An indoor thermometer is a device which measures the indoor temperature and provides readings on a temperature display. Many companies which make thermometers and related products produce indoor thermometers, including models which are integrated into weather stations which may include readouts for outdoor temperatures, barometric pressure, and humidity. Costs vary, from very affordable units found in most hardware stores to expensive weather stations which provide a myriad of options including the ability to store temperature data.
Monitoring indoor temperature may be important to people for a variety of reasons. Some people are simply interested to know, while others may be concerned about the accuracy of a thermostat or the efficiency of a heater. People may also monitor indoor temperatures for the purpose of controlling the temperature for tasks like cooking and craft projects which sometimes require precise temperature ranges. Indoor thermometers are especially important for libraries and archives which need to maintain precise climate conditions to protect their collections.
A simple indoor thermometer may consist of a bulb which can be mounted to the wall to sense temperature in a specific area. People read the thermometer by seeing how far the fluid in the bulb travels up an attached tube. As the room warms up, the fluid expands and rises, and when it cools down, the fluid contracts and falls. An indoor thermometer can also have a digital display and may use sensors which can be placed in remote areas.
The placement of an indoor thermometer is extremely important, because temperatures inside a structure can be variable. Placing it near the ceiling, close to a stove, in an area which gets a great deal of sun, or above a heater will result in a skewed and unusually warm reading. By contrast, if an indoor thermometer is located right next to a door or window, by an air conditioner, in a room which is closed off, or close to the floor, it have unusually low readings. One advantage to remote sensors is that they allow people to place the thermometer unit in a convenient place while locating the sensor in the best spot to sense the temperature.
Many people find it helpful to measure humidity as well as temperature indoors, and it can also be convenient to have a sensor outdoors to compare indoor and outdoor conditions. Units with this capability can be found at many hardware stores and can also be ordered through weather supply catalogs.