Air Conditioners and Dehumidifiers Use Reed Sensors to - Digi-Key

Air Conditioners and Dehumidifiers
Dehumidifiers Use Reed Sensors to
Sense the Upper Limit of Their Reservoirs
REED RELAYS REED SENSORS REED SWITCHES
Introduction
In the summer months, warm and humid air invades the area. This is the case
in most regions of the world. Depending how close one is to the equator this
condition may exist throughout the year. During this time, many businesses and
homes are equipped with air conditioners and Dehumidifiers to cool the air and
reduce the humidity. A typical unit can accumulate up to 15 gallons (60 liters) of
water in a single day. With this much water being produced, care must be taken
with the reservoirs to prevent water overflow. Reed sensors provide a reliable
way to detect maximum levels to either alert the user or turn on a water pump.
Figure 1. MK17-x-3 Sensor physical layout
Features
• Magnet and Reed Sensor are isolated and
have no physical contact by typically having
the magnet mounted to a float and the Reed
Sensor is mounted on the body of the casing
close to the high point of the water and
positioned to accurately pick up the magnetic
field from the magnet in the float.
• The reed switch used in the Reed Sensor is
hermetically sealed and is therefore not
sensitive to rough, wet, moist environments
Figure 2. Pump is off until magnetic float moves up the reed sensor once the water
reaches the highest level in the reservoir.
• The magnet is not affected by its environment
• Tens of millions of reliable operations
• Surface mount and through hole packages
available
• Cylindrical hole and screw fastening mounting
• Contacts dynamically tested
Applications
• Ideal for sensing the water level in air
conditioners and Dehumidifiers
• Ideal for applications sensing any kind of liquid
level in a host of different configurations
Figure 3. When water reaches highest level, magnetic float moves up the reed sensor
switching the pump on. The pump will remain on until the internal circuitry senses the
current change at the lowest point in the tank.
Air Conditioners and Dehumidifiers
Dehumidifiers Use Reed Sensors to
detect Reservoir Full Conditions
Many of us must have our air conditioners running full force in the warm humid
months. The air conditioners do a great job of cooling and reducing the air
temperature. They also remove some of the humidity, but most of the time not
enough to eliminate mildew and mold that loves moist warm environments. This
mold and mildew can cause allergy outbreaks and affect people with asthma.
So, many times air conditioners and Dehumidifiers will be working together in
unison. Both systems condense a serious amount of water vapor from the air
creating large volumes of water. Storage containers or reservoirs must be
monitored in some fashion for potential water overflow. MEDER’s reed sensors
have made an excellent choice in carrying out this monitoring.
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: info@meder.com
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: salesusa@meder.com
Page 1 of 3
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Air Conditioners and Dehumidifiers
Dehumidifiers Use Reed Sensors to
Sense the Upper Limit of Their Reservoirs
REED RELAYS REED SENSORS REED SWITCHES
Specifications
Operate specs
Min Max Units
Must close
close distance
5
25
mm
Must open distance
5
25
mm
Hysteresis
Load Characteristics
Switching voltage
Switching current
Carry current
Contact rating
Static Contact
Contact
resistance
Dynamic contact
resistance
Breakdown voltage
Operate time
Release time
Operate Temp (MK15)
Storage Temp (MK15)
Typical 50%
Min Max Units
200
0.5
1.5
10
150
200
320
0.5
0.1
-20 130
-35 130
Volts
Amps
Amps
Watts
mΩ
mΩ
Volts
msec
msec
°C
°C
A magnet is generally mounted in a float that rides up and down with the water
level in the storage container or reservoir. As the water level reaches the upper
limit, MEDER’s reed sensor, which is conveniently positioned near the top of the
reservoir, will sense this high water mark. For manually emptied air conditioners
and Dehumidifier models, the reed sensor will directly switch off these models.
Some of the models are equipped with a beeping sound and/or a water full light
will be turned on, alerting the user its time to empty the water. Once the water is
emptied, the air conditioner and/or the Dehumidifier will turn back on. However,
in more and more models the reed sensor will switch on a water pump instead,
allowing water to be emptied automatically where the water is pumped into a
water drain system. Having a pump that only turns on when the reservoir is full
is very energy efficient, compared to having the pump running all the time.
The reed sensor is an excellent choice because it can operate reliably over a
wide temperature range, and represents an economical way to carry out the
sensing function. Because MEDER’s sensors use hermetically sealed reed
switches that are further packaged in strong high strength plastic, they can be
subject to rough treatment and environmental concerns such as spillage water,
and moisture without any loss of reliability.
MEDER’s sensors are packaged for surface mounting as well as through hole
mounting. Also, MEDER has cylinder packages and well as screw fastening
packages having lead wires for remote attachment to the electronics.
Surface Mount Series
Series
Series
MK15
MK16
MK17
MK22
MK23MK23-35
MK23MK23-66
Figure 4. MK15 Tape & Reel
MK23MK23-87
MK23MK23-80
Dimensions
mm
W
2.5
H
2.5
L
19.50
W
2.3
H
2.3
L
15.60
W
2.1
H
2.1
L
9.61
W
2.7
H
2.3
L
15.60
W
2.2
H
1.95
L
15.75
W
2.2
H
2.7
L
19.60
W
2.0
H
2.1
L
15.60
W
2.0
H
2.1
L
13.0
Illustration
inches
0.098
0.098
0.768
0.091
0.091
0.614
0.083
0.083
0.378
0.106
0.091
0.614
0.087
0.077
0.620
0.087
0.106
0.772
0.079
0.083
0.614
0.079
0.083
0.512
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: info@meder.com
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: salesusa@meder.com
Page 2 of 3
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Air Conditioners and Dehumidifiers
Dehumidifiers Use Reed Sensors to
Sense the Upper Limit of Their Reservoirs
REED RELAYS REED SENSORS REED SWITCHES
Through Hole Series
Series
MK06MK06-4
MK06MK06-5
MK06MK06-6
MK06MK06-7
Dimensions
mm
W
3.3
H
3.3
L
12.06
W
2.8
H
3.2
L
14.30
W
3.3
H
4.2
L
17.24
W
3.3
H
4.2
L
19.78
Illustration
inches
0.130
0.130
0.475
0.110
0.126
0.563
0.130
0.165
0.679
0.130
0.165
0.779
Cylindrical Panel Mount Series
Series
MK03
MK03
Dimensions
mm
Dia
5.80
L
25.5
Illustration
inches
0.244
1.004
MK14
MK14
Dia
L
4
25.5
0.157
1.004
MK18
MK18
Dia
L
5
17
0.197
0.669
MK20/1
MK20/1
Dia
L
2.72
10
0.107
0.394
Rectangular Screw Flange Mount Series
Series
MK04
MK05
MK05
MK12
MK12
Dimensions
mm
W
13.9
H
5.9
L
23.0
W
19.6
H
6.1
L
23.2
W
H
L
14.9
6.9
32.0
Illustration
inches
0.547
0.232
0.906
0.772
0.240
0.913
0.587
0.272
1.260
**Consult
our factory for your specific design requirements.
**
MEDER electronic
Application
MEDER electronic AG | Germany | tel.: +49(0)7731/8399-0 | Email: info@meder.com
MEDER electronic Inc. | USA | tel.: +1 508.295.0771 | Email: salesusa@meder.com
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