Remote Mounting Of Sensor - A.O. Smith 400 - 2100 Installation & Operation Manual

5
Electrical connections
Figure 5-4_Stand-alone operation
1
TANK
+
2 + SENSOR
3 + B2 INTERMITTENT
4 + B1 LIMITS
5 + A2 CONTINUOUS
6 + A1 LIMITS
7 2 NO HIGH FIRE
+
8 2 C ENABLE
+
9 1 NO LOW FIRE
+
10 + 1 C ENABLE
Figure 5-5_Remote on/off water heater
1
+
2 +
3 +
4 +
5 +
6 +
Remote
7
+
on/off
8 +
9 +
10 +
Figure 5-6_Two-stage (high/low fire) water heater
1
+
2 +
3 +
4 +
5 +
Stage 2 6 +
7
+
8
+
9 +
10
+
Stage 1
Figure 5-7_Field installation safety devices
1
+
2 +
Intermittent
Alarms
3 +
4 +
5 +
6 +
Continuous 7
+
8
Alarms +
9
+
10
+
40
6 1
7 2
8 3
9 4
10 5
TANK
SENSOR
6
B2 INTERMITTENT
7
B1 LIMITS
8
A2 CONTINUOUS
A1 LIMITS
9
2 NO HIGH FIRE
2 C ENABLE
10
1 NO LOW FIRE
1 C ENABLE
TANK
SENSOR
6
B2 INTERMITTENT
7
B1 LIMITS
8
A2 CONTINUOUS
A1 LIMITS
9
2 NO HIGH FIRE
2 C ENABLE
10
1 NO LOW FIRE
1 C ENABLE
TANK
SENSOR
6
B2 INTERMITTENT
7
B1 LIMITS
A2 CONTINUOUS 8
A1 LIMITS
9
2 NO HIGH FIRE
2 C ENABLE
10
1 NO LOW FIRE
1 C ENABLE
Installation & Operation Manual
Figure 5-8_Remote sensor for pump delay
FIELD SUPPLIED
WIRING
TANK
SENSOR
REQUIRED IN ORDER
FOR PUMP DELAY TO
FUNCTION PROPERLY
Remote mounting of a sensor
To mount remote sensor, follow the guidelines below. Take
care to correctly wire sensors to the unit. Erratic temperature
readings can be caused by poor wiring practices. Twist the
wires between the unit and the remote sensor. Turn wires
at least three or four turns per linear foot of wiring. This
1
provides common mode rejection of some types of electrical
2
interferences.
3
1. Do not route temperature sensor wiring with building
power wiring.
4
2. Do not locate temperature sensor wiring next to control
5
contactors.
3. Do not locate temperature sensor wiring near electric
motors.
4. Do not locate temperature sensor wiring near welding
equipment.
5. Make sure good mechanical connections are made to the
sensor, any interconnecting wiring and the controller.
6. Do not mount sensor with leadwire end pointing up in an
1
area where condensation can occur.
2
7. Use shielded wiring to connect the sensor to the control
3
when the possibility of an electrically noisy environment
4 exists. Shielded cable is recommended on all cable runs
of more than 25 feet in length.
5
Ground the cable shield at the
NOTICE
connection to the water heater
temperature control only. Do not
ground the shielded cable at the sensor
end.
To maintain temperature accuracy,
sensor wires should be at least 18 AWG,
see Table 5B.
1
2
Remote Wire Connection
3
Wire Gauge
4
12 GA
5
14 GA
16 GA
18 GA
CONNECTION BOARD
1 TANK
+
2 + SENSOR
3 + B2 INTERMITTENT
4 + B1 LIMITS
5 + A2 CONTINUOUS
6 + A1 LIMITS
7 2 NO HIGH FIRE
+
8 + 2 C ENABLE
9 + 1 NO LOW FIRE
10 + 1 C ENABLE
TABLE 5B
Max. Allowable Length
100 FT
75 FT
50 FT
30 FT
6 1
7 2
8 3
9 4
10 5