Service Handbook COMMERCIAL GAS WATER HEATERS FOR MODELS: BTN 120 thru 400(A) Series 100 - 108 BTR 151 & 201 Series 100 & 101 500 Tennessee Waltz Parkway Ashland City, TN 37015 INSTALLATION CONSIDERATIONS - PRE SERVICE CHECKS CONSTRUCTION - OPERATION & SERVICE - TROUBLESHOOTING 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INTRODUCTION The service handbook is designed to aid in servicing and troubleshooting A. O. Smith BTN and BTR 151/201 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., resolution 0.01" 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.
INSTALLATION CONSIDERATIONS GAS AND ELECTRICAL CHARACTERISTICS Models Gas Type All Models Natural Gas Supply Pressure Minimum Maximum 5.2" W.C. (1.29 kPa) 14.0" W.C. (3.48 kPa) Gas Manifold/ Pressure Volts/Hz Amperes 120/60 120/60 <5 All models require a minimum gas supply pressure of 5.2” W.C. The minimum supply pressure is measured while gas is flowing (dynamic pressure). The supply pressure (dynamic) should never fall below 5.2” W.C.
AIR SUPPLY: Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1,000 BTU of gas supplied. The National Fuel Gas Code also recommends an additional 2.5 cubic feet of “excess” air. For information on minimum make-up air opening sizes for various building installations, refer to the National Fuel Gas Code NFPA 54/ANSI Z223.1.
MAKE-UP AIR – DIRECT COMMUNICATION WITH OUTDOORS: A fresh supply of make-up air for combustion can be supplied to the water heater through make-up air ducts, which directly communicate with the outdoors. (Not Direct Vent.) Two openings are required: one within 12 inches of the top of the enclosure and one within 12 inches of the bottom of the enclosure. Each opening must have a free area of not less than 1 square inch per 4,000 BTU/Hr of the total input of all appliances within the enclosure.
AIR REQUIREMENTS: For safe operation an adequate supply of fresh uncontaminated air for combustion and ventilation must be provided. An insufficient supply of air can cause recirculation of combustion products resulting in contamination that may be hazardous to life. Such a condition often will result in a yellow, luminous burner flame, causing sooting of the combustion chamber, burners and flue tubes and creates a risk of asphyxiation.
MINIMUM CLEARANCES This water heater is approved for installation on combustible flooring in an alcove with minimum clearance from combustion construction as indicated in below Figure and Table. In all installations the minimum combustible clearances from vent piping shall be 6” (15.2 cm). Vent piping passing through a combustible wall or ceiling must be a continuous run (no joints) and retain 6” (15.2 cm) clearance unless an approved reducing thimble is used.
EXTERIOR CLEARANCES The illustration below shows the required clearances for venting units using natural draft venting. The vent must 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 10 feet (for vents of 12 inches in diameter or less). References: NFPA 54/ANSI Z223.1 may allow reduction to 8 feet with a "listed vent cap".
GAS VALVE The supply gas pressure is normally measured at the gas valve inlet gas pressure tap, if available, when the gas is flowing. The manifold gas pressure is measured at the manifold pressure tap of the gas valve when the gas is flowing. Gas valves used are 24 volt AC combination-step opening gas valves. They incorporate the main valve and gas pressure regulator into one body.
GAS VALVE All BTN and BTR water heaters are classified by ANSI as Category I (non-condensing, negative pressure venting) appliances. They are approved for type B vent. The draft inducer does not pressurize the exhaust. For larger applications BTN and BTR 151, 201 water heaters can be common vented together, either in a tapered manifold or constant size manifold. Follow the National Fuel Gas Codes requirements for sizing and installation of fan-assisted products.
VENTING TABLES FOR CATEGORY 1 – TYPE B GAS VENT Multiple Gas Fired Tank-Type Heaters When venting multiple Category 1 tank type heaters using Type B vent pipe, follow the installation tables below which give sizing and data based upon NFPA 54 ANSI Z223.1. MODEL BTN-120 Input: 120,000 Btu/hr Total Vent Height (Feet) Vent Connector Size: 5 inches 6 8 10 20 30 50 100 Rise Vent Connector Diameter (Inches) 120,000 1 Ft. 6 6 5 5 5 5 5 5 120,000 2 Ft. 5 5 5 5 5 5 5 5 120,000 3 Ft.
MODEL BTN-250 Input: 250,000 Btu/hr Total Vent Height (Feet) Vent Connector Size: 6 inches 6 8 10 15 20 30 50 100 Input Btuh/hr Rise Vent Connector Diameter (Inches) 250,000 1 Ft. 8 8 7 7 7 6 6 6 250,000 2 Ft. 7 7 7 7 6 6 6 6 250,000 3 Ft.
DRAFT PROVING PRESSURE SWITCH – SETTINGS DRAFT PROVING PRESSURE SWITCH TABLE Pressure Setting BTN Models BTR Models To Close Switch (Inches W.C.) 120 -2.40" ± 0.07" 154 -2.20" ± 0.07" 180, 250 -1.60" ± 0.07" 199C -3.00" ± 0.10" 199, 200 -1.95" ± 0.07" 275 -2.30" ± 0.07" 310 -2.60" ± 0.10" 366 -2.00" ± 0.07" 400 -1.75" ± 0.07" 151 -2.50" ± 0.10" 201 -2.20" ± 0.07" Note: Pressure Switch Contacts are Normally Open “N.O.” and close on a fall in pressure.
THERMOSTAT AND IGNITION CONTROL BOARD VIEW Servicing should only be performed by a Qualified Service Technician 15
WHITE RODGERS INTEGRATED CONTROL – THERMOSTAT 16 Servicing should only be performed by a Qualified Service Technician
WHITE RODGERS IGNITION CONTROL BOARD Servicing should only be performed by a Qualified Service Technician 17
GAS CONTROL VALVE/ BURNER AREA VIEW 18 Servicing should only be performed by a Qualified Service Technician
BTN/ BTR 151, 201 – ELECTRICAL SEQUENCE The following information will describe the Sequence of Operation for this water heater: 1. Switch power on to unit. 2. Thermostat calls for heat. 3. Ignition Control Board performs diagnostic check on system components. 4. On completion of diagnostics check, the Ignition Control Board sends signal to Exhaust Inducer. 5. Exhaust Inducer begins drawing air through the water heater closing the Prover Switch. 6.
OPERATING SEQUENCE – FLOW CHART 20 Servicing should only be performed by a Qualified Service Technician
HEATER CONTROL BOARD DIAGNOSTIC LED INTERPRETATION AND TROUBLESHOOTING TEST 1 - 120 VAC CHECK TO HEATER: • No Green display "Power" LED On. • Plugs are in receptacles. • Supply power breaker is not “open”. • On/Off heater switch is “On”. TEST 1 120 VAC check to water heater ON/OFF switch. Check for 115-125 VAC black wire to ground\ 115 VAC check to E13 Terminal and 2B receptacle. IF......... THEN............
IGNITION CONTROL BOARD DIAGNOSTIC LED INTERPRETATION AND TROUBLESHOOTING CONDITIONS: • Power On. • Red, heater control “Call for Heat” LED – on. • Red, ignition control board diagnostic LED – Flashing. • Note LED Flash Code before resetting heater. LED Status 1 Flash 2 Flashes 3 Flashes 4 Flashes 5 Flashes 6 Flashes 7 Flashes 8 Flashes Continuous Flash Continuous ON 22 Indication System is in lock out. Draft proving (pressure) switch failed to open within 5 seconds at the end of the last cycle.
TEST 2 - POLARITY CHECK CONDITIONS: • No Green display "Power" LED On. • Plugs are in receptacles. • Supply power breaker is not “open”. • On/Off heater switch is “On”. TEST 1 120 VAC check to water heater ON/OFF switch. Check for 115-125 VAC black wire to ground\ 115 VAC check to E13 Terminal and 2B receptacle. IF......... THEN............ Voltage is not present from on/off switch center black wire to ground Check conditions above.
TEST 3 – CONTINUITY CHECK OF HIGH LIMIT (ECO) CONDITIONS: • Power On – No Hot Water. • Red, heater control “Call for Heat” LED – On. • Red ignition control board diagnostic LED – 4 Flashing. • Note LED Flash Code before resetting water heater control. • See Description of diagnostic LED Flashes. • Turn Power Off. TEST 3 Continuity check of ECO (energy cut-out, high limit). Black to Black wires of upper probe. Power is off. IF......... THEN............ Continuity is indicated (ZERO “0.
TEST 4 – UPPER TEMPERATURE PROBE CONTINUITY CHECK CONDITIONS: • Power On – Water below temperature set point. • Red, water heater control “Reset Status” LED – OFF. • "Call for Heat" LED Off. OHMS RESISTANCE TABLE °F OHMS 70° 120° 140° 180° 11,884 3,759 2,488 1,169 TEST 4 Upper Temperature Probe continuity check. Red wire to red wire – Turn supply power "Off" for this test. IF......... THEN............ Test indicates no continuity. Continuity is indicated. Replace probe.
TEST 5 – CALLING FOR HEAT – NO INDUCER OPERATION CONDITIONS: • Power On – No Hot Water. • Plugs in Receptacles. • Red "Call for Heat" LED-ON. • Inducer "Off". "call for heat" LED indicator "Diagnostic LED indicator" IF......... THEN............ Pin 1 to ground check has no voltage Reset control by interrupting power - note possible reasons for this from flashing LED code. Pin 1 to ground has voltage Pin 3 to ground has no voltage Replace ignition board. Proceed Check wiring harness and plugs.
TEST 6 – INDUCER ON – NO IGNITION CONDITIONS: • Power On. • Plugs in Receptacles. • Inducer operating. • No power to Hot Surface Igniter (HSI) Note LED flash code. TEST 6 IF......... 24 VAC Check of Blower Prover/Low Gas Pressure Circuit THEN............ Ignition board receptacles E1, Pin 7 to ground shows no voltage. E1, Pin 7 has 24 Volt to ground Voltage check of each blower switch terminal to ground shows voltage to only 1 terminal. Replace ignition board.
TEST 7 – INDUCER ON – PROVER SWITCH AND LOW GAS SWITCH CLOSED. NO IGNITER OPERATION CONDITIONS: • Power On. • Plugs in Receptacles. • Inducer ON. • 24V at ignition board E1, Pin 10. • No power to Igniter. TEST 7 Voltage check and continuity check of hot surface igniter circuit Continuity check - Power off- Plug removed from E4 receptacles. Nominal 80 VAC check - Plug in E4- Power "On". THEN............ IF......... Continuity is not indicated between E4 plug pin 2 to 4. Continuity is present.
TEST 8 – IGNITER HEATS – NO MAIN BURNER TEST 8 IF......... IGNITOR HEATS......NO MAIN BURNER THEN............ Short heat up time of igniter. Check control box grounding. Normal (Approximate 20 seconds) Check for 24V from E1, Pin 12 to ground during 4 second trial. warm up - no ignition. ........Yes - Continue................No - Replace Ignition Board. No voltage present E4, Pin 12 to Replace ignition board. ground. 24 Volt was present from E1, Pin Check that air has been purged from gas circuit.
TEST 9 – IGNITER HEATS – NO MAIN BURNER CONDITIONS: • Test 8 completed then: • Turn off power. • Disconnect wires from gas valve. TEST 9 IGNITER HEATS – NO MAIN BURNER THEN............ IF......... Meter reads 0 or 1. Meter indicates pilot and main coil have continuity. 30 • Check meter scale setting to read between 550 and 650 Ohms. • Replace Gas Valve. Valve should be okay, still no gas to main burner, then coil may be stuck. Replace Gas Valve.
TEST 10 – MAIN BURNER IGNITION FOR LESS THAN 5 SECONDS CONDITIONS: • Power On – plug connected. • Main Burner ignites for approximately 5 seconds then goes out. • Tests 8 and 9 completed. • Note flash code on ignition board LED. TEST 10 IF......... No extended main burner ignition. Still no extended main burner ignition. MAIN BURNER IGNITION FOR LESS THAN 5 SECONDS THEN............ Check wiring and plug connections of HSI assembly plug and ignition board receptacles E1, Pin 2.
TEST 11 – WATER HEATER SHUTTING OFF BELOW SETTING CONDITIONS: • Main burner ignited. • Stored water is below temperature setting more than 5° F (Tank Average). • Power Off. • Plug disconnected from heater control board receptacle E3 and E4. WATER HEATER SHUTTING OFF BELOW SETTING TEST 11 (Water Temperature Circuit Check - Continuity) THEN............ IF.........
DISPLAY LIGHTS ON INTEGRATED HEATER CONTROL LED STATUS INDICATION Calling for heat The ECO (Energy Cut-Out) has opened. ACTION Normal status. No action required. • Check for excessively hot water (203° F or higher). • Check the resistance of the temperature probes and continuity of the high limit (ECO). No power Check the breaker. Tank is at a set temperature ± 2° F. No action required. Tank has cooled below 120° F. Preceded by “ECO Open” indication. • Push the manual reset button.
WIRING DIAGRAM 34 Servicing should only be performed by a Qualified Service Technician
NOTES Servicing should only be performed by a Qualified Service Technician 35
NOTES 36 Servicing should only be performed by a Qualified Service Technician
NOTES Servicing should only be performed by a Qualified Service Technician 37
COMMERCIAL GAS 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 1-800-527-1953 www.hotwater.com ©2013 A. O.
