A.O. Smith T-D2-OS User manual

T-D2-IN/T-D2-OS Service Manual
Ver. 1.00
1
CONFIDENTIAL
   
T-D2-IN / T-D2-OS
On-Demand Water Heater
Service Manual
T-D2-IN
A.O. Smith Water Products Company
500 Tennessee Waltz Parkway
Ashland City, TN 37015
Toll Free: 1
-
877
-
737
-
2840
T-D2-OS

T-D2-IN/T-D2-OS Service Manual
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Table of Contents
1.
Specifications………………………………………...…...………….……………………...…………………………
3
2.
Exterior view……………………...…….……………………………………………………………………………....
4
3.
Interior view…………………………….………………………………………………………………………………..
6
4.
List of main components in the interior view…….…………………………………………………….…
8
5.
Schematic diagram…………………………………………………………………………………………………….
10
6.
Wiring diagram………………………………………………………………………………………………………….
11
7.
Wiring diagram checkpoints for diagnosis………………………..………………….………………….…
12
8.
Resistance values of the temperature thermistors…………..…………………………………………
14
9.
Operational flow chart…………………………………………………………………………………………….…
15
10.
Component specifications………………...…………………………………………………………………….…
16
11.
FaultAnalysis &Specifications…………………………………………………………………………………..
36
12.
Controls and settings……………………………………………………………………………………………….…
46
13.
Components diagrams………………………………………………………………..................................
70
14.
Parts list……………………………………………………………………………………………………………………..
73
15.
Revisions……………………………………………………...………………………………………………………......
78

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1. Specifications
Model T-D2-IN T-D2-OS
Dimensions H20.5"×W13.8"×D8.5"
Weight 39 lbs.
Combustion
INPUT
BTU/h Max 199,000
Min 11,000
Combustion System
Power vent
Installation Indoor & Direct-vent Outdoor
Fan motor PWMturbo fan PWN multi blade fan motor
Manifold
Pressure*
Max LP 3.5” WC
Natural 2.0” WC LP 4.4” WC Natural 2.8” WC
Min LP 0.7” WC
Natural 0.4” WC LP 0.9” WC Natural 0.5” WC
Water control
Flow rate 0.75 to 10.0 GPM
Available set
temperatures 99 to 185°F default: 122°F
Temperature
dipswitch settings
104°F, 113°F, 122°F, 131°F, 140°F, 158°F, 176°F,185°F
Bypass valve Yes
Thermistors 3 thermistors (In, Out, Mixing)
Operation
Remote controller
model TM-RE30
PCB model T-D2
Indicators Red LED on PCB during operation & 7-SEG LED
Power supply
control Surge absorber & Power ON-OFF switch
Features
Freezeprotection
Ceramic heaters and Auto-firing system
Self-combustion
improvement Air-FuelRatio Detection System
Easy-Link system
Yes (Up to 4 units)
Multiple-system
N/A
*The manifold pressuremeasurement is based on conditions without front cover.

T-D2-IN/T-D2-OS Service Manual
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2. Exterior view
Top view Bottom view
Side view Front view
COLD 2-7/8" (71mm)
HOT 6-1/2" (164mm)
HOT 5-1/4" (133mm) GAS 4-7/8" (124mm)
GAS 5-1/4" (135mm)
120VAC 3-7/8" (99mm)
120VAC 1-3/8" (36mm)COLD 3-1/4" (84mm)
13-1/8" (334mm)
4-3/8" (113mm)
5-1/8" (130mm)
T-D2-IN
13-3/4" (350mm)
10" (254mm)
1-3/4" (45mm) 1-3/4" (45mm)
1-3/8" (36mm)
3-9/8 ( 101mm)
21-3/8" (544mm) 20-1/4" (520mm)
1-7/8" (47mm)
HOT 5-1/4" (133mm)
120V 1-3/8" (36mm)
GAS 4-7/8" (124mm)
COLD 3-1/4" (84mm)
4-3/8" (113mm)
19-3/8" (493mm)
COLD 2-7/8" (71mm)
1" (26mm)
HOT 6-1/2" (164mm)
9-1/2" (241mm)
120VAC 3-7/8" (99mm)
GAS 5-1/4" (135mm)
2-1/4" (58mm)

T-D2-IN / T-D2-OS Service Manual
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Sideview Frontview
Bottom view
Top view
T-D2-OS
13-3/4" (350mm)
10" (254mm)
1-3/4" (45mm) 1-3/4" (45mm)
21-3/8" (544mm) 20-1/4" (520mm)
1-7/8" (47mm)
HOT 5-1/4" (133mm)
120V 1-3/8" (36mm)
GAS 4-7/8" (124mm)
COLD 3-1/4" (84mm)
4-3/8" (113mm)
19-3/8" (493mm)
COLD 2-7/8" (71mm)
1" (26mm)
HOT 6-1/2" (164mm)
9-1/2" (241mm)
120VAC 3-7/8" (99mm)
GAS 5-1/4" (135mm)
1-5/8" (43mm)
5" (128mm)
7-7/8" (203mm)
13-1/8" (334mm)
COLD 2-7/8" (71mm)
HOT 6-1/2" (164mm)
HOT 5-1/4" (133mm) GAS 4-7/8" (124mm)
GAS 5-1/4" (135mm)
120VAC 3-7/8" (99mm)
120VAC 1-3/8" (36mm)COLD 3-1/4" (84mm)

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3. Interior view
T-D2-IN
1
3
4
5
67
9
8
31
10
11
13
14
15
16
17
18
18
19
2
21
12
23
24
32
25
22
28
29
27
30
20
26

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T
-
D2
-
OS
1
3
4
5
67
9
8
31
10
11
13
14
15
16
17
18
18
19
2
21
12
23
24
32
25
22
28
29
27
30
20
26

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4. List of main components in the interior view
No.
Description Items# in components
diagram
Takagi
Part# Common parts forothermodels
1 Case assembly 001 EK402 (T-D2-IN)
EKK41 (T-D2-OS) T-K3OS
2 Manifold assembly with
gas valve assembly 102 EKH6T (LP model)
T-H2-DV/OS
EKK5K (NA model)
3 Computerboard 701 EK439
4 Igniter 711 EKN74 T-K3, T-K3-Pro, T-K3-SP/OS, T-H2-DV/OS , T-KJr2-IN/OS,
T-K4-IN/OS, T-M50, T-M32
5 Transformer 702 EKH09 T-K3, T-K3-Pro, T-K3-SP/OS,
6 Waterinlet 404 EKK1U T-K3,T-K3-Pro, T-K3-SP/OS,
T-KJr2-IN/OS, T-K4-IN/OS
7 Water outlet 409 EKK1V T-K3, T-K3-Pro, T-K3-SP/OS,
T-KJr2-IN/OS, T-K4-IN/OS
8 Inletthermistor 407 EKK38 T-K3, T-K3-Pro, T-H2-DV/OS ,
T-M50, T-M32
9 Mixing thermistor 408 EKK1A T-K3, Pro, T-M50
10
Overheatcut-off fuse 413 EK333 T-K3, T-K3-Pro, T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS,
T-M50
11
Burnerassembly
(Burners)
101 EKH5W T-H2-DV/OS
12
Hi-limit switch 412 EKN34 T-K3,T-K3-Pro, T-K3-SP/OS,
T-H2-DV/OS , T-M50, T-M32
13
Fan motor 103 EKK25 (T-D2-IN) T-K3, T-K3-Pro, T-K3-SP,
T-H2-DV/OS , T-M50, T-M32
EKK54 (T-D2-OS) T-K3-OS, T-K4-OS
14
Freeze protection
thermostat 713 EKJ59 (T-D2-IN) T-K3, T-K3-Pro, T-K3-SP,
T-M32
710 EKK40 (T-D2-OS) T-K3-OS, T-KJr2-OS, T-K4-OS

T-D2-IN / T-D2-OS Service Manual
Ver. 1.00
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CONFIDENTIAL
No.
Description Items# in components
diagram
Takagi
Part# Common parts forother models
15
Flow sensor 402 EK438
16
Heatexchanger assembly
401 TU002 (T-D2-IN)
EK437 (T-D2-OS)
17
Gas inlet 118 EKK1E T-K3,T-K3-Pro, T-K3-SP/OS, T-KJr2-IN/OS,T-K4-IN/OS,
T-H2-DV/OS
18
Heater 414 EKK2R T-K3, T-K3-Pro,T-K3-SP/OS,
T-KJr2-IN/OS, T-K4-IN/OS
19
Flow adjustmentvalve 402 EK438
20
Surge box 703 EK428 T-KJr2-IN/OS, T-K4-IN/OS
21
Outlet drain plug 410 EKK2E T-K3,T-K3-Pro, T-K3-SP/OS,
T-KJr2-IN/OS,T-K4-IN/OS,
T
-
M50
22
Air-fuel ratio rod
(AFR rod) 108 EKK0E T-K3, T-K3-Pro, T-K3-SP/OS, T-H2-DV/OS, T-M50,T-M32
23
Flame rod 108 EKK0E T-K3,T-K3-Pro, T-K3-SP/OS,
T-H2-DV/OS, T-M50,T-M32
24
Igniterrod 109 EKK0F T-K3, T-K3-Pro, T-K3-SP/OS,
T-H2-DV/OS, T-M50,T-M32
25
Inletdrain plug (water
filter) 405 EKK2B T-K3, T-K3-Pro,T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS
26
120 VAC PowerON-OFF
switch 706 EKK4V T-K3-SP/OS, T-KJr2-IN/OS, T-K4-IN/OS,T-H2-DV/OS
27
Gas valve assembly Included in #102
EKH6T (LP model)
T-H2-DV/OS
EKK5K (NA model)
28
Manifold port N/A N/A
29
Gas inlet port N/A N/A
30
Exhaust chamber Included in #401
TU002 (T-D2-IN) T-H2-DV/OS
EK437 (T-D2-OS)
31
Output thermistor 411 EKK2T
32
Bypass valve 403 EKK0U

T-D2-IN / T-D2-OS Service Manual
Ver. 1.00
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CONFIDENTIAL
5. Schematic diagram
The diagram below refers to both the T-D2-IN and T-D2-OS.
1. When a hot water tap is opened,cold water entersthe T-D2-INor T-D2-OS.
2. The water flow sensor detects this waterflowand sends this information tocomputer.
3. The computer initiatesfan motorand sends signal to igniter to create ignition spark.
4. The main, proportional, and solenoid gas valves open to allow gas input.
5. The gas ignites and flames appear inside the burner chamber.
6. Watercirculates through the heat exchanger and isheated up tothe settemperature.
7. Using thermistors to measure temperatures, the computer modulates the gas and water valves to
ensureproperoutput water temperatures.
8. When the tap is closed, the T-D2-IN or T-D2-OS shuts down.
H
O
T
C
O
L
D
G
A
S
PCB
Hi-limit SW
Inlet drain
plug filter
Mixing
Thermistor
Drain plug
Main gas valve
Gas solenoid valve 2
Fan motor
Flame rod
Igniter rod
Igniter
O.H.C.F
Heater
Flow adjustment valve
with Flow sensor
Gas proportional valve
Gas solenoid valve 1
Air-fuel ratio rod
Gas solenoid valve 3
Output
Thermistor
Bypass valve
Inlet
Thermistor Transformer