33
Reset DTO and DTF
Refit sensor correctly.
Pump is overheated, but no heat transfer from collector
to the cylinder; flow and return are equally warm.
Is there air in system?
Vent the system;
increase system
pressure to at least
static primary pressure
+0.5 bar; if necessary
continue to increase,
switch the pump off and
on for a short time.
Is collector circuit dirty/
blocked?
Remove dirt/blockage.
Pump starts up very late then stops shortly afterwards.
Is switch on temperature difference (DTO) too high?
Reset DTO and DTF
Collector sensor not
registering temperature
correctly?
Set Collector
Temperature Monitoring
Function (OTC) to On
NO
YES
YES
NO
YES
Pump perpetually stops and starts.
Are temperature differentials DTO and DTF too
close?
YES
NO
Is the collector sensor correctly fitted/located?
Set Collector
Temperature Monitoring
Function (OTC) to On
YES
NO
YES
The collector temperature increases considerably
more than the cylinder temperature, the system
cannot dissipate the heat.
Is the solar pump operating correctly ?
NO
Is the cylinder heat exchanger blocked?
unblock/clean
YES
NO
NO
Is the cylinder heat exchanger scaled?
Descale
YES
Is the cylinder heat exchanger too small?
Replace with larger
heat exchanger
YES
Check HND1 is in Auto.
Check pump wiring.
Replace pump.
YES
Does the controller switch to ‘pump On’ (R1 On)?
The solar circuit pump does not run although the
collector is obviously warmer than the cylinder.
Does the pump run in manual operation (HND1 On)?
YES
DTO set too High
lower setting
Suspect fault with
controller, consult
Ariston.
YES
NO
NO
Check pump wiring.
Service / replace
pump.
Does the Indicator Light flash?
YES
NO
There is no power.
Check fuses and power
supply.
