B: How It Works - Danfoss DEVIreg 850 IV Installation Instruction

DEVIreg™ 850 IV
B: How it works
Roof system
The roof system is fully
automated. It gathers in-
formation on moisture
and temperature via digi-
tal sensors continuously.
The sensors are placed on
strategic spots in gutters
or down pipes (for further
information on the sensor
please refer to the sensor
manual). By combining measurements of both moisture and temperature a reliable de-
tection of the situation is achieved. Hence it is known whether heating of the roof area is
needed in order to avoid that the roof is covered by ice and snow.
Standby
The system is on standby and awaits heating of the roof area. Heating of the roof area
will start when the following conditions are fulfilled:
• Measured moisture is higher than the chosen limit for moisture.
• Measured temperature is lower than the chosen melting temperature
Temperature and moisture are measured continuously by the sensors.
Melting ice and snow
The roof area is heated in periods of 3 hours. Within that period a decrease in moisture
will stop the heating and activate post-heating. The post-heating function can be disa-
bled.
Measuring temperature
The heating function is suspended every third hour meaning that the heating cables
are turned off. This is done in order to allow the sensors to measure the temperature,
without being influenced by the heated cables. The temperature measurement may
last up to 20 minutes. If the measured temperature is higher than the chosen melting
temperature the heating period is ended; if not, heating of the roof area is resumed after
the temperature measurement.
Post-heating
If the reason for ending a heating period is a decrease of moisture to below the chosen
level the post-heating period will start. Post-heating ensures that no ice and snow is left
on the roof.
Installation instruction
Standby
(No heating)
Temperature < Melting temperature
and Moisture > Moisture limit
Melting
(Heating)
Moisture < Moisture limit
Post-heating
(Heating)
After 3 hours
temperature
0–20 minutes
(No heating)
Post-heating time elapsed
Temperature >
Melting temperature
Measuring
31