M-thermal technical manual
– part 3
4 Maintenance
In order to ensure optimal availability of the unit, a number of checks and inspections on the unit
and the field wiring have to be carried out at regular intervals.
Caution:
Before carrying out any maintenance or repair activity, always switch off the circuit breaker on
the supply panel, remove the fuse or open the protection devices of the unit.
Make sure that before starting any maintenance or repair activity, also the power supply to the
outdoor unit is switched off.
The described checks must be executed at least once a year:
a) Water pressure
Check if the water pressure is above 0.3 bar. If necessary add water.
b) Water filter
Clean the water filter.
c) Water pressure relief valve
Check for correct operation of the pressure relief valve by turning the red knob along the valve
counter-clockwise:
1. If you do not hear a clacking sound, contact your local dealer.
2. In case the water keeps running out of the unit, close both the water inlet and outlet shut-off
valves first and then contact your local dealer.
d) Pressure relief valve hose
Check that the pressure relief valve hose is positioned appropriately to drain the water.
If the drain pan kit is installed, make sure that the pressure relief valve hose end is positioned in
the drain pan.
e) Auxiliary heater vessel insulation cover
Check that the auxiliary heater insulation cover is fastened tightly around the auxiliary heater
vessel.
f) Sanitary hot water tank pressure relief valve (field supply)
Apply only to the system which installs a sanitary water tank.
Check for correct operation of the pressure relief valve on the sanitary hot water tank.
g) Sanitary hot water electric heater
Apply only to the system which installs a sanitary water tank.
It is advisable to remove lime buildup on the electric heater to extend its life span, especially in
regions with hot water. To do so, drain the sanitary hot water tank, remove the electric heater
from the sanitary hot water tank and immerse in a bucket (or similar) with lime-removing product
for 24 hours.
h) Indoor unit control box
1. Carry out a through visual inspection of the control box and look for obvious defects such as
loose connections or defective wiring.
2. Check for correct operation of contactors by the use of an ohmmeter. All of these contactors
must be in open position.
