Siemens QFA1 Series User manual

1518
QFA1001 QFA1000
Room Hygrostats
QFA1…
for relative humidity
•Hygrostat with single-pole microswitch
•Humidity measuring element made of stabilized plastic texture
•Setpoint knob for the upper switching point
•For controlling humidification equipment
•For controlling dehumidification equipment
•For mounting directly on the wall or on a recessed conduit box
Use
The room hygrostats are used for controlling and monitoring relative humidity in ventila-
tion or air conditioning plant.
They ensure room humidity control within the selectable range of 30 to 90 % relative
humidity by controlling humidification or dehumidification equipment.
They can also be used for monitoring minimum or maximum humidity levels.
Type summary
Type
reference Setpoint setting range
Switching differential 1)
Setpoint
knob
Statically Dynamically
QFA1000 30…90 % r. h. Approx. 4 % r.h. 6 % r.h. Internally
QFA1001
30…90 % r. h. Approx. 4 % r.h. 6 % r.h. Externally
1) The static switching differential is determined at a constant ambient humidity by turning the setting
knob.
The dynamic switching differential is determined by changing the ambient humidity while maintain-
ing the same setpoint adjustment; only the dynamic switching differential is of practical value.
CE1N1518en
2014-07-30
Building Technologies

Ordering
When ordering, please give name and type reference, e.g.:
Room hygrostat QFA1001
Mode of operation
The room hygrostat acquires the relative humidity of the ambient air via its humidity
measuring element, which is made of stabilized plastic texture. This plastic band actu-
ates a microswitch depending on the relative humidity. The microswitch has a fixed
switching differential XSd and a potential-free contact output. If the actual humidity devi-
ates from the adjusted setpoint, the hygrostat switches the humidification or dehumidifi-
cation equipment as shown in the following function diagram.
w
S1 1
2
3
X
Sd
t
t
x
r. F. [%]
1518D01de
Legend:
r. h. Relative humidity in %
S1 Microswitch
1-2 Humidification
1-3 Dehumidification
w Setpoint = upper switching point
x Actual value
XSd Switching differential
t Time
Due to the measuring element’s aging effect, the switching point drifts slowly and con-
stantly. For this reason, recalibration may be required in due time.
At temperatures other than the calibration temperature, the switching point drifts sys-
tematically (temperature influence). Also, in the case of fast humidity changes, the
switching point will temporarily be shifted.
Mechanical design
The room hygrostat is designed for wall mounting. It fits on most commercially available
recessed conduit boxes. The cables are introduced either from the rear (recessed con-
duit boxes) or from above (surface-run wires), after knocking out the cable inlet
tongues.
The unit consists of base and cover.
Base and cover can be separated (snap-on connection).
The base accommodates the humidity measuring element, setpoint setting element
with setting spindle, scale, microswitch and screw terminals.
The cover carries the removable setpoint knob with its imprinted scale.
This model is of the same basic design as the QFA1001, but there is no external
setpoint knob. The setpoint can only be adjusted when the cover is removed.
Function diagram
QFA1001
QFA1000
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Siemens Room hygrostats QFA1001, QFA1000 CE1N1518en
Building Technologies 2014-07-30

1518Z01
60
70
80 90
50 30
7
0
6
0
5
0
4
0
1 2 3
1 Setpoint knob with scale – only with QFA1001
2 Setpoint setting spindle
3 Scale for setpoint adjustment with QFA1000
Mounting notes
The base has cable entries at the rear for mounting the room hygrostat on recessed
conduit boxes. In the case of wall mounting, appropriate holes at the top or bottom can
be knocked out.
The unit should be mounted about 1.5 meters above the floor and at least 0.5 meters
from the closest wall.
Natural circulation of room air must be ensured at the location where the hygrostat is
mounted (no drafts, not in corners, not behind curtains, not in the vicinity of doors and
windows, and not on outer walls). Sources of heat or refrigeration (radiators, comput-
ers, TV sets, concealed heating pipes, hot and cold water pipes) must be located at
adequate distances.
The unit must not be exposed to direct solar radiation.
The room hygrostat is supplied complete with Mounting Instructions.
Disposal
The devices are considered electronics devices for disposal in term of European
Directive 2012/19/EU and may not be disposed of as domestic waste.
•Dispose of the device via the channels provided for this purpose.
•Comply with all local and currently applicable laws and regulations.
Technical data
Setpoint setting range
30…90 %
Humidity measuring element
stabilized plastic texture band
Control mode
2-position
Time constant (v = 0.2 m/s)
approx. 5 min
Switching differential X
Sd
refer to "Type summary"
Setting accuracy 1)
±5 % r.h.
Temperature influence
+0.5 % r.h./K
Humidity calibration at
55 % r.h., 23 °C
Long-term stability
approx. −1.5 % r.h./a
Type of switch
Contact rating
Maximum
Minimum
microswitch (1-pole potential-free changeover switch)
5(3) A, AC 250 V
100 mA, AC 24 V
External protection
Fuse slow max. T5A
Protection degree of housing
IP20 according to EN 60529
Protection class
II according to EN 60730-1
Screw terminals for
max. 2 x 1.5 mm2
Operating elements
Legend
Mounting choices
Mounting location
Mounting Instructions
Functional data
Degree of protection
Electrical connection
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Siemens Room hygrostats QFA1001, QFA1000 CE1N1518en
Building Technologies 2014-07-30

Perm. ambient temperature
Noncondensing
0...40 °C
−25...
+
40 °C
Base
PPS Fortron, glassfiber-reinforced, black
Cover
PC Lexan 940, pure-white
Humidity measuring element
plastic texture
Product standard
EN 60730
-1
Automatic electrical con
trols for household
and similar use
EU Conformity (CE)
CE1T1518xx
2)
QFA1001
QFA1000
0.090 kg
0.090 k
g
1) Can be improved by recalibrating on site
2) The documents can be downloaded from http://siemens.com/bt/download.
Connection diagrams
1
2
3
1518G01
ϕ
1-2 Humidification
1-3 Dehumidification
Diagram 1: Humidification Diagram 2: Dehumidification
1
23
1518A01
ϕ
T5A
L
N
AC 230 V
ϕ
+
1
2 3
1518A02
ϕ
T5A
L
N
AC 230 V
ϕ
–
Dimensions
1518M01
60
70
80 90
50 30
76
76
34
60
75
4,2
4
Dimensions in mm
Environmental conditions
Materials and colors
Directives and Standards
Weight
Internal diagram
Connection diagrams
QFA1000, QFA1001
2004 – 2014 Siemens Switzerland Ltd Subject to change
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Siemens Room hygrostats QFA1001, QFA1000 CE1N1518en
Building Technologies 2014-07-30