ensto ECO900 Instructions D'opération page 18

OPERATING OF THE FROST PROTECTION SYSTEM
The heating resistor of the snow and ice sensors ECOA901 and ECOA903 keeps the surface of the sensor
at a constant temperature of approximately +4 °C. It will melt the snow and ice, which are detected as
moisture. When the temperature measured by the sensor ECOA902 or ECOA904 drops below the set value
in the TEMPERATURE menu and the set humidity level is exceeded, the heating will turn on by closing
the heater relay (connectors 8 and 9). The heating remains on until either the set temperature is attained
or the humidity level drops below its set value.
In the post-heating the heating remains on during the selected time when either the set temperature is
attained or the humidity level drops below its set value. This function can be used for example if there is
still snow beside the heated area after the heating otherwise would switch off. The post-heating can be
used at temperatures below 0 °C.
The lowest operating temperature can be set between -20...-5 °C in the RANGE menu. The factory pre-
determined value for the highest operating limit is +6 °C. Outside these temperature limits the heating
can only be switched on using the continuous heat menu item. An appropriate operating limit prevents
unnecessary energy consumption in cases there is no snow or ice in spite of frost.
In the application GROUND it is possible to set a base temperature under which the temperature of the
heated area may not drop. If the temperature drops under the base temperature, the heating will turn on
irrespective of the humidity level. The lowest operation temperature set in the RANGE menu has however
priority over the base temperature. If the base temperature is set lower than the lowest temperature limit,
the base temperature cannot be exceeded.
The ECO900 frost protection control unit is supplied with an 82 kΩ resistor connected to connectors 20 and
21 but the air temperature sensor ECOA904 can be connected instead. In this case the air temperature is
also shown on basic display mode in addition to the ground/gutter temperature and the humidity level. If
the air temperature drops rapidly, predicting the probably start of rain, the heating will switch on for one
hour below temperatures of +7 °C. Afterwards the heating will switch off or remain on depending on the
set temperature and humidity values.
INSTALLATION OF SENSORS
SENSORS FOR GROUND INSTALLATION ECOA901 AND ECOA902
Figure 8 shows the minimum installation distances. The snow and ice sensor ECOA901 (5 leads) is installed at
least 200 mm outside the heated area. The humidity and temperature sensor ECOA902 (4 leads) is installed
inside the heated area, because the sensor is used to measure the temperature and humidity level on the
surface of the heated area. The heating cables must be at least 25 mm from the ECOA902 sensor.
The sensors must be installed so that they are directly exposed to weather conditions (snow, rain, melt
water). However, the sensors should not be installed in a place where e.g. snow from a snow plough can
cover them. Additionally, dirt on top of the sensor will prevent proper operation. The ground sensors must
lie in a horizontal position even if they are installed on a slope (figure 9).
The sensor is supplied with a metal base plate and a wooden mould. The metal base plate is set in the ground
during the construction phase and the wooden mould is placed on top. A metal protective tube must be
installed to the wooden block for the connection cable. Seal the tube ends to avoid surfacing materials
(e.g. tar, concrete) clogging the tube. After applying the surface, the wooden mould is removed and the
sensor is attached on the steel plate with a M6 x 35mm screw. Any gaps around the sensor should be filled
with e.g. silicone, mortar or suchlike. The highest permissible temperature of the filler
is 80 °C.
The connection cable can be extended to 50 meters by using a 1.5 mm
cable with numbered leads for the extension as it is very helpful for example when trying to locate faults
during a malfunction. The sensors work with low voltage, so it is recommended that their leads are installed
at a sufficiently long distance from the heating circuit supply cables.
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cable. It is recommended to use a
2