The freeze state is a temperature sensing tool for HVAC that monitors heat exchangers to prevent coils from freezing. Frozen statistics can be used on freon-to-air, freon-to-liquid and serve different purposes for the same purpose for each.
Video Freeze stat
Air coil
The purpose of an air coil freezing stat is to keep the refrigerant-to-air heat exchanger (commonly called air coil ) from freezing. This type of stat freezing is commonly used for heating coils exposed to the outside air and is usually mounted on the air supply side of the coil. To accomplish this, they usually close the outside airflow to the mixing box when the temperature reaches a predetermined setpoint. The setpoint for air freezing statistics is usually about 38 degrees Fahrenheit which is approximately when the dew point of the air began to drop below freezing.
Maps Freeze stat
Water coil
The coagulation freeze stat performs a function similar to the coil freeze stat, but is used on different types of HVAC systems. Its function is to keep the freon-to-liquid heat exchanger (so-called fluid rolls) from freezing.
In practical situations, when the air coil freezing stat is not used, passed, or defeated, the air coil can freeze, and this causes a lack of air flow to the facility. Conversely, when the coil freezing stat is not used, the water coils can become so cold that it can freeze the coolant in the exchanger and blow up the exchanger. A ruptured heat exchanger mixes contaminants such as freon and oil into the refrigerator. The cooling fluid intrusion into a balanced cooling system can cause costly damage to components such as a freon compressor, and an inverting valve.
Mechanical
Conceptually, statistics of mechanical freezing are constructed with diaphragms, capillary tubes and light bulbs, and electrical switches. Capillary tubes allow the movement of gas to and from the capillary and diaphragm balls with a decrease or rise in temperature, respectively. When the temperature reaches a certain setpoint, the pressure in the diaphragm will pass through a switch that normally closes the outside airflow while the temperature of the capillary ball is at or below the setpoint. The mechanical freezing statistics can have more than one set of contacts, and the contacts can be NO or NC.
Losses
Profit
- Usually cheaper
- Easy to understand cable
Digital
Digital freezing statistics , also known as electronic statistics, or solid state, using electronic circuits, microprocessors, or microcontrollers in mechanical diaphragm freezing and switching. They also use one or more electrical or electronic sensors in place of capillary tubes and light bulbs for temperature sensing. Digital freeze statistics that use a microcontroller or microprocessor can also perform more sophisticated functions than just opening or closing switch contacts. Digital freeze statistics can perform seemingly intelligent operations such as reversing the refrigerant flow and using some building heat to melt the freon-to-liquid heat exchanger and then restore the refrigerant flow in the normal direction once the coil freezing hazard has been avoided.
Disadvantages
- Requires power to operate
- Usually more expensive than mechanical freezing statistics
- More complex cabling installation
Benefits
- Multiple sensors
- Sensors can be near or far
- There is no capillary tube binding problem
- No capillary tube leakage problem
- Operates in any position
- Operates under various temperatures
- Programmable and setpoint actions
- Can perform functions other than opening or closing one button
See also
References
Source of the article : Wikipedia
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