©
Viessmann 5443202
|
28
SCU124
5.1 Various
Pump starts for a short moment, switches off, switches
on again, etc.
Temperature difference
at the controller too
small?
no
yes
Wrong position of collec-
tor sensors?
yes
Change
∆
Ton and
∆
Toff
correspondingly. Problem
solved?
Mount the collector sen-
sor at solar flow (warmest
collector output); use sen-
sor well of the respective
collector.
Pump starts up very late
The temperature difference between tank and collector
increases enormously during operation; the collector cir-
cuit cannot dissipate the heat.
Collector circuit pump
defective?
no
yes
Heat exchanger calcified?
yes
Check / replace it
Decalcify it
no
Heat exchanger blocked?
yes
no
Clean it
Heat exchanger too
small?
yes
Replace with correctly
sized one.
no
Plausibility control of
the option tube collec-
tor special function
Change
∆
Ton and
∆
Toff
correspondingly.
Switch-on temperature
difference Ton to large?
no
yes
Non-ideal position of the coll-
ector sensor (e.g. flatscrew
sensor instead of sensor in
sensor wells)?
no
Pump is overheated, but no heat transfer from the
collector to the tank, flow and return have the same tem-
perature; perhaps also air / gas bubbles in the lines.
Air in the system; in crease
the system pressure to at
least static primary pres-
sure plus 7. 25 psi (0.5 bar);
if necessary continue to
increase pressure; switch
the pump off and on for a
short time.
Air in the system?
no
yes
Is the collector circuit
blocked at the dirt trap?
yes
Clean the dirt trap
Activate tube collector
function if necessary.
yes
o.k.
yes
o.k.