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

8

Service and Maintenance

The indoor cylinder unit is UNVENTED. Under UK law* the system MUST be serviced once a year by a qualifi ed individual.
Servicing and maintenance of the outdoor unit should only be done by a Mitsubishi Electric trained technician with relevant
qualifi cations and experience. Any electrical work should be done by a tradesperson with the appropriate electrical qualifi cations.
Any maintenance or At no time should the system be operating with the safety devices by-passed or plugged.'DIY' fi xes done by a
non-accredited person could invalidate the Warranty and/or result in damage to the cylinder unit and injury to the person.
* Building regulations – England & Wales Part G3, Scotland P3, Northern Ireland P5.
Basic Troubleshooting for Cylinder Unit
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 low
Heating system does not get up Prohibit, schedule or holiday mode selected
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
Heat emitter is hot in the DHW The 3-way valve may have foreign objects in it, or hot water
mode. (The room temperature rises.) may fl ow to the heating side due to abnormal 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
short time. of scale.
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. Normal operation no action necessary.
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
main controller display. condition
<Power failure>
All setting will be saved for 1 week with no power, after 1 week Date/Time ONLY will be saved.
For more details, refer to the service manual.
<Draining the cylinder unit and its primary heating circuit (local)>
1. Before attempting to drain the cylinder unit isolate from the electrical supply to prevent the booster heaters burning out.
When the ECB is turned off, push down the power lever without pressing the test button.
2. Isolate cold water feed to secondary (potable) circuit.
3. Attach a hose to the drain cock (No.4 on the front side of heat exchanger shown in Figure 3. 2).*1
Open a hot water tap to start draining without a vacuum.
Open the drain cock of the heat exchanger .
4. When the secondary (potable) circuit is drained close drain cock and hot tap.
5. Draining procedure of the thermal store tank (primary circuit) is as follows.
(1) Open the cap of the pressure relief valve to reduce the pressure of the thermal store tank to 0 bar.
(2) Attach a hose to the manual air vent (No. 12 above the thermal store tank shown in Figure 3.2).*1
Open the manual air vent.
(3) Check that the pump valves and the strainer valve are opened.
Open the drain valve (No.13 shown in Figure 3. 2) to drain the water in the thermal store tank.
(4) Open all other drain cocks. (No.3 shown in Figure 3.2 and drain cocks of outdoor unit)
(5) Water remains in the strainer still after the cylinder unit was drained. Drain the strainer by removing the strainer
cover.
*1. The hose should be able to withstand heat as the draining water could be very hot.
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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.
Open the air vent above pump A (refer to page 16).
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.
Contact installer.
Normal operation no action necessary.
Normal operation no action necessary.
Normal operation no action required.
Normal operation no action necessary.
Open the air vent above pump A (refer to page 16). If the symptoms
persist 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 indicted 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.
WARNING
DRAINED WATER MAY
BE VERY HOT
8
Service and Maintenance
Error Codes
Code Error
L3 Circulation water temperature overheat protection
L4 Thermal store tank water temperature overheat protection
Indoor unit temperature thermistor (THW1, THW2, THW3, THW4, THW5A,
L5
THW5B) failure
L6 Circulation water freeze protection
L8 Heating operation error
L9 Low primary circuit fl ow rate detected by fl ow sensor (fl ow sensors1,B)
LF Flow sensor failure (fl ow sensors1,A,B)
LP DHW supply temperature overheat protection
LU Water ciculation pump failure
J0 Communication failure between FTC and wireless receiver
P1 Thermistor (Room temp.) (TH1) failure
J1 - J8 Communication failure between wireless receiver and wireless remote controller
E0 - E5 Communication failure between main controller and FTC
E6 - EF Communication failure between FTC and outdoor unit
U*, F* Outdoor unit failure
Note: To cancel error codes please press F4 button or switch system OFF (Press button E on Main Controller for 3 secs).
Annual Maintenance
It is essential that the cylinder unit is serviced at least once a year by a qualifi ed individual. Any spare parts required
should be purchased from Mitsubishi Electric. Never bypass safety devices or operate the unit without them being fully
operational. For more details, refer to service handbook.
Note: Within the fi rst couple of months of installation, remove and clean the cylinder unit's strainer plus any strainer and
magnetic fi lter that may be fi tted external to the cylinder unit. This is especially important when installing on an existing
system.
In addition to 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 Possible failures
Pressure relief valve (PRV)
Air vent (Auto) 6 years Water leakage
Manometer
Action
Flow rate may be reduced check for;
• Water leakage
• Strainer blockage
• Clogging of piping
• Water circulation pump function (Error code may display during fi lling of
primary circuit, complete fi lling and reset error code.)
Check resistance across the thermistor (THW1,THW3, THW5A).
Check resistance across the thermistor.
See Action for L3.
Re-attach any thermistors that have become dislodged.
See Action for L3. If the fl ow sensor itself does not work,replace it.
Discharge the air for primary circuit.
Turn on the pump A and pump 1 using Manual operation to fl ush debris
on the fl ow sensor.
Caution: The pump valves may be hot, please take care.
Check fl ow sensor cable for damage or loose connections.
See Action for L3.
Check detection value of thermistor is the same as the actual temperature
Check resistance across the thermistor (Cylinder unit and outdoor unit)
Check cloggings of the pump with foreign materials
Check water circulation pump cable for damage or loose connections.
Caution : The pump valves may be hot, please take care
Check connection cable for damage or loose connections.
Check resistance across the thermistor.
Check the room sensor settings.(page 33)
Check wireless remote controller's battery is not fl at.
Check the pairing between wireless receiver to wireless remote controller.
Test the wireless communication. (See the manual of wireless system)
Check connection cable for damage or loose connections.
Check that the outdoor unit has not been turned off.
Check connection cables for damage and miswiring or loose connections.
Press the reset button and recover the system after lowering the
temperature if the thermostat of outdoor unit operates.
Refer to outdoor unit service manual.
Refer to outdoor unit service manual.
Parts which require regular inspection
Parts Check every Possible failures
Water circulation pump
Water circulation pump1 50,000 hrs (7 years)
failure
Parts which must NOT be reused when servicing
* O-ring
* Gasket
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