Mitsubishi Electric EHSC-VM6A Service Manual page 45

Hydrobox, main controller
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24 Heating emitter is hot in
the DHW mode. (The room
temperature rises.)
25
The hydrobox that was
running in the heating
mode before power
failure is running in the
DHW mode after power
recovery.
10-6. Checking Component Parts' Function
Part Name
Water circulation pump
L
Earth leakage breaker for heater
Relay for heater
R
S
T
U
V
W
1.
The 3-way valve may have foreign objects in it, or hot
water may fl ow to the heating side due to malfunctions.
2.
2-way valve (fi eld supply) has tripped.
The hydrobox is designed to run in an operation mode with
a higher priority (i.e. DHW mode in this case) at power
recovery.
N
M
1~
A1 A2
1.
Manually override the 3-way valve several times to check
whether the problem will be solved. (Refer to the service
manual.) If the problem persists replace the 3-way valve
coil with a new one. If still no change replace the entire
3-way valve with a new one.
2.
Check the cause of the trip and check plumbing/wiring to
2-way valve (fi eld suppl).
Normal operation.
After the DHW max. operation time has elapsed or the DHW
max. temperature has been reached, the DHW mode switches
to the other mode.
Measure the resistance between the terminals with a tester.
(Winding temperate 20 °C)
Terminal
L - N
<Water Circulation Pump Characteristics>
EHSC series
80
speed3
(Default setting)
70
speed2
speed1
60
50
40
30
20
10
0
0
10
20
30
40
Flow rate[L/min]
<Recommended water fl ow rate range>
Outdoor heat pump unit
Packaged
PUHZ-W50
PUHZ-W85
PUHZ-HW112
PUHZ-HW140
Split
PUHZ-RP35
PUHZ-RP50
PUHZ-RP60
PUHZ-(H)RP71
PUHZ-(H)RP100
PUHZ-(H)RP125
PUHZ-RP140
* I f the water fl ow rate is less than 7.1 L/min, the fl ow switch will be activated.
If the water fl ow rate exceeds 27.7 L/min, the fl ow speed will be greater than
1.5 m/s, which could corrode the pipes.
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.
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.
45
Check Points
Normal
Abnormal
121Ω
Open or Short
EHPX series
80
speed3
70
speed2
speed1
60
50
40
30
20
10
0
50
0
10
20
30
Flow rate[L/min]
Water fl ow rate range [L/min]
7.1 - 14.3
10.0 - 25.8
14.4 - 27.7
17.9 - 27.7
7.1 - 11.8
7.1 - 17.2
8.6 - 20.1
10.2 - 22.9
14.4 - 27.7
17.9 - 27.7
20.1 - 27.7
(Default setting)
40
50

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