T-D2-IN / T-D2-OS Service Manual
Ver. 1.00
10
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 enters the T-D2-IN or T-D2-OS.
2.
The water flow sensor detects this water flow and sends this information to computer.
3.
The computer initiates fan motor and 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.
Water circulates through the heat exchanger and is heated up to the set temperature.
7.
Using thermistors to measure temperatures, the computer modulates the gas and water valves to
ensure proper output 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
H i - l i m i t S W
I n l e t d r a i n
p l u g f i l t e r
M i x i n g
T h e r m i s t o r
D r a i n p l u g
M a i n g a s v a l v e
G a s s o l e n o i d v a l v e 2
F a n m o t o r
F l a m e r o d
I g n i t e r r o d
I g n i t e r
O . H . C . F
H e a t e r
Flow adjustment valve
with Flow sensor
Gas proportional valve
Gas solenoid valve 1
Air-fuel ratio rod
G a s s o l e n o i d v a l v e 3
O u t p u t
T h e r m i s t o r
B y p a s s v a l v e
I n l e t
T h e r m i s t o r
T r a n s f o r m e r
