User Manual

CA1N1879E / 11.1998 Siemens Building Technologies
2/4 Landis & Staefa Division
FU-IH3
Signal converter
If the FA-H3 dewpoint sensor is used with PRONTO IRC controller types PRRA, PRRB,
PRU..., PRFB-A or PRFB-V, and PRT/F, or with other controllers, the FU-IH3 signal
converter should be used.
Mounting instructions (Ref. 35672) are enclosed with the sensor.
The dewpoint sensor should be fitted to the chilled ceiling at the coldest point, i.e.
directly at the water inlet. Care should be taken to ensure good thermal contact between
the metal surface on the base of the sensor and the chilled ceiling or the inlet pipe.
The sensor should be firmly
secured to the pipe from below
with the cable tie supplied.
50685
+
ø >
7
/
8
–
A
A
A – A
Fixing lugs are provided, allowing the
sensor to be fitted to the underside of the
chilled ceiling using 2 x ø 3 mm screws.
50686
The dewpoint sensor requires no regular maintenance. The performance of the sensor
should be checked at least once per year in "normal" air conditions, and more frequently
if the air is polluted.
When checking performance, it is essential to ensure that no water enters the sensor
housing. To check an installed dewpoint sensor, a sponge or cloth moistened with hot
water can be held against the front (the perforated cover) of the sensor. The
temperature of the sponge or cloth must be at least 20 °C higher than that of the sensor.
With this test, the sensor is shown to be operating correctly if it responds within 3
minutes.
Should this test method be used to check unmounted sensors, ensure that the back of
the sensor remains at room temperature and is not warmed during the test.
Measuring point 100 %rh
Measuring element Condensation-dependent resistance
Resistance: At < 90 %rh < 30 k ohms
With condensation > 300 k ohms
Measured medium Indoor air
Response time <10 mins after start of condensation
Connection cable Multiple-stranded, white,1.5 m, 2 x 0.25 mm
2
Protection standard IP32 to IEC529
Operating conditions
Dewpoint temperature >10 °C
Ambient temperature 10 ... 40 °C
Weight (including packaging) 0.06 kg
Housing colour NCS 0003-R20B
Maintenance None required
Performance test At least every 12 months, but more frequently in
polluted environments (see page 2)
Service life Approx. 10 years
Conformity Meets the requirements for CE marking
Accessories
Mounting notes
Mounting on the
inlet pipe
Mounting on the under-
side of the chilled ceiling
Maintenance notes
Performance test
Technical data
FA-H3