STIEBEL ELTRON SOM 10 - Manual (Page 44)

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Drainback option A drainback system permits the heat transfer fluid to
drain back into the holding tank when solar energy
is not collected.The drainback option will initiate the
filling of the system when solar loading begins.
Note:
The parameter Filling time is used to adjust the
time period for which the pump will be run at 100 %
speed in order to fill the system.
The parameter Stab. time is used for adjusting the
time period during which the switch-off condition will
be ignored after the filling time has ended.
The parameter Initialis. is used for adjusting the time
period during which the switch-on condition must
be permanentely fulfilled for the filling procedure to
start.
The Booster option is used for switching on a se-
cond pump when filling the solar system. The corre-
sponding relay is switched on at 100 % speed for the
duration of the filling time.
A short time (Delay time) after the system has been
emptied, the Drain impulse option will switch on
the solar pump for an adjustable Duration. Thus, a
hydrostatic head will form in the flow pipe. When it
falls back into the holding tank, water pockets remai-
ning in the collector will be sucked down into the
holding tank.
Adjustment channel Description Adjustment range / selection Factory setting
Filling time Filling time 1 ... 30 min 5 min
Stab. time Stabilization time 1.0 ... 15.0 min 2,0 min
Initialis. Initialization time 1 ... 100 s 60 s
Booster Booster option Yes, No No
Relay Booster pump relay selection system dependent system dependent
Drain impulse Drain impulse option Yes, No No
Delay Delay time 1 ... 30 min 3 min
Duration Drain impulse loading duration 1 ... 60 s 10 s
Funct. Activation / Deactivation Activ., Deactivated Deactivated
Solar / Opt. functions / Add new function... / Drainback
S1
S3
S2
S4/TR
R1 R2
booster pump
Exemplary drainback system layout
(R2 = booster pump)