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A.O. Smith 120 trough 500, Service Handbook, Page: 30 / 55

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A.O. Smith 120 trough 500 Service Handbook Download Page 30

BTR TANK TYPE HEATERS

SERVICE HANDBOOK

A.O. Smith Water Products

Service Handbook

Irving, Texas ©2000

Training Department

29

NORMAL OPERATION (continued)

Condition:

• 

Thermostat closed, damper in process of opening

STEP B

TEST FOR 24VAC BETWEEN BLACK AND ORANGE

IF

THEN

24VAC is present

Continue to Step C.

24VAC is not present

See Troubleshooting Step A2

Condition:

• 

Thermostat closed, damper fully open

STEP C

TEST FOR 24VAC BETWEEN BLACK AND YELLOW

IF

THEN

24VAC is present

Continue to Step 11

24VAC is not present

See Troubleshooting Step A3

Summary of Contents for 120 trough 500

Page 1: ......

Page 2: ...RODUCTION This service handbook is designed to aid in servicing and troubleshooting A O Smith BTR water heaters in the field No duplication or reproduction of this book may be made without the express...

Page 3: ...capable of measuring continuity gas pressure gauge or manometer gauge AOS pt no 8099 2 water pressure gauge AOS pt no 4798 thermometer AOS pt no 4870 range 0 220 degree F 1 2 inch socket with extensi...

Page 4: ...r the BTR 120 through 500 model heaters The installation manual covers most of these items in detail Clearance to Combustibles Table MODEL A B C 120 200 1 2 54CM 1 2 54CM 1 2 54CM 250 305 2 5 08CM 2 5...

Page 5: ...ng The vent shall extend at least 3 feet above the highest point where it passes through a roof of a building and at least 2 feet higher than any portion of a building within a horizontal distance of...

Page 6: ...et of air per 1000 BTUH input of the gas input The National Fuel Gas Code also recommends an additional 2 5 cu ft of excess air This 12 5 cu ft minimum supply air per 1000 BTUH input applies to natura...

Page 7: ...s as a relief opening for flue gases should the vent become obstructed or a downdraft condition occur Additionally when the heater is installed in a confined space and communicating with the outdoor a...

Page 8: ...tical to install vertical make up air ducts to the out doors Again two openings are required one within 12 inches of the top of the enclosure and one within twelve inches of the bottom of the enclosur...

Page 9: ...ss for vertical ducts horizontal make up air ducts should be installed When using horizontal ducts two openings are required one within 12 inches of the top of the enclosure and one within twelve inch...

Page 10: ...major cause of combustion problems One common example is in a restaurant installation where exhaust vent equipment was not considered in sizing make up air requirements This may result in air being ba...

Page 11: ...es soaps waxes salts etc are drawn into the combustion chamber with the make up air and once fired mix with water vapor in the gases to form extremely corrosive hydrochloric or hydrofluoric acid and o...

Page 12: ...c Minimum Supply Pressure 4 5 w c 11 w c Manifold Pressure 3 5 w c 10 w c The supply gas pressure is normally measured at the dirt leg or at the gas pressure tapping on the gas supply shutoff valve Th...

Page 13: ...ls The pilot gas regulator is found under its cover screw It is factory preset at 3 5 w c but can be adjusted from 2 5 to 5 inches water column The main gas regulator is found under its cover screw It...

Page 14: ...pressure venting appliances They are approved for type B vent For larger applications BTR water heaters can be common vented together either in a tapered manifold or constant size manifold Follow Nat...

Page 15: ...anically aid a lazy chimney in vertical vent applications They are not designed to allow through the wall vent installations See Power Venter SINGLE UNIT INSTALLATION When mechanically venting the fol...

Page 16: ...r heaters can be used with power vent kits for sidewall venting A O Smith offers power vent kits for use on installations with a maximum of 100 equivalent feet of vent piping The power vent kits also...

Page 17: ...k type water heaters an examination of their sequence of operation is necessary When the thermostat calls for heat the relay in the draft hood assembly activates de energizing the flue damper motor Th...

Page 18: ...BTR TANK TYPE HEATERS SERVICE HANDBOOK A O Smith Water Products Service Handbook Irving Texas 2000 Training Department 17 BTR ELECTRICAL SEQUENCE 100 109 Series...

Page 19: ...park S tops Dam per Motor Energized and Dam per Closed Power to Dam per Relay 4 Interupted Them ostat O pens Main Burner Heats Tank Module M V Term inal Sends 24V To M ain G as Coil 90 Second Trial 5...

Page 20: ...lied to the heater the tank is full of water gas is supplied to the unit STEP 1 TEST THE TRANSFORMER STEP 1 TO TEST THE TRANSFORMER Using a multimeter test for 24 VAC between the secondary transformer...

Page 21: ...TERMINAL TEST Test for 24 VAC between the left high limit terminal and ground IF THEN The meter does not read 24 VAC Check wiring between transformer and high limit The meter reads 24 VAC Go to Step 3...

Page 22: ...t storage water temperature below 185 degrees The meter reads 24 VAC Go to step 4 After Push in Reset 24 VAC is now present Reasons For Resetting Condition Cause Solution High limit open Never set on...

Page 23: ...the damper is closed Go to step 7 Note If the water temperature in the tank is below 120 degrees F temporarily disconnect the jumper wire between the high limit and thermostat to simulate a satisfied...

Page 24: ...y are one piece Regardless of which part is defective both parts should be changed Voltage is present This verifies that the motor is receiving power but not closing the damper Replace the motor AOS p...

Page 25: ...VAC between right terminal and ground IF THEN The meter does not read 24 VAC and the jumper wire between the high limit and the thermostat is in place Replace the thermostat The meter reads 24 VAC Go...

Page 26: ...r 24 VAC between the yellow wire on the PC board and ground Effikal Check from orange wire to neutral IF THEN 24 VAC is not present Check the black wire connections between the PC board and high limit...

Page 27: ...pted Then the motor clutch is disengaged and the damper opens The damper proves it is open via an end switch before power flows through the red wire from the PC board Place the red test probe on the s...

Page 28: ...or close Effikal Damper The wiring colors from the damper PC Board are different from previous series BTR C and BTC Models The heater harness wires still serve the same function Service Switch Adapter...

Page 29: ...ow White 24V common 4 Black Series 110 and 111 heaters and converted model BTR C and BTC heaters with Effikal Dampers NORMAL OPERATION Condition Heater on standby Damper closed High Limit closed STEP...

Page 30: ...tat closed damper in process of opening STEP B TEST FOR 24VAC BETWEEN BLACK AND ORANGE IF THEN 24VAC is present Continue to Step C 24VAC is not present See Troubleshooting Step A2 Condition Thermostat...

Page 31: ...BOARD IF THEN 24VAC is present This is correct 24VAC is not present See Steps 1 thru 4 Check the harness plugs connecting heater and damper for looseness or damage Condition Thermostat closed damper...

Page 32: ...OTING THE EFFIKAL STYLE DAMPER continued Condition Thermostat closed damper is open fully STEP A3 TEST FOR 24VAC BETWEEN BLACK AND YELLOW IF THEN 24VAC is present This is correct continue to Step 11 2...

Page 33: ...HARNESS TEST Test for 24 VAC between terminal 24V on the IID module and 24V GND IF THEN 24 VAC is not present Check the wiring harness 24 VAC is present Go to step 12 Note This test may be easier to...

Page 34: ...ID MODULE TEST STEP 12 IID MODULE TEST Power to the Pilot Valve Using a multimeter test for 24 VAC between terminal PV and 24V GND on the IID during the 90 second trial for ignition IF THEN The meter...

Page 35: ...ot assembly Note The pilot burner mounts on the left side of the main burner IF THEN The igniter is not sparking Check for A 7 64 spark gap Spark cable continuity Ground cable continuity Sparking is p...

Page 36: ...ot assembly is sparking but no pilot flame is established disconnect the pilot valve solenoid leads Using a multimeter set to read ohms test for 20 ohms resistance 5 through the solenoid coil IF THEN...

Page 37: ...AOS meters the black wire is in the com port the red wire is in the 10A port the dial is set to 20M 10A in the DC AMP test area Blue PV wire is disconnected from the ignition PV terminal Install meter...

Page 38: ...Department 37 STEP 15 MAIN BURNER TEST Note BTR series 108 and 109 implemented a new main burner stamping process burners appear the same as illustrated STEP 15 MAIN BURNER TEST Visually check for mai...

Page 39: ...ater than the igniter surface the signal becomes a DC current that the module can interpret The pilot hood must be properly grounded and the pilot flame must remain in contact with both surfaces for t...

Page 40: ...P 17 IID MODULE TEST Pilot is lit Sparking has stopped STEP 17 IID MODULE TEST Power to the Main Valve Using a multimeter test for 24 VAC between terminal MV on the IID and 24V GND IF THEN 24 VAC is n...

Page 41: ...ALVE CHECK BTR 120 400 GAS VALVE STEP 18A MAIN GAS VALVE CHECK Disconnect wires from gas valve TH and TR terminals Using a multimeter test for 68 ohms plus or minus 5 between TH and TR on the main val...

Page 42: ...rage 10A wire to red gas valve wire COM wire to MV terminal of ignition module Turn power on to heater After pilot lights and sparking stops IF THEN 25 to 35 DC Amps is not present Replace the gas val...

Page 43: ...ving Texas 2000 Training Department 42 BTR WIRING DIAGRAM NATURAL AND PROPANE GAS Honeywell Ignition System 110 109 Series IF ANY OF THE ORIGINAL WIRE AS SUPPLIED MUST BE REPLACED USE ONLY TYPE 105 C...

Page 44: ...E REPLACE RELIEF VALVE EXCESSIVE WATER TEMPERATURE CHECK WIRING REPLACE DUAL CONTROLLER LARGE VOLUME WATER RELIEF FROM T P VALVE FAULTY RELIEF VALVE REPLACE RELIEF VALVE PREMATURE TANK LEAKAGE CONDENS...

Page 45: ...nt of lime accumulation during the same period of time will be nearly 2 times greater if water is stored at 140 degrees F than at 120 degrees F A 180 degree setting will build up lime about seven time...

Page 46: ...BTR TANK TYPE HEATERS SERVICE WORKBOOK A O Smith Water Products Service Handbook Irving Texas 2000 Training Department 45 BTR MODELS 197 AND 198 Series 100 101...

Page 47: ...BTR TANK TYPE HEATERS SERVICE WORKBOOK A O Smith Water Products Service Handbook Irving Texas 2000 Training Department 46 BTR MODELS 197 AND 198 continued Series 100 101...

Page 48: ...93314 1 193314 1 6 Gasket 99036 99036 7 Pressure Plate 99037 99037 8 Screws Self Tapping 69852 69852 9 Control Ignition Module 193325 193325 10 Control Dual w ECO 192828 192828 11 Drafthood 192957 4 1...

Page 49: ...BTR TANK TYPE HEATERS SERVICE WORKBOOK A O Smith Water Products Service Handbook Irving Texas 2000 Training Department 48 BTR MODELS 120 through 500 Series 104 105...

Page 50: ...BTR TANK TYPE HEATERS SERVICE WORKBOOK A O Smith Water Products Service Handbook Irving Texas 2000 Training Department 49 BTR MODELS 120 through 500 continued Series 104 111...

Page 51: ...4 193444 193444 19 Inlet Tube 193729 192626 193729 193729 192626 192626 20 Gas Valve Natural 192827 2 192827 2 192827 2 192827 2 192827 2 192827 2 21 Gas Valve LP 192827 3 192827 3 192827 3 192827 3 1...

Page 52: ...BTR 120 400 24VAC 60hz 6A 7 to 3 5 W C STEP OPEN BTR 500 24VAC 60hz Dual Gas Valve STEP OPEN AOS 192827 2 AOS 193366 0 PROPANE GAS BTR 120 400 2 5 10 W C STEP OPEN BTR 500 24VAC 60hz Dual Gas Valve ST...

Page 53: ...ed and corrective action taken if required SERVICE AGENT INSTALLATION DATE MODEL NUMBER SERVICE DATE SERIAL NUMBER LOCATION ADDRESS GAS TYPE CHECK ONE NATURAL PHONE ___ ____ PROPANE I Check Clearances...

Page 54: ...damper blade fully open before ignition sequence occurs yes no Is burner cover plate in place yes no Is burner floor shield in place yes no Does IID lockout occur after 30 sec trial for ignition Propa...

Page 55: ...BTR TANK TYPE HEATERS SERVICE WORKBOOK A O Smith Water Products Service Handbook Irving Texas 1999 Training Department 54 COMMENTS Author Terry Mulder...

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