Room thermometer

A room thermometer is used to measure the average air temperature in living spaces. In general, a measurement accuracy of a few degrees is sufficient here, as there are greater temperature differences at the various points in a room.

Usual indoor and outdoor thermometers

If, on the other hand, emphasis is placed on more reliable information, then accuracies better than 1 ° C can be achieved with simple thermometers.

Kind of usual thermometer

The thermometers offered on the market have very different quality and they usually show errors by several degrees Celsius . A comparison with a calibrated thermometer or measuring probe can make the reading accurate to 0.5 ° to 1 °, which is rarely used. What is more important, however, is the place in the room where it is attached.

Most room thermometers are still expansion thermometers that are filled with alcohol . Rarely the cheap are bimetallic thermometer used often, however small " weather stations " whose sensors with semiconductors - or thermal effect can work.

Attachment of the thermometer and measurement accuracy

The best place for a room thermometer is where it can be easily read and where the temperature roughly corresponds to the mean room temperature . The proximity of a radiator is unsuitable because there are uncontrollable fluctuations, just as it is right next to a window or door . The thermometer should also not be in a place that is often illuminated by the sun , or where the air “stands”.

Those who value more precise measurements can achieve this with little effort:

Comparison with a calibrated thermometer or with the mean value of several devices. The individual piece can have deviations of up to 3 °, 1–2 ° are typical.
When reading, look horizontally at the scale . Otherwise a parallax error of 1 ° and more can occur. A reading accuracy of 0.5 ° is relatively easy to achieve if one imagines the horizontal.
Read off quickly, otherwise your own breathing will soon be noticeable.
When assessing the heating , ensure that there is a suitable time within the heating cycle.

The adjustment of a thermometer to the air temperature takes a certain amount of time, which can take from a few minutes to half an hour. If you want to get a quick result with a relatively sluggish room thermometer, you can accelerate the reading by waving the thermometer with an outstretched hand. The half-life is about 20 seconds, which means after this time the “artificial wind ” has approximated the display on the scale by 50% to the true value.

Overall, it can be said that if a few rules are observed, the average room temperature can be determined with an accuracy of ± 1–2 °. If, on the other hand, the thermometer is mounted in an unfavorable position and no comparison is made with other thermometers, the values can be wrong by 3–5 °, which would include the possible influence of radiation from the sun.