A thermometer measures a room's temperature, but a thermostat controls it. It can be used to start or stop any heating/cooling system at a certain set temperature. Whether it's wall or boiler-mounted, this controller plays an important role for managing your home's or process temperature. Let's dig more into what a thermostat is, the many types of thermostats, and how they work.
Thermostat is basically a temperature sensor. Which changes it's output state depending on the temperature of targeted area. Whenever the temperature exceeds or fall bellow the desired temperature set point value, the switching will be happened.
On the above picture we can see a thermostat, there is a adjuster by which the temperature set value can be changed. As per our requirement we can change the setting by this adjuster.
Usually in any electrical control panel we can see a heater at the bottom area that is controlled by thermostat. When the panel inside temperature will go below the set value then the heater will be On.
Again, in some case there is a panel mount air cooler inside the electrical control panel or switchgear panel. whenever the panel inside temperature go above the set point the cooler start running.
Classification of thermostat:
1. Mechanical thermostat- The phenomenon of thermal expansion of fluid is used into this device. Mercury, which commonly drives mechanical thermostats, expands and contracts in response to temperature variations and mechanically open and close the valve or change the state of electrical contacts.
Another types of mechanical thermostat controls temperature with the use of two bits of metal. These are laminated together in the thermostat's sensor as a bimetallic strip. As the different types of metals expand and contract in response to temperature variations, an electric circuit connected to your heating system is turned on and off. This is how the thermostat measures and regulates heat.
It's crucial to note that a bimetal thermostat isn't as accurate as a digital one. The temperature can vary up to five degrees from the target set point. However, some people prefer mechanical thermostats due to their low cost and simple on/off switch.
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| Engine thermostat |
This type thermostat is also known as digital thermostat, It contains internal components that can provide an accurate and responsive reaction to field temperature. If you think of your room temperature control, The electronic sensors read the current interior temperature and can fine-tune the heating to keep the room within one degree of the target setting. So electronic thermostat have very high accuracy over mechanical thermostat.
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Based on the voltage they use to operate, we can classify it into two types: Line-voltage thermostat & Low-voltage thermostat.
1. Line-voltage thermostat- The most common usage for line-voltage thermostats is to regulate electric resistance heating equipment. The line-voltage thermostat is named for the fact that it operates at the same voltage—120 or 240 volts—on the same electrical circuit as the heating unit. This kind of thermostat functions similarly to a switch by allowing electricity to pass through the device and powering the heater.
2. Low-voltage thermostat- Low-voltage thermostats are utilized in central boiler heating systems as well as central forced air heating systems like furnaces and heat pumps. Compared to a line-voltage thermostat, significantly less voltage is needed in these systems since heat is not generated by electrical resistance heater. The 24 volts needed to operate a low-voltage thermostat makes it perfect for powering system components like fans, pumps, and blowers that control the house's temperature. Low-voltage thermostats operate independently of the heating system's circuitry; instead of providing electricity to the heater to run it, the thermostat communicates with it using low-voltage signals.
Beyond of this two types there are some others name:
- Programmable thermostat- When utilized properly, programmable thermostats' programming features can automate temperature adjustments throughout the house and lower energy use.
- Non- Programmable thermostat- Manual or Non-programable thermostats are the most basic type of thermostat. When utilizing this kind of control, the user has to manually modify the thermostat and temperature settings.
- Wifi thermostat- In addition to having a wireless internet connection, Wi-Fi thermostats have the same programming options as programmable thermostat models.
- Smart thermostat- Among the several kinds of thermostats, smart thermostat models are the most advanced. They are capable of doing all the functions of a Wi-Fi or programmable thermostat, and more.
How thermostat works?
Thermostat is nothing but a temperature sensor, so if you want to know how thermostat works first you have to study about the working principle of different type of temperature sensors.
How do AC thermostats work?
An air conditioner thermostat regulates the temperature of the air in the room. It does this by turning on and off the compressor and fan as needed to achieve the desired temperature. The thermostat is connected to a sensor that measures the temperature in the room. When the sensor senses a particular pre-defined temperature, it sends an electrical signal to the thermostat, which subsequently turns on/off the compressor and fan. The cycle continues until the required temperature is reached or achieved.
How do thermostats work in a boiler?
Broiler thermostats manage the temperature in a broiler house. They measure the temperature on the floor of the house and use it for establishing the desired temperature for the remaining part of the house. The thermostat is typically found near an air intake or an exhaust vent. It measures and compares temperatures at several areas to determine how much heat is required to maintain a specific temperature.
How does the Heat pump thermostat work?
Heat pumps employ a refrigerant to transfer heat from one point to another. A heat pump circulates refrigerant through pipes and coils in a sealed system. The refrigerant absorbs heat from outside air, cools, and becomes a liquid. The liquid then flows into an indoor coil, losing heat to inside air, turning back into a gas, and circulating back out of the outside coil. This procedure will continue until there is no more heat available in the targeted area air, the thermostat works here to check the available heat quantity and control the heat pump.
How to use thermostat?
First of all we should know where this device can be used. In every place it can be industrial or residential application, we can install it for maintaining the temperature. You can use it at your home to maintain the inside air temperature by controlling the heating or cooling device. In the industrial area, any kinds of fluid temperature maintaining is very common job, so the thermostat can also be employed for doing this task.
Now we can go to how to use thermostat, we all know that every heating or cooling equipment must have a control circuit, thermostat have to be incorporated into that control circuit.
Applications of Thermostat
We know that a thermostat is an automatic device that regulates the temperature in any mechanical operation. It measures the temperature of the exhaust and compares it to a predetermined value. If we think about a restaurant kitchen electric appliance, The difference between the set point and current temperature governs the level of fuel flow in order to maintain a stable cooking environment. Now let's see how a thermostat works in different kitchen appliances.
Oven thermostat- An oven thermostat is a necessary component that regulates the temperature of ovens, ensuring accurate cooking conditions. A gas oven thermostat is typically located within the electric ignition system or in a separate control unit. For temperature detection, the sensor and controller often use electrical resistance or bimetallic strips. The data therefore is then transmitted into the controller, which can have an on/off switch for power modulation or an electric relay for more sophisticated temperature control.
Stove thermostat- A stove thermostat measures the temperature of the cooking surface. It is put into the cooking area and features a probe that detects the temperature of the cooking surface. Different stoves have different thermostat requirements. For example, if you have an electric stove, you should use a thermostat with an electric probe; if you have a gas stove, use a thermostat with a gas probe.
Dishwasher thermostat- It will turn off the dishwasher when it reaches a specified temperature and then restart it after it has cooled. This device's aim is to avoid damage to dishes and other items that are cleaned in hot water by preventing them from being exposed to heat for too long.
Ice machine thermostat- The Ice Machine Bin Thermostat is linked to the water pipe that feeds the ice machine. The equipment comprises two sensors that measure the temperature of the water coming from the water line and entering the ice machine. If the temperature goes below a particular threshold, it will activate an electric heating element, which will heat the water until it reaches a predetermined level for safety.
Griddle thermostat- An electric griddle thermostat works by using two probes, one for detecting the temperature at the bottom and one for measuring the temperature near the top. The difference between these two temperatures is then utilized to calculate how much power is required to maintain an even cooking surface.
Refrigerator thermostat- A refrigerator's thermostat senses the inside temperature. When the temperature rises above the specified point, the thermostat activates the cooling system. Once the required temperature is attained, the thermostat stops the cooling operation. This cyclic regulation guarantees that the fridge's temperature remains optimal, protecting the freshness of stored what's inside.
