Fan humidity sensor is called a humidistat. In some models, carefully embedded in advance it is recommended to take into the house. Relative to other humidistat devices produce indoor, channel, depending on the parameters of the measuring point. The first simply hung on the wall, they serve as a sort of switch, fan control, the latter - are equipped with a long probe, penetrating into the duct to control the environment. We assume you can get a separate humidity sensor, based on the sensor to collect humidistat own, rather a curiosity than daily. The company wants to take profit from the manufacture of the device.
Humidistat - the instrument that assesses the level of humidity
Humidistat is not very different from the thermostat. The objective of the instrument is considered closing-opening relay, depending on the amount of vapor in the air. Mentioned, there are indoor hygrostats, channel, sharing of circuits:
- Single loop.
Several continue indefinitely. Each loop contains the relay control a separate device. Is allowed to connect ventilator, humidifier makeshift construction.
Sold complete indoor climate control scheme. From the point of view of moisture naturally. Exhaust fan with humidity sensor in a pair gives the possibility of including the equipment in automatic mode. Hygrostats are set to threshold with some hysteresis. By increasing humidity the device gives a signal that maintains until the value drops below a certain threshold value, the latter is called the width of the hysteresis loop.
Here are the possible schemes of work humidistat:
- Changing the permittivity of the medium between the plates of a capacitor results in variations in capacitance. There is a school formula, where the relationship can be traced directly. From air vapor content permittivity changes result fixes the measuring device.
- Resistive method exploits the phenomenon of resistance changes of a special material that is in contact with moist air (alumina).
- Optical measurements are given to evaluate the transparency of the air, are suitable targets in determining the presence of air gases, smoke, steam.
- Changing the length of the synthetic fiber is often used to determine the relative humidity. Some varieties of fabrics have specific properties, the information is used by many hygrometers. Fan with a humidifier will run until the filaments reach the set, then the device powers down.
- Thermistor bridge composed balanced shoulders capable of determining the existence of water vapor air. One element is enclosed bulb filled with pure nitrogen gas, and the second - controlled environment settings. In order not to mislead the reader, we mention: a thermistor - a synonym for a thermistor. Current heated to a high temperature, and then give off heat. In humid air process is easier. Let's talk more.
Thermistor bridge is formed by two resistive divider. One shoulder is formed by a rheostat (potentiometer) of the ordinary resistor. Segment allows complete customization to the desired value. In the second arm comprises two thermistor mentioned: in a flask in the air. Mid-bridged, it is removed from the resultant effect of the system. In the initial period circuit is in equilibrium, the output current is zero. water vapor change of cooling conditions sensing thermistor, the balance is disturbed. The effect is used to switch the relay status to run fans wet rooms.
The operating principle of the hygrometer Thermistor
The principle of operation is as follows. Nitrogen flask and the outside air is initially uniform temperature. Then the thermistors are beginning to heat up. Nitrogen faster, slower air approaching the operating temperature of 200 ° C.
Glass bulb chosen for several reasons:
- Metal is rapidly oxidized, or one may wish to paint. Need soil, additional processing cycles, increases the cost of the product increases rather big inertia.
- Glass is inert, a poor conductor of heat, but sufficient. By varying air temperature similar amount of vapor will give different relative humidity. Because of the inertia sensors can give failures during cold weather, sharp heating.
As a result of the efforts we get principle of psychrometer. In humid air cooling conditions sensing thermistor better provided with dry nitrogen. Actual fan relay triggers moisture, leading to gradual normalization atmosphere. Hysteresis is caused by the inertia of the device.
Hygrometer with their hands
Understand, many are eager to collect fan humidity sensor with your hands. Diy goals can be useful modern digital equipment:
- temperature and humidity sensors and DHT11 DHT22.
- input-output apparatus, information processing Arduino platform.
Arduino - microprocessor package based on low-cost microcontrollers, has a completely open circuit implementation. Everyone will find out on the Internet, from any components to assemble the printed circuit board, will guidance considers the cost. Connect the fan with a humidity sensor to the bundle will not be working. The most interesting point is the possibility of interaction with personal computers. There are drivers of the library, designed to perform the operation. Smart house with his own hands? Exactly... if crazy enough.
Given the current price humidistat has a great temptation to collect the exhaust fan with a humidity sensor with your hands. We recommend to solve more complex tasks. By combining several types of common network equipment. Considered Soler & Palau often sets the fan humidity sensor equipment, a lot of sense to reinvent the wheel there. If you collect a home humidifier, try to get to work in conjunction with the ventilation, the situation looks interesting. It does not hurt a couple of schemes to develop.
Acceptable pick analog fan humidity sensor. An example will serve as a Honeywell equipment:
The principle of operation is based on the capacitor method. Afraid of unfamiliar words: "platinum electrodes," "special polymer insulation." Equipment hardly be cheap, start studying the issue if necessary. Collect analog parameter measurement scheme, tared sensor also be no easy task.
By the combined temperature and humidity sensors are products of the company Regeltechnik:
- RFF for the interior;
- AFF for the environment.
Note that not talking about a thermistor. Perhaps some rare method, unpopular.
Duct humidity sensors
Let slip, hydrostatic established channel, how to apply, remains unclear. The industry is not difficult to find an explanation. Power plant controls a bunch of options, including the ph-factor wastewater. High humidity channel ventilation system is considered improper functioning of the automated control equipment. At home, in a private house. Blower channel humidity sensor are simply unnecessary. Powerless to control the parameters of the medium.
If channel fan operates simultaneously, supplying several rooms, there is moisture in the channel signal will increase engine speed. For example, it occurs when the system operates at a regime close idle. Fan connection with the humidity sensor together is a powerful tandem to save energy. to the fullest work is just beginning when the need arises.
Permissible control on this principle work the heat exchanger, similar equipment. Operation Mode saves energy.
It is recommended to maintain the relative humidity within the 40 - 60%. Sometimes you have the opposite drainage. Fan with a humidifier capable to bring the parameters back to normal automatically. It has its own built-in humidistat, steam generator with an ultrasonic element of the blade, driving air through the room. Good summer in a dry climate. Enlisting the help of a potentiometer, digital control systems, fans alone can overcome the shortcomings of nature. Bad weather not climate - often leave much to be desired.
The song is sung about humidity sensors today. When domestic manufacturers, dealers disappear espionage mania, reveal more technology, we promise to come back to the topic, to discuss the details. Do not forget the low humidity harms immunity. More precisely, it weakens the mucous membranes.