Thermo Technologies USDT 3002 - Manual (Page 14)

USDT 3002
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Pump starts for a short moment, switches-off, switches-on
again, etc. („controller hunting“)
Is the temperature diffe-
rence at the controller
too small?
no yes
Wrong placing of the
collector sensor?
yes
Change ∆T
on and ∆Toff
accordingly.
Mount the collector sen-
sor at solar feed flow
(warmest collector out-
put); use the immersion
sleeve of the respective
collector.
Pump starts up very late and soon stops working soon. The temperature difference between tank and collector
increases enormously during operation; the collector cir-
cuit cannot dissipate the heat.
Collector circuit pump
defect ?
no yes
Heat exchanger calcified?
yes
Control / replace
Decalification
no
Heat exchanger plugged?
yes no Cleaning
Heat exchanger too
small?
yes New calculation of the
dimension.
no
Plausibility control of the
option tube collector spe-
cial function?
Change ∆T
on and ∆Toff
accordingly.
Switch-on-temperatu-
re difference
∆T
on too
large?
no yes
Collector sensor unfavor-
able placed (e.g. contact
sensor instead of immersion
sleeve sensor?
o.k. no
Pump is overheated, but no heat transfer from collector
to the tank, feed flow and return flow are equally warm,
perhaps also bubble in the lines.
Exhaust the system; in-
crease system pressure
to at least static primary
pressure plus 0,5 bar; if
necessary continue to
increase, switch the pump
for a short time off and
on.
Air in the system?
no yes
Is the collector circuit
plugged at the dirt trap?
yes
Clean the dirt trap
5.1Various:
If necessary activate tube
collector function.
yes
o.k.