A.O. Smith TC-049R3 Service Handbook Download Page 32

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RESIDENTIAL GAS AND ELECTRIC WATER HEATER

SERVICE HANDBOOK

Residential Electric – continued

WIRING DIAGRAM

A-6 Circuit

•

2 Elements

•

2 Thermostats

•

1 High Limit

A-6 Circuit

- Standard on dual

element water heaters non-simultaneous/interlocked operation

A-6 Circuit - Post 1995

Operation: From cold tank of water

Power Enters High-Limit

Through High Limit

Upper Thermostat

Contacts Open

Contacts Closed

Power to Upper /Element

Element Heats Water

Upper Thermostat Satisfied

Power Interrupted to Upper Element

Open

Lower Thermostat

Contacts Closed

Power to Lower Element

Element Heats Water

Power Interrupted to
Lower Element
Lower 1, 2

Open

Lower Thermostat

Satisfied

Switch Power to Lower Thermostat

Closed

Lower Thermostat Contacts Open

A.O. Smith Water Products Company

Technical Training Department

2005

Ashland City, TN

Summary of Contents for TC-049R3

Page 1: ...nted and use a thermocouple as their electrical source Residential Electric Water Heaters having one or two heating elements and common wiring configurations for these models SERVICE HANDBOOK Resident...

Page 2: ...and Approvals 36 Unbalanced 3 phase 37 C 2 Ohms Check 38 C 2 Ohms Check 39 C2 No Hot Water 40 C 2 Grounded Element Check 41 A 6 Ohms Check No Hot Water 42 A 6 No Hot Water Voltage Check 43 A 6 Lack of...

Page 3: ...s supplemental information to the Residential Gas and Electric instructional manual Qualifications Tools Required For servicing gas models Cross top screw driver 3 8 7 16 inch open end wrenches 3 16 i...

Page 4: ...es out through the vent piping Temperature rise is the increase in the temperature from its coldest inlet water temperature to the desired hot outlet setting Typically this is assumed to be 40 degrees...

Page 5: ...X 036091 PSI Inches of Water Column X 073483 Inches of Mercury Hg Centimeters Inches X 2 54 MM millimeters Inches X 25 4 Meters Inches X 0254 Doubling the diameter of a pipe will increase its flow ca...

Page 6: ...all After Lighting Pilot Drain Safety Pan Piped to Drain Thermostat Recommending setting of 125 F Temperature and pressure relief valve tube piped to within 6 of drain Water Shut Off Valve Temperature...

Page 7: ...eir electrical source Construction See also General section of this manual Control There is one control on this style of water heater The control has a main gas regulator pilot gas regulator on off pi...

Page 8: ...AFTER HAVING CONFIRMED THAT THE WATER HEATER HAS BEEN INSTALLED PER THE INSTALLATION MANUAL INSTRUCTIONS Normal Operation Electrical The Pilot Flame heats the end of a thermocouple As the thermocoupl...

Page 9: ...gas valve If the regulator is pushed sufficiently gas flow is interrupted to the main burner Adjusting the temperature dial changes the distance the rod must expand or contract to open or close the g...

Page 10: ...will consistently shut off at this same temperature For this same reason water temperature may drop 15 25 F around the temperature probe before the main burner is activated Keep in mind that hot wate...

Page 11: ...TN 10 12 5 Cubic Feet of Air 1 000 BTU Fuel Enters Here Enters Here Do not forget that your gas or oil furnace and gas clothes dryer also require a like amount of air When calculating air supply provi...

Page 12: ...2005 Ashland City TN 11 Manifold Gas Pressure Test Testing with Gas Pressure Gauge Pilot Gas Pressure Test Gas pressure checks are done with flowing gas Supply gas pressure checks are taken ahead of t...

Page 13: ...together and this joint is heated a small electrical current will be produced A thermocouple uses this science Thermocouple output test Procedures Conditions Meter set for DC millivolt testing Test f...

Page 14: ...you will hear a click inside the valve replace the control valve internal safety does activate between 1 and 3 MV valve is within tolerance and will interrupt gas flow if pilot looses heat or ECO open...

Page 15: ...ed jacket or vent piping is noted If then any of the above conditions exist raise the supply air temperature or increase stored water temperature or increase the size of the tank You would not wish to...

Page 16: ...mable Vapor Ignition Resistant The AO Smith products are based on Corderite Combustion Containment known as C3 Technology The C3 Technology design features a sealed from non designated air intake open...

Page 17: ...the long narrow crevasse accessory LDO SCREEN LINT DUST OIL SCREEN S An easy to clean screen designed to minimize lint dust and oil based contaminants from being drawn into the Flame Arrestor along wi...

Page 18: ...es burn off the top surface of the arrestor and cannot escape down through the arrestor The arrestor works somewhat like a check valve Service Inspect the bottom ports of the flame arrestor by removin...

Page 19: ...at is integral with the thermocouple Temperature cutoff points range from 160 C to 200 C depending on model The TCO is an automatic reset thermal switch When activated it will open the thermocouple ci...

Page 20: ...ot outage due to increased combustion chamber temperatures below the main burner This may open the automatic reset thermal cut off switch TCO The flame arrestor having contained a flammable vapor igni...

Page 21: ...he connections to the bottom of the gas control valve 11 Reattach the piezo cable to the piezo button 12 Remount the inner door 13 Follow the pilot lighting instructions including gas and gasket leak...

Page 22: ...uting of the thermocouple and pilot burner tube through the pilot assembly seal These are all critical to maintaining the C3 TECHNOLOGY integrity of the combustion chamber PIEZO IGNITER C3 TECHNOLOGY...

Page 23: ...Condensation Discolored Water Smelly Water Chlorination Process Lack of hot water Thermal Expansion Temperature and Pressure Relief Valve Operation Parts Replacement The parts on these models may chan...

Page 24: ...IS BEHIND THESE PANELS RECOMMENDED SETTING IS 125 ELECTRICAL JUNCTION BOX ADJACENT CONDUIT ENTRANCE RATING PLATE WITH MODEL AND SERIAL NUMBER HOT WATER TO FIXTURES DRAIN LINE INSTALL THERMAL EXPANSION...

Page 25: ...rvicing of Residential Electric Tank Type Water Heaters The illustrations are for two element models but the information also applies to single element models TEMPERATURE PRESSURE RELIEF VALVES Multip...

Page 26: ...X 8 25 Supply electrical fusing or breakers should be sized at least 125 of expected heater amperage Water weighs 8 25 pounds per gallon at 120 F 49 C of Hot water Mixed temp Cold divided by Hot temp...

Page 27: ...compared to the surface area of the element i e High Watt Density Element will have the most wattage per square inch of element surface If the above elements generated 4 500 w each B might be conside...

Page 28: ...nk 110 170 2 59T Style 4000 A 6 A 7 C 2 X X Lower Tank 110 170 3 89T33 A 6 X Upper Tank 90 150 3 89T13 C 2 A 7 X Lower Tank 90 150 2 59T Style 4000 A 6 X Lower Tank 90 150 2 AW Style 7135 A 7 X X Uppe...

Page 29: ...erminal And High Limit 4 to Element Thermostat 1 2 is Closed Element is On Tank Water is Heated Thermostat 1 2 Opens C 2 Circuit Prior to 1996 After having confirmed that the water heater has been ins...

Page 30: ...ING DIAGRAM Note If used on a normally two element heater controls will be located behind the upper service cover and the element behind the lower service cover Thermostat Satisfies T2 Contacts Open P...

Page 31: ...mostat Upper Thermostat 1 4 Closed Lower Thermostat Contacts Open Through High Limit Upper Thermostat Lower Thermostat Contacts Closed 1 4 Contacts Open 1 2 Contacts Closed Power to Upper Element Elem...

Page 32: ...Limit Through High Limit Upper Thermostat L1 T4 Contacts Open L1 T2 Contacts Closed Power to Upper Element Element Heats Water Upper Thermostat Satisfied Power Interrupted to Upper Element L1 T2 Open...

Page 33: ...tricity is used during Off Peak times of the day This circuit allows use of an Off Peak meter which interrupts power to the lower element during the time of day when electricity is more expensive This...

Page 34: ...r Element Is On No Power To Lower High Limit Term 1 Top 1 3 Of Tank Is Heated Upper Thermostat 1 2 Opens 3 4 Closes Power From Upper Thermostat 1 To Lower High Limit 1 Lower High Limit 1 2 Is Closed L...

Page 35: ...imits 4 Wire WIRING DIAGRAM A 7 Post 1995 Four wire circuit for non simultaneous element operation This circuit permits off peak meter usage and connection to 3 phase supply circuit Interrupts power t...

Page 36: ...lement is On Top 1 3 of Tank is Heated Upper Thermostat 1 2 Opens Upper Thermostat 3 4 Closes Power Flows Between Upper Thermostat 4 and Lower High Limit L1 Lower High Limit L1 and Lower Thermostat T2...

Page 37: ...Smith residential electric water heaters meet this code The American Society of Heating Refrigeration and Air Conditioning Engineer ASHRAE guidelines follow the National Appliance Energy Conservationi...

Page 38: ...0 25 0 14 4 21 7 12 5 10 8 6 3 4000 4000 33 3 19 2 28 9 16 7 14 4 8 3 4500 4500 37 5 21 6 32 5 18 8 16 2 9 4 5000 5000 N A 36 1 20 8 18 0 10 4 6000 6000 N A N A 21 7 12 5 See A 7 Circuit 3 Supply Wire...

Page 39: ...k lead Common port Red lead in or OHMS port Dial indicator set to scale above expected indication Note Volts divided by amps OHMS Disconnect wires from the element terminals Test probe on each termina...

Page 40: ...k position of heater ON OFF switch if applicable rated voltage is present continue to next step Test voltage between 2 and 4 or L1 and L4 of high limit If then rated voltage is not present press high...

Page 41: ...at Ohms resistance test of element check for water leaks in piping or fixtures Complaint Water Too Hot Conditions Tank water above thermostat setting 10 F Power on Voltage Check Test between 4 and 2 o...

Page 42: ...A grounded element is suspected whenever the water temperature becomes excessively hot and or the end user must push the high limit reset to reactivate the heater Amperage measures the flow of current...

Page 43: ...ck Test Conditions This test uses the multimeter s battery as the electrical supply Power to the water heater is OFF Multimeter set to OHMS scale testing Black lead Common port Red lead in or OHMS por...

Page 44: ...s Tank is full of cold water Power is on to the heater Voltage Check Test between 1 and 3 or L1 and L3 If then correct supply voltage is present continue correct supply voltage is NOT present check di...

Page 45: ...int Lack of Hot Water Conditions Upper thermostat satisfied Lower portion of tank still calling for heat Test between high limit 4 and thermostat 4 and L4 and T4 If then correct supply voltage is pres...

Page 46: ...it reset to reactivate the heater Amperage measures the flow of current through a wire Watts divided by volts Amps Test Conditions Wires on the water heater are all connected to their proper terminals...

Page 47: ...it 2 two wire single phase circuit or 3 connection to an off peak meter or time clock This third wiring system interrupts power to the lower thermostat during the designated time period but does not i...

Page 48: ...Black lead Common port Red lead in or OHMS port Dial indicator set to scale above expected indication Note Volts divided by amps OHMS Disconnect wires from the element terminals See OHMS Resistance Ta...

Page 49: ...in heater junction box continue to next step Test between upper high limit terminals 2 and 4 If then the proper voltage is not present push the reset button if this establishes proper voltage conduct...

Page 50: ...or L1 and L3 If then proper voltage is not present check wiring to upper thermostat and heater junction box check that off peak meter is not Open proper voltage is present continue to next step Test...

Page 51: ...er high limit L4 and lower thermostat T2 If then proper voltage is not present check jumper between lower high limit 2 and lower thermostat 1 replace lower thermostat proper voltage is present continu...

Page 52: ...ust push the high limit reset to reactivate the heater Amperage measures the flow of current through a wire Watts divided by volts Amps Conditions Power on Thermostats are satisfied Clamp the jaws of...

Page 53: ...he upper element and thermostat For this reason the lower element will normally accumulate lime faster and fail more often than the upper element Lower thermostats will fail more often than upper ther...

Page 54: ...ended to supplement service and maintenance information found in the heater installation and operation manual Why water heaters leak information 54 55 Index of Technical Bulletins Water Hammer 56 Mine...

Page 55: ...ter temperature drop during usage Store water at a higher temperature install a mixing valve to reduce danger of scalding Contaminated Air Bleaches floor waxes detergents salt and many other household...

Page 56: ...um forms on the electric elements Elements become excessively hot and may split Split elements often leak to the outside of the heater Inspect and clean elements as necessary Add a water softener Inst...

Page 57: ...r hammer can manifest itself in a number of ways The most common are Expanded Tank Shell This can be demonstrated by measuring the circumference at various locations along the shell Pressures in exces...

Page 58: ...de a popping of water trapped under lime deposits or the sizzling of water trapped next to elements boiling it to steam THE FIX Treatment of a limed up heater is relatively simple Since CaCO3 is a bas...

Page 59: ...the heater 2 Drain the heater 3 Remove the anode 4 Add UN LIME to the tank 20 40 gallon models use 3 gallons of UN LIME 41 65 gallon models use 5 gallons of UN LIME 66 100 gallon models use 7 gallons...

Page 60: ...red water is the end result of the bacteria feeding process Water heaters and storage tanks usually require new anode rods as presence of iron bacteria contributes to premature anode failure The requi...

Page 61: ...k c water with little or no dissolved oxygen d and temperatures below 138 F Items that can increase the potential for this bacteria are a water softeners b well water c and long periods of no water mo...

Page 62: ...ex for every 25 gallons of tank capacity STEP 7 Reinstall anode rod s after inspecting and replacing as needed STEP 8 Open cold water supply valve and refill the system Then draw the water to every ho...

Page 63: ...or you STEP 1 At the faucet nearest to the water heater time in seconds how long it takes to fill a 1 gallon bucket flow rate Gallon per minute gpm 60 seconds seconds to fill a 1 gallon bucket If the...

Page 64: ...ket flow rate Gallon per minute gpm 60 seconds seconds to fill a 1 gallon bucket If the bucket fills in 10 sec 6 gpm 12 sec 5 gpm 15 sec 4 gpm 20 sec 3 gpm 24 sec 2 5 gpm STEP 2 Turn both upper and lo...

Page 65: ...is another cause PRVs are designed to conserve water and prolong fixture life Many PRVs also act as very effective check valves Again do not remove them Water softeners in the system may also act as...

Page 66: ...on check again The pressure should increase only slightly then hold steady throughout the recovery cycle The expanded water is flowing back from the heater and into the pressurized storage bladder of...

Page 67: ...be the same or less than the certified working pressure of the tank generally 150 psi and be below the lowest pressure rating of any system components It is not acceptable to install a relief valve t...

Page 68: ...n these service calls Comments ______________________________________________________________ I feel that this handbook is difficult 1 2 3 okay 4 5 6 very easy to understand and use Comments _________...

Page 69: ......

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