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During the operation of the heat pump, cooling of the heat exchanger of the outdoor unit causes it to freeze. When
the evaporator is frozen, the outdoor unit automatically evaluates this state and starts the defrosting process. The
frequency of defrost cycles depends on several factors, the most important of which are air temperature, humidity
and required power.
During the evaporator defrosting process, the evaporator is reheated using the energy stored in the heating water
and at the same time the fans start running at full speed, which dries the evaporator. During this process, you can
see water vapour rising from the evaporator, which may seem like the unit is burning. However, in this case, it is not
a dangerous state but a normal operating condition, so do not disconnect the outdoor unit from the power supply.
The heat pump user interface in the States and faults lists the last ten fault states (codes) of the heat pump.
Complete operating data is accessible via the heat pump's web interface.
The controller has the Fault autoreset function. Thanks to this function, the heat pump can resume operation
after a critical fault has been removed, e.g. a sufcient system ow restored. If the autoreset is activated times,
it is clear that this is not a random fault. The heat pump remains in a fault state and requires professional atten-
tion. The autoreset function can be restored in the States and faults section, which should only be done after
consultation with a service organization.
Fault xxx
Frost protection. A fault occurs if the output water temperature is lower than the safe limit. The default limit for frost
protection is °C. When the output water temperature is lower, the heat pump stops running until the output water temper-
ature reaches a safe level again. Meanwhile, bivalent operation is started. The heat pump starts minutes after reaching
a safe temperature.
This fault typically occurs when the system is started, when the system is lled with cold water from the water main.
Another typical situation where this fault occurs is the cooling of the heating water during the defrosting process of the
outdoor unit. This can have two causes.
. Low temperature of heating water (below °C) in the system, where heating water does not carry enough energy to
defrost the outdoor unit.
. The second possible cause is a reduced ow of heating water through the heat pump, e.g. due to a clogged heating
water lter.
If the frost protection fault occurs repeatedly, contact a service organization.
Fault xxx
Insufcient ow. The insufcient heating water ow fault occurs when the current water ow is lower than required. The
value of the required ow directly depends on the current power of the outdoor unit, i.e. the higher the power of the outdoor
unit, the higher the required value of the heating water ow. This is also the reason why the fault can occur seemingly
randomly, e.g. only when heating the heat water tank, when high power and therefore high heating water ow is required.
A typical cause of a ow fault is clogging of the heating system with dirt. The second possible cause is that the heating
system contains a constricted point. This point with an insufcient cross-section (e.g. control valve) affects the total ow,
even if the cross-section of all other parts of the heating system is sufcient. Random and short-term faults can also be
caused by aeration of the heating system or low pressure of heating water.
All these cases require the attention of a service organization, which locates and eliminates the cause of the fault.
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