A thermostat is a critical device to anyone who operates a heating, ventilation, and air conditioning system. It lifts the burden of continually adjusting your system to give the results you desire. By so doing, you only need to set the thermostat to a specific temperature; then it shall tune the HVAC system to attain that temperature. Thermostats come in different designs; however, they generally work the same way. Some HVAC units come complete with an inbuilt thermostat. However. For others, you might have to purchase it separately and pair it with the HVAC unit.
Understanding the thermostat is essential especially if you use it daily. Knowing how it works and identifying flaws in its operations will help you avert problems that could be life-threatening. In this article, we shall tell you all about the thermostat to equip you with the knowledge you need to handle this device.
Is a thermostat a thermometer?
Although they both deal with temperature, there is a big difference between a thermostat and a thermometer. A thermometer reads the temperatures and gives the results. In contrast, on the other hand, a thermostat reads the temperature in a room. It regulates it through sending signals to the HVAC unit to either increase or to reduce operations to attain the desired temperature.
The word thermostat is derived from two Greek words: thermo, which means “heat,” and statos, which means “to remain the same or unchanged.” Therefore, as the name suggests, the thermostat is a device that measures and maintains the temperatures at the same level.
How do thermostats work?
The thermostat works on the principle that matter expands when heated and contracts when cooled. A mechanical thermostat uses this idea of thermal expansion to switch on or off an electric circuit. To understand this better, let us look at the two most common types of thermostats.
This category of thermostats has two pieces of different metals that are joined side by side together. This metal strip is the bridge of an electric current that switches the air conditioning unit. The two metals have different expansion and contraction rates. When the strip is hot due to high temperatures in the room, the inner metal expands, making it bend outward hence disconnecting the electric flow. Consequently, the air conditioning unit is switched off, and the room begins to cool.
When the temperatures go below the set levels, the metal begins to contract and straighten to restore its original shape. Therefore, the electric circuit is completed, and the air conditioning unit is turned on again. When you adjust the temperature dial, you change the temperature at which the circuit switches on and off.
You should note that the thermostat does not switch the heating unit on and off every few seconds. Doing so will be pointless as you might not even realize the effects of the air conditioner. The metal strip takes up to an hour to expand and contract. This depends on the temperatures inside and outside your home.
As we have seen, thermostats built with bimetallic strips take too long to react to changes in temperature. In this case, you might have to endure some long episodes of discomfort before the thermostat reacts to the change. The alternative design of thermostats responds more quickly to temperature changes reducing the time taken by the air conditioner to respond accordingly.
This design uses a pair of metal discs with a glass-filled bellows in between. The metal discs have a large surface area to allow them to respond quickly to changes in temperatures. They are also corrugated to make them springy and flexible. When the room is hot, the gas in the bellows expands, forcing the discs apart. Consequently, the current flow is broken, and the heating system is turned off, making the room to cool. When temperatures drop below the set level, the gas contracts forcing the discs together. In this case, the flow of current is restored, and the heating is turned on.
This design has also been tried using dilute alcohol instead of gas. In a nutshell, the substance used in the unit largely depends on the temperature ranges that the thermostat shall be operating.
This design uses the change of state of wax from solid to liquid when subjected to heating. The thermostat is commonly used in cooling engine and mixer showers. The wax is contained in an enclosed chamber. When the temperatures are high, the wax melts and expands, pushing a rod out of the chamber, switching on the cooling system. The same principle is used in the mixer shower, where the rod turns off the water heater when the water gets too hot.
In terms of longevity, wax thermostats tend to last longer, especially when it comes to vehicle engines.
Internet-linked smart thermostats
Machine learning technology has brought notable changes in the HVAC industry. Thermostats are not an exception. In the recent past, a new generation of smart thermostats have come up to help you solve the wastage of energy through unnecessary heating of your home. For example, if you are working away from home, you might incur high energy bills. This might be the case if you occasionally leave your heating system on. The thermostat has no way of realizing that there is no one at home that might not require heating. Smart thermostats have come just to solve this problem.
These smart thermostats learn the different adjustments you make, which they, in turn, use to adjust the heating of your home even in your absence. In this case, if you occasionally leave your unit off when you leave in the morning for work, when you forget to switch it off, the thermostat will switch it off on your behalf.
They also have a phone application that allows you to monitor the operations of your thermostat remotely when you are away from home. These personalization features allow you to focus on what is important to you rather than worry about the air conditioner at home.
Thermostat issues and how to solve them
Now that we know what thermostats are and the different types that exist, you probably know the one you have installed or the one that will suit your needs. However, having a thermostat is no guarantee that your heating automation will be seamless. Some flaws might make the unit problematic.
This is a significant factor that can make your thermostat unresponsive to changes in temperature. If your thermostat is not regularly and properly cleaned, it might stop working. To clean your thermostat, make sure that you dust the outer cover in your daily routine cleaning. The inside should be cleaned at least ones a month to prevent excessive tampering with the system.
To clean the thermostat, use a dry paper towel both on the outside and inside. In case you fear damaging the unit while cleaning, then contact an HVAC expert to service the system on your behalf regularly
Thermostat position in your house
You are likely to get thermostat issues if you have positioned it at the wrong spot in your house. For example, if your thermostat is near the window, it will get hit directly by the sun. in this case, it will respond to the higher temperatures outside the house hence sending the wrong signal to the HVAC unit.
You should also not place your thermostat near a fireplace or any appliance that emits heat. It should be centrally located so that it can respond to the general temperatures of the room. In case your thermostat is near a source of heat or in direct sunlight, then contact an HVAC expert to get it relocated.
If you install the thermostat wrongly, then it will not work accordingly. Whereas thermostats my be easy to install, getting them to work as required might needs some level of expertise. In case there are loose wires not firmly attached to the thermostat, it might not be working due to poor installation. HVAC systems are expensive to buy, install, and repair. Faulty connections to the thermostat might damage the unit, making you incur repair expenses. To avoid this, consult an expert when you wish to install a thermostat. In case you have installed already, call an expert to get the unit checked before it causes further damage.
Modern thermostats are computerized. Therefore, they are programmed by the manufacturer to have certain computerized features.
If your thermostat as been working well but has suddenly begun showing defects that you do not understand, then probably the program has defects. In this case, the only option is to replace the thermostat with a new one.
Change the batteries
Some thermostats are battery-powered. In this case, they might stop working is the battery is dead. You should therefore check whether the unit is battery powered and replace the batteries with new ones. Be sure to check for any detailed advice from the manufacturer concerning the type of batteries to use.
Like any other electronic device, thermostats age; when this happens, they tend to have more problems than newer ones generally. If this happens, then don’t bother much repairing the unit. It has probably reached its maximum performance lifespan. The best thing to do is to replace it with a new one.
If properly installed, how the thermostat works will largely depend on the HVAC system with which it is paired. Similarly, issues like age and cleaning of a thermostat also impact significantly on how the system performs. In case you have a thermostat already, ensure it is well maintained for optimal operation. If you are considering installing one, then this article should have given you a plethora of options to choose from and techniques to employ in caring for your thermostat.