Riello SUN 1 PLUS 2 RS Installation Instructions Manual page 35

System 3 - STANDARD SOLAR HEATING WITH EXCESS HEAT DISSIPA-
TION
The controller calculates the temperature differential between
collector sensor S1 and storage cylinder sensor S2. If the differ-
ential exceeds or is equal to the set activation temperature dif-
ferential (DT O), relay 1 activates the solar pump and the storage
cylinder is charged until the deactivation temperature differen-
tial (DT F) or maximum storage cylinder temperature (S MX) is
reached.
Sensor S3 is used for the thermostat function for supplementary
heating, activated by relay 2, or for excess heat dissipation when
thermostat activation temperature (AH O) is reached.
This function can be combined with three adjustable time
bands.
When maximum collector temperature (CMX) is reached, relay 1
activates the solar pump and relay 2 activates the 3-way valve
to dissipate excess heat via a heat dissipater. For safety reasons,
excess heat is dissipated only until the temperature in the stor-
Relay out-
Control differential
puts
R1 DT (S1-S2)
R2 S1 (CMX)
Sensor-input
S1
S2 Storage cylinder bottom temperature
S3 Storage cylinder top temperature
S4/VFD Collector flow/return temperature
PWM
VFD
S1
V1 (R2)
S4/VFD/TMAN
P1 (R1)
S4/VFD/TRIT
Notes
Solar pump (P1)
Three-way valve (V1)
Description
Collector temperature
age cylinder falls below the fixed safety deactivation tempera-
ture of 95 °C [200 °F].
Optionally, sensors S3 and S4 can be used for metering purposes.
Sensor S3 can be used as a reference sensor for the storage cyl-
inder safety deactivation function (OSEM). If the thermal energy
metering function (OHQM) is activated, sensors S4 and VFD can
be used as flow and return sensors.
VBus
S3/TSS
S2
35
Fig. 4