Plum ZAB-14, Service And Assembly Manual

Page: 36 / 60

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13.4 Connecting temperature
sensors
The regulator cooperates only with CT4i
and CT2S sensors. It is forbidden to use
different sensors.
Sensor leads can be extended with wires
with section of at least 0,5mm
2
. Total
length of the sensor leads cannot exceed
15 m.
The boiler temperature sensor should be
fitted in the thermometric pipe, situated
in
the boiler shell. The feeder
temperature sensor must be fitted on the
surface of the feeder screw pipe. The
domestic hot water temperature sensor -
in the thermometric pipe welded into the
tank. It is best to fit the mixer
temperature sensor in a tube (sleeve)
placed in the stream of water flowing in
the pipe, but it is also possible to clip it
onto the pipe, covering the sensor and
the pipe with thermal insulation.
The sensors must be secured
against coming loose from the
measured surfaces.
Good thermal contact between the
sensors and the measured surface must
be ensured. For this purpose, use
thermally conductive paste. Do not pour
oil or water over the sensors.
The sensor cables should be separated
from mains leads. Otherwise, the
temperature indications can be incorrect.
Minimum distance between these leads
should be at least 10 cm.
The sensor leads cannot have contact
with hot elements of the boiler and
heating system. The temperature
sensors’ leads are resistant to
temperature up to 100 °C.
13.5 Connecting weather sensor
The regulator cooperates only with a
weather sensor of the CT4-P type. The
sensor should be installed on the coldest
wall of the building, usually this is the
northern wall, under a roof. The sensor
should not be exposed to direct sunlight
and rain. The sensor should be fitted at
least 2 m above the ground, far from
windows, chimneys and other heat
sources
which could disturb the
temperature measurement (at least 1,5
m).
Connect the sensor using cable of 0,5
mm
2
cross-section, up to 25 m long.
Polarity of the leads is insignificant.
Connect the other end of the cable to the
regulator.
Attach the sensor to the wall using
tackbolts. To access the tackbolts holes,
unscrew the sensor lid.
Fig. 30 Connecting weather senor CT4-P.
13.6 Checking temperature sensors
Temperature sensors CT4/CT4-P/CT2S
can be checked by measuring their
resistance at the given temperature. In
the case of finding significant differences
between
the value of measured
resistance and the values presented in
the table below, the sensor must be
changed.