Service Handbook COMMERCIAL GAS HIGH EFFICIENCY WATER HEATERS MODELS COVERED: BTH 120 THRU 500 SERIES 100, 101 AND BTH 400/500 SERIES 104 500 Tennessee Waltz Parkway Ashland City, TN 37015 SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVICE TECHNICIAN PRINTED IN THE U.S.A.
TABLE OF CONTENTS INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 QUALIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 TOOLS REQUIRED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 GENERAL INFORMATION . . . . .
INTRODUCTION The service handbook is designed to aid in servicing and troubleshooting A. O. Smith Cyclone Xi BTH commercial water heaters in the field. No duplication or reproduction of this book may be made without the express written authorization of the A. O. Smith Corporation. The following text and illustrations will provide you with a step by step procedure to verify proper installation, operation, and troubleshooting procedures.
TOOLS REQUIRED • ELECTRICAL MULTIMETER CAPABLE OF MEASURING CONTINUITY/ OHMS, AC & DC VOLTS, AMPERES, MICROAMPERES, MILLIVOLTS, and FREQUENCY (Hz) • • UEi Model DL289 or equivalent DIGITAL MANOMETER + 60" W. C. in .01" 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.
GENERAL INFORMATION INSTALLATION REQUIREMENTS FOR THE 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 limite
GAS SUPPLY SYSTEMS Low pressure building gas supply systems are defined as those systems that cannot under any circumstances exceed 14” W.C. (1/2 PSI Gauge). These systems do not require pressure regulation. Measurements should be taken to insure that gas pressures are stable and fall within the requirements stated on the water heater rating plate. Readings should be taken with all gas burning equipment off (static pressure) and with all gas burning equipment running at maximum rate (dynamic pressure).
INSTALLATION QUICK TIPS – BTH 120 AND 150: GAS PRESSURE ADJUSTMENT PROCEDURE: MANIFOLD GAS PRESSURE BTH 120 AND 150 MODELS Main line gas pressure to the water heater for natural gas should be between a maximum of 10.5" w.c. (2.62 kPa) for natural gas, 14.0" w.c. (3.49 kPa) for propane and a minimum of 4.8 w.c. (1.20 kPa) for Natural Gas, and 8.5" w.c. (2.12 kPa) for Propane Gas. Also see "Gas Pressure Specifications" Table on Page 4.
2. “Clock” the meter as in step (2) above. 3. Repeat steps (1) and (2) until the specified input rate is achieved. 4. Turn the manual gas control valve to “OFF”. Replace the pressure regulator cover screw. Remove the pressure gauge or manometer from the manifold pressure tap and replace the set screw in the manifold pressure tap.
INSTALLATION QUICK TIPS – BTH 300, 400, 500 GAS PRESSURE ADJUSTMENT PROCEDURE: MANIFOLD GAS PRESSURE BTH 300, 400, 500 A minimum dynamic gas supply pressure of 5.2" w.c. (1.30 kPa) for Natural Gas and 11" w.c. (2.74 kPa) for Propane (LP) Gas is required before making any adjustment to the gas control pressure regulator. Attempts to adjust the regulator during periods of low gas supply pressure could result in over firing of the water heater when the gas supply pressure returns to normal.
INSTALLATION QUICK TIPS – BTH 300, 400, 500 SEE MANUAL FOR COMPLETE INSTALLATION INSTRUCTIONS & DETAILS Servicing should only be performed by a Qualified Service Technician 9
INSTALLATION – VENTING CATEGORY AND MATERIALS CYCLONE VENTING Category IV • • • • 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 through 1 pipe. Positive pressure in vent, above atmospheric. These models will produce excessive condensate in vent.
VENTING TABLES – BTH 120 - 250 Maximum equivalent feet of intake and vent pipe using 3" PVC is 50 feet (15.2 m). Equivalent feet must include any 90° elbows (two 45° elbows equal one 90° elbow). Three inch diameter 90° elbows are equivalent to 5' (1.5 m) of pipe. Maximum equivalent feet of intake and vent pipe using 4" PVC is 120 feet (36.6 m). Equivalent feet must include any 90° elbows (two 45° elbows equal one 90° elbow). Four inch diameter 90° elbows are equivalent to 5' (1.5 m) of pipe.
CONCENTRIC VENTING Concentric venting allows for a single wall penetration. For multiple water heater installation using this vent practice, any additional vents of this type may be located 12" (30.5 cm) on centerline to either side of the first vent or 12" (30.5 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.
VENT CONDENSATION 6” PIPE FIELD SUPPLIED 6” x 4” REDUCER FIELD SUPPLIED 4” PIPE FIELD SUPPLIED EXHAUST ELBOW VENT CONNECTION FACTORY INSTALLED VENT (EXHAUST) CONNECTION Failure to properly install the drain line on the condensate elbow will result in a water heater shut down and a “blocked exhaust” fault message. The average dew point of natural gas flue products is 127 °F (53 °C) . Propane flue products is 119 °F (48 °C).
VENTING – ALL MODELS – SINGLE PIPE DIRECT VENT – USING OUTSIDE AIR TERMINATION CLEARANCES SIDEWALL POWER VENT POWER VENT (using room air for combustion) EXTERIOR CLEARANCES FOR SIDEWALL VENT TERMINATION G V D H A v E L v B FI XE D CLOSED V F OPERABLE V B B C OPERABLE V B FI XE D CLOSED M X V B V K J A X V B V VENT TERMINAL X AIR SUPPLY INLET AREA WHERE TERMINAL IS NOT PERMITTED Figure 1 Vent terminal clearances for “Power Vent” installations.
VENTING – ALL MODELS – TWO PIPE DIRECT VENT – USING OUTSIDE AIR TERMINATION CLEARANCES SIDEWALL DIRECT VENT DIRECT VENT (using outdoor air for combustion) EXTERIOR CLEARANCES FOR SIDEWALL VENT TERMINATION G V D H A v E L v B F B B C FI XE D CLOSED V OPERABLE V OPERABLE V B B FI XE D CLOSED V M X V X V K J A B V VENT TERMINAL X AIR SUPPLY INLET AREA WHERE TERMINAL IS NOT PERMITTED Figure 2 Vent terminal clearances for “Direct Vent” installations.
VENT TERMINATION – DIRECT VENT – ALL MODELS WHEN LOCATING THE TERMINALS ON A SIDEWALL, THE FOLLOWING SPECIFICATIONS PERTAINING TO TERMINAL LOCATION MUST BE FOLLOWED. 1. The intake vent terminal and the exhaust vent terminal 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).
DIRECT VENTING – ALL MODELS The air intake provided on the unit contains an air intake screen to prevent large particles from entering the unit. WHEN THE UNIT IS TO BE SET UP AS A DIRECT VENT, THE BALANCE PLATE AND AIR INTAKE SCREEN MUST BE REMOVED BEFORE GLUING PIPE TO THE CONNECTOR. THE INLET VENT PIPE MAY THEN BE GLUED TO THE AIR INTAKE PROVIDED ON THE UNIT. 45° PVC Elbow AIR INTAKE SCREEN Remove the balance plate (BTH400/ 500 only) and air intake screen before gluing intake air pipe to the fitting.
CONTROL OVERVIEW Interaction with the water heater controller is through an LCD display called the User Interface Module (UIM). This screen is also referred to as the “desktop” or “desktop menu”. Up and down buttons and three operation buttons allow navigation through the control menus and to make adjustments to the water heater. Operation of the three lower buttons is defined immediately above them on the screen.
The table of status icons describes graphically operational details of the water heater. Below is a legend of all the status icons: Status Icon Description The temperature of the water in the tank has fallen and the water heater will now initialize a new heating cycle. The temperature of the water in the tank has reached the Operating Set Point. The control is unable to initiate any further heating cycles.
ADJUSTING TANK TEMPERATURE – OPERATING SET POINT – DIFFERENTIAL The Operating Set Point of this water heater determines 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.
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.
CHANGING THE DISPLAY UNITS The desktop menu Display Settings has the option of selecting between degrees Fahrenheit and degrees Celsius for temperature displays. 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.
ACTION: Press Update to accept the change or Cancel to reject it.
FAULT AND WARNING CONDITIONS – ADVANCED DIAGNOSTIC INFORMATION This water heater control has the ability to monitor almost all aspects of the water heater’s operation. In the event of an undesirable or unsafe condition that occurs, the water heater control will detect this condition and determine the appropriate action. The water heater control will display the information on the desktop in plain text that accurately describes the condition and diagnostics information that can be used to correct the issue.
ACCESS TO THE CURRENT FAULT OR WARNING When a fault or warning has been detected by 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.
FAULT CODES All faults, warnings, and errors are given in plain English text. Some have a Code alpha/numeric value assigned. Please read the full English text and not the alpha/numeric value when calling for assistance. Following is a complete list of all faults, warnings, and errors for this commercial gas control.
VIEWING THE FAULT HISTORY – VIEWING INFORMATION ABOUT THE HEATER The controller for this water heater will store a history of the most recent ten Fault and Warning conditions that occurred and store them in the Fault History. The information about the fault or warning will include diagnostic information as well as an estimate of how long ago the fault occurred. ACTION: Press the SELECT button for more information. DISPLAY: ACTION: Press the DOWN key to scroll through the Fault History.
CONTROL SEQUENCE (TYPICAL ALL MODELS) TYPICAL SEQUENCE 1. When the control is powered it should display “waiting for connection” and “UIM v2.06”*. The manufacturer and unit model will be next. The next display will include water temperature, temperature setting and heater status. * This number may change as software revisions are made. 2. The control performed selected system diagnostic checks immediately upon power up.
CONTROL SEQUENCE FLOW CHART Servicing should only be performed by a Qualified Service Technician 29
CONTROLS – CENTRAL CONTROL BOARD – CCB The Central Control Board or CCB is contained in the housing shown below. Access to the board and the wiring harness plugs can be accomplished by removing two Phillips screws holding the cover. Remove these screws to release cover The CCB is controlled by the 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.
This is the back of the UIM.
CONTROLS – GAS CONTROL VALVE BTH 120 The gas control valve on the BTH 120 has a built-in adjustable pressure regulator. The adjustment screw is accessed by removing the cap screw marked "regulator" in the illustration. Inlet gas pressure 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 199 AND 250 Pressure readings may be taken on the gas control valve by connecting to the pressure ports on the valve. The 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.
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.
CONTROLS – GAS CONTROL VALVE, ORIFICE CHART – BTH 400/500 The gas control valve has a built-in field adjustable pressure regulator. The regulator may be adjusted by removing the 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.
CONTROLS – PRESSURE SWITCHES – ALL MODELS All BTH models are provided with four pressure switches. These switches are essential to the safe and proper operation of the unit. The switches are wired to the central control board (CCB) individually and each is monitored individually. The CCB is set up to shut the unit down whenever there is a failure of any of the switches and declare a fault for each individual switch. It is important to understand the purpose of each switch.
CONTROLS – PRESSURE SWITCHES – BTH 120 THROUGH 250 Note: Check the website www.hotwater.
CONTROLS – PRESSURE SWITCHES – BTH 300, 400, 500 Note: Check the website www.hotwater.
CONTROLS – CONNECTIONS, IGNITER, FLAME SENSOR, SIGHT GLASS, POWERED ANODES The connections for the hot surface igniter and the flame sensor are shown below. 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.
HOT SURFACE IGNITER / FLAME SENSOR / CONTROL TIMING HOT SURFACE IGNITER This water heater is equipped with an electric hot surface igniter. The igniter material is silicone carbide and should not be handled with bare hands because of possible damage to the igniter. The normal ohm reading at 77 °F (25 °F) is listed between 40 and 70 ohms. The minimum igniter current monitored 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).
BLOWER SPEED CONTROL BTH 199 AND 250 The input of the BTH 199 and BTH 250 is determined by blower. The input of the water heater may be determined by clocking the meter as shown on Page 5 or by making sure the blower is receiving the proper signal. The blower rpm is controlled by the Central Control Board (CCB). The rpm of the blower may be measured by attaching a MULTIMETER that has a Hertz (Hz) setting as shown in the illustration below.
VARIABLE FREQUENCY DRIVE – BTH 400 AND 500 The Cyclone Xi BTH 400 and 500 models have a variable frequency drive (VFD) that controls the rpm of the blower motor. The VFD receives a signal from the central control 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.
VARIABLE FREQUENCY DRIVE – BLOWER SPEED AND PRESSURE READINGS The instructions for the VFD are sent from the CCB in the form of a DC current. The chart below lists the current readings, the frequency signal displayed by the VFD, and the pressure switch settings needed for the CCB to let the burner operate. The frequency numbers displayed may vary slightly with slight variations in the DC voltage generated by the CCB. If the water heater exhibits poor run characteristics check the frequency display.
WIRING DIAGRAM – BTH 120 - 300 44 Servicing should only be performed by a Qualified Service Technician
WIRING DIAGRAM – BTH 400, 500 Servicing should only be performed by a Qualified Service Technician 45
NOTES 46 Servicing should only be performed by a Qualified Service Technician
NOTES Servicing should only be performed by a Qualified Service Technician 47
COMMERCIAL GAS HIGH EFFICIENCY WATER HEATERS Visit the "Information Central" link of www.hotwater.com for a listing of available Service 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 Copyright © 2012 A. O. Smith Water Heater Company, All rights reserved.
