Miscellaneous - Viessmann SCU345 Manual

9.1

Miscellaneous

Pump is overheated, but no heat transfer from
the collector to the tank, flow and return have
the same temperature; perhaps also bubbling in
the lines.
Air or gas bubbles in the system?
no
Are valves or Vent the system;
non-return valves increase the system
defective? pressure to a static
primary pressure of
yes
at least plus 0,5 bar;
if necessary continue
Replace
to increase pressure;
switch the pump off
and on for a short
time.
Pump starts up very late.
Switch-on temperature difference ∆Ton too
large?
no
Change ∆Ton and
∆Toff correspondingly.
Non-ideal position of the collector sensor (e.g.
flatscrew sensor instead of sensor in immersion
sleeves)?
no yes
Minimum limitation Activate evacuated
active tube collector func-
tion if necessary.
66
Pump starts for a short moment, switches off,
switches on again, etc.
Temperature difference at the controller too
small?
no
yes
Wrong position of the col-
lector sensor?
no
Plausibility
trol of the evacu-
ated evacuated
yes
tube collector and
antifreeze function
o.k.
yes
Change ∆Ton and ∆Toff
correspondingly.
no o.k.
yes
con- Mount the collec-
tor sensor at solar
flow (warmest col-
lector output); use
immersion sleeve
of the respective
collector.
The temperature difference between tank and col-
lector increases enormously during operation; the
collector circuit cannot dissipate the heat.
Collector circuit pump / valve defective?
no
Check / if necessary, replace
Heat exchanger calcified?
no
Decalcify it
Heat exchanger blocked?
no
Clean it
Heat exchanger too small?
Replace with correctly sized one.
yes
yes
yes
yes