State Industries GS675HRVIT, GS675YRVIT User Manual

RESIDENTIAL GAS WATER HEATERS

500 Tennessee Waltz Parkway,

Ashland City, TN 37015

www.statewaterheaters.com

Low Lead Content

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 condence 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 1010 197218-003

WHENEVER MAINTENANCE ADJUSTMENT OR SERVICE IS REQUIRED.

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.

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

• Qualied Installer: A qualied 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 qualied 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.

GENERAL SAFETY

TABLE OF CONTENTS

SAFE INSTALLATION, USE AND SERVICE.................................. 2

GENERAL SAFETY.....................................................................3-4

TABLE OF CONTENTS ..................................................................5

INTRODUCTION ............................................................................ 5

Preparing for the Installation ................................................... 5

INSTALLATION REQUIREMENTS FOR THE

COMMONWEALTH OF MASSACHUSETTS ................................. 6

TYPICAL INSTALLATION ............................................................ 7-8

LOCATING THE NEW WATER HEATER .................................. 9-11

Facts to Consider About Location ...................................... 9-10

Insulation Blankets ................................................................ 10

Combustion Air and Ventilation for Appliances

Located in Unconned Spaces ............................................. 10

Combustion Air and Ventilation for Appliances

Located in Conned Spaces ............................................ 10-11

INSTALLING THE WATER HEATER ....................................... 12-22

Chemical Vapor Corrosion .................................................... 12

Water Piping ....................................................................12-13

Closed Water Systems ......................................................... 12

Thermal Expansion ............................................................... 12

Temperature-Pressure Relief Valve ...................................... 13

Gas Piping ............................................................................ 14

Sediment Traps (Drip Legs) .................................................. 15

Filling the Water Heater ........................................................ 15

Venting .................................................................................. 15

Vent Pipe Termination ...................................................... 15-16

Planning the Vent System ................................................16-17

Condensate........................................................................... 17

Blower Assembly Installation ...........................................17-18

Installation of Vent System...............................................18-21

Vent Pipe Preparation ......................................................21-22

LIGHTING & OPERATING LABEL ............................................... 23

TEMPERATURE REGULATION .................................................. 24

FOR YOUR INFORMATION ......................................................... 25

Start Up Conditions

Smoke/Odor .................................................................. 25

Thermal Expansion ....................................................... 25

Strange Sounds ............................................................ 25

Operational Conditions ......................................................... 25

Smelly Water ................................................................. 25

“Air” in Hot Water Faucets ............................................. 25

High Temperature Shut Off System ............................... 25

PERIODIC MAINTENANCE ....................................................26-28

Venting System Inspection....................................................26

Burner Operation and Inspection .......................................... 26

Burner Cleaning .................................................................... 26

Housekeeping ..................................................................26-27

Anode Rod Inspection...........................................................27

Temperature-Pressure Relief Valve Operation ..................... 27

Draining.................................................................................27

Service .................................................................................. 28

LEAKAGE CHECKPOINTS .......................................................... 28

REPAIR PARTS ............................................................................ 29

TROUBLESHOOTING ............................................................30-32

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

• GAMA - Gas Appliance Manufacturer’s Association

• UL - Underwriters Laboratories Inc.

This gas-red water heater is design certied 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 pages, READ THE ENTIRE MANUAL BEFORE ATTEMPTING

TO INSTALL OR OPERATE THE WATER HEATER.

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 Ofce 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.

2. The installation must conform with these instructions and the local code authority having jurisdiction. In the absence of local codes,

8. Complies with SCAQMD rule #1146 and districts having equivalent NOx requirements.

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 satised:

INSTALLATION OF CARBON MONOXIDE DETECTORS At the time of installation of the side wall horizontal vented gas fueled equipment, the installing plumber or gastter 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 gastter 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 qualied 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 certied.

SIGNAGE A metal or plastic identication 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 identies “special venting systems,” the following requirements should be satised 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.

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 (DRIP LEG) (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) CONTROL (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.

(U) PROPANE GAS MAIN BURNER

WITH IGNITER ASSEMBLY

(SIDE VIEW)

TYPICAL INSTALLATION

MIXING VALVE USAGE

FIGURE 2.

This appliance has been design certied 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 inrm, 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 satises 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 Qualied 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.

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.

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 identication 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 conned 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 unconned space.

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 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 Conned 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 conned 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

). If the conned 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,

/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

/kW) of total input of all appliances in the enclosure.

/kW) of the

total input of all appliances in the enclosure.

A. ALL AIR FROM INSIDE BUILDINGS: (See Figure 5 and 6)

The conned space should be provided with two permanent openings communicating 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. 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 conned space, but not less than 100 square inches (645 cm

). One opening should commence within 12 inches

/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 conned 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

(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

/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

/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.

/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 specied. 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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