DORA
90 LT - 120 LT
fig. 44- Safety thermostat reset
The intervention of the safety
thermostat may occur due to a
fault in the control board or the
ATTENTION
absence of water in the boiler
tank.
NB!: The intervention of the thermostat ex-
cludes the operation of the electrical resist-
ance but not the heat pump system within the
allowed operating limits.
If the operator is unable to elim-
inate the fault, switch off the
equipment and contact the Tech-
ATTENTION
nical Assistance Service, com-
municating the model of the
product purchased.
7.3
CHECK/REPLACEMENT OF THE
SACRIFICIAL ANODE
The integrity of the Mg anodes must be checked at least
once every two years (once a year is recommended). The
check should be carried out by a qualified technician.
The magnesium anode (Mg), also known as an "sacrificial" an-
ode, prevents any eddy currents generated inside the boiler
from triggering surface corrosion.
Magnesium is, in fact, a less noble metal than the material lin-
ing the inside of the boiler, therefore, it attracts the negative
charges first that are formed by heating the water, and is con-
sumed. The anode, therefore, "sacrifices" itself and corrodes
instead of the boiler tank. The integrity of the Mg anode must
be checked at least every two years (preferably once a year).
The operation must be performed by qualified personnel.
Before carrying out the check, you must:
• Close the cold water inlet.
• Proceed with emptying the boiler (see par. "7.4 EMPTYING
THE BOILER").
• Remove the bottom cover 1.
• Disconnect the heating element safety thermostat electri-
cal connection from the power board and remove the water
NTC probes from the dedicated pipe in the element flange.
• Remove the flange by unscrewing the bolts 3. The corrosion
of the anode 4 can then be checked; if it affects more than
2/3 of the anode surface, proceed with replacement.
The flange has a special gasket which must be replaced if the
anode is checked or replaced.
7.4
EMPTYING THE BOILER
If not in use, especially in case of low temperatures, it is advis-
able to drain the water inside the boiler. For the equipment in
question, just open the drain cock as per the example hydrau-
lic connections chap. "6.7 HYDRAULIC CONNECTIONS" on
page 136 (see fig. 35).
NB!: In case of low temperatures, remember
to empty the system to avoid freezing.
cod. 3541T620 - Rev. 06 - 12/2022
3
4
2
1
fig. 45
4
fig. 46
EN
147