What are thermostats? Different types of thermostats

What are thermostats?

The thermostat is a device for adjusting the temperature of the system so that the system temperature is maintained near the desired setpoint temperature.  The thermostat does this by switching the heating or cooling or deactivating the device or adjusting the fluid flow of heat transfer needed, to maintain the correct temperature.

A thermostat may be a control unit for heating or cooling and a system or component of a heater or air conditioner. Thermostats can be built in various ways and may use various sensors to measure temperature. The output from the sensor then controls the heating or cooling of the apparatus.

Common sensor technologies include:

• Bimetal mechanical or electrical sensors
• Expanding wax pellets
• Electronic thermistors and semiconductor devices

Bimetallic type thermostat:

These thermostats are used In the steam or hot water of the radiator system, the thermostat may be entirely equipped with a bimetal strip. In general, this is an automatic valve that regulates flow based on temperature. Mechanical thermostats are used to regulate dampers in roof turbine vents, reducing heat loss in cold or cold building periods.

The thermostat is a type of valve that opens and closes automatically according to the coolant temperature. The thermostat is installed between the radiator and the engine cooling circuit.

Wax pellets thermostat:

This kind of thermostat is used in an internal combustion engine to maintain the core temperature of the engine at optimal operating temperatures by regulating the coolant flow to an external heat sink, usually an air-cooled radiator.

This type of thermostat operates mechanically. It makes use of wax pellets in closed spaces. The wax is solid at low temperatures but as the machine heats up the wax melts and expands. The enclosed space has an expansion provision that operates the stick that opens the valve when the operating temperature is exceeded.

The operating temperature is fixed but is determined by the particular composition of the wax, so this type of thermostat is available to maintain different temperatures, usually in the range of 70 to 90 ° C (160 200 ° F). Modern machines run the heat, that is, more than 80 ° C (180 ° F), to run more efficiently and reduce pollutant emissions.

Electronic Thermostat:

These are small, self-contained circular units with increased flange for attachments to plates or metal parts from heating or air conditioning, subject to ambient temperature. The internal sensor generally consists of a bimetal disk with electrical contacts in the centre.

At the switching temperature, the disk flips from concave to convex (or vice versa) causes the contacts to open or close depending on the mode needed to switch (normally closed or open normally). This device can also be used as an overheating prevention switch.

The interior of a thermostat of two ordinary household-only heat wires used to regulate gas-fired heaters through an electric gas valve. Similar mechanisms can also be used to control oil stoves, boilers, boiler zone valves, electric attic fans, electric furnaces, electric baseboard heaters, and household appliances such as refrigerators, coffee pots, and hair dryers.

What Are the Different Types of Thermostats?

Thermostats are essential devices for controlling heating, ventilation, and air conditioning (HVAC) systems, ensuring indoor temperatures are maintained comfortably. While many thermostat models are available, they are primarily categorized based on their operation and functionality.

Line-Voltage Thermostats

Line-voltage thermostats are commonly used with electric resistance heating systems, such as electric baseboard heaters, in-wall heaters, and radiant heaters. These thermostats operate on the same electrical circuit as the heating unit, using either 120 or 240 volts. They function as a switch, supplying power directly to the heater. This type of thermostat is often used for controlling individual heaters, but in some cases, it can also control central heat pump systems, including ductless mini-split systems.

Low-Voltage Thermostats

Low-voltage thermostats are typically used with central HVAC systems like furnaces, heat pumps, and boiler-based systems. They operate using only around 24 volts, making them more energy-efficient than line-voltage thermostats. These thermostats regulate system components such as blowers, pumps, and fans by sending low-voltage signals to the heating or cooling system, rather than directly supplying power. Low-voltage thermostats are ideal for systems that do not use electrical resistance to produce heat.

Thermostat Categories Based on Features

In addition to their voltage types, thermostats can be further categorized by the features and functions they offer:

Manual Thermostats

Manual thermostats are the simplest type, requiring users to manually adjust temperature settings. They come in both mechanical and digital models. Older mechanical thermostats are commonly seen in line-voltage systems, while digital models can be found in both line-voltage and low-voltage applications. While cost-effective, manual thermostats do not offer advanced programming or automation features.

Programmable Thermostats

Programmable thermostats provide automation options that allow users to set schedules for temperature adjustments. These thermostats help reduce energy consumption by optimizing the operation of heating and cooling systems. There are several types of programmable thermostats:

• Weekly models: Apply the same schedule for all days of the week.
• 5-2 models: Allow one schedule for weekdays and a separate one for weekends.
• 5-1-1 models: Offer different schedules for weekdays, Saturdays, and Sundays.
• 7-day models: Enable unique temperature schedules for each day of the week.

Wi-Fi Thermostats

Wi-Fi thermostats offer the benefits of programmable models but also allow for remote control through a wireless internet connection. With Wi-Fi capabilities, users can adjust settings from anywhere via a smartphone or computer. These thermostats often include additional features such as touchscreen displays, real-time weather updates, and energy usage tracking.

Smart Thermostats

Smart thermostats are the most advanced type, incorporating all the features of Wi-Fi and programmable thermostats, with added intelligence. They can learn a user’s temperature preferences, monitor home occupancy, and adjust settings accordingly for maximum efficiency. Smart thermostats can also provide alerts for potential HVAC system issues and remind users about maintenance tasks, improving system performance and longevity.

Comparing Different Types of Thermostats: Features, Control, and Applications

Choosing the right thermostat is essential for efficient temperature control and energy management. Each type of thermostat offers unique functionalities, making it suitable for specific heating and cooling systems. The table below compares the key types of thermostats based on voltage, control methods, features, and ideal use cases to help you make an informed decision.

Here’s a comparison of the main types of thermostats based on their functionality, control, and features: