Last updated: August 8, 2021

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Mould on the walls or a heating bill that rises into the utopian? If you don't regularly check your room temperature at home, such problems may have already accompanied you one or the other time. But measuring the room temperature with a thermometer is really simple and you can save money.

Our thermometer test 2021 will help you to better orientate yourself in your purchase decision and show you all the advantages and disadvantages of the different types of thermometers. To support you even better, we have also answered the most common questions. So there's nothing standing in the way of your thermometer purchase.




Summary

  • With a thermometer you have a constant overview of your room temperature and can react quickly if your rooms are permanently too warm or cold, so you can easily save money.
  • In combination with a hygrometer, you also have an overview of the prevailing humidity in your rooms and can effectively prevent mould.
  • Combination devices provide you with many more additional functions. For example, you can use certain devices as a calendar, alarm clock or radio.

The Best Thermometer: Our Choices

Thermometer: Buying and evaluation criteria

In order to keep an overview of the wide range of thermometer products, we have summarised a few criteria to help you find your way around. We have subdivided the whole thing as follows:

Below we explain exactly what you should look for in these criteria before you decide on a thermometer.

Accuracy

In order to have a full overview of the prevailing temperatures in your home, the readings should be as precise as possible. A temperature deviation of +/- 1 degree Celsius is acceptable and should be taken into account with every device.

After all, the accuracy of a measurement is essential for a measuring instrument. The resolution of the scale also plays an important role in the purchase decision.

Accordingly, you should definitely pay attention to the corresponding measuring accuracy of your new thermometer, because this is how the device provides you with ideal added value.

You can usually find out the respective accuracy of the thermometer in the product description. In addition, the manufacturer's information usually provides information about an existing calibration.

Field of application

At this point, you should already think about the primary use you want to have. For example, it is decisive whether you want to monitor only one room or even several rooms with one thermometer. Or whether you want a combination device that covers the indoor and outdoor area.

So-called hygrometers also monitor the humidity in the room to give you a complete overview. Therefore, you should be clear before buying which areas of application the thermometer should cover.

Mounting

There are also a few important points to consider when mounting the thermometer. Thermometers that are mounted on the wall are particularly practical. They can be mounted at eye level and offer a good overview from there.

Thermometers that can be stood up, however, are just as practical and do not require any additional material for mounting.

They can easily be moved from one place to another and offer you a certain flexibility.

So you should think beforehand about which thermometer to consider and then how best to mount it in your home. Each mounting has its own advantages.

Accessories

Depending on the thermometer, it may also include certain other functions and accessories. The combination thermometers that measure the indoor and outdoor temperature come with sensors that you can attach to the outside of the windows with a cable.

This gives you an overview of the indoor temperature and you can also read what the temperature is outside so that you can dress accordingly.

Some thermometers can also display the time or function as an alarm clock.

Thermo-hygrometers are also combination thermometers that not only measure the temperature, but also the humidity in the respective room air. This is helpful to keep humidity low through proper heating and ventilation and thus prevent mould growth.

Thermometer: Frequently asked questions and answers

The following explanations are intended to give you an even better and comprehensive insight into thermometers. We have therefore formulated the most important questions and answers to ease your last concerns about your new thermometer.

What is a thermometer and how does it work?

A thermometer is a device that is used to measure temperatures. Depending on the area of application, the temperature measurements fulfil different purposes and are recorded differently.

Thermometer-1

In principle, a thermometer is based on the expansion of liquids, which allows temperatures to be determined precisely.
(Image source: PublicDomainPictures / pixabay)

However, digital thermometers also provide a very accurate measurement, but they are not based on the expansion of liquids, but on electrical conductivity.

The digital thermometer contains a sensor that changes its electrical conductivity when the temperature rises or falls. This allows this thermometer to give an equally accurate temperature reading.

What types of thermometers are there?

There are analogue, digital or electric thermometers. These types have different functions and a different construction. Therefore, each type has certain advantages and disadvantages, which we have listed below.

Type Advantages Disadvantages
analogue thermometer with liquid durable, very accurate, simple very sensitive and fragile, scale sometimes difficult to read if too small
digital thermometer comprehensive, very accurate, decorative, additional functions, waterproof Screen can fade, batteries needed, can break sooner due to technology, more expensive
electric thermometer very accurate, easy to read not suitable for room temperature
thermo-hygrometer combination of air temperature and humidity, wide range of applications, very accurate expensive, can break sooner

The analogue thermometers with liquid consist of a scale and a tube. This tube is filled with coloured alcohol and sealed airtight. The liquid expands when it is warm and contracts when it is cold.

The change in temperature can be read from the rising or falling level of the liquid and from the scale.

Digital thermometers measure completely without liquid. They have sensors whose electrical conductivity is measured, which changes at certain temperatures.

In an electrical thermometer, the change in resistance of an electrical semiconductor is related to the temperature. However, this thermometer is not used for measuring room temperatures.

What do thermometers cost?

As different as the construction and the measuring method of the various types of thermometers are, they are all equally suitable for measuring indoor temperatures. However, they differ particularly in price.

Type Price
analogue thermometer with liquid approx. 2 to 15 euros
digital thermometer approx. 6 to 15 euros
electric thermometer approx. 10 to 30 euros
thermo-hygrometer approx. 8 to 25 euros

Analogue classic thermometers are already available in the low-price segment, but somewhat higher-priced ones may have a larger scale and also allow easier installation.

The classic digital thermometer, which can only display the temperature, is already available for a very low price.

However, these simple devices are hardly offered any more, the trend is towards thermo-hygrometers.

These cost only a fraction more and directly include other functions, such as time display and, of course, humidity.

How accurate are thermometers?

As with many measuring aids we use every day, thermometers do not have 100 per cent accuracy. High-quality thermometers are calibrated at the factory before they are sold to ensure the most accurate measurement and display possible.

If your thermometer is not calibrated or is not calibrated properly, this will immediately be reflected in the measurement result. Calibrated devices guarantee the best results.

Thermometer-2

A thermo-hygrometer measures temperature to within +/- 1 degree Celsius. The humidity measurement can have a deviation of +/- 2-3 percent.
(Image source: Projekt_Kaffebart / pixabay)

In general, thermometers can measure temperature with a deviation of +/- 1 degree Celsius. However, it also depends on where the thermometers are placed.

They should never be exposed to direct sunlight or heat sources. This will influence the result. In addition, the place of installation should not be changed often, as the external conditions change each time and no longer provide reliable comparative values.

What alternatives are there to a thermometer?

Since a temperature reading only works accurately with a thermometer, there are no similarly precise alternatives. However, there are one or two decorative options that use a similar mechanism.

Type Description
Galileo thermometer The Galileo thermometer is a thermometer consisting of a glass cylinder filled with water and containing buoyancy balls. The spheres are filled with different liquids. They are coloured differently and therefore have a decorative purpose. Depending on the temperature, one of the liquid-filled spheres rises to the top. Small plates hang from these small balls and indicate the approximate temperature.
Thermal strips Another simple way of reading the approximate temperature is to use thermal strips. These strips change colour depending on the outside temperature. However, this method does not give an exact temperature either, but only a frame and does not serve to measure the room temperature.

However, to obtain an accurate measurement of temperature and humidity, you should rely on the classic thermometers.

Otherwise, there are lots of instructions on the Internet on how to make your own thermometers with your family, for example. These won't give you an exact reading, but they will help you to better understand the exact function and measuring method.

Can I control a thermometer via WLAN or an app?

There are some models on the market that are controlled via WLAN, app or radio. In the meantime, different devices in the entire household can also be connected, but each can also be controlled separately.

This gives you full control over each individual room and you can make direct adjustments to perfect the temperature and humidity.

Thermometer-3

Weather stations are a great way to track indoor and outdoor temperatures and give you an outlook on the likelihood of rain.
(Image source: Myriams photos / pixabay)

Some thermometers send data to an app so you can analyse and better monitor specific areas. Other apps also give you direct feedback and recommendations for action.

Indoor and outdoor temperatures can also be displayed separately. Depending on which additional areas of application you want.

Do I have to calibrate a thermometer?

No, because most thermometers available for home use have already been calibrated at the factory. If you notice deviations, for example in comparison to other thermometers in your household, you can recalibrate certain models.

A simple calibration of a liquid thermometer is done using two fixed points.

  1. Preparation: First fill a container with ice water, which generally has a temperature of zero degrees Celsius, and a container with boiling water, which has a temperature of 100 degrees Celsius.
  2. Calibration: Now dip the thermometer to be calibrated into the vessel with the ice water and mark this point on the scale. Then immerse it in the vessel with the boiling water and mark the indicated value on the scale as well.
  3. Division: This distance between the two values can now be divided by 100. These 100 steps then always indicate one degree Celsius.

For normal household use, additional calibration is not necessary. This is usually only carried out for investigations with a thermometer in the laboratory or in industry. The problem here would be anyway that the commercially available thermometers do not have a scale up to 100 degrees Celsius.

Nevertheless, you can fill a container with ice water at home and check with the thermometer whether it shows zero degrees Celsius.

Conclusion

With a thermometer, you can get a good overview of your room temperature for little money. This way you can easily reduce your heating costs and at the same time create a cosy atmosphere in your home.

By combining it with a hygrometer, you can also get an overview of your air humidity and adjust your ventilation accordingly. This not only saves you money, but also reduces the risk of mould. With many additional functions, such as a weather station, you can control other areas of your home.

But you can also keep track of the prevailing temperatures outside your four walls. There are hardly any limits to your wishes. Control via radio, Wi-Fi and app is also no problem and helps you to use your thermometer even more flexibly.

Image source: Kurganov / 123rf

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