Danfoss EFIT 850, Инструкция по установке и эксплуатации, Страница: 32 / 36

32
User Manual
B: How it works
Roof system
The roof system is fully automated .
It gathers information on moisture
and temperature via digital 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 measure-
ments of both moisture and tem-
perature a reliable detection 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 mois-
ture will stop the heating and activate post-heating . The post-heating function can be
disabled .
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 .
Appendix B
Standby
(No heating)
Melting
(Heating)
Post-heating
(Heating)
Measuring
temperature
(No heating)
Temperature < Melting temperature
and
Moisture > Moisture limit
Moisture < Moisture limit
After 3 hours
0-20 minutes
Post-heating time elapsed
Temperature >
Melting temperature