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8
Service and Maintenance
Annual Maintenance (cylinder unit and hydrobox)
It is essential that the indoor unit is serviced at least once a year by a qualifi ed individual. Any required parts 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.
Notes
▪ Within the fi rst couple of months of installation, remove and clean the indoor unit's strainer plus any additional fi lter items that are fi tted external to the in-
door unit. This is especially important when installing on an old/existing pipe work system.
▪ The pressure relief valve and T&P valve should be checked annually by turning the knob manually so that the medium is discharged, thus cleaning the seal
seat.
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
Pressure relief valve (PRV)
Manometer
Inlet control group (ICG)*1
Mud trap*2
*1 OPTIONAL PARTS for UK
en
*2 Cylinder unit: ERST17D-*M*BE
<Draining particles from the magnetic filter>
Note: DRAINED WATER MAY BE VERY HOT
1. Turn OFF the unit via the user interface.
2. Turn OFF the circuit breaker.
3. Check if body of the magnet fi lter is still fi tted tight (a).
4. Close the isolating valves.
5. Put a suitable bottle below the magnetic fi lter.
6. Remove fastener and open the cap of the fi lter (b).
7. Collect the water and particles in the bottle.
8. Wash the inside mesh and magnet and remove particles from them.
9. Put the inside mesh and magnet back into the fi lter.
10. Fit the cap with fastener.
11. Open the isolating valves.
12. Check the pressure of the water circuit.
<Draining particles from the magnetic filter (ONLY Cylinder unit: ERST17D-*M*BE)>
Note: DRAINED WATER MAY BE VERY HOT
1. Turn OFF the unit via the user interface.
2. Turn OFF the circuit breaker.
3. Check if body of the magnet fi lter is still screwed tight (a).
4. Close the isolating valves.
5. Hold the motor of mixing valve and pull hard to remove it from the valve.
6. Put a suitable bottle below the magnetic fi lter.
7. Open the cap of the fi lter with 2 spanners (b).
8. Collect the water and particles in the bottle.
9. Wash the inside mesh and magnet and remove particles from them.
10. Put the inside mesh and magnet back into the fi lter.
11. Screw the cap with 2 spanners.
12. Reattach the motor on the mixing valve.
13. Open the isolating valves.
14. Check the pressure of the water circuit.
35
Replace every Possible failures
6 years
Water leakage
Parts which require regular inspection
Parts
Check every
Pressure relief valve (3bar)
1 year
Temperature and pressure
(turning the knob
relief valve
manually)
Immersion heater*3
2 years
Water circulation pump
20,000 hrs (3 years)
(Primary circuit)
Magnetic fi lter
3 years
Mud trap*4
1 year
*3 Cylinder unit: EHPT20X-MEHEW and OPTIONAL PART
*4 Cylinder unit: ERST17D-*M*BE
Parts which must NOT be re-used when servicing
* O-ring
* Gasket
Note:
• Always replace the gasket for pump with a new one at each regular main-
tenance (every 20,000 hours of use or every 3 years).
a
b
Possible failures
It could seize and risk
burst of expansion ves-
sel
Earth leakage causing
circuit breaker to activate
(Heater is always OFF)
Water circulation pump
failure
Flow rate decrease due
to clogging
Flow rate decrease due
to clogging
a. body
b. cap
a
a body
b
b cap
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