Thermostat | Its Types And Working Methodology

Are you feeling hot in the weather? Then you’ll be longing to cool off. Feeling a little cool? You’ll have to warm up initially. Our bodies are incredible self-regulating machines that can regulate their temperature to within a slight amount of 37°C (98.6°F). The rest of the world, on the other hand, isn’t quite that helpful. We have to continuously switch our heaters on and off if we want our homes to maintain a more or less constant temperature, or we can rely on devices called thermostats to accomplish the job for us. A thermometer can measure the temperature of a room, but a thermostat can manage it. This controlling dial is crucial for managing the temperature of your home, whether it’s located on the wall or the boiler. Let’s look at what a thermostat is, the different types of thermostats, and how they work.

What do you mean by a Thermostat?

How do you oversee the temperature in your home? There are numerous options available now, ranging from smartphone apps to the old-fashioned temperature dial. You may have temperature control on a wall in your home to control the heating system, but it is not a thermometer, although it is generally marked in degrees. It’s called a thermostat, and it’s derived from two ancient Greek words: thermo (heat) and statos (standing and associated with words like stasis, status quo, and static—meaning to remain the same). At its most primitive level, a thermostat is a set of controls for regulating the temperature in a heating system. You can choose the desired temperature, and the thermostat will strive to maintain that temperature in your room or boiler. Whenever the temperature in the house begins to drop, a thermostat activates the heating system to warm it up. The thermostat operates to turn off the heating when the inside temperature reaches the pre-set point, in this way preventing you from becoming overheated.


How does a Thermostat work?

It’s certain that things expand when they heat up and contract when they cool down (water is an exception in that it expands when it heats up and contracts when it freezes). A mechanical thermostat (which uses thermal expansion) uses this principle to turn an electric circuit on and off. Among the most commonly used types are bimetallic strips and gas-filled bellows.

Bimetallic strips in traditional Thermostat

A bimetallic strip is comprised of two pieces of different metals bolted together in a typical thermostat (or bimetal strip). In an electrical circuit connected to your heating system, the strip acts as a bridge. The “bridge” is normally down, the strip is carrying power across the circuit, and the heating is turned on. When one of the metals in the strip heats up faster than the other, the entire strip bends somewhat. It eventually bends to the point where the circuit is broken open. When the “bridge” is raised, the electricity is turned off, the heating is turned off, and the chamber begins to cool.

But what happens after that? The strip cools and stretches back to its original shape when the room cools. It eventually snaps back into the circuit and restores electricity flow, allowing the heater to turn back on. You can modify the temperature at which the circuit turns on and off by setting the temperature control. Because it takes time for the metal strip to expand and contract, the heating doesn’t turn on and off every few seconds, which would be pointless (and annoying); depending on how well-insulated your home is and how cold it is outside, it could take an hour or more for the thermostat to turn back on after it’s been turned off.

Gas-filled bellows in Thermostat

Bimetallic strips have the drawback of taking a long time to heat up or cool down, therefore they do not react fast to temperature changes. A different type of thermostat uses a pair of metal discs with gas-filled bellows in between to detect temperature changes more quickly. The discs are perforated (have ridges in them) to make them springing and flexible, and they have a huge surface area to react quickly to heat. The gas in the bellows increases as the room warms, forcing the discs apart. The inner disc presses against a microswitch in the thermostat’s centre, shutting out the electric circuit (and hence the heating). The gas in the bellows shrinks as the chamber cools, forcing the metal discs back together. When the inner disc moves away from the microswitch, the electric circuit is activated, and the heating is turned back on. Corrugated bellows thermostats are also seen in various applications (for example, vintage cars), and they’re occasionally filled with a volatile (low-boiling) liquid-like diluted alcohol instead of gas; the particular chemical within depends on the temperature range over which they must work.

Wax Thermostat

To summarise what we’ve learned thus far, all mechanical thermostats (all non-electronic ones) use materials that change size or shape as temperature rises. As a result, bimetallic thermostats depend on metals expanding as they heat up, whereas gas bellows rely on gas expansion. Some thermostats go further than that, relying on the transition of a material from liquid to gas. Wax thermostats are the most frequent type, and they can be found in radiator valves, automotive engines, and shower mixers. Inside a sealed room, they utilise a small plug of wax. As the temperature rises, the wax melts (turns from solid to liquid), expands significantly and pushes a rod out of the chamber, which turns something on or off (such as the engine cooling system in a car or regulating the hot and cold water mixture in a shower to keep your body from simmering like a lobster). In the intense circumstances within a vehicle engine, wax thermostats are more efficient and last longer.

Smart Thermostats

We spend just about half to a third of our time at home; the rest of the day is spent at work or on the road. At home, we usually have a programmer or thermostat that turns the heating on or off based on the time of day or the temperature inside. But, at most, that’s a simplistic system. To prevent a cold home, many of us just turn up the heat, squandering a lot of energy and money in the process. This is the issue that the latest generation of smart thermostats is intended to fix. They observe how you change the temperature manually at different times of day, or during the week vs the weekend, and contrast it to objective temperature and humidity measures to create a reliable schedule they can follow automatically in the future. They usually allow you to manage them remotely using a simple smartphone app, so you can, for example, turn up the heat on the train on your way back home.

System Zoning- reduced energy bills

There are usually rooms in your home that are consistently warmer or cooler than others. There could be various factors for this. For one thing, heat rises, thus rooms on the second and third levels are frequently overheated. As a result, basement rooms are frequently overly cold. Areas with high ceilings have a hard time keeping heat, and rooms that get a lot of sunshine have a hard time cooling down. These are only a few causes, but there’s only one definite way to balance out your home’s temperature: system zoning. 

The system zoning is quite clear and simple. Multiple thermostats are connected to a control panel, which controls dampers within your forced-air system’s ductwork. The thermostats continuously monitor the temperature in their designated zone and subsequently open or close the ductwork dampers by the thermostat’s settings. System zoning is useful for heating and cooling separate bedrooms based on the desired temperature setting, as well as for residences with uneven room temperatures. Simply close the door and close the damper if your guest room is normally empty. When executed properly, system zoning can help you save money on your electricity bills. Because of the preliminary cost of installation, many residents are uncomfortable or unwilling to make the switch to programmable thermostats and system zoning. This is a valid concern for anyone who isn’t building a new house or upgrading an old HVAC system, but there are alternatives. Although installing a standard zoned system is not a do-it-yourself project. Homeowners can use existing ductwork that can be retrofitted with a damper system.

The flex dampers, which are provided in circular and square duct versions, are filled with air to restrict or stop airflow within the duct. They’re heat, age, moisture, airborne pollutants, and ozone resistant, and even if punctured, which is unlikely, most holes won’t hinder performance. Steel or flexible ducts should have flex dampers installed. The dampers can be simply replaced by entering through a register. Most brands of zone-control panels are compatible with flex dampers.

setting up

Here are a few recommendations on how to make the most of your thermostat-

  • This type of equipment should be placed in an area of the house where there is a constant supply of fresh air. If you put your thermostat in a bright area or behind a curtain, it won’t be able to reliably sense the temperature.
  • To begin, set it to the lowest temperature that is suitable for you. This will be around the 18 to 21-degree range for the majority of folks.

On cold winter days, it may be enticing to increase the temperature, but this isn’t essential. The concept behind a thermostat is that it will respond to colder weather by ensuring that the heating is turned on for long enough to warm the house to the desired temperature. On a chilly day, though, because it takes longer to warm up a house, you may arrange the heating to turn on sooner.

The location of a Thermostat

Placing the thermostat at the right location is also very significant to get most of the good results. The thermostat should probably be placed in the room where most people spend the most time. It should be at least 18 inches (46 centimetres) away from an outside wall and about 5 feet (1.5 metres) off the ground. This should not be subjected to any heat sources besides the room’s air, such as sunshine, other appliances, heater vents, windows, or hot-water pipes. It’s also a good idea to avoid placing a thermostat near stairwells or in corners, as this will obstruct air circulation.