HVAC Contractor | Furnace Repair | Heater Repair | AC Repair Near Me

HVAC Thermostats: How it works and everything else you need to know

Nature doesn’t always give us what we want. It might be a hot day and nature gives us more sun. It can also be a snowy day and nature pumps more snow. But we can make what we want possible. Technology expands the limit of this possibility. technology gives you the possibility of feeling the exact temperature you want to feel. HVAC thermostat makes it possible to regulate it.

What is HVAC?

HVAC is a common term that people use. You might have a general idea of what it is. But do you know exactly what it means? Read on!

HVAC stands for: Heating, Ventilation, and Air Conditioning. You can’t completely control the changing quality and temperature of air in the environment. But you can do that in an enclosed space. That’s what HVAC does.

It provides thermal comfort and acceptable air quality in your house. HVAC is the use of various systems to control the temperature and humidity of air to a desired level in your house.

Simply put, the increases the indoor temperature when too cold. It decreases the temperature when it’s too hot. 

HVAC shouldn’t be tagged as just a temperature control system, as many people do. It is also responsible for the quality of air in your house. It removes odor, dust, carbon-dioxide, and excessive moisture from the air in your house. 

A control comes along with the HVAC system. This is to avoid the need for opening the HVAC unit to adjust temperatures. The control is a convenient solution. It is called the HVAC .

HVAC Thermostat 

All home appliances that heat or cool to a set point temperature use thermostats. Examples of such are building heaters, water heaters, pressing iron, ovens, refrigerators, air conditioners, etc. 

If you have a HVAC system in your house or in your office, you would see the HVAC thermostat mounted on the wall. 

What Does The HVAC Thermostat Do?

It controls and maintains temperature levels. Imagine you want to warm your room using your building heater. You put on the switch, when the room gets as warm as you want, you turn it off. After some time, the room gets cold again; you put it on. And keep doing that to maintain your desired temperature.

The thermostat saves you from such discomfort. It keeps your HVAC system smart.

That’s not all. It also detects changes in the room temperature and sends signals to the HVAC system to adjust the changes. This means you can set your desired room temperature, and the thermostat does the work of maintaining it for you.

Simply put, when the room is too cold during the winter, the thermostat signals the heater and the heater produces more heat. When it’s too hot in the summer, the thermostat signals the to produce cooler air.

How Does The HVAC Thermostat Work?

Who wouldn’t want to know how such a convenient little beauty operates? It’s not a hard concept. It’s a pretty cool technology. Let’s talk about science.

Mechanical thermostats make use of bimetallic strips as its heat sensor. It comprises two different metals. These metals have different expansivity. The strip works with the principle of thermal expansion. When heated, it expands and bends. When cooled, it goes back to its original shape and straightens. 

The bimetallic strip is integrated into the circuit. It serves as a switch. One end of the strip is fixed at a point. The other end is set free. Whenever the strip bends, it opens the circuit. Just as seen in the below diagram. This makes the heating element unable to get voltage and turns it off. When the strip is cooled, it straightens, thus causing a continuous circuit. The voltage begins to flow again. 

Electrical thermostats make use of a different type of heat sensor, like thermocouples, thermistors, and other semiconductor devices. 

Signs Of A Broken Thermostat

If your HVAC system has a faulty HVAC thermostat, the room can get as cold as a freezer, or as hot as an oven without considering the desired temperature. Sometimes homeowners blame their thermostat for a malfunction, when the problem is a setting-related problem. It could also be a weak battery. So before pointing fingers on the thermostat, check the issues I listed above.

 Here are signs that signify broken thermostats.

1. HVAC system won’t come on

If switching on your thermostat won’t switch on the HVAC system, then the thermostat must be faulty. But before reaching out to professionals for thermostat repair, check for dead batteries, cut wire or dust buildup inside the thermostat. 

2. HVAC system won’t turn off

Does your room keep getting hot and hotter, exceeding the desired temperature? Or it keeps getting colder than required even after manually switching the thermostat. Then you should call professionals for thermostat repair. 

3. HVAC system not reaching set temperature or exceeding it

If the HVAC unit isn’t giving you the temperature you set, then it might be that the thermostat can’t detect the room temperature. To confirm if it’s a broken thermostat, place a thermometer near the thermostat and wait for some minutes till the thermometer settles. If you get a different reading from what the thermostat gives, then you can call professionals for thermostats service or repair.

4. Unresponsive thermostat

Your thermostat is not responding if the display is showing a blank screen. Or if the displayed temperature refuses to change even after a restart. But before reaching out to a HVAC professional, check out for dead batteries.

Thermostat Location 

The location of the thermostat is as important as the thermostat itself. You shouldn’t expose the thermostat to external heat sources like sunlight, heater vents, windows or hot-water pipes. If not, the HVAC unit would keep the room even when it has reached the desired temperature.


You got more questions? You can contact us here. We are certified HVAC contractors, we sell, install and repair HVAC units. We provide consistent, professional service and great products at fair prices. You don’t have to go anywhere else when you have us. We also give free estimates for system replacement if you have a faulty one. Book an appointment with us here.