Data sheet FED sensors
Sequence control
of cooling and heating circuit
Products
FED-IF: with integrated sensor FED-FF: with remote sensor
The FED sensors are used in applications in
which a cooling and a heating circuit are to be
controlled by one controller.
Both FED-IF and FED-FF sensors can be
applied to chilled ceilings, fancoils and induction units.
For control of cooling and heating circuits in
fancoil and induction units use the FED-FF
with remote sensor.
By placing the sensor in the air inlet a quicker
reaction time of the air temperature changes
is achieved. Using the remote sensor, the
remote temperature adjuster can be placed
directly on the cabinet.
Ordering and
specifications
Type Code no. Sensor Capillary tube Setting range
FED-IF 013G5463 Integrated sensor 4 + 11 m
FED-FF 013G5462 Remote sensor 2 + 2 + 2 m
Application
Sequence control of chilled ceiling and radiator Sequence control of fancoils and induction units
Cooling circuit
17-27 °C
Cooling circuit
RA-C
FED-IF
Heating circuit/radiator
RA-N
CD-ST VD.33.T1.02 © Danfoss 06/99 1
FED-FF
RA-C
Heating circuit
RA-C
RA-N
Data sheet Climate controls: FED sensors
FED sensor design
Cooling
adapter
Actuator
Remote temperature adjuster
Remote sensor
(only FED-FF)
Capillary reel
(only FED-IF)
Heating
adapter
Temperature setting
The FED sensors are applied with the RA-N
and the RA-C valves.
The FED sensors are equipped with a reverse
device for the control of cooling circuits. With
the reverse device the valve in the cooling
Comfort temperature ~ 22 °C at Xp = 0 K
The FED sensors have been developed for
room temperature control via water-based
cooling and heating systems.
The FED sensors are based on the self-acting
principle. The liquid-filled sensors control the
circuit will open when the temperature rises
above the setpoint temperature.
The valve in the heating circuit will open when
the temperature falls below the setpoint temperature.
valves via capillaries and adapters.
The scale shows the approximate set-point
offset from the comfort temperature which is
approximately 22° C at X
= 0 K.
p
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Data sheet Climate controls: FED sensors
Sequence control The control is done by the sensor, in which a
neutral zone is built-in. In the neutral zone
neither an activation of the valve in the heating circuit nor of the valve in the cooling circuit
takes place. In that way it is secured that cooling and heating do not take place simultaneously.
The neutral zone is in the area from
0.5 - 2.5 °C dependending on the system
design. If the differential pressure is high on
both circuits (~0.6 bar), the neutral zone is at
a minimum. On the other hand if the differential pressure is low on both circuits (~0.1 bar),
the neutral zone is at a maximum.
An adjustment of the neutral zone can be
made by turning the knob of the cooling adapter with a pair of pointed pliers. Turning clockwise the neutral zone is increased, turning
counter-clockwise the neutral zone is decreased. The factory setting of the neutral
zone is marked in the knob recess.
Irrespective of the temperature setting of the
FED-sensor the necessary neutral zone will
always be kept. See also figures below.
Sequence control
of cooling and heating circuit
Neutral zone
Water flow through heating circuit
Water flow through cooling circuit
Adjustment of the neutral zone
Factory setting
mark
Setting of comfort temperature
- example: hotter t
➠ t
1
2
Setting of comfort temperature
example: colder t
➠ t
1
0
CD-ST VD.33.T1.02 © Danfoss 06/99 3
Data sheet Climate controls: FED sensors
Temperature control
through sequence control
with FED sensor
a) Control of heating circuit - FED with RA-N valve
Xp = 0 K
Xp = 2 K
Note! Example at neutral zone = 2 °C. Setpoint = 22 °C
b) Control of cooling circuit - FED with RA-C valve
Xp = 0 K
Xp = 3 K
The FED sensor controls in sequence via two
temperature scales: one for the heating circuit
(a) and one for the cooling circuit (b).
When the setting knob is turned a parallel
control of both temperature scales is taking
place. The neutral zone ensures that cooling
and heating do not take place simultaneously.
Sequenzing with FED thermostat
Waterflow,
Waterflow,
heating
cooling
Example
A setting in the red temperature area means
that the set point of both cooling and heating
circuit is raised.
A setting in the blue temperature area lowers
the set point of both cooling and heating circuits.
The setting knob is turned to rise the room
temperature with 2 °C from 22 °C to approximately 24 °C at X
Due to the neutral zone the set point of the
cooling valve at X
0.5-2.5 K higher depending on the system
= 0 K on the heating valve.
p
= 0 K will be between
p
design.
The valve in the heating circuit will open at a
sensor temperature below 24 °C. If an RA-N
valve is mounted in the heating circuit and
dimensioned at the presetting N, the RA-N
valve will provide full water quantity at a Pband of 2 K, i.e. a sensor temperature of
22°C.
If the neutral zone e.g. is 2 K the valve in the
cooling circuit will start opening at a sensor
temperature above 26 °C (setpoint: 24 °C +
neutral zone: 2 K).
With a RA-C valve in the cooling circuit (dimensioned at presetting N) the valve will provide full water quantity with a P-band of 3 K,
i.e. at a sensor temperature of 29 °C (setpoint:
24 °C + neutral zone: 2 K + P-band: 3 K).
Setpoint on knob
(N = neutral zone)
Sequence control when rising the setpoint
temperature with 2 °C.
Neutral
zone
Waterflow, heating
Waterflow, cooling
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Data sheet Climate controls: FED sensors
Limiting the set temperature of FED sensors
Serial coupling
The set temperature of the remote temperature adjuster depends on the sensor type and
the valves, which are used with the sensors.
It is easy to limit or lock the set temperature
by means of the built-in locking/limiting device.
Maximum limitation of temperature areaMinimum limitation of temperature area
Several possibilities of placing the FED remote temperature adjuster
Via the soft but strong ø 0.8 mm capillary and
the patented serial coupling of capillary and
adapters it is possible to control two valves in
sequence.
The FED sensors are delivered with the cooling adapter closest to the remote temperature
adjuster and the heating adapter furthest
It is easy to change the order of the valves:
Just loosen the actuators from the adapters
and exchange the adapters. The FED sensor
still controls in the right sequence.
The interchange of valve adapters provide
numerous possibilities of placing the FED
remote temperature adjuster.
away from the remote temperature adjuster.
CD-ST VD.33.T1.02 © Danfoss 06/99 5
Data sheet Climate controls: FED sensors
Design
1. Heating adapter
2. Actuator
3. Adjustment bellow
4. Capillary reel (only FED-IF)
5. Cooling adapter
6. Neutral zone adjustment
knob
7. Reverse device
8. Adjustment bellow
9. Actuator
10. Capillary reel
11. Remote temperature
adjuster
12. Bellow
13. Remote temperature
sensor (only FED-FF)
Dimensions
FED-IF
FED-FF
VD.33.T1.02 © Danfoss 06/99 CD-ST
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