Mitsubishi Electric EHST20C-VM6HA Service Manual page 74

Annual Maintenance Log Book
Contractor name
Site name
Cylinder maintenance record sheet
Warranty number
No. Mechanical
Turn OFF water supply, drain tank, remove mesh from strainer clean and
1
replace in strainer. *1
Keep water supply OFF, open hot water taps and check the expansion

vessel charge pressure. Top up if necessary (1 bar).
Turn water supply ON, open the pressure relief valve and then the
expansion valve in turn. Check for unrestricted discharge to the tundish
3
and that the valves reseat correctly. Check there are no blockages in the
tundish and associated pipe work.
In hard water areas de-scaling of the immersion heaters may be required.
4
Drop the primary/heating system pressure to zero check and if neces-
sary top up the expansion vessel (1 bar). Air valve of expansion vessel is
5
TR-41.
Check and if necessary top up the concentration of anti-freeze/inhibitor (if
6
used in the system).
Top up the primary/heating system using an appropriate filling loop and
7
re-pressurise to 1 bar.
Heat system and check pressure does not rise above 3 bar and no water
8
is released from the safety valves.
9 Release any air from the system.
To check the 3-way valve for inside leaks, confirm that the temperature of
10
the heat emitter does not rise when running the DHW mode.
Refrigerant SA models only
1 Refer to outdoor unit manual.
Electrical
1 Check condition of cables.
Check rating and fuse fitted on the electricity supply.

Controller
Check field settings against factory recommendations.
1
Check operation of motorized valves ensure they reseat correctly.

Check battery power of wireless thermostat and replace if necessary.
3
Outdoor heat pump unit maintenance record sheet
Model number
Mechanical
Inspect grill, heat exchanger fins air inlet for trapped debris/damage.
1
 Check condensate drain provision.
Check integrity of water pipe work and insulation.
3
4 Check all electrical connections.
Check and record the operation voltage.
5
* All the above checks should be carried out once a year.
*1. Be sure to reattach the mesh after washing.
Note:
Within the first couple of months of installation, remove and clean the strainer. 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 instruc-
tions. 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
Pressure relief valve (PRV)
Air vent (Auto/Manual)
Drain cock (Primary circuit)
6 years
Flexible hose
Manometer
Inlet control group (ICG)*
*
OPTIONAL PARTS for UK
Engineer name
Site number
Model number
Serial number
Frequency
Frequency
Frequency
Frequency
Serial number
Frequency
Possible failures
Water leakage due to
brass/copper corrosion
(Dezincification)
74
Notes
Notes
Notes
Notes
Notes
Parts which require regular inspection
Parts Check every
Immersion heater  years
20,000 hrs (3 years)
Pump
Parts which must NOT be reused 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).
Possible failures
Earth leakage causing
circuit breaker to activate
(Heater is always OFF)
Pump failure