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Installation Instruction
B: How it works
Roof system
The roof system is fully automated. It
gathers information on moisture and
temperature via digital sensors con-
tinuously. 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 mois-
ture and temperature a reliable detec-
tion of the situation is achieved. Hence it is known whether heating is required to prevent ice and snow
from covering the roof area.
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 setpoint 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 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.
32 | © Danfoss | 2018.10
GX-850M ver. IV
Standby
(No heating)
Temperature < Melting temperature
and
Moisture > Moisture limit
Melting
(Heating)
Moisture < Moisture limit
Post-heating
(Heating)
Temperature >
Melting temperature
Measuring
After 3
temperature
hours
0-20 minutes
(No heating)
Post-heating time elapsed
VUAPA422
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