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A.O. Smith BTH 120 Series, Service Handbook

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A.O. Smith BTH 120 Series Service Handbook Download Page 23

21

Servicing should only be performed by a Qualified Service Technician

ACTION:

Press 

Change

 then use the 

UP

 and 

DOWN

 buttons to change the 

Operating Set Point

.

DISPLAY:

Note: 

This procedure can also be used to change the 

Differential

. The Tank 

Upper

 and 

Lower Temperatures

 

are not user changeable. They are determined by the temperature probes on the heater.

ACTION:

Press 

Update

 to accept the change or 

Cancel

 to reset it.

DISPLAY:

Summary of Contents for BTH 120 Series

Page 1: ...ennessee Waltz Parkway Ashland City TN 37015 PRINTED IN THE U S A 1012 316586 002 SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVICE TECHNICIAN Service Handbook COMMERCIAL GAS HIGH EFFICIENCY WATER HEATERS http waterheatertimer org How to troubleshoot gas water heater html ...

Page 2: ......

Page 3: ...RATURE OPERATING SET POINT DIFFERENTIAL 20 CHANGING THE DISPLAY UNITS 22 FAULT AND WARNING CONDITIONS ADVANCED DIAGNOSTIC INFORMATION 24 ACCESS TO THE CURRENT FAULT OR WARNING 25 FAULT CODES 26 VIEWING THE FAULT HISTORY VIEWING INFORMATION ABOUT THE HEATER 27 CONTROL SEQUENCE TYPICAL ALL MODELS 28 CONTROL SEQUENCE FLOW CHART 29 CONTROLS CENTRAL CONTROL BOARD CCB 30 CONTROLS GAS CONTROL VALVE BTH 1...

Page 4: ...a resource for installation and service information This handbook is intended for use by licensed plumbing professionals and reference should be made to the instruction manual accompanying the product This handbook contains supplemental information to the product s instruction and operation manual QUALIFICATIONS ANSI Z223 1 Sec 3 3 83 Qualified Agency Any individual firm corporation or company tha...

Page 5: ... increments Note A digital manometer is required for testing pressure switches and can replace a gas pressure gauge draft gauge or slack tube manometer for checking gas pressure UEi model EM200 or equivalent WATER PRESSURE GAUGE w LAZY HAND AND HOSE BIBB CONNECTION THERMOMETER 1 1 16 INCH SOCKET WITH EXTENSION FOR POWERED ANODE REPLACEMENT SET OF NUMBERED DRILL BITS DIGITAL MANOMETER DIGITAL MULTI...

Page 6: ...crawl space or an attic the hard wired carbon monoxide detector with alarm and battery back up may be installed on the next adjacent floor level In the event that the requirements of this subdivision can not be met at the time of completion of installation the owner shall have a period of thirty 30 days to comply with the above requirements provided that during said thirty 30 day period a battery ...

Page 7: ...ust be equipped with a gas supply regulator The minimum supply pressure is measured while gas is flowing dynamic pressure The supply pressure should be measured with all gas fired appliances connected to the common main firing at full capacity If the supply pressure drops more than 1 5 W C 0 05 PSI Gauge as gas begins to flow to the water heater then the supply gas system including the gas line an...

Page 8: ...it and operating controls for proper operation 5 Check the vent system seams and joints and ensure that there is no leakage of flue products into the room 6 Verify correct input rate see below HIGH ALTITUDE INSTALLATIONS BTH 120 150 For water heater installation locations with elevations above 6 500 feet 1982 meters consult the High Altitude Installation section of the owners manual 1 Attach a pre...

Page 9: ...O THE FAN SPEED WHICH IN EFFECT CONTROLS THE AMOUNT OF GAS FLOW THEREFORE THE UNIT WILL SELF ADJUST TO ACQUIRE THE CORRECT AMOUNT OF INPUT Supply gas pressure to the water heater must not exceed a maximum of 10 5 w c 2 62 kPa for natural gas or 14 w c 3 49 kPa for propane The minimum supply gas pressure is 4 8 w c 1 20 kPa for natural gas and 8 5 w c 2 12 kPa for propane gas Once the unit is insta...

Page 10: ...anifold pressure using a pressure gauge manometer connected to the manifold pressure tap on the gas control valve If manifold pressure adjustment is required remove cover screw from top of the gas control valve Using a small screwdriver turn adjusting screw clockwise to increase gas pressure or counter clockwise to decrease gas pressure to obtain 4 0 w c 1 0 kPa for Natural Gas and 10 w c 2 49 kPa...

Page 11: ...9 Servicing should only be performed by a Qualified Service Technician INSTALLATION QUICK TIPS BTH 300 400 500 SEE MANUAL FOR COMPLETE INSTALLATION INSTRUCTIONS DETAILS ...

Page 12: ...ped with provision for draining condensate from vent system PH of condensate approximately 3 59 within tolerance for cast iron drains Type venting May be installed Direct Vent draws all fresh air for combustion from and discharges flue gases to the outdoor atmosphere through 2 pipes May be installed Conventional Vent uses room air for combustion and discharges flue gases to the outdoor atmosphere ...

Page 13: ...M 3 Maximum Pipe Ft M 4 Maximum Pipe Ft M ONE 1 7 2 1 45 13 7 115 35 TWO 2 7 2 1 40 12 2 110 33 5 THREE 3 7 2 1 35 10 7 105 32 FOUR 4 7 2 1 30 9 1 100 30 5 FIVE 5 7 2 1 95 29 SIX 6 7 2 1 90 27 4 VENTING TABLES BTH 300 400 500 Maximum equivalent feet of intake and vent pipe using 4 PVC is 70 feet 21 3 m Equivalent feet must include any 90 elbows two 45 elbows equal one 90 elbow Four inch diameter 9...

Page 14: ...0 5 cm on centerline vertically above the first vent Concentric kits may be extended to a maximum allowable length of 5 feet 152 cm Schedule 40 PVC pipe must be carefully measured and cut to the desired length Do not use couplings when extending the length of a concentric termination The use of couplings will restrict the flow through the termination and may cause improper combustion For more info...

Page 15: ... Q HOW DO THE PH VALUES OF CONDENSATE AND CARBONATED COLA DRINK COMPARE A The pH of the BTH condensate average 4 5 which is approximately 4 times less concentrated than the limit of 4 3 recommended by the DMA Any water flow in the drain rapidly dilutes the condensate even more A can of leading carbonated cola drink measured a pH of 2 5 which is 300 times more concentrated than the BTH condensate Q...

Page 16: ...12 inches 30 cm J Clearance to a non mechanical air supply inlet into building or combustion air inlet to any other appliance 6 inches 15 cm for appliances up to 10 000 Btu hr 3 kW 12 inches 30 cm for appliances between 10 000 Btu hr 3 kW and 100 000 Btu hr 30kW 36 inches 91cm for appliances above 100 000 Btu hr 30 kW 4 feet 1 2 m below or to side of opening 1 foot 30 cm above opening D Vertical c...

Page 17: ...cm 6 inches 15 cm J Clearance to a non mechanical air supply inlet into building or combustion air inlet to any other appliance 6 inches 15 cm for appliances up to 10 000 Btu hr 3 kW 12 inches 30 cm for appliances between 10 000 Btu hr 3 kW and 100 000 Btu hr 30 kW 36 inches 91 cm for appliances above 100 000 Btu hr 30 kW 6 inches 15 cm for appliances up to 10 000 Btu hr 3 kW 9 inches 23 cm for ap...

Page 18: ...nal must terminate on the same exterior wall and must be located at a minimum of 24 61cm from the vertical centerline of the exhaust vent terminal see Figure below In colder climates increasing this separation to at least 48 122 cm will reduce possibility of frost over from side winds blowing exhaust vapors to the air intake of the direct vent 2 The horizontal centerline of the intake vent termina...

Page 19: ...VED BEFORE GLUING PIPE TO THE CONNECTOR THE INLET VENT PIPE MAY THEN BE GLUED TO THE AIR INTAKE PROVIDED ON THE UNIT Remove the balance plate BTH400 500 only and air intake screen before gluing intake air pipe to the fitting 45 PVC Elbow 3 120 250 4 300 500 Two 3 or 4 45 PVC elbows with air intake screens are provided with each unit Both elbows are to be used in direct vent applications The screen...

Page 20: ...mediately above them on the screen While the water heater is operating the user interface will display the desktop screen if there are no active faults or warnings An example of this screen is shown below The first temperature on this screen is the temperature of the water inside the tank The second temperature on this screen is the Operating Set Point The Operating Set Point is the temperature at...

Page 21: ...ted by the control but can also occur when an external system like an energy management system has asked the water heater to discontinue any further heat cycles The blower is being energized The blower pressure switch has been made The igniter has been energized The igniter has been energized and sufficient current for ignition has been detected The control has requested that the gas control valve...

Page 22: ...s the regulated temperature for the water in the tank This parameter is adjusted in the desktop Temperature menu Items in this menu allow you to monitor different temperature readings in the tank along with adjusting the Operating Set Point and Differential ACTION From the desktop screen press Menu DISPLAY ACTION From the Main Menu press Select to enter the Temperatures screen DISPLAY ...

Page 23: ... DOWN buttons to change the Operating Set Point DISPLAY Note This procedure can also be used to change the Differential The Tank Upper and Lower Temperatures are not user changeable They are determined by the temperature probes on the heater ACTION Press Update to accept the change or Cancel to reset it DISPLAY ...

Page 24: ...splays This can be found in the Display Settings menu Also in this menu you may adjust how the back light operates and the contrast of the LCD screen ACTION From the Main Menu press the DOWN button to highlight Display Settings then press Select DISPLAY ACTION Use the UP and DOWN buttons to highlight the desired setting then press Change Again use the UP and DOWN buttons to scroll through the opti...

Page 25: ...23 Servicing should only be performed by a Qualified Service Technician ACTION Press Update to accept the change or Cancel to reject it DISPLAY ...

Page 26: ...at may cause the water heater to operate in a less than optimal condition but does not pose a safety concern Note When these conditions occur continued heating cycles will continue and the heater will attempt to regulate the water in the tank to the Operating Set Point Example of a Warning Faults This is a safety related condition that has been detected by the heater Note When these conditions occ...

Page 27: ...the control it will automatically be displayed on the screen and the back light will blink If you choose to leave the current fault or warning by pressing the Back key you can always return to the fault through the display menu ACTION To get to the current fault information screen press Menu DISPLAY ACTION Press the DOWN button for more information DISPLAY ...

Page 28: ...be Short 0x46 Lower Probe Short 0x47 Upper Probe Open 0x48 Lower Probe Open 0xB4 Flame Probe Short 0xA9 Flame Detect Error 0xA5 Energy Cut Out ECO 0xA6 Low Gas 0xA7 Blocked Air Intake 0xA8 Blocked Exhaust Event 0xAC Blower Prover Failure 0x1AC Blower Prover Open 0xAE Igniter Current Error 0x1AE Low Igniter Current 0xB2 Ignition Failure 0xAA Gas Control Valve Error 0x1AA Gas Control Valve Failure E...

Page 29: ...ormation DISPLAY ACTION Press the DOWN key to scroll through the Fault History If you select a specific fault or warning you may press the VIEW button to view details regarding this fault DISPLAY Viewing Information About the Water Heater The control for this water heater monitors many different aspects of the water to ensure safe and optimal operation Much of the information monitored is availabl...

Page 30: ...determined time period then will be turned off 8 The control will monitor the flame sense probe to confirm a flame is present If a flame is not verified within predetermined time period the gas control valve will immediately be closed and the blower will continue to run for approximately 30 seconds inter purge The control will try for ignition two more times before lockout 9 If a flame is confirme...

Page 31: ...29 Servicing should only be performed by a Qualified Service Technician CONTROL SEQUENCE FLOW CHART ...

Page 32: ...he settings given through the desk top menu UIM The CCB also monitors all pressure switches the hot surface igniter tank temperatures the gas control valve the powered anodes and the flame sensor The CCB directly controls blower speed on the BTH 199 and 250 models and indirectly controls blower speed on the BTH 400 and 500 by means of a Variable Frequency Drive see Page 42 Note Improper operation ...

Page 33: ...31 Servicing should only be performed by a Qualified Service Technician This is the back of the UIM ...

Page 34: ...re may be read at the inlet pressure tap only if the manual shut off valve is in the ON position Leaving the knob in the OFF position will not allow the burner to fire and will generate a fault code on the UIM User Interface Module CONTROLS GAS CONTROL VALVE BTH 150 The gas control valve on the BTH 150 has a built in pressure regulator The regulator may be adjusted by removing the cap screw Inlet ...

Page 35: ...he manifold pressure on this valve is 0 WC 0 kPa when the water heater is running Refer to the Gas Pressure Specifications table on Page 4 Note Tubing shown on pressure connections is installed for manometer connections It is not supplied with the water heater WARNING Do not attempt adjustments on this gas control valve unless you have a combustion analyzer Contact the help line listed on the wate...

Page 36: ... Technician CONTROLS GAS CONTROL VALVE ORIFICE CHART BTH 300 400 100 101 The gas control valve has a built in field adjustable pressure regulator The gas control valve for the BTH Natural gas model is shown below This is a 24V solenoid operated gas control valve ...

Page 37: ... cap screw The adjustment screw is underneath The gas control valve for the BTH 500 Natural gas model is shown below This is a 24V solenoid operated gas control valve For Series 100 and 101 For Series 104 ORIFICE CHART BTH 120 thru 500 Model Series 120 100 101 150 100 101 199 100 101 250 100 101 300 100 101 400 100 101 500 100 101 400 500 104 Natural 0 186 0 199 NA NA 0 274 0 314 0 347 NA Propane ...

Page 38: ...ally closed The blocked outlet proving switch electrical contacts will open on a rise in pressure If a fault occurs check to see if the condensate is allowed to flow freely from the exhaust elbow and for obstructions in the exhaust venting and exhaust vent terminal Also check that the equivalent feet of vent pipe for the specific model has not been exceeded Check the vent length tables on Page 11 ...

Page 39: ...y be performed by a Qualified Service Technician CONTROLS PRESSURE SWITCHES BTH 120 THROUGH 250 Note Check the website www hotwater com for Technical Bulletin A023 06 Air Pressure Switches under Literature Technical Bulletins ...

Page 40: ...nly be performed by a Qualified Service Technician CONTROLS PRESSURE SWITCHES BTH 300 400 500 Note Check the website www hotwater com for Technical Bulletin A023 06 Air Pressure Switches under Literature Technical Bulletins ...

Page 41: ...Also shown is the burner sight glass These features are typical for all models Flame Sensor Hot Surface Igniter Mounting Bolts Burner sight glass The new Cyclone Xi commercial water heater is equipped with powered anodes These anodes do not need replacement The CCB monitors the current through the anodes and will declare a fault if there is a disconnected wire or if there is no water in the tank P...

Page 42: ... by the CCB is 2 7 amps Once this threshold is met a check mark will appear by the igniter icon in the UIM display FLAME SENSOR This water heater is equipped with an electronic flame sensor The flame sensor senses flame by passing a small electric current through the burner flame This type of flame sensing is also known as flame rectification The CCB is looking for a minimum current of 7 micro amp...

Page 43: ...METER that has a Hertz Hz setting as shown in the illustration below If the Hz signal is within 5 of the numbers in the chart below the reading is normal Model High Speed Hz Low Speed Hz 199 N 182 172 250 N 227 178 199 Propane LP 200 194 250 Propane LP 254 191 Note Removing the plug shown in the illustration will cause the blower to accelerate and the input of the water heater to increase to a muc...

Page 44: ...ntrol board that instructs the VFD to transmit the proper frequency to the blower to produce the proper blower speed and proper input Three conditions must be met for the frequency drive to start the blower 1 120VAC must be supplied to the VFD 120VAC input 2 The ignition control board closes an enable circuit terminals LI1 and 15V 3 The ignition control board sends a 1 10VDC instruction terminals ...

Page 45: ...ncy display If the frequency is more than 5 out of range check the DC volt signal at the terminals OV and AI1 shown on Page 42 Voltage Frequency Speed Instructions VFD Model Series Ignition Low Speed Purge High Speed Run Volts 0 10 VDC Frequency Hz Pressure w c Volts 0 10 VDC Frequency Hz Pressure w c Volts 0 10 VDC Frequency Hz Pressure w c BTH 400 100 7 53 150 5 3 7 77 155 5 85 7 77 155 5 3 BTH ...

Page 46: ...44 Servicing should only be performed by a Qualified Service Technician WIRING DIAGRAM BTH 120 300 ...

Page 47: ...45 Servicing should only be performed by a Qualified Service Technician WIRING DIAGRAM BTH 400 500 ...

Page 48: ...46 Servicing should only be performed by a Qualified Service Technician NOTES ...

Page 49: ...47 Servicing should only be performed by a Qualified Service Technician NOTES ...

Page 50: ... Handbooks For additional information contact A O Smith Corporation 500 Tennessee Waltz Parkway Ashland City TN 37015 Tech Support 800 527 1953 Parts 800 433 2545 www hotwater com COMMERCIAL GAS HIGH EFFICIENCY WATER HEATERS Copyright 2012 A O Smith Water Heater Company All rights reserved ...

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