A.O. Smith 300 Series Installation And Operating Manual
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A.O. Smith 300 Series Installation And Operating Manual

Residential gas water heaters power direct vent gas models with hot surface ignition not for use in manufactured (mobile) homes
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RESIDENTIAL GAS WATER HEATERS
WARNING: If the information in these instruc-
tions 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 flam-
mable 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 sup-
plier'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.
ALL TECHNICAL AND WARRANTY QUESTIONS: SHOULD BE DIRECTED TO THE LOCAL DEALER FROM WHOM THE WATER HEATER WAS
PURCHASED. IF YOU ARE UNSUCCESSFUL, PLEASE CONTACT THE COMPANY LISTED ON THE RATING PLATE ON THE WATER HEATER.
KEEP THIS MANUAL IN THE POCKET ON HEATER FOR FUTURE REFERENCE
1906
WHENEVER MAINTENANCE ADJUSTMENT OR SERVICE IS REQUIRED.
Installation and Operating Manual
POWER DIRECT VENT GAS MODELS
NOT FOR USE IN MANUFACTURED (MOBILE) HOMES
•
AN ODORANT IS ADDED TO THE GAS USED
BY THIS WATER HEATER.
WITH HOT SURFACE IGNITION
SERIES 300, 301
WARNING
Read and understand instruction
manual and safety messages
before installing, operating or
servicing this water heater.
Failure to follow instructions and
safety messages could result in
death or serious injury.
Instruction manual must remain
with water heater.
•
For Your Safety
100304526_2000545240 _Rev. 01

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Summary of Contents for A.O. Smith 300 Series

  • Page 1 Installation and Operating Manual RESIDENTIAL GAS WATER HEATERS POWER DIRECT VENT GAS MODELS WITH HOT SURFACE IGNITION NOT FOR USE IN MANUFACTURED (MOBILE) HOMES SERIES 300, 301 WARNING: If the information in these instruc- tions is not followed exactly, a fire or explosion may result causing property damage, personal injury or death.

  • Page 2: Table Of Contents

    TABLE OF CONTENTS Safe Installation, Use And Service ....3 Low Profile Side Wall Vent Termination... 30 General Safety .

  • Page 3: Safe Installation, Use And Service

    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.

  • Page 4: General Safety

    GENERAL SAFETY WARNING WARNING Read and understand instruction Fire Hazard manual and safety messages For continued protection against before installing, operating or risk of fire: servicing this water heater. • Do not install water heater on Failure to follow instructions and carpeted floor.
  • Page 5 GENERAL SAFETY CAUTION WARNING Improper Installation, use and service may result • Before servicing the water heater, make sure the blower assembly is unplugged in property damage. or the electrical supply to the water • Do not operate water heater if flood damaged. heater is tumed "OFF".

  • Page 6: Introduction

    INTRODUCTION Thank You for purchasing this water heater. Properly and maintenance of the gas-fired water heater. It installed and maintained, it should give you years of trouble also contains warnings throughout the manual that free service. you must read and be aware of. All warnings and instructions are essential to proper operation of the This water heater is suitable for potable water heating water heater and your safety.

  • Page 7: Installation Requirements For The Commonwealth Of

    INSTALLATION REQUIREMENTS FOR THE COMMONWEALTH OF MASSACHUSETTS 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 finished grade in the area of the venting, including but not limited to decks and porches, the following requirements shall be satisfied:...

  • Page 8: Massachusetts

    INSTALLATION GRAPHIC: GAS-FIRED POTABLE WATER HEATING/SPACE HEATING SYSTEM • If your water heater will be installed in the Commonwealth of Massachusetts, refer to the following graphic during installation and during modifications to the water supply system. TYPICAL MIXING VALVE INSTALLATION COMBINATION SPACE HEATING / POTABLE WATER HEATING SYSTEM EXPANSION TANK COLD WATER INLET...

  • Page 9: Typical Installation

    TYPICAL INSTALLATION GET TO KNOW YOUR WATER HEATER - GAS MODELS (LIST REFERENCING FIGURES 1-5) 1 Termination Elbow with Vent Screen 16 Flexible Manifold Tube (see Figure 3 35 Gas Orifice (see Figure 3 & 2 *Vent Pipe & Figure 4) Figure 4) 3 *Vent Pipe Elbow (long radius) 17 ***Control Harness...

  • Page 10: Replacement Parts And Deliming Products

    Natural gas and Propane main burner with igniter assembly for 40k and 45k Vacuum relief valve install BTU/hr models (item 13 in Figure 1). per local codes (not supplied with heater). Flare †† † Figure 6. Notes: Items not supplied with the water heater. ** The side recirculation loop connections may not be used as the primary water inlet and outlet connections.

  • Page 11: Water Piping - Mixing Valve Usage

    WATER PIPING - MIXING VALVE USAGE This appliance has been design certified as complying with ANSI/CSA Standard for water heaters and are considered Mixing Valves suitable for combination Water (Potable) Heating and Space Heating but not space heating only applications. Water temperature over DANGER The water supply pressure should not exceed 80 psi.

  • Page 12: Water Heater Operation

    Some people are more likely to be permanently injured WATER HEATER OPERATION by hot water than others. These include the elderly, Figure 10 shows the water heater’s sequence of operation children, the infirm and the physically/mentally disabled. when a call for heat is initiated. The ignition control module Table 1 (published by U.S.

  • Page 13: Electrical Requirements & Wiring Diagram

    ELECTRICAL REQUIREMENTS & WIRING DIAGRAM CAUTION: LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN SERVICING CONTROLS. WIRING ERRORS CAN WARNING CAUSE IMPROPER AND DANGEROUS OPERATION. VERIFY PROPER OPERATION AFTER SERVICING. Electric Shock Hazard NOTE: REFER TO THE “INSTALLATION CHECKLIST” Disconnect power before BEFORE OPERATING THIS HEATER.

  • Page 14: Safety Lockouts

    SAFETY LOCKOUTS This water heater has several lockout features designed The switch will auto reset once the temperature drops to prevent the heater from operating in unsafe conditions. sufficiently. HIGH LIMIT CONTROLS (ENERGY CUT OFF) BLOWER AIR PRESSURE SWITCHES Thermostat/Water Temperature The blower/heater is equipped with two air pressure This feature is a part of the gas control valve/thermostat switches located in the junction box (see Figure 5, item...

  • Page 15: Clearances To Combustibles

    Clearances For Servicing WARNING When installing the heater, consideration must be given to proper location. Location selected should be as close to Fire or Explosion Hazard the wall as practicable and as centralized with the water piping system as possible. •...

  • Page 16: Important Notes And Warnings

    INSULATION BLANKETS WARNING Insulation blankets are available to the general public for external use on gas water heaters but are not necessary Breathing Hazard - Carbon Monoxide Gas with these products. The purpose of an insulation blanket is to reduce standby heat loss encountered with storage tank •...

  • Page 17: Installing The New Water Heater

    INSTALLING THE NEW WATER HEATER WATER PIPING Consult a Qualified Installer or Service Agency. Follow manufacturer’s instructions for installation of valves. Water temperature over DANGER Before changing the factory setting on thermostat, read 125°F can cause severe "Operating The Temperature Control System" section in burns instantly resulting in severe injury or death.

  • Page 18: Combo Heating

    COMBO HEATING 2. Install a drain valve at the lowest point of the heating loop so that water can be drained from the heating This section serves as a guide for the installation and use module without affecting the water heater. of “Combo”...

  • Page 19: Closed Water Systems

    CLOSED WATER SYSTEMS SHUT-OFF VALVE Water supply systems may, because of code requirements HOT-WATER COLD- OUTLET or such conditions as high line pressure, among others, WATER INLET have installed devices such as pressure-reducing valves, UNION UNION check valves, and back flow preventers. Devices such as these cause the water system to be a closed system.

  • Page 20: Temperature-Pressure Relief Valve

    TEMPERATURE-PRESSURE RELIEF VALVE No valve or other obstruction is to be placed between the T&P valve and the tank. Do not connect discharge piping directly to the drain unless a maximum of 6” air gap is WARNING provided. To prevent bodily injury, hazard to life, or property damage, the relief valve must be allowed to discharge Explosion Hazard water in adequate quantities should circumstances...

  • Page 21: Temperature-Pressure Relief Valve And Pipe

    Note: The purpose of a temperature-pressure relief valve HIGH ALTITUDE INSTALLATION is to prevent excessive temperatures and pressures in the storage tank. The T&P valve is not intended for the constant WARNING relief of thermal expansion. A properly sized thermal expansion tank must be installed on all closed systems to control thermal expansion, see "Closed Water Systems"...

  • Page 22: Sediment Traps

    Make sure the gas supplied is the same type listed on the The appliance and its individual shut-off valve should be model rating plate. The inlet gas pressure must not exceed disconnected from the gas supply piping system during 14” w.c. for natural gas and propane gas. The minimum any pressure testing of that system at test pressures in inlet gas pressure shown on the rating plate is that which excess of 1/2 psi.

  • Page 23: Filling The Water Heater

    Contaminants in the gas lines may cause improper FILLING THE WATER HEATER operation of the gas control valve/thermostat that may result in fire or explosion. Before attaching the gas line be CAUTION sure that all gas pipe is clean on the inside. To trap any dirt or foreign material in the gas supply line, a sediment Property Damage Hazard trap must be incorporated in the piping.

  • Page 24: Venting

    VENTING Plan the vent system layout so that proper clearances are VENT KIT maintained from plumbing and wiring. Vent pipes serving A Vent Kit included with this water heater may be used power vented appliances are classified by building codes as for standard sidewall or roof termination.

  • Page 25: Termination Clearances (Side Wall)

    TERMINATION CLEARANCES (SIDE WALL) R N E E C O I N S I D D E T A Vent terminal Air supply inlet Area where terminal is not permitted F I X E S E D C L O R A B O P E F I X E...

  • Page 26: Termination Types

    TERMINATION TYPES ROOF VENT TERMINATION (STANDARD) The combustion air intake and exhaust vent system and Important: When terminating the vents through a roof, termination may be installed in one of the following type the following specifications pertaining to terminal location terminations: must be followed (see Figure 23).

  • Page 27: Side Wall Vent Option For Cold Climates

    SIDE WALL VENT OPTION FOR COLD CLIMATES Some winter weather conditions present a risk of ice accumulation at the intake termination screen. Such accumulation will restrict intake air flow. If local conditions present this risk, the termination configuration shown in Figure 24 is recommended.

  • Page 28: Deluxe Horizontal Venting Kit

    DELUXE HORIZONTAL VENTING KIT “Mushroom” Vent Terminal The Deluxe Horizontal Venting kit was an optional through- “MUSHROOM” VENT TERMINAL the-wall-only concentric flue system for use only on U.S. residential and light duty commercial Power Direct Vent gas water heaters. This section gives directions for replacing series 300 and 310 PDV water heaters terminated with the Deluxe Horizontal Venting Kit.
  • Page 29 SCREW O-RING VENT 3” VENT 3” VENT PIPING PIPING PIPING (INTAKE) (EXHAUST) Figure 28. 100304526_2000545240 _Rev. 01 www.hotwater .com...

  • Page 30: Low Profile Side Wall Vent Termination

    LOW PROFILE SIDE WALL VENT TERMINATION 3. To fasten the Base to the wall, use the supplied screws and anchors. A 3/16” hole, 1-3/16” deep, will need to The Low Profile termination is certified to be used on all be drilled for the anchors. Locate the anchor hole using PDV model series 300/301 and 310/311 water heaters.

  • Page 31: Concentric Vent Termination

    CONCENTRIC VENT TERMINATION 45° ELBOW (SEE A concentric vent termination kit (see Table 3) may be LOCAL used for vertical or horizontal terminations. Figure 33 CODES) PIPE NIPPLE illustrates the concentric vent kit for a horizontal (side wall) installation. To prevent rain water from entering the exhaust VENT SCREEN outlet, slope the vent kit at a downward pitch of 1/4”...

  • Page 32: Multiple Concentric Vent Termination

    MULTIPLE CONCENTRIC VENT TERMINATION When two concentric vent kits are being installed, the vent hood centers shall be either less than 9.5” apart or more than 43.5” apart. Spacings between 9.5” and 43.5” are not allowed due to the possibility of exhaust cross circulation (see Figure 35).

  • Page 33: Tee Termination (Sidewall & Roof)

    TEE TERMINATION (SIDEWALL & ROOF) WALL MOUNTED VENT SCREEN SUPPORT BRACKET A Tee fitting as the exhaust termination and a 90° fitting (INSTALL IN APPLY 8” MIN. TERMINATION) SEALANT as the air intake termination are permitted on the water TO BOTH heater models listed in Table 4.

  • Page 34: Vent Pipe Material

    VENT PIPE MATERIAL installation requires a vent riser, suitable drainage must be provided to ensure condensation does not accumulate The combustion air intake pipe material may be PVC, ABS, (see Figure 50). The specified maximum lengths are for CPVC or polypropylene. each of the intake and exhaust systems and not for the This heater is certified to use Schedule 40 PVC or CPVC, combined lengths of both systems.
  • Page 35 PRESSURE SWITCH 2 PIPE CONC. VENT WATER HEATER VENT SIZE (INSIDE SETTINGS EQUIV. VENT LENGTH EQUIV. VENT LENGTH HEATER INPUT DIAM.) (in. W.C.) MODEL (BTU/HR) N.C. N.O. MAX. MIN. MAX. MIN. 40 gal. 7’ plus 7’ plus term. elbow 50’ plus term. 45’...

  • Page 36: Vent Screens

    Vent Screens VENT VENT SCREEN WARNING SIZE (INSIDE RESTRICTIVE DEBRIS DIAM.) Breathing Hazard - Carbon Monoxide Gas Failure to install the appropriate screen could result in improper heater operation with attendant risk of property damage, personal injury or death by fire or carbon monoxide poisoning.

  • Page 37: Vent Pipe Installation

    Vent Pipe Installation Vent Pipe Runs The following guidelines should be followed when installing 1. The exhaust vent system must not, under any the air intake and exhaust vent system: circumstances, be run downhill then run uphill thus • Venting should be as direct as possible with a minimum forming a valley.

  • Page 38: Vent Pipe Preparation

    VENT PIPE PREPARATION Primer: It is recommended that Tetrahydrofuran (THF) be 1. INITIAL PREPARATION used to prepare the surfaces of pipe and fittings for • Make sure the solvent cement you are planning to solvent welding. Do not use water, rags, gasoline use is designed for the specific application you are or any other substitutes for cleaning PVC or CPVC attempting.
  • Page 39 C. Test dry fit of the joint RECOMMENDED BRUSH* SIZE FOR Tapered fitting sockets are designed so that PRIMER AND CEMENT APPLICATIONS an interfaced fit should occur when the pipe is Nominal inserted about 1/3 to 2/3 of the way into the socket. Brush Size Pipe (IPS) Occasionally, when pipe fitting dimensions are at...

  • Page 40: Blower Assembly Installation

    BLOWER ASSEMBLY INSTALLATION 1. This power vented water heater comes with blower assembly installed. 2. After unit is set in place, make sure blower assembly is still mounted securely. Make sure there is no damage to blower. 3. Make sure there is no packing material in the inlet or discharge of the blower.

  • Page 41: Connections To The Blower And Air Duct

    Connections To The Blower And Air Duct Figure 47 shows the configuration for heaters direct 1. The vent piping connects into the rubber coupling connected to 2” venting. located on the top of the blower assembly. This 2” VENT 2” INLET PIPE PIPE coupling includes gear clamps to connect the venting...

  • Page 42: Condensate (Exhaust)

    • The restrictive screen (see Figure 41) and the air intake Analyze entire vent system to make sure that piping should be secured in place with a screw. To prevent condensate will not become trapped in a section of damage to the equipment, first position the restrictive vent pipe and therefore reduce open cross sectional screen in place, then drill a pilot hole suitable for the screw area of vent.

  • Page 43: Installation Checklist

    INSTALLATION CHECKLIST Note: Use and complete this checklist before lighting the heater. Correct any conditions that do not meet these instructions. Vent Termination Water Heater Location Horizontal  Centrally located with the water piping system.  12” min. above grade/snow level. Located as close to gas piping and vent pipe system ...

  • Page 44: Lighting Instructions

    LIGHTING INSTRUCTIONS Read and understand these directions thoroughly before This heater is equipped with a Honeywell gas control/ attempting to operate the water heater. Make sure the thermostat and a hot-surface igniter. This control is a burner viewport is not missing or damaged. Make sure combination gas valve, thermostat and ignition controller the tank is completely filled with water before operating for use on this power vented water heater.

  • Page 45: Operating The Temperature Control System

    OPERATING THE TEMPERATURE CONTROL SYSTEM It is recommended that lower water temperatures be used The water heater should be located in an area where to avoid the risk of scalding. It is further recommended, the general public does not have access. If a suitable in all cases, that the water temperature be set for the area is not available, a cover should be installed over the lowest temperature which satisfies your hot-water needs.

  • Page 46: Gas Control Valve/Thermostat

    GAS CONTROL VALVE/THERMOSTAT 130°F 140°F 150°F 155°F 120°F 110°F 70°F ON/OFF TEMPERATURE SWITCH SETTING DIAL Figure 51. Approximate Time to induce a 2nd Temperature Temperature and 3rd Degree burn Dial Setting °F to adult skin VERY HOT Less than 1 second About 1.5 seconds Less than 5 seconds More than 30 seconds...

  • Page 47: For Your Information

    FOR YOUR INFORMATION START UP CONDITIONS OPERATIONAL CONDITIONS Condensation Smelly Water Whenever the water heater is filled with cold water, some Each water heater contains at least one anode rod for condensate will form while the burner is ON. A water corrosion protection of the tank.

  • Page 48: Periodic Maintenance

    PERIODIC MAINTENANCE GENERAL UPKEEP Chemical vapor corrosion of the flue and vent system may occur if air for combustion contains certain chemical Make it a habit to look around the heater, the vent piping, vapors. Spray can propellants, cleaning solvents, and the hot and cold water pipes.

  • Page 49: Combustion Chamber And Burner Cleaning

    operation, make sure that (1) no one is in front of or around the outlet of the T&P valve discharge line, and (2) that BLUE TIPS water discharge will not cause any property damage, as LIGHT BLUE water may be extremely hot. Use care when operating INNER INCORRECT CONES ARE...

  • Page 50: Draining And Flushing

    DRAINING AND FLUSHING To Flush The Water Heater Storage Tank Follow Step 1 through Step 7 in the Periodic draining and cleaning of sediment from the tank "To Drain The Water Heater Storage Tank" section. maybe necessary. It is recommended that the tank be 1.

  • Page 51: Anode Rod Maintenance

    ANODE ROD MAINTENANCE CAUTION Property Damage Hazard • Avoid water heater damage. • Inspection and replacement of anode rod required. The anode rod is a sacrificial metal rod that helps avoid corrosion and premature failure (leaks) in the tank. The anode rod is a consumable item.

  • Page 52: Leakage Checkpoints

    LEAKAGE CHECKPOINTS SERVICE Leakage from other appliances, water lines, or ground seepage should also be checked. If a condition persists or you are uncertain about the operation of the water heater contact a service agency. * To check where threaded portion enters tank, insert Use this guide to check a “leaking”...

  • Page 53: Reference Parts Listing

    REFERENCE PARTS LISTING Replacement parts may be ordered 12 Outer Gas Door 37 Hot-Surface Igniter (see Figure 3 13 Manifold Door Assembly (behind outer & Figure 4) (see also Figure 60 & through your plumber or the local door) (see Figure 3 & Figure 4) (see Figure 61) distributor.
  • Page 54 Shown with Junction Box Cover removed for clarity. Natural gas and Propane (LP) main burner with igniter assembly for 40k and 45k Btu/hr models (item 13 in Figure 1). † Flare †† Figure 62. Notes: Figure 60. Items not supplied with the water heater. ** The side recirculation loop connections may not be used as the primary water inlet and outlet connections.

  • Page 55: Troubleshooting Guidelines

    TROUBLESHOOTING GUIDELINES These guidelines should be utilized by a qualified service IGNITION STATE AND TIMING agent. IGNITION STATE TIMING 5 seconds (NG models) LOCKOUTS Pre-purge 15 seconds (LP models) Soft Lockout • Occurs when a system safety device trips to break the Hot Surface Igniter 10 seconds sequence of operation.

  • Page 56: System Status And Error Codes

    SYSTEM STATUS AND ERROR CODES The micro-controller inside the gas control monitors the ignition sequence, temperature settings, and overall operation of the heater. If any of these parameters does not operate properly the controller will shut down the water heater, diagnose the failure and flash an error code.

  • Page 57: Corrective Actions

    CORRECTIVE ACTIONS See the table below for corrective actions corresponding to the Corrective Action Number in the "System Status And Error Codes" section above. If following those corrective actions does not resolve the error, refer to "Other Symptoms" table later in this manual.
  • Page 58 Corrective Action Corrective Action Number 1. Gas supply is turned off or gas pressure is too low. Ensure supply pressure and manifold gas pressures are within requirements. Manifold pressure is nonadjustable, if gas supply pressure proves correct and manifold pressure is off by more than 0.3” WC replace the control. 2.

  • Page 59: Other Symptoms

    OTHER SYMPTOMS Problem Possible Cause(S) Corrective Action 1. Thermostat set too low 1. Turn temperature knob to higher setting 2. Leaking faucets/Wasted hot water 2. Repair faucets 3. Wrong piping connections 3. Correct piping: dip tube must be in cold inlet Insufficient 4.
  • Page 60 500 Tennessee Waltz Parkway, Ashland City, TN 37015 • Technical Support: 800-527-1953 • Parts: 800-433-2545 • Fax: 800-644-9306 www.hotwater.com Copyright © 2018 A. O. Smith Corporation. All rights reserved.

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301 series

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