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Service And Maintenance; Serial Number - Mitsubishi Electric ecodan EHPT series Operation Manual For User

Cylinder unit, hydrobox, ftc box
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Service and Maintenance

The following table is to be used as a guide to possible problems. It is not exhaustive and all problems should be investigated by the installer or another competent person.
Users should not attempt to repair the system themselves.
At no time should the system be operating with the safety devices by-passed or plugged.
Fault symptom
Cold water at taps
(systems with DHW tank)
Heating system does not get up to
set temperature.
The cooling system does not cool
down to the set temperature. (ONLY
for ER series)
After DHW operation room tempera-
ture rises a little.
Heating emitter is hot in the DHW
mode. (The room temperature rises.)
Schedule function inhibits the sys-
tem from operating but the outdoor
unit operates.
Pump runs without reason for short
Mechanical noise heard coming from
indoor unit
Noisy pipework
Water discharges from one of the
relief valves
Small amounts of water drip from
one of the relief valves.
An error code appears in the main
remote controller display.
Heat pump is forced to turn ON and
<Power failure>
All setting will be saved for 1 week with no power, after 1 week Date/Time ONLY will be saved.

Serial number

■ The serial number is indicated on the SPEC NAME PLATE.
Sequential number for each unit: 00001–99999
Month of manufacture: A (1), B (2), C (3), D (4), E (5), F (6), G (7), H (8), J (9), K (10), L (11), M (12)
Year of manufacture (western calendar) : 2018
Possible cause
Scheduled control off period
All hot water from DHW tank used
Heat pump or electric heaters not working
Prohibit, schedule or holiday mode selected
Incorrectly sized heat emitters
The room in which the temperature sensor is located is
at a different temperature to the rest of the house.
Battery problem *wireless control only
When the water in the circulation circuit is unduly hot,
Cooling mode starts with a delay for the protection of
the outdoor unit.
When the outdoor ambient temperature is significantly
low, Cooling mode does not start running to avoid
freezing of the water pipes.
At the end of the DHW mode operation the 3-way valve
diverts hot water away from the DHW tank into space
heating circuit. This is done to prevent the cylinder unit
components from overheating. The amount of hot water
directed into the space heating circuit is dependent on
the type of system and the pipe run between the plate
heat exchanger and the cylinder unit.
The 3-way valve may have foreign objects in it, or hot
water may flow to the heating side due to malfunctions.
Freeze stat. function is active.
Pump jam prevention mechanism to inhibit the build up
of scale.
Heaters switching on/off
3-way valve changing position between DHW and
heating mode.
Air trapped in the system
Loose pipework
The system has overheated or overpressurised
Dirt may be preventing a tight seal in the valve
The indoor or outdoor unit is reporting an abnormal
Smart grid ready input (IN11 and IN12) is used, and
switch-on and off commands are input.
8, 2019
Check schedule settings and change if necessary.
Ensure DHW mode is operating and wait for DHW tank to re-heat.
Contact installer.
Check settings and change as appropriate.
Contact installer.
Reposition the temperature sensor to a more suitable room.
Check the battery power and replace if flat.
Normal operation no action necessary.
If the freeze stat. function is not necessary, contact installer to change the
Normal operation no action necessary.
Contact installer.
Normal operation no action necessary.
Normal operation no action necessary.
Normal operation no action necessary.
Normal operation no action necessary.
Try bleeding radiators (if present) If the symptoms persist contact installer.
Contact installer.
Switch off power to the heat pump and any immersion heaters then con-
tact installer.
Twist the valve cap in the direction indicted until a click is heard. This
will release a small amount of water flushing dirt from the valve. Be very
careful the water released will be hot. Should the valve continue to drip
contact installer as the rubber seal may be damaged and need replacing.
Make a note of the error code number and contact installer.
Normal operation no action necessary.

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