THE PATHFINDER TO YOUR THERMAL SENSORS
The most important things to know
to choose meaningfully.
Thermal sensors are devices created with the scope of monitoring and informing about the temperature of a given physical space.
At the residential level, these devices are usually placed in the most important rooms of a house. Their goal is to inform the thermostat about the different room temperatures so that it can balance those variations and consequently avoid cool and hot spots.
Thermal sensors are especially useful if you live in a big space or during certain moments of the day. For instance, if when you are at home, you spend most of your time in the office room, then you may want your thermostat to adjust the temperature of your home based on the one present in that room. Instead, during the night, you may want your bedroom and your kids’ room to become the point of reference for the thermostat.
As per seen, heating your home based on the temperature detected directly by the thermostat might not always be efficient and in this situation, thermal sensors can be an excellent solution to increase your comfort while decreasing energy costs.
Time saved thanks to autonomous regulation of the thermostat.
Quality of life improved thanks to balanced temperature management across homerooms.
Peace of mind increased thanks to room-based temperature readings.
Savings increased thanks to targeted heating based on room prioritisation.
Thermal sensors can be of different types. They can be powered by wires or batteries and used to monitor outdoor or indoor air temperatures but also other substances like solids and liquids. However, these are aspects that can be shared among the different types of thermal sensors when classified attending their operating principles. Hereafter follows an overview of the main varieties of thermal sensors:
These sensors measure temperature variances based on a voltage change. The way they work, it is quite simple. Imagine two strips of metal that have distant properties and that are brought together, welding one of their ends while keeping the other one free. When the two metals are heated through the welded junction, the strips reach different temperatures that translate into a voltage gradient at the free end. Thermocouples are popular because of their simplicity, low costs and the full range of temperatures that they can cover, from -200ºC to 2.000ºC. As a counterpart, their sensitivity is not their strength, meaning that they are not the best solution if you want to detect a fraction of a degree changes in temperatures.
They measure temperature variances based on electrical resistance changes of metals. In this case, RTDs are made of highly conductive metals like copper or platinum that increase their resistance as temperatures raise (PTC, Positive Temperature Coefficient). They are slightly more sensible than thermocouples, offer the highest level of accuracy on their measurements and cover a wide range of temperatures, from -250ºC to 650ºC. The main disadvantage is related to their cost.
As RTDs, they measure temperature variances based on the electrical resistance of ceramics or polymers. They are generally made of semiconductor materials that, depending on the type selected, make their resistance go up (PTC) or down (NTC, Negative Temperature Coefficient) as temperature raises. They present the highest level of sensitivity, react very fast to temperature changes and offer a high level of accuracy on their measurements. As a counterpart, the range of temperatures that they can cover may seem tight, from -40ºC to 250ºC.
The selection of an appropriate thermal sensor may seem challenging, especially considering the wide variety of sensors of all types that are available in the market. However, the truth is that the decision process as you will see, should not be that difficult:
Most residential thermal sensors are thermistors able to measure a sufficient range of temperatures for home living and provide an acceptable level of accuracy and sensitivity.
If you already have a thermostat at home or you plan to buy a new one you should verify if it supports thermal sensors and how many of them. This will narrow down your choice automatically. If possible, select thermal sensors of the same brand of the thermostat to enhance collaboration between devices.
Thermal sensors are usually battery-powered. They are easy to install and will remain available in case of an eventual power outage. In case you decide to buy them, make special attention to battery life. The number of thermal sensors installed in a house can be quite high for which buying sensors with long-lasting batteries will reduce the level of maintenance required. For your information, thermal sensors that use Bluetooth or other low-power communication protocols generally consume less energy than those using high-power communication protocols like Wi-Fi. Remember that all devices that are not directly connected to the internet will require a hub if you want to control them from remote.
Like with all internet-connected devices, it is essential to consider the distance between the thermal sensors and the hub. Consider that the communication range specified by manufacturers might correspond to ideal conditions, not taking into account the obstruction that walls may oppose.
In addition to temperature monitoring, some devices may include additional sensors. For instance, built-in occupancy sensors will tell your thermostat, which are the rooms that are occupied and therefore, which are the rooms that it should consider for deciding if further heating or cooling is needed.
This refers to the area that the occupancy sensor can monitor. Occupancy sensors with a greater field of view cover a wider area with, generally, a lower distance coverage. Sensors with a smaller field of view cover a narrower area with, usually, a higher distance coverage. For instance, an intrusion sensor with a field of view of 130º may be able to cover a distance of about 7 metres, while an intrusion sensor with an area of view of 110º may be able to cover about 10 metres.