A.O. Smith GTS-305-NE Page 59 Service Manual Download

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On-Demand Gas Tankless Water Heater Service Manual

Summary of Contents for GTS-305-NE

Page 1: ...E GT 305 NE ATO 305 P GTS 305 PE GT 305 PE ATI 505 N GTS 505 NI GT 505 NI ATI 505 P GTS 505 PI GT 505 PI ATO 505 N GTS 505 NE GT 505 NE ATO 505 P GTS 505 PE GT 505 PE ATI 705 N GTS 705 NI GT 705 NI ATI 705 P GTS 705 PI GT 705 PI ATO 705 N GTS 705 NE GT 705 NE ATO 705 P GTS 705 PE GT 705 PE ATI 705A N GTS 705 NIA AGT 705 NI ATI 705A P GTS 705 PIA AGT 705 PI ATO 705A N GTS 705 NEA AGT 705 NE ATO 705...

Page 2: ...505i 25 705e o ASME 705i ASME 26 PC Board 305e o 305i 505e 505i 27 28 705e o ASME 705i ASME 29 Water Flow Control Assembly 305e 305i 505e 505i 30 31 505e 505i 32 33 705e o ASME 705i ASME 34 Heat Exchanger 305e 35 37 505e o 38 40 305i 41 44 505i 45 49 705e o ASME 50 51 705i ASME 52 54 Gas Pressure Setting Procedure 55 56 Manifold Pressure Settings 57 Dip Switches 58 On Demand Gas Tankless Water Hea...

Page 3: ...ak detector Teflon tape Using this Manual Repairs should be performed by a qualified service technician The following information can be referenced for additional information Operation and Installation Manual Hot Water System Design Manual Technical Sheets Technical Bulletins Technical Support Visit the brand website for additional support including contact information for our Technical Service De...

Page 4: ... state law requiring a certain temperature water at the hot water tap then you must take special precautions Water temperature over 125 F can cause severe burns instantly or death from scalds Children disabled and elderly are at highest risk of being scalded Feel water before bathing or showering Temperature limiting valves are available WARNING Temperature Settings Time to Produce 2nd 3rd Degree ...

Page 5: ...m relief in cold water line per section 19 MGL 142 Figure 1a Typical water piping installation Storage Tank Hot Water Return Line Explosion Hazard If the temperature and pressure relief valve is dripping or leaking have a qualified service technician replace it Examples of a qualified service technician include Licensed plumbers authorized gas company personnel and authorized service personnel Do ...

Page 6: ... 305 15 000 199 000 NG LP 705 705 ASME Outdoor e o Input Min Max BTU Flow Rate Hot water capacity 45 F Temp Rise 0 6 5 3 GPM 2 3 20 1 LPM 5 3 GPM 20 1 LPM Efficiency Rating 83 505 0 6 8 5 GPM 2 3 32 0 LPM 7 3 GPM 27 6 LPM 98 140 F 37 60 C 1 83 98 140 F 37 60 C 2 98 140 F 37 60 C 2 83 8 7 GPM 32 9 LPM 19 000 237 000 NG LP 0 6 9 8 GPM 2 3 37 LPM 15 000 199 000 NG LP Residential Series 100 101 NOTE 1...

Page 7: ... 45 F Temp Rise 0 6 7 5 GPM 2 3 28 4 LPM 6 6 GPM 25 0 LPM Efficiency Rating 83 505 0 6 9 4 GPM 2 3 35 5 LPM 7 4 GPM 28 0 LPM 98 140 F 37 60 C 1 83 98 140 F 37 60 C 2 15 000 199 000 NG LP Residential Series 200 201 NOTE 1 Minimum activation flow is approximately 0 6 gallons minute 2 3 liters min Max temperature is 160 71 C with the commercial controller for commercial and hydronic applications only...

Page 8: ...Schematic Diagrams Outdoor Model NOT PRESENT ON ALL MODELS LOCATED ON BRACKET NEAR FAN ON SOME MODELS NOT PRESENT ON ALL MODELS On Demand Gas Tankless Water Heater Service Manual 8 ...

Page 9: ...Schematic Diagrams Indoor Model NOT PRESENT ON ALL MODELS NOT PRESENT ON ALL MODELS LOCATED ON BRACKET NEAR FAN ON SOME MODELS On Demand Gas Tankless Water Heater Service Manual 9 ...

Page 10: ...oard monitors inlet outlet water temperature temperature set point and water flow rate Combustion fan energized Purges combustion chamber Spark igniter begins sparking Gas control valve opens to minimum fire rate Flame rod proves ignition Spark igniter stops sparking 3 Normal Operation PC Board monitors flame rod fan motor frequency outlet water temperature controller temperature set point and wat...

Page 11: ...ner cover and ensure all burners are properly seated Remove burner plate and inspect burner surface for condensation or debris 12 Flame Failure Check that the gas is turned on at the water heater and gas meter Check for obstructions in the flue outlet Ensure gas line meter and or regulator is sized properly Ensure gas type and pressure is correct Bleed all air from gas lines Ensure proper venting ...

Page 12: ...arness to motor for damaged and or loose connections Measure resistance of motor winding 65 Water Flow Control Fault The water flow control valve has failed to close during the bath fill function Immediately turn off the water and discontinue the bath fill function Contact a state qualified or licensed contractor to service the appliance 71 SV0 SV1 SV2 and SV3 Solenoid Valve Circuit Fault Check wi...

Page 13: ...ange wire turns to red QS Water Flow Sensor Black Red 11 13 VDC 5 5 6 2 K ohms F2 1 3 Yellow Black 4 7 VDC 1 1 4 mega ohms F2 2 3 Bypass Flow Control only on 505e o and 505i Brown White 2 6 VDC unit in operating mode 15 35 K ohms G1 1 5 5 2 e t i h W e g n a r O 5 3 e t i h W w o l l e Y 5 4 d n u o r G e t i h W d e R IG Ignition System Gray Gray 90 110 VAC N A C1 1 2 FM Combustion Fan Motor Red ...

Page 14: ...ermistor 4 3 5 F e v o b a e e s e t i h W e t i h W Heat Exchanger Temperature Thermistor 1 1 3 4 F e v o b a e e s e t i h W k n i P 2 1 3 3 F e v o b a e e s e t i h W e g n a r O Surge Protector Black White 108 132 VAC N A D2 1 3 Blue Brown 108 132 VAC N A D1 1 3 With the power off check the continuity through the surge protector Check by placing one meter lead on the top pin 1 and bottom pin ...

Page 15: ... black QS Water Flow Sensor Black Red 11 13 VDC 5 5 6 2 K ohms F2 1 3 Yellow Black 4 7 VDC 1 1 4 mega ohms F2 2 3 Bypass Flow Control Brown White 2 6 VDC unit in operating mode 15 35 K ohms G1 1 5 5 2 e t i h W e g n a r O 5 3 e t i h W w o l l e Y 5 4 d n u o r G e t i h W d e R IG Ignition System Gray Gray 90 110 VAC N A C1 1 2 FM Combustion Fan Motor Red Black 6 45 VDC N A E1 1 2 White Black 5 ...

Page 16: ...going Water Thermistor 4 3 4 F e v o b a e e s e t i h W e t i h W Heat Exchanger Temperature Thermistor 1 1 3 3 F e v o b a e e s e t i h W k n i P Surge Protector Black White 108 132 VAC N A D2 1 3 Blue Brown 108 132 VAC N A D1 1 3 With the power off check the continuity through the surge protector Check by placing one meter lead on the top pin 1 and bottom pin 3 Check by placing one meter lead ...

Page 17: ...L BR Y INDOOR MODEL ONLY COMBUSTION FAN FM R BK Y W E1 W 4 1 Y BK R BY PASS SERVO MODEL ONLY 1 1 THERMAL FUSES R R OVERHEAT SWITCH H2 H1 MODULATING SOLENOID VALVE POV H3 P P H4 Y FLAME ROD H5 SV1 H7 H6 SV0 BL BK SV2 BK P Y BK MAIN SOLENOID VALVE SOLENOID VALVE 1 SOLENOID VALVE 2 F6 Y BR BL BK P P CN2 Y P R 12 1 SOLENOID VALVE 3 H8 BR BK SV3 GY C1 IG GY GY IGNITER GND GY SURGE PROTECTOR 3 1 BR BL G...

Page 18: ...AME ROD H 3 SV1 H 5 H 4 SV0 O BK SV2 BK P R BK MAIN SOLENOID VALVE SOLENOID VALVE 1 CENTER SOLENOID VALVE 2 LEFT Y Y O BK O O CN2 R P W 12 1 SOLENOID VALVE 3 RIGHT H 6 Y BK SV3 GY C 1 IG GY GY IGNITER GND GY FUSE 3A BK W AC120V AC120V HOT NEUTRAL HOT NEUTRAL GROUND GND BK REMOTE CONTROLLER SPARK ELECTRODE 5 4 Spare Parts Only Gas type 1 2 3 O F F Dip SW2 6 C D E F G H F 1 G 1 CN3 CN4 CN1 CN12 CN5 ...

Page 19: ...valve V2 4 Connect drain hose H3 to service valve V1 5 Pour approximately 4 gallons of virgin food grade white vinegar or citric acid into pail 6 Place the drain hose H3 and the hose H2 to the pump inlet into the cleaning solution 7 Open both service valves V1 and V2 on the hot water and cold water lines 8 Operate the pump and allow the cleaning solution to circulate through the water heater for a...

Page 20: ... valve Pull out the gas manifold Figure 1 8 Remove the four screws attaching the gas connection to the underneath side of the water heater See Figure 2 Figure 2 Gas connection attached with 4 screws Regulator screw access 9 Pull the gas connection down to disconnect it from the gas control assembly 10 Pull out the gas control assembly Remove the wire harness from the 4 solenoids 11 Replace the O r...

Page 21: ...tening the three screws that hold the gas manifold to the gas valve 15 Attach wiring harness connector black brown wires to the gas manifold 16 Attach ignition line 17 Perform the Gas Pressure Setting Procedure Figure 4 Figure 5 Circular gaskets re use in gas valve w o l l e y k c a l b 1 V S e u l b k c a l b 2 V S SV0 black pink POV pink pink connector not shown Figure 3 12 Attach wire harness t...

Page 22: ... These screws are machine screws and must be used at these locations Figure 7 8 Pull out the gas manifold and remove the connector at the ignitor at the left side of the gas manifold 9 Remove the 3 screws attaching the gas connection to the underneath side of the water heater Figure 8 10 Remove the screw attaching the gas valve to the rear of the case 11 Pull the gas connection down to disconnect ...

Page 23: ... 14 Install the gas connection with 3 screws 15 Replace the circular gasket included in kit in the gas valve Figure 10 16 Start the 2 screws that attach the gas manifold to the gas valve Tighten the 5 screws that hold the gas manifold to the combustion chamber Finish tightening the 2 screws that hold the gas manifold to the gas valve 17 Attach ignition line 18 On indoor models install the bracket ...

Page 24: ...ews that attach the fan assembly to the bottom of the burner 8 Pull out the fan assembly 9 Install the fan assembly by inserting the tab on the fan assembly into the slot at the base of the heat exchanger and attaching with two screws 10 Attach the wire harness to the solenoid on the gas manifold brown black wires 11 Attach the wire harness to the fan assembly white yellow black red wires 12 Attac...

Page 25: ...assembly 10 Install the fan assembly by inserting the tab on the fan assembly into the slot at the base of the heat exchanger and attaching with two screws 11 Push ducting over fan assembly inlet and secure with metal clamp 12 Attach the wire harness to the solenoid on the gas manifold brown black wires 13 Attach the wire harness to the fan assembly white yellow black red wires 14 Attach the air t...

Page 26: ...Figure 14 7 Remove the three screws attaching the fan motor to the fan casing Figure 14 8 Pull out the fan motor 9 Install the new fan motor and tighten with three screws 10 Attach the wire harness to the fan assembly white yellow black red wires 11 On indoor models install the bracket with the remote controller 12 Install front panel using 4 screws 13 Turn on water supply power supply and gas sup...

Page 27: ...remove it and install it on the new PC board See Figure 15 14 Attach connections for the remote controller 15 Attach plastic guard 16 Perform the Gas Pressure Setting Procedure Figure 15 Screw Screw Remote controller terminals NOT for 120 V power If these 2 terminals are present then this is a surge protector board with terminals to connect freeze protection solenoid valves and should be installed...

Page 28: ...ment Instructions Switch No F O F 5 6 4 3 ON 1 2 Switch No F O F 5 6 4 3 ON 1 2 Propane LPG Natural Gas NG SW2 setup for 305i Switch No F O F 5 6 4 3 ON 1 2 Switch No F O F 5 6 4 3 ON 1 2 Propane LPG Natural Gas NG SW2 setup for 305e Propane LPG Natural Gas NG SW2 setup for 505e PC Board On Demand Gas Tankless Water Heater Service Manual 28 305i 305e 505i 505e 100 101 and 200 201 Series ...

Page 29: ... Pressure Setting Procedure Figure 16 Screw SW1 SW2 Burner test point Potentiometer Surge protector Screw Switches 1 8 SW1 Configure the dip switches the same as on the original PC board If necessary refer to the Dip Switch section or to the Operation and Installation Manual for more information on these dip switches Switches 1 4 SW2 or Switches 1 6 SW2 Configure according to the diagrams based on...

Page 30: ...eft on the water line Pull out the water line Figure 17 6 Remove the 4 screws attaching the water inlet to the underneath side of the water heater Figure 18 Remove the water flow assembly Figure 17 Due to design changes the new valve may appear different than the installed valve in color size and in the number of wires in the harness connections NOTICE Water inlet Figure 18 1 screw and bracket wat...

Page 31: ...e water inlet using 4 screws The 2 shorter screws can be installed first to connect the water flow assembly to the bottom of the compartment Then install the 2 longer screws through the water inlet 10 Replace the O ring on the water line included in kit Attach the water line to the water flow assembly with 1 screw and bracket 11 Install the front panel using 4 screws 12 Turn on the water supply po...

Page 32: ...om of the burner 8 On indoor models loosen the ducting from the fan assembly by pinching open the metal clamp 9 Pull out the fan assembly 10 Remove 2 screws and 2 brackets at the water flow servo assembly The brackets can be left on the water lines Pull out the water lines Remove the water flow assembly Figure 21 2 screws Wire harness connection on the fan assembly Solenoid on the manifold Wire ha...

Page 33: ...ter flow assembly to the water inlet using 4 screws The 2 shorter screws can be installed first to connect the water flow assembly to the bottom of the compartment Then install the 2 longer screws through the water inlet 18 Replace the O ring on the water lines included in kit Attach the two water lines to the bypass servo assembly with 1 screw each 19 Install the fan assembly by inserting the tab...

Page 34: ...mbly and the bypass servo assembly Attach the new water flow servo assembly to the bypass servo assembly with 2 screws 11 Attach the wire harness to the water servo valve 12 Place inside the water heater 13 Attach the water flow assembly to the water inlet using 4 screws The 2 shorter screws can be installed first to connect the water flow assembly to the bottom of the compartment Install the 2 lo...

Page 35: ... the manifold to make room to pull out the fan assembly 7 Remove the 2 screws that attach the fan assembly to the bottom of the burner 8 Pull out the fan assembly 9 Remove 1 screw from the water outlet bracket Remove the bracket by rotating and moving it up toward the bend in the tube where the diameter is smaller 10 Remove 1 screw and 1 bracket at the water flow servo assembly Figure 28 Fan Assem...

Page 36: ... wire harness from the burner cover plate 16 Remove the 2 screws attaching the burner to the heat exchanger Pull out the burner 17 Unscrew the ignition line connection Figure 32 18 Remove the wire harness attachments sensors heating elements fusible link brackets Ensure that the small O ring in the thermistor is removed 19 Remove 3 screws behind the fan Figure 33 20 Remove 2 screws above the exhau...

Page 37: ...crews at the gas control assembly Replace the lower and upper packings included in kit for the manifold plate removing any residue 29 Attach the gas manifold with 6 screws at heat exchanger 30 Attach the ignition line at the burner cover plate 31 Attach the PC Board to the heat exchanger with 1 screw Connect Water Lines Figure 30 32 Attach the water outlet line and bracket with 1 screw 33 Attach t...

Page 38: ... on the manifold to make room to pull out the fan assembly 7 Remove the 2 screws that attach the fan assembly to the bottom of the burner 8 Pull out the fan assembly 9 Remove 1 screw from the water outlet bracket Remove the bracket by rotating and moving it up toward the bend in the tube where the diameter is smaller 10 Remove 2 screws and 2 brackets at the bypass servo assembly Fan Assembly Gas M...

Page 39: ... not necessary to disconnect the wire harness from the burner cover plate 16 Remove the 2 screws attaching the burner to the heat exchanger Pull out the burner 17 Unscrew the ignition line connection Figure 40 18 Remove the wire harness attachments sensors heating elements fusible link brackets Ensure that the small O ring in the thermistor is removed 19 Remove 3 screws behind the fan Figure 41 Di...

Page 40: ...sure that the two black packings Figure 43 are intact on the gas control assembly Attach the gas manifold with 3 machine screws at the gas control assembly Replace the lower and upper packings included in kit for the manifold plate removing any residue Connect Water Lines Figure 38 28 Attach the gas manifold with 6 screws at heat exchanger 29 Attach the ignition line at the burner cover plate Inst...

Page 41: ... attached to the solenoid on the manifold to make room to pull out the fan assembly 7 Remove the 2 screws that attach the fan assembly to the bottom of the burner 8 Loosen the ducting from the fan assembly by pinching open the metal clamp 9 Pull out the fan assembly 10 Remove 1 screw from the water outlet bracket Remove the bracket by rotating and moving it up toward the bend in the tube where the...

Page 42: ...ove Gas Manifold Figure 46 16 Remove the 8 screws attaching the burner cover plate to the combustion chamber Move the cover plate to the side It is not necessary to disconnect the wire harness from the burner cover plate 17 Remove the 2 screws attaching the burner to the heat exchanger Pull out the burner 18 Disconnect the pressure tube from the heat exchanger and unscrew the ignition line connect...

Page 43: ...r plate over the air intake passage Figure 50 23 Remove the 4 screws attaching the heat exchanger to the air intake exhaust assembly Figure 51 24 Pull apart the heat exchanger and air intake exhaust assembly Figure 52 25 Remove 4 screws attaching the bracket on top of the heat exchanger Pull off the bracket Figure 53 4 screws bracket 9 screws cover plate Figure 50 4 screws Figure 51 Figure 52 Figu...

Page 44: ...and then attach the burner with 2 screws Install Gas Manifold and Connect PC Board 34 Make sure that the two black packings Figure 54 are intact on the gas control assembly Attach the gas manifold with 3 machine screws at the gas control assembly Replace the lower and upper packings included in kit for the manifold plate removing any residue 35 Attach the gas manifold with 6 screws at heat exchang...

Page 45: ...Pull out the harness attached to the solenoid on the manifold to make room to pull out the fan assembly 7 Remove the 2 screws that attach the fan assembly to the bottom of the burner 8 Loosen the ducting from the fan assembly by pinching open the metal clamp 9 Pull out the fan assembly Fan Assembly Gas Manifold Burner cover plate PC Board Gas Control Valve Figure 55 2 screws Wire harness connectio...

Page 46: ...r assembly Remove Gas Manifold Figure 58 13 Remove the 6 screws that attach the gas manifold to the combustion chamber part of the heat exchanger assembly 14 Remove the 3 screws that attach the gas manifold to the gas valve These screws are machine screws and must be used at these locations 15 Pull out the ignition line and remove the gas manifold Figure 57 Water outlet connection Bypass servo ass...

Page 47: ...t the burner Disconnect Gas Line and Wire Harness Attachments 18 Disconnect the pressure tube from the heat exchanger and unscrew the ignition line connection Figure 59 19 Remove the wire harness attachments sensors heating elements fusible link brackets Ensure that the small O ring in the thermistor is removed Figure 60 Pressure tube Ignition line connection 8 screws burner cover plate 2 screws b...

Page 48: ...ng the bracket on top of the heat exchanger Pull off the bracket Figure 66 At right and left upper corners of water heater Near fan assembly location 4 screws bracket 9 screws cover plate Figure 63 4 screws Figure 64 Figure 65 Figure 66 26 Install the largest O ring included in kit over the water outlet tube and the two smaller O rings included in kit over the bypass servo tubes Figure 57 27 Insta...

Page 49: ...ings Figure 67 are intact on the gas control assembly Attach the gas manifold with 3 machine screws at the gas control assembly Replace the lower and upper packings included in kit for the manifold plate removing any residue 36 Attach the gas manifold with 6 screws at heat exchanger 37 Attach the ignition line at the burner cover plate Connect Water Lines Figure 57 38 Attach the PC Board to the he...

Page 50: ...tions Figure 68 9 Pull out the gas manifold and remove the connector at the ignitor at the left side of the gas manifold 10 Remove the 9 screws attaching the burner cover plate to the combustion chamber Figure 69 11 Remove the 2 screws attaching the burner to the heat exchanger Pull out the burner Figure 69 12 Remove the wire harness attachments sensors heating elements fusible link brackets Ensur...

Page 51: ...ure 73 23 Make sure that the black gasket Figure 74 is intact on the gas control assembly Replace the lower and upper gaskets included in kit for the manifold plate removing any residue Figure 75 24 Attach the electrical connector to the ignitor on the manifold and attach the gas manifold with 2 machine screws at the gas control assembly Figure 68 25 Attach the gas manifold with 5 screws at heat e...

Page 52: ...7 9 Remove the 2 screws that attach the gas manifold to the gas valve These screws are machine screws and must be used at these locations Figure 77 10 Pull out the gas manifold and remove the connector at the ignitor at the left side of the gas manifold 11 Remove the 9 screws attaching the burner cover plate to the combustion chamber Figure 78 12 Remove the 2 screws attaching the burner to the hea...

Page 53: ...ter outlet tube and the two smaller O rings included in kit over the water inlet tubes Figure 82 20 Slide the fusible link between the water outlet and inlet tubes and onto the new heat exchanger Figure 82 21 Attach brackets at the back and side holding the fusible link Install the heat exchanger hooking it on the brackets in the back 22 Install the 4 screws at the top and bottom of the heat excha...

Page 54: ... attach the gas manifold with 2 machine screws at the gas control assembly Figure 77 28 Attach the gas manifold with 5 screws at heat exchanger Figure 77 29 Connect wire harness attachments 30 Attach the ignition line at the burner cover plate 31 Attach the 3 electrical connectors to the solenoid valves 32 Attach the wire harness to the fan assembly white yellow black red wires 33 Attach the brack...

Page 55: ...re 86 or 87 CAUTION Do not touch the areas at or near the heat exchanger or combustion chamber These areas become very hot and could cause burns 100 101 and 200 201 Series Models 305e o 305i 505e o 505i Figure 86 Potentiometer POT Burner test point Dip switches SW1 Potentiometer POT Burner test point Dip switches SW1 Figure 87 On Demand Gas Tankless Water Heater Service Manual 55 Models 705e o ASM...

Page 56: ...ifold pressure Refer to the data plate on the unit Install rubber access plug H Move No 7 and No 8 dip switches of the SW1 bank to the ON position to calibrate Forced High combustion Figure 90 I Check the burner test point pressure J Adjust the high pressure Potentiometer POT Figure 86 or 87 on the PC Board to obtain the correct high fire manifold pressure Refer to the data plate on the unit K Mov...

Page 57: ...h Fire Low Fire 305e o 2 9 0 56 4 2 0 88 505e o 3 3 0 56 5 1 0 88 705e o ASME 2 8 0 65 3 8 0 80 305i 2 7 0 52 4 4 0 92 505i 3 3 0 52 5 0 0 92 705i ASME 3 0 0 67 3 7 0 83 less than 10200 ft 3109 m Natural Gas Propane Gas On Demand Gas Tankless Water Heater Service Manual 57 Inch W C Inch W C ...

Page 58: ...atural Gas 2 OFF Outdoor model ON Indoor model 3 4 5 6 OFF position 1 OFF Long Flue ON Short Flue and Outdoor Models 2 Settings dependent on altitude 3 4 OFF if using standard controller 5 OFF 120ºF default temperature without a controller ON 140ºF default temperature without a controller 6 OFF position 7 OFF position Used for low fire and high fire settings Refer to the gas pressure setting proce...

Page 59: ...Notes On Demand Gas Tankless Water Heater Service Manual 59 ...

Page 60: ... 500 Tennessee Waltz Parkway Ashland TN 37015 ...

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