Em-40-sm service manual, Testing – Slant/Fin EM-10 Service Manual User Manual
Page 13
13
EM-40-SM Service Manual
DHW Tank Sensor
An optional DHW Tank Sensor may be connected to the
control. If the sensor is required, connect the two wires
from the sensor to the Com (common sensor) and Sys/D
(DHW) pins.
Outdoor Sensor
An optional Outdoor Sensor may be connected to the
control. If the sensor is required, connect the two wires from
the Outdoor Sensor to the Com (common sensor) and Out
(outdoor sensor) pins. The outdoor sensor is used by the
control to measure the outdoor air temperature.
External Input
The control can accept an external input signal from an
external control. If an external input signal is required,
connect the positive 0-10 V (dc) wire to the +V(in) pin and
connect the negative 0-10 V (dc) wire to the Com/- pin.
The wiring harness must be unplugged from the connector
on the control before testing. To remove the wiring harness,
push down on the tab on the connector and pull away from
the control.
The following tests are performed using standard testing
practices and procedures and should only be carried out
by properly trained and experienced persons.
A good quality electrical test meter, capable of reading
from at least 0-300 V (ac) and at least 0-2,000,000 Ohms,
is essential to properly test the wiring and sensors.
TEST THE SENSORS
In order to test the sensors, the actual temperature at
each sensor location must be measured. A good quality
digital thermometer with a surface temperature probe is
recommended for ease of use and accuracy. First measure
the temperature using the thermometer and then measure
the resistance of the sensor at the control. Using the chart
below, estimate the temperature measured by the sensor.
The sensor and the thermometer readings should be close.
If the meter reads a very high resistance, there may be a
broken wire, a poor wiring connection or a defective sensor.
If the resistance is very low, the wiring may be shorted,
there may be moisture in the sensor or the sensor may
be defective. To test for a defective sensor, measure the
resistance directly at the sensor location.
Testing
Outdoor
Sensor
Temperature
Resistance
°F
°C
-50
-46
490,813
-45
-43
405,710
-40
-40
336,606
-35
-37
280,279
-30
-34
234,196
-25
-32
196,358
-20
-29
165,180
-15
-26
139,402
-10
-23
118,018
-5
-21
100,221
0
-18
85,362
5
-15
72,918
10
-12
62,465
15
-9
53,658
Temperature
Resistance
°F
°C
20
-7
46,218
25
-4
39,913
30
-1
34,558
35
2
29,996
40
4
26,099
45
7
22,763
50
10
19,900
55
13
17,436
60
16
15,311
65
18
13,474
70
21
11,883
75
24
10,501
80
27
9,299
85
29
8,250
Temperature
Resistance
°F
°C
90
32
7,334
95
35
6,532
100
38
5,828
105
41
5,210
110
43
4,665
115
46
4,184
120
49
3,760
125
52
3,383
130
54
3,050
135
57
2,754
140
60
2,490
145
63
2,255
150
66
2,045
155
68
1,857
Temperature
Resistance
°F
°C
160
71
1,689
165
74
1,538
170
77
1,403
175
79
1,281
180
82
1,172
185
85
1,073
190
88
983
195
91
903
200
93
829
205
96
763
210
99
703
215
102
648
220
104
598
225
107
553