Service And Maintenance; Troubleshooting - Mitsubishi Electric EHPT20Q-VM2EA Manual De Funcionamiento

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Service and Maintenance

Troubleshooting

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 fl ow rate is too low.
Heating system does not get Prohibit, schedule or holiday mode selected
up to set temperature.
Incorrectly sized radiators or low fl ow 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 At the end of the DHW mode operation the 3-way
temperature rises a little. valve 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 3-way valve may have foreign objects in it,
the DHW mode. (The room or hot water may fl ow to the heating side due to
temperature rises.) abnormal malfunctions.
Schedule function inhibits the Freeze stat function may be active, to prevent
system from operating but the freezing.
outdoor unit is operational.
Pump runs without reason for Pump jam prevention control routine to inhibit the
short time. build up of scale.
Mechanical noise (minor) Booster heater switching on/off
heard coming from cylinder
Pump operates during hot water supply
unit
3-way valve changing position between DHW and
heating mode.
Abnormal cylinder noise Air present in pump A
during delivery of domestic
hot water supply
Noisy pipework Air trapped in the system
Loosely supported pipe work.
Water discharges from one of The system has overheated or overpressurised
the pressure relief valves
Small amounts of water drip Dirt may be preventing proper tight seal in the
from one of the pressure valve
relief valves.
An error code appears in the The indoor or outdoor unit is reporting an abnormal
main controller display. condition
<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 fl at.
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 fl ushing 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.
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Service and Maintenance
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 qualifi cations.
Parts which require regular replacement
Parts Replace every
Pressure relief valve (PRV)
Air vent (Auto) 6 years
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 leakage
Possible failures
Water circulation pump
failure
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