-1/2 (622) 24-1/2 (622)
SHorizontal Length between Water Inlet and Outlet 5-3/8 (137) 5-1/2 (140) 5-1/2 (140) 5-3/4 (146) 5-3/4 (146)
TControl String from Jacket 5 (127) 5 (127) 5 (127) 7 (178) 7 (178)
Approximate shipping weight lbs. (Kilograms) 250 (113) 301 (137) 301 (137) 381 (173) 381 (173)
NOTE: All dimensions in inches (millimeters) except pipe size which is NPT
BTU INPUT/OUTPUT
TEMPERATURE RISE AND PRESSURE DROP
20 DEG. F
RISE
30 DEG. F
RISE
40 DEG. F
RISE
MODELS INPUT RATING BTU/HR
NATURAL & PROPANE (LP) GAS
OUTPUT RATING BTU/HR
NATURAL & PROPANE (LP) GAS
GPM PD-FT
HEAD
GPM PD-FT
HEAD
GPM PD-FT
HEAD
HW 300 300,000 240,000 24 8 16 3 12 2
HW 399 399,000 319,200 32 16 21 7 16 5
HW 420 420,000 336,000 34 18 22 8 17 5.5
HW 520 520,000 416,000 42 12 28 5 21 4
HW 670 Nat 660,000 528,000 53 22 35 10 26 5.5
HW 670 Prop 670,000 536,000 54 22 36 10 27 5.5
TABLE 1. DIMENSIONS AND CAPACITY DATA
FIGURE 1. DIMENSIONS
TABLE 2. FLOW, HEAD AND TEMPERATURE RISE

7
TABLE 3. RECOVERY CAPACITIES
MODELS TYPE OF
GAS
INPUT °F 20 40 50 60 70 80
BTU/HR KW °C (11) (22) (28) (33) (39) (44)
HW 300
Natural
300,000 88
GPH 1,455 727 582 485 416 364
Propane LPH 5,506 2,753 2,202 1,835 1,573 1,377
HW 399
Natural
399,000 117
GPH 1,935 967 774 645 553 484
Propane LPH 7,323 3,662 2,929 2,441 2,092 1,831
HW 420
Natural
420,000 123
GPH 2,036 1,018 815 679 582 509
Propane LPH 7,708 3,854 3,083 2,569 2,202 1,927
HW 520
Natural
520,000 152
GPH 2,521 1,261 1,008 840 720 630
Propane LPH 9,544 4,772 3,818 3,181 2,727 2,386
HW 670 Natural 660,000 193
GPH 3,200 1,600 1,280 1,067 914 800
LPH 12,113 6,057 4,845 4,038 3,461 3,028
HW 670 Propane 670,000 196
GPH 3,248 1,624 1,299 1,083 928 812
LPH 12,297 6,148 4,919 4,099 3,513 3,074
ELECTRICAL REQUIREMENTS
MODELS SUPPLY VOLTAGE
(VOLTS)
FREQUENCY
(HZ)
CURRENT
(AMPS)
HW 300 120 60 12
HW 399 120 60 12
HW 420 120 60 12
HW 520 120 60 12
HW 670 120 60 12
TABLE 4. ELECTRICAL REQUIREMENTS

8
FIGURE 2. COMPONENT LOCATIONS
CONTROL COMPONENTS

9
THERMAL BALANCER
Figure 5 shows the internal wiring of the thermal balancer. The
device may be tested after disconnecting the four leads from
their respective terminals on the unit.
1. Apply a test light to the yellow and red leads.
• The lamp should light as the contact in this circuit is
normally closed when the resistor is cool.
2. Apply a light to the black and yellow leads.
• The lamp should not light as the contact in this circuit is
normally open when the resistor is cool.
3. Remove the test light.
4. Apply 120 volts to the white and red leads which power the
1900 ohm resistor. After a warming period the contacts of
the thermal balancer should operate.
5. Remove the test light.
6. Apply the test light as described in steps 1 and 2.
While the resistor is still warm the lamp indications should be the
opposite as described previously.
MANUAL RESET HIGH LIMIT
This boiler is equipped with a manual reset high limit switch,
located under the small cover on the side of the jacket, see
Figure 6. This device provides positive shutdown of the boiler
in the event of boiler or system malfunction. Should the surface
temperature of the copper tubing heat exchanger reach 250°F
(120°C), the high limit switch will activate, the gas control valve
will close, the pilot and main burners will be extinguished. If
the high limit switch should shut off unit, check the following
conditions:
• No water in boiler.
• Restricted water ow through the boiler.
• Improper wiring (boiler ring without circulating pump
operating).
• Pump failure.
After correcting failure condition remove the protector switch
cover and push the reset button. The high limit switch may be
reset after the coil surface cools to 6°F (3.3°C) below the trip
setting.
AUTO RESET HIGH LIMIT
The high limit is a safety device wired in series with the ignition
system. Set the high limit control to approximately 100°F above
the maximum designed system temperature. If the boiler outlet
water temperature should exceed the high limit setting, the main
gas control valve will close but the circulating pump will continue
to operate. Maximum adjustable setting is 115°C (239°F) cut-out
with a 30°C (86°F) to 250°C (482°F) adjustable differential, see
Figure 3.
INTERMITTENT IGNITION CONTROL MODULE
The Honeywell S-8600 control module contains the electronic
components of the system and also serves as a control wiring
system for the controls mounted on the boiler. The control
module performs the following functions:
1. Checks for safe-start by sensing for a false ame condition
on start-up.
2. Generates a potential of 15,000 volts for spark ignition of the
pilot burner.
3. Opens the pilot valve.
4. Discontinues ignition spark when the pilot flame is
established. The S-8600 control used on propane
gas models provides safety lockout if the pilot
fails to ignite within the pilot flame establishing
period. The S-8600 control used on natural gas
models continues trial for ignition until pilot flame
is established.
5. After proof of pilot ame, opens then main valve.
6. On a power loss, shuts the boiler down. When power is
restored it will begin a new ignition cycle.
7. On a loss of ame, shuts off main gas and starts trial for pilot
ignition.
Please refer to TROUBLESHOOTING SECTION for more
information.
FIGURE 3. AUTO RESET HIGH LIMIT
FIGURE 4. S-8600 INTERMITTENT IGNITION CONTROL
MODULE (IID)
FIGURE 5. THERMAL BALANCER
FIGURE 6. HIGH LIMIT SWITCH

10
PRESSURE RELIEF VALVE
An ASME rated pressure relief valve is furnished with the boiler.
A tting for the pressure relief valve is provided in the top of the
boiler. Never operate the heating elements without being certain
the boiler is lled with water and a properly sized pressure relief
valve is installed in the pressure relief valve opening provided.
The pressure rating of the pressure relief valve should be equal
to or less than the rated pressure capacity of any component
in the system including the boiler. Should the valve need to be
replaced, call the toll free phone number listed on the back of this
manual for further technical assistance.
A discharge pipe from the pressure relief valve should terminate
at an adequate oor drain. Do not thread, plug, or cap the end of
the drain line.
The Discharge Pipe:
• Shall not be smaller in size than the outlet pipe size of the
valve, or have any reducing couplings or other restrictions.
• Shall not be plugged or blocked.
• Shall not be exposed to freezing temperatures.
• Shall be of material listed for hot water distribution.
• Shall be installed so as to allow complete drainage of both
the pressure relief valve and the discharge pipe.
• Must terminate a maximum of six inches above a oor
drain or external to the building. In cold climates, it is
recommended that the discharge pipe be terminated at an
adequate drain inside the building.
• Shall not have any valve or other obstruction between the
pressure relief valve and the drain.
Once the boiler is installed and lled with water and the system
is pressurized, manually test the operation of the pressure relief
valve.
Explosion Hazard
Pressure Relief Valve must
comply with ASME code.
Properly sized Pressure Relief
Valve must be installed in
opening provided.
Can result in overheating and
excessive tank pressure.
Can cause serious injury or death.
Water Damage Hazard
Pressure Relief Valve discharge pipe must
terminate at adequate drain.
•
CAUTION
If any pressure relief valve is replaced, the replacement valve
must comply with the current editions of the ASME Boiler and
Pressure Vessel Code, Section IV or CSA B51, as applicable.
Select a pressure relief valve with a discharge NOT less than the
boiler input, and a pressure rating NOT exceeding the working
pressure of any component in the system.
A. O. Smith supplies a 125 psi pressure relief valve for hot water
supply systems and 50 psi pressure relief valve for space heating
application.
An ASME rated temperature and pressure relief valve must be
installed on each and every water storage tank in a hot water
supply system.
The storage tank temperature and pressure (T & P) relief valve
must comply with the applicable construction provisions of the
Standard for Relief valves and Automatic Gas Shutoff Devices
for Hot Water Supply Systems, Z21.22 - CSA 4.4. The T & P
valve must be of the automatic reset type and not embody a
single-use type of fusible plug, cartridge or linkage.
The T & P relief valve should have a maximum temperature
rating of 100°C (210°F), a pressure rating NOT exceeding the
lowest rated working pressure of any system component, and a
discharge capacity exceeding the total input of the water boilers
supplying water to the storage tank.
Locate the T & P relief valve (a) in the top of the storage tank or
(b) in the side of the tank on centerline within upper 6 inches from
the top of the tank. See Figure 29 to Figure 42 on Pages 47 to 60.
Tapping shall be threaded in accordance with the latest version
of the Standard for Pipe Threads, General Purpose (inch), ANSI/
ASME B.120.1.

11
USE ANTI-SCALD VALVE(S) in the hot water system to reduce
the risks of scalds at points of use such as lavatories, sinks and
bathing facilities.
A change in water temperature in the storage tank lower than the
Tank Temperature Control setting will cause the sensor to close
its contacts and consequently energize the boiler.
If the Tank Temperature Control is out of calibration, replace it
with a new one; do not attempt to x this control.
THERMOMETERS
Thermometers should be obtained and field installed as
shown in the installation diagrams.
Thermometers are installed in the system as a means of
detecting a possible liming condition in the boiler. An
increase of 5°F (3°C) over the normal temperature rise
through the boiler is an indication that lime is present. The
term "temperature" designates the difference between the
boiler inlet and outlet water temperature.
An increase of 5°F (3°C) above the recorded temperature
rise may signify a liming condition in the coils or heat
exchanger. Refer to Cleaning and Flushing Instructions on
Page 40 for deliming instructions.
Record temperature rise at initial start-up for future
reference.
DRAIN VALVE (NOT SUPPLIED)
A drain valve must be obtained and installed on each boiler
and tank for draining purposes.
TANK TEMPERATURE CONTROL
The water temperature in the storage tank is controlled by the
Tank Temperature Control. The sensing element is mounted
inside the hot water storage tank.
The tank temperature control is adjustable from 100°F (37.7°C)
to 220°F (104.4°C). It is recommended that lower water
temperatures be used to avoid the risk of scalding. It is further
recommended, in all cases, that the water temperature be set
for the lowest temperature which satises the user’s hot water
needs. This will also provide the most energy efcient operation
of the boiler and minimize scale formation.
The boiler should be located in an area where the general public
does not have access to set temperatures. Setting the water
temperature at 120°F (49°C) will reduce the risk of scalds.
Some people are more likely to be permanently injured by
hot water than others. These include the elderly, children, the
inrm and the physically/mentally disabled. Table 5 shows the
approximate time-to-burn relationship for normal adult skin. If
anyone using hot water provided by the boiler being installed ts
into one of these groups or if there is a local code or state law
requiring a certain water temperature at the point of use, then
special precautions must be taken. Contact a qualied service
technician or qualied agency.
Water Temperature
°F (°C)
Time for 1st Degree Burn
(Less Severe Burns)
Time for Permanent Burns
2nd & 3rd Degree
(Most Severe Burns)
110 (43) (normal shower temp.)
116 (47) (pain threshold)
116 (47) 35 minutes 45 minutes
122 (50) 1 minute 5 minutes
131 (55) 5 seconds 25 seconds
140 (60) 2 seconds 5 seconds
149 (65) 1 second 2 seconds
154 (68) instantaneous 1 second
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, Sept. 15, 1978)
Water temperature over 125°F (52°C)
can cause severe burns instantly
resulting in severe injury or death.
Children, the elderly and the
physically or mentally disabled are at
highest risk for scald injury.
Feel water before bathing or
showering.
Temperature limiting devices such as
mixing valves must be installed
when required by codes and to
ensure safe temperatures at fixtures.
TABLE 5. TEMPERATURE AND TIME TO PRODUCE BURNS

12
BOILER INSTALLATION CONSIDERATIONS
HYDRONIC SYSTEM
All modern hydronic type boilers are exceptionally fast heating
units. The low water volumes in relation to ring rates require
special attention to water ow rates for smooth, efcient
operation. These considerations for the A. O. Smith copper heat
exchanger boilers are covered below.
Conventional 20 ºF (10 ºC) drop in systems for a fully loaded
boiler will maintain the following approximate ow rates:
MODELS GPM (LPM)
HW-300 24 (91)
HW-399 32 (121)
HW-420 34 (127)
HW-520 42 (158)
HW-670 54 (203)
Figure 29 to Figure 42 on Pages 47 to 60 show typical installations
of the boiler with pipe sizing and circulating pump selected by the
installer to provide adequate water ow whenever the boiler is
ring.
In a system with several large zones of which any might be
smaller than approximately 1/3 of the system should include a
hydronic balancer as shown in the piping diagrams. The balancer
connects between the system supply and the return line before
the circulating pump inlet. Adjustment of the balancing cock
should permit adequate boiler ow rate when only the smallest
zone is in operation.
Attention should be given to balancing inputs and water ow
rates where wide variations of system ow rates can occur.
The recommended minimum ow rates that will result in
approximately 50 ºF (30 ºC) temperature rise across the boiler
are as follows:
MODELS GPM (LPM)
HW-300 10 (36)
HW-399 13 (49)
HW-420 13 (49)
HW-520 17 (63)
HW-670 21 (81)
Pipe sizing and boiler loop pump selection data are shown in
Table 8 for several different temperature rises across the boilers.
MODEL TEMP. RISE °F
(°C) GPM *PUMP SIZE
PIPE
SIZE
HW-300
20 (10)
30 (15)
30 (15)
40 (20)
24
16
16
12
1-1/2" PR
150
125
100
2"
1-1/2"
1-1/4"
1"
HW-399
20 (10)
35 (15)
40 (20)
40 (20)
32
18
16
16
60-13
1-1/2" HV
150
125
2"
1-1/2"
1-1/2"
1-1/4"
HW-420
20 (10)
35 (15)
40 (20)
40 (20)
34
19
17
17
60-13
1-1/2" HV
150
125
2"
1-1/2"
1-1/2"
1-1/4"
HW-520
20 (10)
20 (10)
35 (17)
40 (20)
42
42
24
21
2-1/2"
1-1/2" HV
1-1/2" HV
150
2-1/2"
2"
1-1/2"
1-1/2"
HW-670
20 (10)
30 (15)
35 (17)
40 (20)
54
36
31
27
60-13
2-1/2"
2"
1-1/2" HV
3"
2-1/2"
2"
1-1/2"
NOTE: Pipe loop sizes and pump selections based on 50
equivalent feet of pipe and ttings.
*All pump sizes listed are B & G model numbers.
HOT WATER SUPPLY BOILER SYSTEM - GENERAL
WATER LINE CONNECTIONS
Piping diagrams will serve to provide the installer with a
reference for the materials and methods of piping necessary for
installation. It is essential that all water piping be installed and
connected as shown on the diagrams. Check the diagrams to
be used thoroughly before starting installation to avoid possible
errors and to minimize time and material cost. It is essential that
all water piping be installed and connected as shown on the
diagrams. Figure 29 to Figure 42 on Pages 47 to 60.
These boilers can be used ONLY in a forced circulation hot water
heating system. Since most forced circulation systems will be of
the closed type, install the water supply line as shown on piping
diagrams, Fast lling of large pipe, old radiator installations and
pressure purging of series loop systems (where high pressures
are not available) requires bypassing of the pressure reducing
valve. Generally, pressure purging is not possible with a well
pump system. High point air venting is essential.
If the system is of the open type, a pressure reducing valve
will not be required as the water supply to the system will be
controlled by a manually operated valve. An overhead surge tank
is required.
TABLE 6. WATER FLOW RATES
TABLE 7. MINIMUM WATER FLOW RATES RESULTING IN
TEMPERATURE RISE
TABLE 8. PUMP AND PIPE SIZING DATA
(PIPING FROM TEES IN MAIN TO BOILER BRANCHES)

13
COOLING PIPING
When the boiler is used in conjunction with a refrigeration system
it must be installed so that the chilled medium is piped in parallel
with the boiler with appropriate valves to prevent the chilled
medium from entering the boiler, see Figure 7.
Water temperature in the heating system must be reduced to less
than 1000F (38°C) before cooling system is started, or damage to
the chiller unit may occur.
FIGURE 7. SCHEMATIC SHOWING PROPER PIPING
ISOLATION OF THE BOILER FROM THE CHILLER
If the boiler is connected to chilled water piping or its heating coils
are exposed to refrigerated air, the boiler piping system must be
equipped with ow valves or other automatic means to prevent
gravity circulation through the boiler during the cooling cycle.
CIRCULATING PUMP
Constant circulating pump operation of the boiler voids the
warranty. Constant water ow through the unit will “wash” away
the copper’s natural protective coating. This is called velocity
erosion. This erosion is not as great a problem when intermittent
circulating operation is used per the recommended installation
procedure. Constant circulation of water through the building’s
system main is permissible as long as the water does not
constantly ow through the boiler. Only all bronze or stainless
steel circulating pumps are to be used with the unit when it is
installed in hot water supply systems.
FIGURE 8. A TYPICAL CIRCULATING PUMP
Although each circulating pump that requires oiling is oiled and
operated by the manufacturer, It must be oiled again before
operated. See Figure 8 above.
Refer to the pump manufacturer’s instructions for lubrication
requirements.
CLOSED WATER SYSTEMS
Water supply systems may, because of code requirements
or such conditions as high line pressure, among others, have
installed devices such as pressure reducing valves, check
valves, and back ow preventers. Devices such as these cause
the water system to be a closed system.
THERMAL EXPANSION
As water is heated, it expands (thermal expansion). In a closed
system the volume of water will grow when it is heated. As the
volume of water grows there will be a corresponding increase
in water pressure due to thermal expansion. Thermal expansion
can cause premature tank failure (leakage). This type of failure
is not covered under the limited warranty. Thermal expansion
can also cause intermittent Temperature-Pressure Relief Valve
operation: water discharged from the valve due to excessive
pressure build up. This condition is not covered under the limited
warranty. The Temperature-Pressure Relief Valve is not intended
for the constant relief of thermal expansion.
A properly sized thermal expansion tank must be installed on
all closed systems to control the harmful effects of thermal
expansion. Contact a local plumbing service agency to have a
thermal expansion tank installed. An expansion tank or a similar
device may be required in the inlet supply line between the boiler
and the meter or valve to compensate for the thermal expansion
of water under supply pressure, see Piping Diagrams section on
Page 47.
An air separator as shown in the piping diagrams is recommended
especially for modern commercial hydronic systems.
VENT VALVES
It is recommended that automatic, loose key or screwdriver type
vent valves be installed at each convector or radiator.
MANIFOLD HEADERS
Split systems with individual supply and return lines from the boiler
room should normally have this piping connected to supply and
return manifold headers near the boiler. To achieve good water
distribution with maximum pressure drop for several circuits,
manifolds of at least 2-1/2" (64 mm) diameter are suggested on
HW-399, HW-420, HW-520 and HW-670 units. HW-300 units
should have 1-1/2" (38 mm) diameter manifolds.
The circuits should be spaced on the header at a minimum of
3" (76 mm) center to center. Install a balancing cock in each
return line.
Manifold headers are recommended for split systems with
or without zone valves and also those installations with zone
circulating pumps. If the system is to be split at remote points,
good practice requires special attention be given to main pipe
sizing to allow balancing of water ow.
The boiler piping system of a hot water boiler connected to
heating coils located in air handling units where they may be
exposed to refrigerated air circulation must be equipped with
ow control valves or other automatic means to prevent gravity
circulation of the boiler water during the cooling cycle.

14
FLOW SWITCH
The ow switch is a safety device which must be installed at the
water outlet of the unit to prevent main burner operation in the
event of inadequate water ow through the unit.
An accessory package containing a ow switch is available for
this application.
This switch may be mounted in a horizontal pipe line or a vertical
pipe line with upward water ow. Do not install the switch where
the water ow is downward.
For proper performance mount the switch in a section of pipe where
there is a straight run of at least 5 pipe diameters on each side
of the ow switch (i.e. do not locate adjacent to valves, elbows,
orices, etc.).
The ow switch shall be mounted in a standard 1-1/2" x 1-1/2"
x 1" tee for a 1-1/2" pipe application. For larger pipe sizes use
a reducing tee in order to keep the switch as close to the pipe
as possible. Install the ow switch in the branch (top) opening of
the reducing tee and provide adequate paddle length in the ow
stream. For example in a 2" pipe installation use a 2" x 2" x 1"
reducing tee. For 2", or 3" pipe use paddle segments as supplied.
For other pipe sizes (i.e. 1-1/4", 1-1/2" and 2-1/2") trim the paddle
to the proper pipe size, see Figure 9 below. If a standard tee is
used, install a face or hex bushing in the top opening. The paddle
must be adjusted or trimmed to the size of the pipe in which it will
be installed.
Any part of the paddle must not touch the pipe or any restrictions
in the pipe. Screw the ow switch in position so the at of the
paddle is at right angles to the ow. The arrow on the side case
must point in the direction of the ow.
Minimum Pipe Rate
Model Number
Contacts Closed
(Flow)
Contacts Open
(No Flow)
GPM LPM GPM LPM
HW-300 5.8 22.0 3.7 14.0
HW-399 7.5 28.4 5.0 18.9
HW-420 7.5 28.4 5.0 18.9
HW-520 13.7 51.9 9.5 36.0
HW-670 13.7 51.9 9.5 36.0
The ow switch may be eld adjusted to obtain higher minimum
ow rates than those shown inTable 9.
To adjust the ow rate setting:
1. Remove the ow switch cover.
2. For higher ow rate - turn the range adjusting screw
clockwise.
3. For lower ow rate-turn the range adjusting screw
counterclockwise.
The switch is factory set at approximately the minimum ow rate,
refer to Table 9. It must not be set lower than the factory setting
as this may result in the switch failing to return at a 'no ow'
condition.
4. Replace ow switch cover. Where units are installed in
multiples, each boiler must be individually protected by a ow
switch.
TABLE 9. FLOW SWITCH
FIGURE 9. FLOW SWITCH

15
GENERAL REQUIREMENTS
REQUIRED ABILITY
Installation or service of this boiler requires ability equivalent
to that of a qualied service technician in the eld involved.
Plumbing, air supply, venting, gas supply, and electrical work are
re quired.
LOCATION
When installing the boiler, consideration must be given to proper
location. The location selected should provide ade quate air
supply and be as centralized with the piping system as possible.
This location should also be such that the gas ignition system
components are protected from water dripping, spraying,
etc.) during boiler operation and service (circulating pump
replacement, control replacement, etc.).
Some local codes permit operation of gas appliances if installed 18
inches or more above the oor. This may reduce the risk if location in
such an area cannot be avoided.
A hot water boiler installed above radiation level or as required by
the authority having jurisdiction, must be provided with a low water
cutoff device at the time of boiler installation.
REPLACING EXISTING COMMON VENTED BOILER
When an existing boiler is removed from a common venting
system, the common venting system is likely to be too large
for proper venting of the appliances remaining connected to it.
At the time of removal of an existing boiler, the following steps
shall be followed with each appliance remaining connected to
the common venting system placed in operation, while the other
appliances remaining connected to the common venting system
are not in operation.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and
horizontal pitch and determine there is no blockage or
restriction, leakage, corrosion and other deciencies which
could cause an unsafe condition.
3. Insofar as is practical, close all building doors and windows
and all doors between the space in which the appliances
remaining connected to the common venting system are
located and other spaces of the building. Turn on clothes
dryers and any appliance not connected to the common
venting system. Turn on any exhaust fans, such as range
hoods and bathroom exhausts, so they will operate at
maximum speed. Do not operate a summer exhaust fan.
Close replace dampers.
4. Place in operation the appliance being inspected. Follow
the lighting instructions. Adjust thermostat so appliance will
operate continuously.
5. Test for spillage at the draft hood relief opening after 5
minutes of main burner operation. Use the ame of a match
or candle, or smoke from a cigarette, cigar or pipe.
6. After it has been determined that each appliance remaining
connected to the common venting system properly vents
when tested as outlined above, return doors, windows,
exhaust fans, replace dampers and any other gas-burning
appliance to their previous condition of use.
7. Any improper operation of the common venting system should
be corrected so the installation conforms with the National
Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CSA B149.1,
Installation Codes. When resizing any portion of the common
venting system, the common venting system should be
resized to approach the minimum size as determined using
the appropriate tables in the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and/or CSA B149 .1, Installation Codes.

16
AIR REQUIREMENTS
For safe operation an adequate supply of fresh uncontaminated
air for combustion and ventilation must be provided.
An insufcient supply of air can cause recirculation of combustion
products resulting in contamination that may be hazardous to
life. Such a condition often will result in a yellow, luminous burner
ame, causing sooting of the combustion chamber, burners and
ue tubes and creates a risk of asphyxiation.
Do not install the boiler in a conned space unless an adequate
supply of air for combustion and ventilation is brought in to that
space using the methods described in the Conned Space
section that follows.
Never obstruct the ow of ventilation air. If you have any doubts
or questions at all, call your gas supplier. Failure to provide the
proper amount of combustion air can result in a re or explosion
and cause property damage, serious bodily injury or death.
UNCONFINED SPACE
An unconned space is one whose volume is not less than 50
cubic feet per 1,000 Btu/hr (4.8 cubic meters per kW) of the
total input rating of all appliances installed in the space. Rooms
communicating directly with the space, in which the appliances
are installed, through openings not furnished with doors, are
considered a part of the unconned space.
Makeup air requirements for the operation of exhaust fans,
kitchen ventilation systems, clothes dryers and replaces shall
also be considered in determining the adequacy of a space to
provide combustion, ventilation and dilution air.
UNUSUALLY TIGHT CONSTRUCTION
In unconned spaces in buildings, inltration may be adequate
to provide air for combustion, ventilation and dilution of ue
gases. However, in buildings of unusually tight construction (for
example, weather stripping, heavily insulated, caulked, vapor
barrier, etc.) additional air must be provided using the methods
described in the Conned Space section that follows.
Breathing Hazard - Carbon Monoxide Gas
Install appliance in accordance with
the Instruction Manual and NFPA 54 or
CAN/CSA-B149.1.
To avoid injury, combustion and ventilation
air must be taken from outdoors.
Do not place chemical vapor emitting
products near the boiler.
Breathing carbon monoxide can cause brain damage or
death. Always read and understand instruction manual.
CHEMICAL VAPOR CORROSION
Boiler corrosion and component failure can be caused by the
heating and breakdown of airborne chemical vapors. Spray can
propellants, cleaning sol vents, refrigerator and air conditioning
refrig erants, swimming pool chemicals, calcium and sodium
chloride (water softener salt), waxes, and process chemicals
are typical compounds which are potentially corrosive. These
materials are corrosive at very low concentration levels with little
or no odor to reveal their presence.
Products of this sort should not be stored near boiler. Also, air
which is brought in contact with boiler should not contain any
of these chemicals. If necessary, uncontaminated air should be
obtained from remote or outside sources. Failure to observe this
requirement will void warranty.
INSTALLATION CLEARANCES
These boilers are approved for installation on combustible
ooring in an alcove with minimum clearance to combustibles of:
HW
300
HW
399
HW
420
HW
520
HW
670
TOP 28" (711.2) 28" (711.2) 24" (609.6) 24" (609.6) 24" (609.6)
SIDES 6" (152.4) 6" (152.4) 24" (609.6) 24" (609.6) 24" (609.6)
REAR 6" (152.4) 6" (152.4) 24" (609.6) 24" (609.6) 24" (609.6)
VENT 6" (152.4) 6" (152.4) 6" (152.4) 6" (152.4) 6" (152.4)
2 inches (51 mm) clearance is allowable from combustible
construction for hot water pipes.
Sufcient area should be provided at the front and rear of the unit for
proper servicing. Clearances of 24 inches (609.4 mm) in the rear and
48 inches (1,219 mm) in the front are required by code. In a utility
room installation, the door shall be wide enough to allow the boiler
to enter or to permit the replacement of another appliance such as
a boiler.
LEVELING
Each unit should be checked after installation to be certain that it
is level prior to starting the unit.
If the unit is not level, obtain and insert shims under the legs of
the unit to correct this condition.
SYSTEM CONNECTIONS
The system installation must conform to these instructions and to
the requirements of the local code authority having jurisdiction. Good
practice requires that all heavy piping be supported.
TABLE 10. INSTALLATION CLEARANCES

17
CONFINED SPACE
A conned space is one whose volume is less than 50 cubic
feet per 1,000 Btu/hr (4.8 cubic meters per kW) of the total input
rating of all appliances installed in the space.
Openings must be installed to provide fresh air for combustion,
ventilation and dilution in conned spaces. The required size for
the openings is dependent on the method used to provide fresh
air to the conned space and the total Btu/hr input rating of all
appliances installed in the space.
DIRECT VENT BOILERS
Boilers installed in a direct vent conguration that derive all air
for combustion from the outdoor atmosphere through sealed
intake air piping are not factored in the total boiler input Btu/hr
calculations used to determine the size of openings providing
fresh air into conned spaces.
EXHAUST FANS
Where exhaust fans are installed, additional air shall be provided
to replace the exhausted air. When an exhaust fan is installed
in the same space with a boiler, sufcient openings to provide
fresh air must be provided that accommodate the requirements
for all appliances in the room and the exhaust fan. Undersized
openings will cause air to be drawn into the room through the
boiler’s vent system causing poor combustion. Sooting, serious
damage to the boiler and the risk of re or explosion may result.
It can also create a risk of asphyxiation.
LOUVERS AND GRILLES
The free areas of the fresh air openings in the instructions that
follow do not take in to account the presence of louvers, grilles or
screens in the openings.
The required size of openings for combustion, ventilation and
dilution air shall be based on the “net free area” of each opening.
Where the free area through a design of louver or grille or screen
is known, it shall be used in calculating the size of opening
required to provide the free area specied. Where the louver and
grille design and free area are not known, it shall be assumed
that wood louvers will have 25% free area and metal louvers and
grilles will have 75% free area. Non motorized louvers and grilles
shall be xed in the open position.
FRESH AIR OPENINGS FOR CONFINED SPACES
The following instructions shall be used to calculate the size,
number and placement of openings providing fresh air for
combustion, ventilation and dilution in conned spaces. The
illustrations shown in this section of the manual are a reference
for the openings that provide fresh air into conned spaces
only. Do not refer to these illustrations for the purpose of vent
installation. See Venting section on Page 21 for complete venting
installation instructions.
OUTDOOR AIR THROUGH TWO OPENINGS
The conned space shall be provided with two permanent
openings, one commencing within 12 inches (300 mm) of the top
and one commencing within 12 inches (300 mm) of the bottom of
the enclosure. The openings shall communicate directly with the
outdoors. See Figure 10.
Each opening shall have a minimum free area of 1 square inch
per 4,000 Btu/hr (550 mm2 per kW) of the aggregate input rating
of all appliances installed in the enclosure. Each opening shall
not be less than 100 square inches (645 cm2).
OUTDOOR AIR THROUGH ONE OPENING
Alternatively a single permanent opening, commencing within 12
inches (300 mm) of the top of the enclosure, shall be provided.
See Figure 11. The boiler shall have clearances of at least 1
inch (25 mm) from the sides and back and 6 inches (150 mm)
from the front of the appliance. The opening shall directly
communicate with the outdoors or shall communicate through
a vertical or horizontal duct to the outdoors or spaces that freely
communicate with the outdoors and shall have a minimum free
area of the following:
1. 1 square inch per 3000 Btu/hr (700 mm2 per kW) of the total
input rating of all appliances located in the enclosure, and
2. Not less than the sum of the areas of all vent connectors in
the space.
FIGURE 10. OUTDOOR AIR THROUGH TWO OPENINGS
FIGURE 11. OUTDOOR AIR THROUGH ONE OPENING

18
The conned space shall be provided with two permanent vertical
ducts, one commencing within 12 inches (300 mm) of the top and
one commencing within 12 inches (300 mm) of the bottom of the
enclosure. The vertical ducts shall communicate directly with the
outdoors. See Figure 13.
Each duct opening shall have a minimum free area of 1 square
inch per 4,000 Btu/hr (550 mm2 per kW) of the aggregate input
rating of all appliances installed in the enclosure.
When ducts are used, they shall be of the same cross sectional
area as the free area of the openings to which they connect.
The minimum dimension of rectangular air ducts shall be not less
than 3 inches.
AIR FROM OTHER INDOOR SPACES
The conned space shall be provided with two permanent
openings, one commencing within 12 inches (300 mm) of the top
and one commencing within 12 inches (300 mm) of the bottom of
the enclosure. See Figure 14.
Each opening shall communicate directly with an additional
room(s) of sufcient volume so that the combined volume of all
spaces meets the criteria for an Unconned Space.
Each opening shall have a minimum free area of 1 square inch
per 1,000 Btu/hr (1100 mm2 per kW) of the aggregate input rating
of all appliances installed in the enclosure. Each opening shall
not be less than 100 square inches (645 cm2).
OUTDOOR AIR THROUGH TWO HORIZONTAL DUCTS
The conned space shall be provided with two permanent
horizontal ducts, one commencing within 12 inches (300 mm) of
the top and one commencing within 12 inches (300 mm) of the
bottom of the enclosure. The horizontal ducts shall communicate
directly with the outdoors. See Figure 12.
Each duct opening shall have a minimum free area of 1 square
inch per 2,000 Btu/hr (1100 mm2 per kW) of the aggregate input
rating of all appliances installed in the enclosure.
When ducts are used, they shall be of the same cross sectional
area as the free area of the openings to which they connect.
The minimum dimension of rectangular air ducts shall be not less
than 3 inches.
OUTDOOR AIR THROUGH TWO VERTICAL DUCTS
The illustrations shown in this section of the manual are a
reference for the openings that provide fresh air into conned
spaces only.
Do not refer to these illustrations for the purpose of vent
installation.
FIGURE 12. OUTDOOR AIR THROUGH TWO HORIZONTAL
DUCTS
FIGURE 13. OUTDOOR AIR THROUGH TWO VERTICAL
DUCTS
FIGURE 14. AIR FROM OTHER INDOOR SPACES

19
Fittings and unions in gas line must be of metal to metal type.
Apply joint compounds (pipe dope) sparingly and only to the
male threads of pipe joints. Do not apply compound to the rst
two threads. Use compounds resistant to the action of liqueed
petroleum gases. The boiler and its gas connection must be leak
tested before placing the boiler in operation.
SIZING GAS SUPPLY LINE (FOR SINGLE BOILER
INSTALLATIONS AND FOR INSTALLATIONS OF MULTIPLES
OF TWO OR THREE OF SAME SIZE BOILERS).
Use Table 11 or CAN/CSA B149.1 (current edition) to size
iron pipe or equivalent gas supply line. Table 11 is based on a
pressure drop of 0.3 inches of water and a specic gravity of 0.60
approximately that of natural gas. (Propane (LP) gas has an S.G.
of about 1.53). If the service pressure is ve inches water column
or less, use one pipe size larger in order to minimize pressure
drop in the line.
Distance
from Gas
Meter
Nominal Iron Pipe Size (Inches)
1/2 3/4 1 1 1/4 1 1/2 22 1/2 3 4
10 (3) 132 278 520 1,050 1,600 3,050 4,800 8,500 17,500
20 (6) 92 190 350 730 1,100 2,100 3,300 5,900 12,000
30 (9) 73 152 285 590 890 1,650 2,700 4,700 9,700
40(12) 63 130 245 500 760 1,450 2,300 4,100 8,300
50 (15) 56 115 215 440 670 1,270 2,000 3,600 7,400
60 (18) 50 105 195 400 610 1,150 1,850 3,250 6,800
70 (21) 46 96 180 370 560 1,050 1,700 3,000 6,200
80 (24) 43 90 170 350 530 990 1,600 2,800 5,800
90 (27) 40 84 160 320 490 930 1,500 2,600 5,400
100 (30) 38 79 150 305 460 870 1,400 2,500 5,100
125 (38) 34 72 130 275 410 780 1,250 2,200 4,500
150 (45) 31 64 120 250 380 710 1,130 2,000 4,100
175 (53) 28 59 110 225 350 650 1,050 1,850 3,800
200 (60) 26 55 100 210 320 610 980 1,700 3,500
*The heating value of Natural Gas is approximately 1,050 Btu/Ft.3.
Propane (LP) Gas has a heating value of approximately 2,500 Btu/Ft3.
1 cu. meter=35.31 cu. feet.
Where it is necessary to use more than the average number of
pipe ttings i.e. elbows, tees, and valves in gas supply line, use a
pipe larger than specied to compensate for increased pressure
drop.
GAS CONNECTIONS
Make sure the gas on which boiler is to operate is same as that
specied on the rating plate. Do not install boiler if equipped for
a different type of gas. Consult your gas supplier.
This boiler is not intended to operate at gas supply pressure
other than shown on the rating plate. A lock-up or positive shut-
off type regulator must be installed in gas supply line. For proper
gas regulation the lock-up style regulators must be installed no
closer than a minimum of 3 feet from the boiler and a maximum
of 8 feet away from the boiler. Exposure to higher gas supply
pressure may cause damage to gas control valves which can
result in re or explosion. If overpressure has occurred such as
through improper testing of gas lines or emergency malfunction
of supply system, the gas control valves must be checked for safe
operation. Make sure that the outside vents on supply regulators
and the safety vent valves are protected against blockage. These
are parts of the gas supply system, not boiler. Vent blockage may
occur during ice build-up or snowstorms.
The boiler must be isolated from the gas supply piping system by
closing its main manual gas shut off valve during any pressure
testing of the gas supply piping system at test pressures equal
to or less than 1/2 psig.
Disconnect the boiler and its main manual gas shut-off valve
from the gas supply piping during any pressure testing of the gas
supply system over 1/2 psig. The gas supply line must be capped
when not connected to the boiler.
It is important to guard against gas control valve fouling from
contaminants in the gas ways. Such fouling may cause improper
operation, re or explosion. If copper supply lines are used they
must be approved for gas service.
When local codes require a main manual shut-off valve outside
the boiler jacket, a suitable main manual shut-off valve must be
installed in a location complying with those codes.
Before attaching gas line be sure that all gas pipe is clean
on inside. To trap any dirt or foreign material in the gas supply
line, a sediment trap must be incorporated in piping. The
sediment trap must be readily accessible and not subject to
freezing conditions. Install in accordance with recommendations
of serving gas supplier. Refer to the current edition of the National
Fuel Gas Code, ANSI Z223.1/NFPA 54 or the Natural Gas and
Propane Installation Code, CAN/CSA B149.1
Size of gas supply piping may be larger than heater connection
on installations where a signicant run of piping is required.
To prevent damage, care must be taken not to apply too much
torque when attaching gas supply pipe to boiler gas inlet. When
installing and tightening gas piping use a second wrench to hold
the gas control valve to keep the valve from turning. To prevent
damage to the gas control valve do not use pipe wrench on the
valve body.
TABLE 11.
MAXIMUM CAPACITY OF PIPE IN CUBIC FEET OF GAS
PER HOUR (BASED UPON A PRESSURE DROP OF 0.3
INCH WATER COLUMN AND 0.6 SPECIFIC GRAVITY GAS)

20
TABLE 12. SUGGESTED PIPE SIZE FOR MULTIPLE GAS APPLIANCES (NATURAL GAS)
Nominal Maximum Capacity of Pipe in BTU/hr and kW for Gas Pressures of 14 in. W.C. (0.5 psi) or Less and
Iron Pipe a Pressure Drop of 0.5 in. W.C. (based on 0.60 Specic Gravity Gas w/Heating Value of 1,000 BTU’s/Ft3) Size Length of Pipe in Feet (Meters) (Inches) 10 (3.05) 20 (6.1) 30 (9.14) 40 (12.19) 50 (15.24) 60 (18.29) 70 (21.34) 80 (24.38) 90 (27.43) 100 (30.48) 125 (38.1) 150 175 200
1 1/2 BTU/hr 2,100,000 1,460,000 1,180,000 990,000 900,000 810,000 750,000 690,000 650,000 620,000 550,000 500,000 460,000 —
kW 615 428 346 290 264 237 220 202 190 182 161 146 135 —
2 BTU/hr 3,950,000 2,750,000 2,200,000 1,900,000 1,680,000 1,520,000 1,400,000 1,300,000 1,220,000 1,150,000 1,020,000 950,000 850,000 800,000
kW 1,157 805 644 556 492 445 410 381 357 337 299 278 249 234
2 1/2 BTU/hr 6,300,000 4,350,000 3,520,000 3,000,000 2,650,000 2,400,000 2,250,000 2,050,000 1,950,000 1,850,000 1,650,000 1,500,000 1,370,000 1,280,000
kW 1,845 1,274 1,031 879 776 703 659 600 571 542 483 439 401 375
3 BTU/hr 11,000,000 7,700,000 6,250,000 5,300,000 4,750,000 4,300,000 3,900,000 3,700,000 3,450,000 3,250,000 2,950,000 2,650,000 2,450,000 2,280,000
kW 3,222 2,255 1,830 1,552 1,391 1,259 1,142 1,084 1,010 952 864 776 718 668
4 BTU/hr 23,000,000 15,800,000 12,800,000 10,900,000 9,700,000 8,800,000 8,100,000 7,500,000 7,200,000 6,700,000 6,000,000 5,500,000 5,000,000 4,600,000
kW 6,736 4,627 3,749 3,192 2,841 2,577 2,372 2,197 2,109 1,962 1,757 1,611 1,464 1,347
TABLE 13. SUGGESTED PIPE SIZE FOR MULTIPLE GAS APPLIANCES (PROPANE GAS)
Nominal Maximum Capacity of Pipe in BTU/hr and kW for Gas Pressures of 14 in. W.C. (0.5 psi) or Less and
Iron Pipe a Pressure Drop of 0.5 in. W.C. (based on 0.60 Specic Gravity Gas w/Heating Value of 1,000 BTU’s/Ft3) Size Length of Pipe in Feet (Meters) (Inches) 10 (3.05) 20 (6.1) 30 (9.14) 40 (12.19) 50 (15.24) 60 (18.29) 70 (21.34) 80 (24.38) 90 (27.43) 100 (30.48) 125 (38.1) 150 175 200
1 1/2 BTU/hr 3,276,000 2,277,600 1,840,800 1,544,400 1,404,000 1,263,600 1,170,000 1,076,400 1,014,000 967,200 858,000 780,000 717,600 670,800
kW 959 667 539 452 411 370 343 315 297 283 251 228 210 196
2 BTU/hr 6,162,000 4,290,000 3,432,000 2,964,000 2,620,800 2,371,200 2,184,000 2,028,000 1,903,200 1,794,000 1,591,200 1,482,000 1,326,000 1,248,000
kW 1,805 1,256 1,005 868 768 694 640 594 557 525 466 434 388 366
2 1/2 BTU/hr 9,828,000 6,786,000 5,491,200 4,680,000 4,134,000 3,744,000 3,510,000 3,198,000 3,042,000 2,886,000 2,574,000 2,340,000 2,137,200 1,999,800
kW 2,878 1,987 1,608 1,371 1,211 1,097 1,028 937 891 845 754 685 626 585 3 BTU/hr 17,160,000 12,012,000 9,750,000 8,268,000 7,410,000 6,708,000 6,084,000 5,772,000 5,382,000 5,070,000 4,602,000 4,134,000 3,822,000 3,556,800
kW 5,026 3,518 2,856 2,421 2,170 1,965 1,782 1,690 1,576 1,485 1,348 1,211 1,119 1,042
4 BTU/hr 35,880,000 24,648,000 19,968,000 17,004,000 15,132,000 13,728,000 12,636,000 11,700,000 11,232,000 10,452,000 9,360,000 8,580,000 7,800,000 7,176,000
kW 10,508 7,219 5,848 4,980 4,432 4,021 3,701 3,427 3,290 3,061 2,741 2,513 2,284 2,102