Settings And Safety Devices - Potterton SIRIUS THREE FS 70 Installation Manual

4 Description of the product
Tab.11 Description of the safety devices
Device
Safety thermostats
NTC flue gas sensor
Flame detector by ionisation
Hydraulic pressure switch
Post-circulating pump
Frost protection device
Anti-blocking of the pump
Anticipatory start-up of the circulat­
ing pumps
22
4.2.5

Settings and safety devices

Important
The settings and safety devices are only operational if the boiler is
powered up.
Description
The safety thermostats suspend the supply of gas to the burner if the water in the pri­
mary circuit overheats. To resume normal operation of the boiler, eliminate the cause of
this interruption.
Caution
The safety thermostats must in no circumstances be switched off or
disconnected.
The control panel blocks the gas supply to the burner in the event of overheating. To
resume normal operation of the boiler, switch off the boiler and switch it back on again
with the ON/OFF switch.
The boiler is put into safety lock-down in the event of gas shortage or incomplete cross-
lighting on the burner.
Thanks to this device, the burner can only operate if the system pressure is higher than
0.5 bar (0.05 MPa).
When the pressure switch detects a pressure lower than 0.8 bar (0.08 MPa), a warning
message is displayed, without stopping the circulating pump.
After the burner stops, depending on the room thermostat setting and if in heating
mode, the circulating pump runs for a further 3 minutes.
When the flow temperature is lower than 5 °C, the burner starts up and runs until the
flow temperature reaches 15 °C. This device runs under the following conditions:
The boiler is switched on
The gas supply is working
The pressure in the system is higher than 0.5 bar (0.05 MPa)
If there are no heating or domestic hot water requirements for 24 consecutive hours, the
pumps start up automatically and run for 10 seconds.
The pumps connected directly to the appliance's terminal blocks are started up every
Friday at 10:00 a.m. and run for 30 seconds.
In heating mode only, the appliance can start up the circulating pumps before burner ig­
nition. The duration and activation of anticipatory start-up depends on the installation re­
quirements and the operating temperatures. The duration of anticipatory start-up of the
circulating pumps therefore varies from a few seconds to several minutes.
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