State GS6 75 YRVIT User Manual
RESIDENTIAL GAS WATER HEATERS
500 Tennessee Waltz Parkway,
Ashland City, TN 37015
www.statewaterheaters.com
Instruction Manual
GAS MODELS POWER VENT GS675YRVIT AND GS675HRVIT
WITH HOT SURFACE IGNITION
Thank you for buying this energy efficient water heater. We
appreciate your condence in our products.
You should thoroughly read this manual before installation and/
or operation of this water heater. Please pay particular attention
to the important safety and operating instructions as well as the
WARNINGS and CAUTIONS.
• For Your Safety •
AN ODORANT IS ADDED TO THE GAS USED
BY THIS WATER HEATER.
ALL TECHNICAL AND WARRANTY QUESTIONS: SHOULD BE DIRECTED TO THE LOCAL DEALER FROM WHOM THE WATER HEATER WAS
PURCHASED. IF YOU ARE UNSUCCESSFUL, PLEASE WRITE TO THE COMPANY LISTED ON THE RATING PLATE ON THE WATER HEATER.
KEEP THIS MANUAL IN THE POCKET ON HEATER FOR FUTURE REFERENCE
PRINTED 1112 197218-005
WHENEVER MAINTENANCE ADJUSTMENT OR SERVICE IS REQUIRED.
1
SAFE INSTALLATION, USE AND SERVICE
Your safety and the safety of others is extremely important in the installation, use and servicing of this water heater.
Many safety-related messages and instructions have been provided in this manual and on your own water heater 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 water heater.
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 appliance can cause low level exposure to some of the substances listed in the Act.
IMPORTANT DEFINITIONS
• Qualied Installer: A qualied installer must have ability equivalent to a licensed tradesman in the elds of plumbing,
air supply, venting and gas supply, including a thorough understanding of the requirements of the National Fuel Gas
Code as it relates to the installation of gas red water heaters. The qualied installer must also be familiar with the
design features of water heaters, and have a thorough understanding of this instruction manual.
• Service Agency: A service agency also must have ability equivalent to a licensed tradesman in the elds of plumbing,
air supply, venting and gas supply, including a thorough understanding of the requirements of the National Fuel Gas
Code as it relates to the installation of gas red water heaters. The service agency must also have a thorough
understanding of this instruction manual, and be able to perform repairs strictly in accordance with the service guidelines
provided by the manufacturer.
• 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.
2
GENERAL SAFETY
3
GENERAL SAFETY
4
TABLE OF CONTENTS
SAFE INSTALLATION, USE AND SERVICE.........................................2
GENERAL SAFETY...............................................................................3
TABLE OF CONTENTS .........................................................................5
INTRODUCTION ................................................................................... 5
Preparing for the Installation .............................................................5
TYPICAL INSTALLATION ......................................................................7
Replacement Parts and Deliming Products ....................................... 7
TYPICAL INSTALLATION ......................................................................8
Mixing Valve Usage ...........................................................................8
Facts to Consider About the Location ...............................................9
LOCATING THE NEW WATER HEATER .............................................. 9
Insulation Blankets ..........................................................................10
Combustion Air and Ventilation for Appliances Located in Unconned
Spaces ............................................................................................10
Combustion Air and Ventilation for Appliances Located in Conned
Spaces ............................................................................................10
INSTALLING THE NEW WATER HEATER .........................................12
Chemical Vapor Corrosion ...............................................................12
Water Piping ....................................................................................12
Closed Water Systems ....................................................................12
Thermal Expansion .........................................................................12
Temperature-Pressure Relief Valve ................................................. 13
Gas Piping ....................................................................................... 14
Sediment Traps ...............................................................................15
Filling the Water Heater ...................................................................15
Venting ............................................................................................15
Vent Pipe Termination ......................................................................15
Planning the Vent System ...............................................................16
Condensate ..................................................................................... 17
Blower Assembly Installation ...........................................................17
Installation of Vent System ..............................................................18
Vent Terminal Installation, Sidewall ................................................. 18
Installation of Vent System, Sidewall ...............................................20
Installation of Vertical Vent System .................................................20
Vent Pipe Preparation .....................................................................21
TEMPERATURE REGULATION ......................................................... 24
FOR YOUR INFORMATION ................................................................ 25
Start Up Conditions .........................................................................25
PERIODIC MAINTENANCE ................................................................ 26
Venting System Inspection ..............................................................26
Burner Operation and Inspection ....................................................26
Burner Cleaning ..............................................................................26
Housekeeping .................................................................................26
Anode Rod Inspection ..................................................................... 27
Temperature-Pressure Relief Valve Operation ................................ 27
Draining and Flushing .....................................................................28
Drain Valve Washer Replacement for Selected Models with Plastic
Drain Valves ....................................................................................28
Service ............................................................................................28
LEAKAGE CHECKPOINTS ................................................................. 29
REPAIR PARTS LIST .......................................................................... 30
TROUBLESHOOTING GUIDELINES ..................................................31
Trouble Shooting .............................................................................31
TROUBLESHOOTING GUIDELINES ..................................................33
NOTES: ............................................................................................... 34
LIMITED RESIDENTIAL GAS WARRANTY ........................................ 35
INTRODUCTION
Thank You for purchasing this water heater. Properly installed and
maintained, it should give you years of trouble free service.
Abbreviations Found In This Instruction Manual:
• ANSI - American National Standards Institute
• NFPA - National Fire Protection Association
• ASME - American Society of Mechanical Engineers
• AHRI - Air-Conditioning, Heating and Refrigeration Institute
• UL - Underwriters Laboratories Inc.
• CSA - Canadian Standards Association
This gas-red water heater is design certied by Underwriters
Laboratories Inc. under American National Standard for Gas Water
Heaters ANSI Z21.10.3 (current edition).
PREPARING FOR THE INSTALLATION
1. Read the “General Safety” section, page 3 and 4 of this manual
rst
and then the entire manual carefully. If you don’t follow the
safety rules, the water heater will not operate properly. It could cause
DEATH, SERIOUS BODILY INJURY AND/OR PROPERTY DAMAGE.
This manual contains instructions for the installation, operation,
and maintenance of the gas-red water heater. It also contains
warnings throughout the manual that you must read and be aware
of. All warnings and all instructions are essential to the proper
operation of the water heater and your safety. Since we cannot put
everything on the rst few
BEFORE ATTEMPTING TO INSTALL OR OPERATE THE
WATER HEATER.
pages, READ THE ENTIRE MANUAL
2. The installation must conform with these instructions and the local
code authority having jurisdiction. In the absence of local codes,
installations should comply with the National Fuel Gas Code (ANSI
Z223.1/NFPA 54) and the National Electrical Code (NFPA 70).
These publications are available from The National Fire Protection
Association, 1 Batterymarch Park, Quincy, MA 02269.
3. The water heater when installed must be grounded in accordance
with the local codes, or in the absence of local codes: the National
Electrical Code (NFPA 70).
4. If after reading this manual you have any questions or do not
understand any portion of the instructions, call the local gas utility
or the manufacturer whose name appears on the rating plate.
5. Carefully plan the place where you are going to put the water
heater. Correct combustion, vent action, and vent pipe installation
are very important in preventing death from possible carbon
monoxide poisoning and res, see Figures 1 and 2.
Examine the location to ensure the water heater complies with
the “Locating the New Water Heater” section in this manual.
6. For California installation this water heater must be braced,
anchored, or strapped to avoid falling or moving during an
earthquake. See instructions for correct installation procedures.
Instructions may be obtained from California Ofce of the State
Architect, 400 P Street, Sacramento, CA 95814.
7. Massachusetts Code requires this water heater to be installed in
accordance with Massachusetts 248-CMR 2.00: State Plumbing
Code and 248-CMR 5.00. For more information see next page.
5
INSTALLATION REQUIREMENTS FOR THE COMMONWEALTH OF MASSACHUSETTS
For all side wall terminated, horizontally vented power vent, direct vent, and power direct vent gas fueled water heaters installed
in every dwelling, building or structure used in whole or in part for residential purposes, including those owned or operated by
the Commonwealth and where the side wall exhaust vent termination is less than seven (7) feet above nished grade in the
area of the venting, including but not limited to decks and porches, the following requirements should be satised:
INSTALLATION OF CARBON MONOXIDE DETECTORS At the time of installation of the side wall horizontal vented gas fueled equipment, the installing plumber or gastter should observe that a hard wired carbon monoxide detector with an alarm
and battery back-up is installed on the oor level where the gas equipment is to be installed. In addition, the installing plumber
or gastter should observe that a battery operated or hard wired carbon monoxide detector with an alarm is installed on each
additional level of the dwelling, building or structure served by the sidewall horizontal vented gas fueled equipment. It should
be the responsibility of the property owner to secure the services of qualied licensed professionals for the installation of hard
wired carbon monoxide detectors.
In the event that the side wall horizontally vented gas fueled equipment is installed in a crawl space or an attic, the hard wired
carbon monoxide detector with alarm and battery back-up may be installed on the next adjacent oor level.
In the event that the requirements of this subdivision can not be met at the time of completion of installation, the owner should
have a period of thirty (30) days to comply with the above requirements provided that during said thirty (30) day period, a battery operated carbon monoxide detector with an alarm should be installed.
APPROVED CARBON MONOXIDE DETECTORS Each carbon monoxide detector as required in accordance with the above
provisions should comply with NFPA 720 and be ANSI/UL 2034 listed and CSA certied.
SIGNAGE A metal or plastic identication plate should be permanently mounted to the exterior of the building at a minimum
height of eight (8) feet above grade directly in line with the exhaust vent terminal for the horizontally vented gas fueled heating
appliance or equipment. The sign should read, in print size no less than one-half (1/2) inch in size, “GAS VENT DIRECTLY
BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS.”
INSPECTION The state or local gas inspector of the side wall horizontally vented gas fueled equipment should not approve
the installation unless, upon inspection, the inspector observes carbon monoxide detectors and signage installed in accordance
with the provisions of 248 CMR 5.08(2)(a) 1 through 4.
EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a)1 through 4:
1. The equipment listed in Chapter 10 entitled “Equipment Not Required To Be Vented” in the most current edition of NFPA 54
as adopted by the Board; and
2. Product Approved side wall horizontally vented gas fueled equipment installed in a room or structure separate from the
dwelling, building, or structure used in whole or in part for residential purposes.
MANUFACTURER REQUIREMENTS - GAS EQUIPMENT VENTING SYSTEM PROVIDED When the manufacturer of Product
Approved side wall horizontally vented gas equipment provides a venting system design or venting system components with
the equipment, the instructions provided by the manufacturer for installation of the equipment and the venting system should
include:
1. Detailed instructions for the installation of the venting system design or the venting system components; and
2. A complete parts list for the venting system design or venting system.
MANUFACTURER REQUIREMENTS - GAS EQUIPMENT VENTING SYSTEM NOT PROVIDED When the manufacturer of
a Product Approved side wall horizontally vented gas fueled equipment does not provide the parts for venting the ue gases,
but identies “special venting systems,” the following requirements should be satised by the manufacturer:
1. The referenced “special venting system” instructions should be included with the appliance or equipment installation
instructions; and
2. The “special venting systems” should be Product Approved by the Board, and the instructions for that system should include
a parts list and detailed installation instructions.
A copy of all installation instructions for all Product Approved side wall horizontally vented gas fueled equipment, all venting
instructions, all parts lists for venting instructions, and/or all venting design instructions should remain with the appliance or
equipment at the completion of the installation.
6
TYPICAL INSTALLATION
REPLACEMENT PARTS AND DELIMING PRODUCTS
Replacement parts and recommended delimer may be ordered
through authorized servicers or distributors. Refer to the Yellow Pages
for where to call or contact the water heater manufacturer at, 500
Tennessee Waltz Parkway, Ashland City, TN 37015. When ordering
parts, please call 1-800-821-2017 and provide complete model and
serial numbers (see rating plate), quantity and name of part desired,
see Figure 1. Standard hardware items may be purchased locally.
VACUUM RELIEF VALVE
*INSTALL PER LOCAL
CODES
(A) VENT PIPE
(B) ANODE
(C) HOT WATER OUTLET
(D) OUTLET (120 VAC)
(E) FLUE BAFFLE
(F) GAS SUPPLY
(G) MAIN MANUAL GAS
SHUT OFF VALVE
(H) GROUND JOINT UNION
(J) SEDIMENT TRAP
(K) OUTER DOOR
(L) UNION
(M) INLET WATER SHUT
OFF VALVE
(N) COLD WATER INLET
(O) INLET DIP TUBE
(P) TEMPERATURE AND
PRESSURE RELIEF VALVE
(Q) RATING PLATE
(R) INSULATION
(S) VENT TERMINAL
(T) DRAIN VALVE
(U) IGNITER AND MAIN
BURNER
(V) FLUE
(W) METAL DRAIN PAN
(X) GAS CONTROL VALVE/TSTAT
(Y) CONTROL HARNESS*
(Z) MOTOR & BLOWER
(AA) CONDENSATE FITTING
INSTALL THERMAL EXPANSION
TANK IF WATER HEATER IS
INSTALLED IN A CLOSED
WATER SYSTEM.
TEMPERATURE INDICATORS
TEMPERATURE ADJUSTMENT BUTTONS
(U) NATURAL GAS MAIN BURNER
WITH IGNITER ASSEMBLY
FIGURE 1.
7
(U) PROPANE GAS MAIN BURNER
WITH IGNITER ASSEMBLY
(SIDE VIEW)
TYPICAL INSTALLATION
MIXING VALVE USAGE
FIGURE 2.
This water heater has been design certied as complying with American
National Standard for water heaters and is considered suitable for:
Water (Potable) Heating and Space Heating: All models are
considered suitable for water (potable) heating and space heating.
HOTTER WATER CAN SCALD:
Water heaters are intended to produce hot water. Water heated to a
temperature which will satisfy space heating, clothes washing, dish
washing, and other sanitizing needs can scald and permanently injure
you upon contact. Some people are more likely to be permanently
injured by hot water than others. These include the elderly, children,
the inrm, or physically/mentally handicapped. If anyone using hot
water in your home ts into one of these groups or if there is a local
code or state law requiring a certain temperature water at the hot
water tap, then you must take special precautions. In addition to
using the lowest possible temperature setting that satises your
hot water needs, a means such as a Mixing Valve should be used
at the hot water taps used by these people or at the water heater.
Mixing valves are available at plumbing supply or hardware stores.
Consult a Qualied Installer or Service Agency. Follow mixing valve
manufacturer’s instructions for installation of the valves. Before
changing the factory setting on the thermostat, read the “Temperature
Regulation” section in this manual, see Figure 21.
8
LOCATING THE NEW WATER HEATER
FACTS TO CONSIDER ABOUT THE LOCATION
Carefully choose an indoor location for the new water heater, because
the placement is a very important consideration for the safety of the
occupants in the building and for the most economical use of the
appliance. This water heater is not for use in manufactured
(mobile) homes or outdoor installation.
Whether replacing an old water heater or putting the water heater in
a new location, the following critical points must be observed:
1. Select a location indoors as close as practical to the vent terminal or
location to which the water heater vent piping is going to be connected,
and as centralized with the water piping system as possible.
2. Selected location must provide adequate clearances for servicing
and proper operation of the water heater.
Installation of the water heater must be accomplished in such a manner
that if the tank or any connections should leak, the ow will not cause
damage to the structure. For this reason, it is not advisable to install
the water heater in an attic or upper oor. When such locations cannot
be avoided, a suitable metal drain pan should be installed under the
water heater. Drain pans are available at your local hardware store.
Such a drain pan must have a clearance of at least 1.0” (2.5cm)
greater than any point on the water heater’s outer jacket and must
be piped to an adequate drain. The pan must not restrict combustion
air ow. For example, if a circular pan is used, it must be a minimum
of 27” (69cm) in diameter, see Figure 1.
Water heater life depends upon water quality, water pressure and
the environment in which the water heater is installed. Water heaters are
sometimes installed in locations where leakage may result in property
damage, even with the use of a drain pan piped to a drain. However,
unanticipated damage can be reduced or prevented by a leak detector or
water shut-off device used in conjunction with a piped drain pan. These
devices are available from some plumbing supply wholesalers and
retailers, and detect and react to leakage in various ways:
• Sensors mounted in the drain pan that trigger an alarm or turn off the
incoming water to the water heater when leakage is detected.
• Sensors mounted in the drain pan that turn off the water supply to
the entire home when water is detected in the drain pan.
• Water supply shut-off devices that activate based on the water
pressure differential between the cold water and hot water pipes
connected to the water heater.
• Devices that will turn off the gas supply to a gas water heater while
at the same time shutting off its water supply.
INSTALLATIONS IN AREAS WHERE FLAMMABLE LIQUIDS
(VAPORS) ARE LIKELY TO BE PRESENT OR STORED
(GARAGES, STORAGE AND UTILITY AREAS, ETC.): Flammable
liquids (such as gasoline, solvents, propane (LP or butane, etc.) and
other substances (such as adhesives, etc.) emit ammable vapors
which can be ignited by a gas water heater’s hot surface igniter or
main burner. The resulting ashback and re can cause death or
serious burns to anyone in the area.
Also, the water heater must be located and/or protected so it is not
subject to physical damage by a moving vehicle.
This water heater must not be installed
must be protected by metal or wood panel beneath appliance extending
beyond full width and depth of appliance by at least 3” (7.6 cm) in any direction,
or if appliance is installed in an alcove or closet, entire oor must be covered
by the panel. Failure to heed this warning may result in a re hazard.
9
directly on carpeting. Carpeting
Minimum clearances between the water heater and combustible
construction are 0 inch at the sides and rear, 5.5” (14.0 cm) from the
front and 12” (30.5 cm) from the top (standard clearance). If clearances
stated on the heater differ from standard clearances, install water
heater according to clearances stated on the heater.
Adequate clearance 24” (61.0 cm) for servicing this appliance should
be considered before installation, such as changing the anodes, etc.
A minimum clearance of 5.5” (14.0 cm) must be allowed for access to
replaceable parts such as the thermostats, drain valve and relief valve.
When installing the heater, consideration must be given to proper
location. Location selected should be as close to the wall as practicable
and as centralized with the water piping system as possible.
Propellants of aerosol sprays and volatile compounds (cleaners,
chlorine based chemicals, refrigerants, etc.), in addition to being highly
ammable in many cases, will also react to form corrosive hydrochloric
acid when exposed to the combustion products of the water heater.
The results can be hazardous, and can also cause product failure.
INSULATION BLANKETS
Insulation blankets are available to the general public for external use
on gas water heaters but are not necessary with these products. The
purpose of an insulation blanket is to reduce the standby heat loss
encountered with storage tank heaters. Your water heater meets or
exceeds the Energy Policy Act standards with respect to insulation and
standby loss requirements, making an insulation blanket unnecessary.
Should you choose to apply an insulation blanket to this heater, you
should follow these instructions (for identication of components
mentioned below, see Figure 1). Failure to follow these instructions
can restrict the air ow required for proper combustion, potentially
resulting in re, asphyxiation, serious personal injury, or death.
FIGURE 3. FIGURE 4.
A gas water heater cannot operate properly without the correct amount
of air for combustion. Do not install in a conned area such as a closet,
unless you provide air as shown in the “Locating The New Water
Heater” section. 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 death, serious bodily injury, or property damage.
FIGURE 5.
If this water heater will be used in beauty shops, barber shops, cleaning
establishments, or self-service laundries with dry cleaning equipment, it
is imperative that the water heater or water heaters be installed so that
combustion and ventilation air be taken from outside these areas.
• Do not apply insulation to the top of the water heater, as this will
interfere with safe operation of the blower assembly.
• Do not cover outer door,
• Do not allow insulation to come within 2” (5.1 cm) of the oor to
prevent blockage of combustion air ow to the burner.
• Do not cover the instruction manual. Keep it on the side of the
water heater or nearby for future reference.
• Do obtain new warning and instruction labels from the manufacturer
for placement on the blanket directly over the existing labels.
• Do inspect the insulation blanket frequently to make certain it
does not sag, thereby obstructing combustion air ow.
thermostat or temperature & pressure
relief valve.
COMBUSTION AIR AND VENTILATION FOR APPLIANCES LOCATED IN UNCONFINED SPACES
UNCONFINED SPACE is space whose volume is not less than
50 cubic feet per 1,000 Btu per hour (4.8 cubic meters per kW) of the aggregate
input rating of all appliances installed in that 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 unconned space.
In unconned spaces in buildings, inltration may be adequate to
provide air for combustion, ventilation and dilution of ue gases.
However, in buildings of tight construction (for example, weather
stripping, heavily insulated, caulked, vapor barrier, etc.), additional air
may need to be provided using the methods described in “Combustion
Air and Ventilation for Appliances Located in Conned Spaces.”
COMBUSTION AIR AND VENTILATION FOR APPLIANCES LOCATED IN CONFINED SPACES
CONFINED SPACE is a space whose volume is less than 50 cubic
feet per 1,000 Btu per hour (4.8 cm per kW) of the aggregate input
rating of all appliances installed in that space.
When drawing combustion air from inside a conventionally
constructed building to a conned space, such a space should be
provided with two permanent openings. ONE WITHIN 12 INCHES
(30 cm) OF THE ENCLOSURE TOP AND ONE WITHIN 12 INCHES
(30 cm) OF THE ENCLOSURE BOTTOM. Each opening should have
a free area of one square inch per 1000 Btu/hr (22 cm
total input of all appliances in the enclosure, but not less than 100
square inches (645 cm
2
). If the conned space is within a building of
tight construction, air for combustion and ventilation must be obtained
from outdoors. When directly communicating with the outdoors or
communicating through vertical ducts, two permanent openings,
10
2
/kW) of the
located in the above manner, should be provided. Each opening
should have a free area of not less than one square inch per 4000
Btu/hr (5.5 cm
If horizontal ducts are used, each opening should have a free area
of not less than one square inch per 2000 Btu/hr (11cm
2
/kW) of total input of all appliances in the enclosure.
2
/kW) of the
total input of all appliances in the enclosure.
A. ALL AIR FROM INSIDE BUILDINGS: (See Figure 5 and 6)
The conned space should be provided with two permanent openings
communicating directly with an additional room(s) of sufcient volume
so that the combined volume of all spaces meets the criteria for an
unconned space. The total input of all gas utilization equipment installed
in the combined space should be considered in making this determination.
Each opening should have a minimum free area of one square inch
per 1,000 Btu per hour (22 cm
utilization equipment in the conned space, but not less than 100 square
inches (645 cm
2
). One opening should commence within 12 inches
2
/kW) of the total input rating of all gas
(30 cm) of the top and one commencing within 12 inches (30 cm)
of the bottom of the enclosures.
FIGURE 8.
FIGURE 6.
B. ALL AIR FROM OUTDOORS: (See Figures 7, 8, 8B and 9)
The conned space should be provided with two permanent openings,
one commencing within 12 inches (30 cm) of the top and one
commencing within 12 inches (30 cm) from the bottom of the enclosure.
The openings should communicate directly, or by ducts, with the outdoors
or spaces (crawl or attic) that freely communicate with the outdoors.
1. When directly communicating with the outdoors, each opening should
have a minimum free area of 1 square inch per 4,000 Btu per hour
2
(5.5 cm
/kW) of total input rating of all equipment in the enclosure,
see Figure 7.
FIGURE 7.
2. When communicating with the outdoors through vertical ducts,
each opening should have a minimum free area of 1 square inch
per 4,000 Btu per hour (5.5 cm
2
/kW) of total input rating of all
equipment in the enclosure, see Figure 8.
3. When communicating with the outdoors through horizontal ducts,
each opening should have a minimum free area of 1 square inch
per 2,000 Btu per hour (11 cm
2
/kW)) of total input rating of all
equipment in the enclosure, see Figure 9.
FIGURE 8B.
5. Alternatively a single permanent opening may be used when
communicating directly with the outdoors, or with spaces that freely
communicate with the outdoors. The opening shall have a minimum free
area of 1 square inch per 3,000 BTU per hour (8.3 cm
rating of all equipment in the enclosure. See Figure 8B.
2
/kW) of total input
4. When ducts are used, they should be of the same cross-sectional
area as the free area of the openings to which they connect. The
minimum short side dimension of rectangular air ducts should not
be less than 3 inches (7.6 cm), see Figure 9.
FIGURE 9.
5. Louvers and Grilles: In calculating free area, consideration should
be given to the blocking effect of louvers, grilles or screens protecting
openings. Screens used should not be smaller than 1/4 inch (6.4 mm)
mesh. If the free area through a design of louver or grille is known, it
should be used in calculating the size opening required to provide the
free area specied. If the design and free area is not known, it may be
assumed that wood louvers will be 20-25 percent free area and metal
louvers and grilles will have 60-75 percent free area. Louvers and grilles
should be xed in the open position or interlocked with the equipment
so that they are opened automatically during equipment operation.
6. Special Conditions Created by Mechanical Exhausting or Fireplaces:
operation of exhaust fans, ventilation systems, clothes dryers or
replaces may create conditions requiring special attention to avoid
unsatisfactory operation of installed gas utilization equipment.
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