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How does a thermostat work?

While a thermometer is a tool to read a room’s temperature, a thermostat is able to control it. Whether it’s wall or boiler-mounted, this control dial is essential for regulating your home’s temperature. Let’s take a deeper look at what a thermostat is, what types of thermostats there are and how they work.

What is a thermostat?

How do you control your home’s temperature? Today there are many options, ranging from smartphone apps to the traditional temperature dial. These are all forms of thermostats. At its core, a thermostat is simply the controls used to regulate temperature in a heating system. You can set a preferred temperature, and the thermostat works to keep your room or boiler at this desired level. If the home starts to drop in temperature, a thermostat switches the heating on to warm it up. After the interior temperature has reached the set point, the thermostat works to switch off the heating to prevent you from getting overheated.

Within this basic framework, there are a number of features and options:

  • Some thermostats are wireless and battery-operated
  • Others are connected with wires to the boiler itself.
  • Programmable thermostats use a set schedule to run the heating at certain times of the day.
  • Smart thermostats learn and adapt to your routine

You can find out the differences between programmable and smart thermostats here.

The types of thermostats

Thermostats come in a range of shapes, sizes and styles. The main two types of thermostats are digital and mechanical. These vary in a few key ways. Today, most new thermostats are digital or electronic. Digital thermostats have internal components capable of providing an accurate, responsive reaction to room temperature. The electronic sensors read the current interior temperature and can fine-tune the heating accordingly, keeping the room within a single degree of the target setting.

By contrast, a mechanical thermostat usually controls the temperature with the use of two bits of metal. These are laminated together in the thermostat’s sensor in a bimetallic strip. As the different types of metals expand and contract with temperature changes, an electric circuit connected to your heating system is switched on and off. This is how the thermostat is able to read and regulate heat. What’s important to note about a bimetal thermostat is that it isn’t as accurate as a digital model would be; the temperature can vary as much as five degrees from the target set point. However, some prefer mechanical thermostats because of their affordability and easy-to-use on/off switch.

How to set your thermostat

Here are a few handy tips for how to use your thermostat.

  • This type of device needs to be located in an area of the home with a fresh flow of air. If you place your thermostat in a particularly sunny area or behind a curtain, it won’t be able to sense the temperature accurately.
  • To get started, set it to the lowest temperature that you find comfortable. For most people, this will fall in the 18 to 21-degree range.

While it may be tempting to turn up the thermostat on cold days, this isn’t necessary. The idea behind a thermostat is that it will react to the colder weather and make sure the heating is kept on long enough to warm up the house to the set point of your choosing. However, because it can take longer to warm up a house on a chilly day, you could program the heating to switch on earlier.

Programmable thermostats have both time and temperature settings, so that you can regulate the temperature at different periods of the day. This allows to you save energy by turning off the heating when you’re at work, yet still return home to a warm house later in the day. You’ll need to take the warm-up and cool-down times into account when programming your thermostat.

How to use a mechanical thermostat

Mechanical thermostats regulate heat thanks to the expansion of their internal metallic strips. This strip carries electricity through the connected circuit, switching on the heating. As the strip heats up, one of the metals expands enough to open the circuit and switch off the heating, cooling the room down. To regulate this mechanism on your thermostat, use the temperature dial that you can adjust to the preferred temperature. This sets the point for the circuit to switch off and on.

Metal strips take some time to expand or contract, so the process can be rather gradual. One solution to this is to look for a mechanical thermostat with a gas-filled bellows sandwiched in between two metal discs. These metal discs are designed to have a fairly large surface area, allowing them to react quickly to heat. The gas in the bellows is what expands and contracts, controlling the electric circuit and heating accordingly. While this may sound complicated, from the user’s perspective all you need to do with the thermostat is set the desired temperature, and the mechanical components will do the rest!

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