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EGULUS - SRS 3 Controller - www.re
ulus
Settings menu 5
D 5.6 - ΔT R1 menu 5.x = switch-on/switch-off temperature difference for relay R1
If this temperature difference between the reference sensors is exceeded and the other conditions as in Table
5.14 are also met, then the controller switches the pump on. When the temperature difference drops below ΔT
R1 Off, then the pump is switched off again
Settings range: ΔT R1 4-20 °C, ΔT R1 off 2-19 °C. Default settings: ΔT R1 10 °C, ΔT R1 off 3 °C
1) Setting the temperature difference too big will lead to switching the circulation pump on and
off due to uselessly high temperature difference between a collector and storage tank which
could lead to a mild reduction of annual solar yield. It may also cause more frequent solar pump
switching on and off (so called cycling). Selecting the right ΔT will depend on the size of the solar
system, length of the solar piping and quality of pipe insulation. Generally spoken, the shorter the
distance between a collector and a tank and the better pipe insulation, the lower value of ΔT can
be selected, and vice versa.
2) Setting the temperature difference too small may lead to solar pump operating even under
unfavorable conditions (no or little sunshine). Solar system then remains in operation even with
minimum gain and the pump power consumption may be higher than the solar gains.
For most current solar systems the values of ΔT between 8 and 12 K are used.
Situations described in 1) and 2) may occur also if the sensors are improperly located or their compensation
set to a wrong value.
Please refer to special rules described in Chapter D 7.9 when switching pumps with controlled speed.
D 5.7 - ΔT R2
menu 5.x = switch-on/switch-off temperature difference for relay R2
If this temperature difference between the reference sensors is exceeded and the other conditions as in Table
5 are also met, then the controller switches the pump and/or the valve on. When the temperature drops below
ΔT R2 Off, then the pump is switched off again.
Settings range: ΔT R2 4-20 °C, ΔT R2 Off 2-19 °C. Default setting: ΔT R2 10 °C, ΔT R2 Off 3 °C
1) Setting the temperature difference too big will lead to switching the circulation pump off even
when the sun is still shining. Temperature increase in the collector will make the pump start again.
The pump will then keep switching on and off.
2) The right ΔT value depends on the number and type of solar collectors and the flow rate of
solar liquid set. If a too small temperature difference is set, the pump may run permanently.
This may be caused by placing sensors differently in a collector and in a tank, improperly set
sensor compensation… Even a small difference between the measured and real temperature will
influence the controller.
D 5.8 - Tset S3 menu 5.x = thermostat function at sensor S3
If the temperature at sensor S3 falls below this value, the relay R2 together with backup heating is switched
on. If the temperature at sensor S3 exceeds this value plus hysteresis, the relay is switched off.
Settings range: Tset 0-99 °C / default setting: 60 °C
In Energy saving mode (D 5.16) other settings may apply
D 5.9 - Hysteresis menu 5.x = Hysteresis for thermostat function at sensor S3
Hysteresis value for backup heating on (see D 5.8 Tsetpoint S3 above)
If the Energy saving mode is active (see D 5.16), the system heats up until Tmin S3+hysteresis temperature is
reached.
Setting range: Hysteresis 2 to 20 °C / default setting: 10 °C
Caution
Caution
Caution
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