Mitsubishi Electric EHPT20Q-VM2EA Service Manual page 49

3-way valve
<DHW>
B
A
B
AB
Thermistors
<Thermistor Characteristics Charts>
Thermistor R0 = 15k ± 3%
B constant = 3480 ± 2%
1 1
Rt = 15exp {3480 ( )}
–
273+t 273
0°C
10°C
20°C
25°C
30°C
40°C
50
40
30
20
10
0
-20 -10 0 10 20 30 40 50
Temperature (°C)
GCH15010
Part Name
<Heating>
Motor
Indicator (red)
B
A
Release button
Valve
A B
AB
Thermistor R0 = 17.6k
B constant = 3970 ± 2%
Rt = 17.6exp {3970 (
0°C
10°C
20°C
30°C
40°C
50°C
60°C
70°C
80°C
600
500
400
300
200
100
0
-20 -10 0 10 20 30 40 50 60 70 80 90 100
(1) Check the movement of the red indicator. The red indicator normally points
to A in DHW mode and to B in Heating mode as shown to the left.
(2) If each indicator position is correct but the 3-way valve does not work prop-
erly, the motor may not fit onto the valve securely, so remove the motor by
pressing the release button, and reinstall it.
A
Disconnect the connector then measure the resistance with a tester.
(At ambient temperatures of 10 - 30°C.)
Thermistor
TH1
THW1
THW2
THW3
THW4
THW5A
THW5B
± 3%
1 1
)}
–
273+t 323
Temperature (°C)
49
Check Points
Normal Abnormal
Open or short
Open or short
Open or short
Thermistor R0 = 5.1k ± 2%
B constant = 3300 ± 2%
1 1
Rt = 5.1exp {3300 ( )}
–
273+t 318
0°C
10°C
20°C
30°C
40°C
50°C
60°C
70°C
80°C
80
70
60
50
40
30
20
10
0
-20 -10 0 10 20 30 40 50 60 70 80 90 100
Temperature (°C)