Mitsubishi Electric EHPT20X-VM2HA, Service Manual

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Part Name Check Points
Booster heater
Measure the resistance between the terminals with a tester.
Thermostat (90 °C) and thermal cut out (121 °C)
90 °C
Manual reset
water
thermostat
121 °C
Thermal
cut-out
AWG18 AWG18
9
10
Terminal Normal Abnormal
9-10
110(±35)mΩ
Open or Short
2kW heater (230V, 1 phase)
1 2
2kW
AWG15 FEP WHITE AWG15 FEP WHITE
Terminal Normal Abnormal
1-
26.5(+3/-1.3)Ω
Open or Short
2 + 4kW heater (230V, 1 phase)
1 2
2kW
AWG15 FEP WHITE AWG15 FEP WHITE
3 4
2kW
AWG13 FEP BLUE AWG13 FEP BLUE
2kW
Terminal Normal Abnormal
1-
26.5(+3/-1.3)Ω
Open or Short
3-4
13.3(+1.5/-0.6)Ω
Open or Short
3 + 6kW heater (400V, 3 phase)
5 6
AWG15 FEP WHITE AWG15 FEP WHITE AWG13 FEP BLUE
2kW
4
AWG15 FEP WHITE
2kW 2kW
2 3
1kW
1
1kW 1kW
AWG13 FEP BLUE AWG13 FEP BLUE
Terminal Normal Abnormal
1-=-3=1-3
105.8(+11.8/-5)Ω
Open or Short
4-5=5-6=4-6
52.9(+5.8/-2.5)Ω
Open or Short
Earth leakage breaker for heater
If a short circuit occurs on the booster heater, immersion heater, or each power line, a short-circuit
breaker will trip and power source will be blocked.
Eliminate the causes of short circuit and then turn on the breaker again.
Relay for heater R S T A1 A2
U V W
When the applied voltage is not 230V AC across the terminals A1-A2, check the terminals R-U,
S-V, and T-W are open.
When the applied voltage is 230V AC across the terminals A1-A2, check the terminals R-U, S-V,
and T-W are short.
Flow switch
Flow
1
2
3
Measure the resistance between the terminals with a tester.
State of moving part Normal Abnormal
Paddle vertical (Flow < 5.5 l/min)
Open Other than open
Paddle inclined (Flow > 5.5 l/min)
Short Other than short
Thermistors
Disconnect the connector then measure the resistance with a tester.
(At ambient temperatures of 10 - 30°C.)
Thermistor Normal Abnormal
TH1
4.3 - 9.5 kΩ
Open or short
TH
THW1
THW
THW5B
THW3
160 - 410 kΩ
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