Service And Maintenance - Mitsubishi Electric ecodan EHPT20Q-VM2EA Operation Manual

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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 Possible cause
Cold water at taps System or power input is OFF.
DHW is scheduled "OFF"
All reserves of hot water from thermal store tank have been
used.
Heat pump or booster heater not working
Air exists within pump A
Flow sensor jam / defect
Supply flow rate is too low.
Heating system does not get up Prohibit, schedule or holiday mode selected
to set temperature.
Incorrectly sized radiators or low flow rate setting
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
After DHW operation room tem- At the end of the DHW mode operation the 3-way valve
perature rises a little. diverts hot water away from the thermal store tank into
space heating circuit. This is only temporary and done to
prevent system components from potential overheating.
The amount of hot water directed into the space heating
circuit is dependent on the pipe run between the outdoor
unit and the cylinder unit.
Heating emitter is hot in the DHW The 3-way valve may have foreign objects in it, or hot
mode. (The room temperature water may flow to the heating side due to abnormal
rises.) malfunctions.
Schedule function inhibits the Freeze stat function may be active, to prevent freezing.
system from operating but the
outdoor unit is operational.
Pump runs without reason for Pump jam prevention control routine to inhibit the build up
of scale.
short time.
Mechanical noise (minor) heard Booster heater switching on/off
coming from cylinder unit
Pump operates during hot water supply
3-way valve changing position between DHW and heating
mode.
Abnormal cylinder noise during Air present in pump A
delivery of domestic hot water
supply
Noisy pipework Air trapped in the system
Loosely supported pipe work.
Water discharges from one of the The system has overheated or overpressurised
pressure relief valves
Small amounts of water drip from Dirt may be preventing proper tight seal in the valve
one of the pressure relief valves.
An error code appears in the The indoor or outdoor unit is reporting an abnormal condi-
main controller display. tion
<Power failure / outage>
Following any power failure (i.e. interrupted power input), ALL settings will be SAVED for a 1 week period only.
After 1 week, only Date / Time will be SAVED upon main controller.
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Solution
Turn on the power/system
Check schedule settings and change if necessary.
Ensure DHW mode is operating and wait for thermal store tank to
re-heat.
Contact installer.
Contact installer.
Contact installer.
Increase the delivery amount. (open tap further.)
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 routine operation no action necessary.
Contact installer.
Normal operation no action necessary.
Normal operation no action necessary.
Normal operation no action required.
Normal operation no action necessary.
Normal operation no action necessary.
Contact installer.
Try bleeding radiators (if present) If the symptoms persist contact
installer.
Contact installer.
Switch off power to the cylinder unit and the booster heater then
contact installer.
Twist the valve cap in the direction indicated 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 plus any other observation(s) and
contact installer.
5 Service and Maintenance
Maintenance to the cylinder unit and outdoor unit should be carried out annually by a competent person only. Users
should NOT try to service or replace parts of the cylinder unit by themselves. Failure to observe this instruction could
result in injury to the user, damage to the unit and invalidate product warranty.
In addition to routine annual servicing it is necessary to replace or inspect some parts after a certain period of system
operation. Please see tables below for detailed instructions.Replacement and inspection of parts should always be
done by a competent person with relevant training and qualifications.
Parts which require regular replacement
Parts Replace every Possible failures
Pressure relief valve (PRV)
Air vent (Auto) 6 years Water leakage
Manometer
Parts which require regular inspection
Parts Check every
Water circulation pump 1
50,000 hrs (7 years)
(i.e. main heating circuit pump)
Parts which must NOT be reused when servicing
* O-ring
* Gasket
Possible failures
Water circulation pump
failure
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