A.O. Smith TC-049-R2 Service Handbook Download Page 25

Page: 25 / 61

RESIDENTIAL GAS AND ELECTRIC WATER HEATER

SERVICE HANDBOOK

A.O. Smith Water Products Company

Training Department

2002

Ashland City, Tennessee

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

Operation: From cold tank of water

A-6 Circuit - Post 1995

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 Open

Lower Thermostat

Contacts Closed

Power to Lower Element

Element Heats Water

Power Interrupted to
Lower Element
Lower 1, 2

Open

Switch Power to Lower Thermostat

Closed

Lower Thermostat

Satisfied

Summary of Contents for TC-049-R2

Page 1: ...a thermocouple as their electrical source The second portion of this Handbook addresses service issues of Residential Electric Water Heaters having one or two heating elements and common wiring config...

Page 2: ...TRIC HANDBOOK INTRODUCTION This service handbook is designed to aid in servicing and troubleshooting A O Smith Residential Gas and Electric water heaters in the field No duplication or reproduction of...

Page 3: ...et of marked drill bits electrical multimeter gas pressure gauge or monometer water pressure gauge thermometer tubing cutter if pilot tube is to be replaced hose to drain tank container to measure gal...

Page 4: ...erature rise Thermal efficiency is approximately the amount of generated BTU British Thermal Units which enters the water A percentage of the total BTU passes out through the vent piping Temperature r...

Page 5: ...olumn 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 fl...

Page 6: ...Pressurize to Equal Supply Water Pressure Water Shut Off Valve Temperature and pressure relief valve tube piped to within 6 of drain Thermostat Recommending setting of 125 F Safety Pan Piped to Drain...

Page 7: ...ank Type Water Heaters which are vented atmospherically and use a thermocouple as their electrical source Construction See also General section of this manual Control There is one control on this styl...

Page 8: ...s gas The main flame burns until the tank reaches set temperature then the thermostat interrupts this main gas flow AFTER HAVING CONFIRMED THAT THE WATER HEATER HAS BEEN INSTALLED PER THE INSTALLATION...

Page 9: ...ound the probe cools and heats As the rod expands it pushes against a lever actuated gas valve If the regulator is pushed sufficiently gas flow is interrupted to the main burner Adjusting the temperat...

Page 10: ...is is approximately 120 degrees F the heater may shut off at 110 to 130 F The heater will consistently shut off at this same temperature For this same reason water temperature may drop 15 25 F around...

Page 11: ...ucts Do not forget that your gas or oil furnace and gas clothes dryer also require a like amount of air When calculating air supply provisions also consider the presence of whole house exhaust fans or...

Page 12: ...moke source to verify Manifold Gas Pressure Test Gas pressure checks are done with flowing gas Supply gas pressure checks are taken ahead of the gas control and as close to the heater as possible Pilo...

Page 13: ...its own electrical generating system When two dissimilar metals are joined together and this joint is heated a small electrical current will be produced A thermocouple uses this science Thermocouple...

Page 14: ...mocouple cools If then internal safety does not activate between 1 and 3 MV you will hear a click inside the valve replace the control valve internal safety does activate between 1 and 3 MV valve is w...

Page 15: ...here are small black or red granules on the main burner or top of the heater or corroded jacket or vent piping is noted If then any of the above conditions exist raise the supply air temperature or in...

Page 16: ...uildup Aluminum Hydroxide Condensation Discolored Water Smelly Water Chlorination Process Lack of hot water Thermal Expansion Temperature and Pressure Relief Valve Operation Parts Replacement The part...

Page 17: ...RESSURE DRAIN LINE HOT WATER TO FIXTURES ELECTRICAL JUNCTION BOX ADJACENT CONDUIT ENTRANCE RATING PLATE WITH MODEL AND SERIAL NUMBER TEMPERATURE AND PRESSURE RELIEF VALVE OPENING MAY BE ON SIDE OR TOP...

Page 18: ...IAL ELECTRIC WATER HEATERS This portion of this manual applies to the Operation and Servicing of Residential Electric Tank Type Water Heaters The illustrations are for two element models but the infor...

Page 19: ...U Recovery Rate KW X 3413 divided by Temp Rise X 8 25 Rise F KW X 3413 divided by GPH X 8 25 Supply electrical fusing or breakers should be sized at least 125 of expected heater amperage Water weighs...

Page 20: ...ed enter the water Watt Density the density of the wattage output of the element compared to the surface area of the element i e High Watt Density Element will have the most wattage per square inch of...

Page 21: ...dels Newer Models 1 Location Temperature Range F 2 59T Style 4100 A 6 A 7 X A 6 Upper Tank 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...

Page 22: ...that the water heater has been installed per the installation manual instructions C 2 Circuit Single element Single thermostat Single High Limit C 2 Circuit Prior to 1996 Power Enters High Limit 1 an...

Page 23: ...le Element Single Thermostat Single High Limit Operation from a cold tank of water WIRING DIAGRAM Note If used on a normally two element heater controls will be located behind the upper service cover...

Page 24: ...wer Interrupted to Upper Element Upper Thermostat 1 2 Open Switch Power to Lower Thermostat Upper Thermostat 1 4 Closed Lower Thermostat Contacts Open Through High Limit Lower Thermostat Contacts Clos...

Page 25: ...ed operation Operation From cold tank of water A 6 Circuit Post 1995 Power Enters High Limit Through High Limit Upper Thermostat L1 T4 Contacts Open L1 T2 Contacts Closed Power to Upper Element Elemen...

Page 26: ...ts 2 Thermostats 2 High Limits 4 wire Some electrical utilities give discounts if electricity is used during Off Peak times of the day This circuit allows use of an Off Peak meter which interrupts pow...

Page 27: ...d Terminal 3 Of Upper Thermostat Upper High Limit 1 2 Is Closed Upper Thermostat 3 4 Is Open Upper Thermostat 1 2 Is Closed Upper Element Is On No Power To Lower High Limit Term 1 Top 1 3 Of Tank Is H...

Page 28: ...nessee 27 Residential Electric continued A 7 Circuit 2 Elements 2 Thermostats 2 High Limits 4 Wire WIRING DIAGRAM A 7 Post 1995 Four wire circuit for non simultaneous element operation This circuit pe...

Page 29: ...mostat 3 Upper High Limit 1 2 is Closed Upper Thermostat 3 4 is Open Upper Thermostat 1 2 is Closed Upper Element is On No Power to Lower High Limit Terminal 1 Top 1 3 of Tank is Heated Upper Thermost...

Page 30: ...the A O 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 Conse...

Page 31: ...r non simultaneous operation amperage will be as if wired single phase SIMULTANEOUS DUAL ELEMENTS both elements on when entire tank is cold Element Wattage Upper Lower Full Load Current in Amperes Con...

Page 32: ...res Power to the water heater is OFF Multimeter set to OHMS scale testing Black lead Common port Red lead in or OHMS port Dial indicator set to scale above expected indication Note Volts divided by am...

Page 33: ...k circuit breaker fused disconnect check wire connections in heater junction box check position of heater ON OFF switch if applicable rated voltage is present continue to next step Test voltage betwee...

Page 34: ...rated voltage is not present check wiring from control rated voltage is present repeat Ohms resistance test of element check for water leaks in piping or fixtures Complaint Water Too Hot Conditions T...

Page 35: ...ut be certain that possible amperage will not exceed the multimeter s limit Complaint A grounded element is suspected whenever the water temperature becomes excessively hot and or the end user must pu...

Page 36: ...nditions 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 port Dial ind...

Page 37: ...the meter to a scale below the voltage expected Complaint No hot water Test Conditions 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 cor...

Page 38: ...nt 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 prese...

Page 39: ...e 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 through a wire Watts divided by volts Amps...

Page 40: ...iring may be a See Pages 25 and 27 1 three wire 3 phase circuit 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 lowe...

Page 41: ...ocedure Power to the water heater is OFF Multimeter set to OHMS scale testing Black lead Common port Red lead in or OHMS port Dial indicator set to scale above expected indication Note Volts divided b...

Page 42: ...eck power from the breaker fused disconnect the proper voltage is present check wiring in heater junction box continue to next step Test between upper high limit terminals 2 and 4 If then the proper v...

Page 43: ...oltage is present continue to next step Test between lower high limit terminal 1 and 3 or L1 and L3 If then proper voltage is not present check wiring to upper thermostat and heater junction box check...

Page 44: ...ower thermostat setting Test between lower high limit 4 and lower thermostat 2 or lower high limit L4 and lower thermostat T2 If then proper voltage is not present check jumper between lower high limi...

Page 45: ...uspected 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 through a wire Watts d...

Page 46: ...e 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 therm...

Page 47: ...e are available on the A O Smith website www hotwater com This information is intended to supplement service and maintenance information found in the heater installation and operation manual Why water...

Page 48: ...er 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 49: ...5 grains hardness Hard Water Electric Water Heaters See above explanation Lime calcium forms on the electric elements Elements become excessively hot and may split Split elements often leak to the ou...

Page 50: ...s directly related to the intensity of the surge pressure EFFECTS The damage from water hammer can manifest itself in a number of ways The most common are Expanded Tank Shell This can be demonstrated...

Page 51: ...rs Symptoms often include 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 simp...

Page 52: ...e by weld bead on plug If the tank is new with lime build up to any degree 1 Turn off 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...

Page 53: ...more favorable Soluble iron in the water provides food for the bacteria Rusty discolored water is the end result of the bacteria feeding process Water heaters and storage tanks usually require new ano...

Page 54: ...vel of sulfur in the water b activated hydrogen from cathodic reactions within the tank c water with little or no dissolved oxygen d and temperatures below 138 F Items that can increase the potential...

Page 55: ...el in the anode opening add one gallon of household chlorine bleach e g Clorox or Purex for every 25 gallons of tank capacity STEP 7 Reinstall anode rod s after inspecting and replacing as needed STEP...

Page 56: ...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 bu...

Page 57: ...t 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 bucket fills in 10 sec 6 g...

Page 58: ...They serve a useful purpose Do not remove them The use of pressure reducing valves PRV is another cause PRVs are designed to conserve water and prolong fixture life Many PRVs also act as very effectiv...

Page 59: ...e manufacturers instructions for installing the expansion tank Run the thermal expansion check again The pressure should increase only slightly then hold steady throughout the recovery cycle The expan...

Page 60: ...erature is below its reset temperature The pressure rating on the relief valve should be the same or less than the certified working pressure of the tank generally 150 psi and be below the lowest pres...

Page 61: ...7 1953 Website www hotwater com For every technical problem there is a solution A O Smith Water Products Company proudly introduces our service handbooks and product training CDs To place an order cal...

Search results

Summary of Contents for TC-049-R2

Reviews:

Related manuals for TC-049-R2

Brands by name

Popular brands

A.O. Smith TC-049-R2, Service Handbook

Search results

Summary of Contents for TC-049-R2

Reviews:

Related manuals for TC-049-R2

Brands by name

Popular brands