Mitsubishi Electric EHGT17D-YM9ED Service Manual page 55

No. Fault symptom
20 Noise during hot water 1.
draw off typically
2.
worse in the morning.
21 Mechanical noise 1.
heard coming from
2.
the unit.
3.
22 Water circulation Water circulation pump jam prevention
pump runs for a short mechanism (routine) to inhibit the build-up of
time unexpectedly. scale.
23 Milky/Cloudy water Oxygenated water
(Sanitary circuit)
24 Heating mode has The time of "Delay" set in "Economy settings
been on standby for for pump" is too short. (Go to "Service menu"
a long time (does → "Auxiliary settings" → "Economy settings for
not start operation pump").
smoothly.)
25 The heat pump unit The heat pump unit is designed to run in an
that was running in operation mode with a higher priority (i.e. DHW
the heating mode mode in this case) at power recovery.
before power failure
is running in the
DHW mode after
power recovery.
1.
26 The energy monitor
value seems not cor-
rect.
Note:
There could be some
discrepancies between
the actual and the
calculated values.
If you seek for accuracy,
please make sure to
connect power meter(s)
and heat meter to FTC
board. Both should be
locally supplied.
2.
3.
4.
Smart grid ready input (IN11 and IN12) is used,
27 Heat pump is forced
and switch-on and off commands are input.
to turn ON and OFF.
Annual Maintenance
It is essential that the heat pump unit is serviced at least once a year by a qualified individual. Any spare parts required should be purchased from Mitsubishi Electric.
NEVER bypass safety devices or operate the unit without them being fully operational.
<Annual maintenance points>
Use the Annual Maintenance Log Book as a guide to carrying out the necessary checks on the heat pump unit.
OCH722A
Possible cause
Loose airing cupboard pipework.
Heaters switching on/off.
Heaters switching on/off.
3-way valve changing position between
DHW and heating mode.
Heat pump unit (compressor) running
Incorrect setting of the energy monitor
Non-connectable type of external meter
(local supply) is connected.
External meter (local supply) failure
FTC board failure
1. Install extra pipe fastening clips.
2. Normal operation no action necessary.
Normal operation no action necessary.
Normal operation no action necessary.
Water from any pressurised system will release oxygen bubbles when water is
running. The bubbles will settle out.
Increase the time of "Delay" in "Economy settings for pump" .
• 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 (ex. Heating
mode).
1. Check the setting by following the procedure below.
(1) Check if the DIP switch on FTC board is set as the table below.
Consumed electric energy
Electric energy meter
SW3-4
(Local supply)
OFF Without
ON With
(2) In the case external electric energy meter and/or heat meter is not used,
check if the setting for electric heater and water pump(s) input is correct by
referring to <Energy monitor setting> in "8-5. Service menu".
(3) In the case external electric energy meter and/or heat meter is used, check if
the unit of output pulse on external meter matches with the one set at the main
remote controller by referring to <Energy monitor setting> in "8-4. Service
menu".
2. Check if the external meter (local supply) is connectable type by referring to
<Energy monitor setting>" in "8-5. Service menu".
3. Check if signal is sent to IN8 to IN10 properly. (Refer to section 5. WIRING
DIAGRAM)
Replace the external heat meter if defective.
4. Check the FTC control board.
• Check for faulty wiring.
• If no problem found with the wiring, the FTC control board is faulty. Replace the
board.
Normal operation no action necessary.
55
Explanation - Solution
Delivered heat energy
Heat meter
SW3-8
(Local supply)
OFF Without
ON With