VDH MC2-FC, Руководство пользователя, Страница: 7 / 44

MC2-FC mode FC
Document no.:200064 Version: 1.5
Page 7 of 44
1.5 Defrost
The controller supports 3 defrost methods, which are described in detail below.
A defrost action can be started manually or on the basis of clock time intervals or real-time intervals
(P810..P843). A defrost action only starts when the defrosting temperature is lower than the defrost
release temperature (P850).
Off-cycle defrost: During the defrost, the "Cooling ventilation" function of the evaporators is
switched on and the cooling is blocked. The defrost will stop automatically when the maximum
defrost time (P518) has elapsed. If there are multiple evaporators, the evaporators are defrosted at
the same time.
Electric defrost: During a defrost, the "Cooling ventilation" function of the evaporators remains
switched off. The defrost will stop automatically when the end-defrost temperature (P519) is
reached or the maximum defrost time (P518) has elapsed. After a defrost, a dripoff takes place. After
an electric defrost, the ventilation can be released on the basis of the time and/or the temperature
(P521, P529, P530). If there are multiple evaporators, the evaporators are defrosted one after the
other.
Hotgas defrost: This defrost method requires one or more other cells (in the same sub-network)
that cool to supply hotgas. The number of cooling cells required for hotgas defrosting can be
configured (P524.). When a cell is waiting for 15 for hotgas, other cells in the sequence of descending
cooling demand are forced to start cooling in order to supply hotgas. When two or more cells are
waiting for hotgas, the waiting time of 15 minutes is skipped.
During a defrost, the "Cooling ventilation" function of the evaporators remains switched off. The
defrost will stop automatically when the end-defrost temperature (P519) is reached or the
maximum defrost time (P518) has elapsed. Defrost will also stop if there is no more hotgas available.
After the defrost, the dripoff and a pumpdown take place. After a hotgas defrost, the ventilation can
be released on the basis of time and/or temperature (P521, P529, P530). If there are multiple
evaporators, the evaporators are defrosted one after the other.