STIEBEL ELTRON SOM 8 PLUS - Page 44

44
Drainback option A drainback system permits the heat transfer uid to
drain back into the holding tank when solar energy
is not collected.The drainback option will initiate the
lling of the system when solar loading begins.
Note:
A drainback system requires additional
components such as a holding tank. The
drainback option should only be activated
if all components required are properly in-
stalled.
The parameter Filling time is used to adjust the
time period for which the pump will be run at 100 %
speed in order to ll the system.
The parameter Stabilisation is used for adjusting
the time period during which the switch-o condi-
tion will be ignored after the lling time has ended.
The parameter Initialis. is used for adjusting the
time period during which the switch-on condition
must be permanentely fullled for the lling proce-
dure to start.
The Booster option is used for switching on a se-
cond pump when lling the solar system. The corre-
sponding relay is switched on at 100 % speed for the
duration of the lling 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 ow pipe. When it
falls back into the holding tank, water pockets re-
maining 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 Stabilisation time 1.0 ... 15.0 min 2,0 min
Initialis. Initialisation 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)
295931-36390-8667 SOM 8 plus_en.indb 44 20.10.2011 13:14:41