HVAC Thermostat Systems Explained: Everything You Need to Know

Is your home feeling drafty and struggling to keep up with the extreme heat waves of the summer? Are your energy bills skyrocketing during winter? Did you know that using a thermostat will save you up to 10% in heating and cooling costs per year?

Yes, you read that right! According to Energy Star, you can save up to $180 in energy costs yearly when you program your thermostat with a schedule. Why suffer when you can get the right thermostat for your home to help you out?

When choosing the best thermostat system, the main issue is that there are so many of them to choose from. Choosing a thermostat is not as easy as it was in the ’80s. Back then, once you got a new system, you would also get a thermostat to go with it.

However, there are many options and brands to choose from today, and you may get confused. The good news is that we have HVAC thermostat systems explained comprehensively below, and this will help you know what to go for, whether you are installing a new heating and cooling system or replacing your old thermostat. Read on to find out more;

Types Of Thermostat Systems

Finding the right thermostat system depends on the needs of your home. There are several types as seen below;

Mechanical Thermostats

Also known as manual thermostats, these are the most basic type in the market. They can be manually customized to meet the demands of the house. You only need to do some physical tuning and setting them up to ensure that they can shift effectively from heating to cooling.

These manual thermostats are perfect for people who are usually at home often and prefer a fixed temperature. They do not offer a hands-off control; hence you have to set it up manually.


  • Cheaper to install.
  • Troubleshooting is easier as they are simple devices.
  • They are familiar to most people, hence easy to operate.


  • Expensive to maintain.
  • They have few options when it comes to control and customization.
  • They have a longer delay on changes in temperature as their bi-metallic strips response cause variations in temperature.

Non-Programmable Thermostats

These types of thermostats do not have any pre-settings or smart technology. They can only be set manually and adjusted via their physical interface. This means that if you want to change the home’s temperature, you have to manually adjust the setting on the thermostat.

They have a significant similarity with mechanical thermostats, with the only difference being that non-programmable thermostats have a digital display setting instead of the mechanical meter or dial in the manual thermostat.

Non-programmable thermostats perform all the essential functions of thermostats, with the major difference being that you cannot set it to change temperatures while you are away. Therefore, they are great if you know that there will always be someone at the house or for people who work from home.


  • Modes: Cool, Heat, Off, Emergency Heat
  • Fan: On. Off, Auto
  • Temperature-Set: You can use the up and down buttons to set the temperature to what you desire.


  • They have a lower upfront cost since they are more basic than programmable thermostats.
  • They are easy to use.
  • They are reliable as they will communicate with the heating system to maintain your temperature preference hence achieving high efficiency.


  • They cannot be programmed; hence they are not ideal for people who are rarely at home.

Programmable Thermostats

These are more advanced types, as the thermostat senses the room’s temperature and relays the message to the HVAC to either cool or heat the room. They can be programmed to your temperature preferences daily, weekly, or even monthly, based on what you choose.

This feature allows you to save lots of money on heating and cooling, especially when no one is home. For example, your air conditioning may take a break during the day while you are at work and kick in before you get back hence saving you money and ensuring that you also come back to a cool house.

Programmable thermostats are ideal for people who live in climates with drastic temperature changes, such as Florida, where days can be pretty warm and winter nights very chilly. They will help you set the temperature to ensure you are cool during the day and warm on the cold mornings without manually adjusting day and night. Incredible, right?

Programmable thermostats are more expensive than their non-programmable counterparts. They are about $20 more for single-stage and $70 for two-stage programmable thermostats. However, the price is worth it as you will be saving up to 15% on your heating and cooling costs with this thermostat.


  • Modes: Heat, Cool, Off, Emergency Heat
  • Temperature Set: You can use the up and down arrows to set the temperature to what you prefer.
  • Fan: Auto, On, Off
  • Programmable Schedule: This will vary from one model to another, but it generally has night, daytime, and wake settings. It also has an away mode for when you are on vacation or away from home for a long time. Some of the popular preset programs include the 7-day program, 5-2, and 5-1-1 programs. With the 7-day program, you can set a different cooling and heating schedule every day of the week. This is perfect for people whose schedule varies day by day. For the 5-2 program, you can set one schedule for Monday to Friday and another one for the weekend. For the 5-1-1 program, one heating and cooling schedule can be used for Monday through Friday, another one for Saturday, and another for Sunday.


  • They are perfect for areas with drastic temperature changes.
  • They can be customized.
  • They are more accurate, hence ensuring that energy is used efficiently.
  • Some models come with remote monitoring control options, making them more convenient when you are not home.
  • They have better in-home comfort levels as you can program them to begin heating or cooling the home just before you get home.


  • Complex installation.
  • They are complicated to program.
  • Some of them may be incompatible with your HVAC system as they are not universal.
  • They have higher upfront costs than regular digital thermostats.

Wi-Fi Thermostats

As per their name, these thermostats rely on the wireless network and connect to the local Wi-Fi for remote access. They are almost similar to smart thermostats, except that they need a Wi-Fi connection to work and control the temperature through the thermostat’s app. The wireless connection is usually for your phone, tablet, or computer to connect to the device, and not the thermostat connecting wirelessly to the HVAC appliances.

Wi-Fi thermostats are also programmable, meaning that you can also override a preprogrammed temperature setting if your schedule has changed.


  • Highly economical to run.
  • You can access and control the thermostat remotely from anywhere.
  • You can change the preset values on the already running programmed routine.
  • They are perfect for people who want to control the temperature setting even when they are not home.


  • They are costly.
  • They are not for everyone. If you are not tech-savvy, then this thermostat may be challenging to operate.
  • They may not be compatible with your HVAC system.

Smart Thermostats

These are the newest kids on the block and have the latest and most advanced features. The world is slowly saying goodbye to digital technology and incorporating smart technology as it is the future.

Smart thermostats are also connected to virtual assistants such as Google Home or Alexa; thus, you can control and adjust the temperature with your voice. They will also send you notifications in case there is a problem with your system. This will ensure that maintenance is done regularly; hence they will last long.

Smart thermostats use two types of technologies. The first one is geolocation fencing that uses the location of your cell phone to adjust the temperature in your home. Once the phone leaves that area, it switches to the preset temperature, and when it is within a few meters from the location, it starts heating or cooling according to your preferences. The other one is algorithm software where it learns all your behaviors over a few weeks and adjusts to the desired temperature when there is an activity in the home.


  • They are energy-efficient- they also allow you to monitor your energy usage in real-time; thus, you will manage your consumption better.
  • They will inform you of maintenance needs such as changing the furnace and air conditioner filters when it is time.
  • They offer finer control of the HVAC system to reduce your carbon footprint.
  • They can automate your heating and cooling with little to no manual input.
  • They help lower your home’s energy usage.


  • They are more expensive than manual thermostats. Some of the units also need professional installation.
  • They have complex programming; hence it may be challenging to understand what all the commands on your display screen mean. You need to learn and try to figure out the software and the different buttons.
  • They open up the possibility of hackers accessing your system.
  • Not all smart thermostats will work with every home’s existing HVAC system.

Thermostat Compatibility

You need to know the type of system you have when choosing a thermostat; otherwise, you will buy one that is incompatible, resulting in losses. So, how do you do this? Below are factors to consider when it comes to the thermostat compatibility with your HVAC system.


HVAC systems have different power voltages. They include:

Millivolt Power

These include gas-fired heaters that do not use a lot of electricity because they do not have a blower fan. They are mainly used for supplementary heat.

24V Power

These are known as low-voltage systems. They include heat pumps, boilers, and most split systems with gas or oil furnaces.

110V Or 240V Power

They are referred to as high-voltage or line-voltage systems. They include furnaces and electric baseboard systems.

It would be best if you used a thermostat that is compatible with the HVAC system’s power. Most residential HVAC systems use 24V power, and there are different categories of the 24V thermostat.

Staged Heating And Cooling

For a long time, furnaces and air conditioners were manufactured in one operating mode; they were either off or running at full capacity. This is what is referred to as single-stage heating and cooling. However, with advancements in technology, there have been other performance tiers introduced. They include:

Single-stage Systems

These are on and off operations, as stated above. They use 100% of their capacity; therefore, regardless of the temperature in the house, they will blow all the cooled or heated air at full blast. Once the thermostat notes that the desired temperature has been achieved, the system shuts down.

Two-Stage Systems

These offer two stages of cooling and heating in the home. The first stage usually is at 65% capacity and the second at 100%. Most of the time, these units run at the first stage, as it offers better efficiency, balanced temperatures and is quieter. However, when the outdoor temperatures change rapidly, the system will have to run at 100% capacity to compensate for these changes.

Variable Capacity Systems

These operate at any capacity, between 40-100%. Due to this feature, these systems are the most efficient, offer the best and precise cooling and heating, and are the quietest of them all.

Therefore, you will find thermostats made in single-stage, two-stage, and variable capacity types compatible with the HVAC systems at home.

Single-Stage thermostats

These are used in single-stage HVAC systems. They have one wire for heating, another for cooling, and the others accommodate the fan, 24V power, or a wire. These are best for when you have separate heating and air conditioning units.

Two-stage thermostats

These are best for heating or cooling units with multiple speeds. They have terminals to accommodate two AC wires, heating wires, power, common wire, and other functions. It uses its temperature sensor to know whether to use first-stage or second-stage heating/cooling based on the indoor temperature. Once it does that, it sends the heating or cooling signal to the appropriate wire.

Variable Capacity thermostats

They are also known as communicating thermostats. These have four wires, one for heating, another for cooling, and two wires to provide power and communication between the components and the thermostat. Therefore, they do not give direct signals for first or second-stage heating or cooling to be done, but instead, the temperature sensors and components send information to the thermostat. The device then responds by controlling the exact heating or cooling needed to keep the home comfortable.

Other Features

Some of the other features that you should look into for compatibility are:

  • Cooling-Only: Only designed to cool the home.
  • Heating-Only: Designed only to heat the house.
  • Hot Water: They control the temperature of the home’s water heater.
  • Furnaces: They use forced air to push warm air into rooms.
  • Heat Pump: They transfer heat from the source to the home.
  • Gas Fireplaces: These are single-room heating sources.
  • Zoned HVAC: This is whereby the heating and cooling are individually controlled in various areas from the same HVAC system. For example, you can set less heat in the bedrooms and more in the living room during winter. Here, you will need zoned thermostats.
  • Heat Pump With Auxiliary Heat: They have auxiliary heat with a backup heat source.

How Do You Ensure Your Thermostat Is Compatible With Your HVAC System?

  • Check to see the product description. It will either say that it works with one-stage, two-stage, or multi-stage heating or cooling. Choose one that is compatible with the system you have in place.
  • You can also use the compatibility checker on the manufacturer’s website. Here, you will be given a chart and asked to fill in the wire colors of your current thermostat. Once you do that, you will be told if it is compatible or not. You can also use Ecobee’s site, whereby you will need to take a picture of the thermostat’s wiring and email their customer service for confirmation.
  • You can also buy from a local dealer that sells these types of equipment and one that you can trust.

Features To Look For:

With the advancement in technology, modern thermostats are becoming more advanced. Below is a list of incredible features that you should look out for:

Precise Temperature Control

In The older models, there was no precision. Therefore, there is no need to spend your hard-earned money on a thermostat with no precise temperature control. Modern systems will allow you to set a variance and give you flexibility on the temperature ranges.

Separate Humidity Controls

Humidity is crucial as too much of it will lead to condensation and mold growth. Therefore, go for a thermostat with separate humidity controls as it is more effective.

Fan Speed

Go for a thermostat that allows you to run the fan on its own and adjust the fan speed for some time. This will help circulate air evenly, filter the air and ensure that there is the distribution of fresh air all over the home.

Auto Changeover

This feature is great for places with a wide temperature variety; hence, it will automatically switch from heating to cooling based on the home’s indoor temperature.

Automatic Temperature Controls

Smart thermostats come with geofencing features and use your phone to learn your behavior and automatically adjust your home’s temperature. All you have to do is download the thermostat app on the phone and install the geofencing feature. A geofence or electronic boundary will be created near your home, and once you cross it, the app turns the thermostat off or on, as programmed. This is a great feature, especially when you are on vacation.

Easy-To-Use Controls

Some thermostats can be quite complex to understand and know they work. It is recommended to get one that has easy-to-use controls. Look for simple touch controls and a backlit display to make it easy for you to monitor any temperature changes and adjust the thermostat accordingly.

App Control

This feature is found in smart thermostats, whereby you can control your home’s temperatures remotely. Some models come with voice control features like Siri and Alexa.

Helpful Reminders

Imagine your thermostat informing you that it is time to replace your AC filter. Isn’t that a great feature? Some thermostats have that feature; hence they will monitor and track your energy consumption and the status of the HVAC system. If there is a problem, you will receive alerts on your phone. If there is an issue with the home, such as an unexplainable increase in temperature, you will receive alerts that the pipes may overheat. This will help you fix the problem before it worsens later on.

You can also get energy tracking reports whereby you will be informed if other areas of the house are consuming more energy than others or even how much energy you are consuming. This will help you zone your home to conserve more energy and save money on energy bills.

The Best HVAC Thermostat Systems For Your Home

With the many different options to choose from, you may wonder which thermostat is the best for your home. Worry not! We have compiled a list of HVAC thermostat systems that we love and why you need to check them out.

Ecobee Smart Thermostat With Voice Control EB-STATe5-01

This is one of the best smart thermostats we have out there. It has a simple interface, with lots of bells and whistles for programming. It also learns your heating and cooling preferences and does so accordingly, with no hassles. It has a sensor that you can place in the less-used areas of the house.

Once the sensor detects any activity, the thermostat averages the sensor’s temperature and that of itself to heat or cool your home accordingly. This is one of the reasons we love it, as the previous Ecobee models had inconsistent sensing behavior, which is rectified with this thermostat.

Why We Love It:

  • It has a state-of-the-art SmartSensor that will help manage your hot and cold spots while keeping your home comfortable.
  • The SmartSensor detects both the occupancy and temperature of every room to ensure you get the best comfort.
  • It is Energy Star certified and will save you up to 23% annually on cooling and heating costs.
  • You can call your friends, change the temperature and even control your smart home with your voice. Amazing, right? All you need to say is, “Alexa, call mom.”
  • The SmartSensor is improved and has up to five years of battery life.
  • It has a Follow Me mode that will detect which rooms are in use when activated and signal the thermostat to adjust the temperature accordingly.
  • It is pretty easy to install.
  • You can play your favorite music with Spotify Connect. You can also pair your thermostat with a Bluetooth speaker and enjoy streaming music.
  • It has a Smart Recovery Feature, which, when enabled, can use the local weather information, analyze your HVAC system and your habits to ensure that it always gives you the correct temperatures at the right time.
  • It is powered by a 24VAC power supply using a C wire; hence you can rely on it even in winter.
  • It is compatible with most HVAC systems; hence there is no need to worry.
  • It can use your air conditioner to lower humidity if you do not have a dehumidifier installed.

Honeywell Home RTH8560D Programmable Thermostat System

The Honeywell RTH8560HD programmable thermostat is the perfect option for you if you are looking for an affordable appliance with a stellar performance. It has multiple programming schedules such as the 7-day,5-2 day,5-1-1 day, and one week.

It has a Smart Response Learning technology that senses whether the home needs heating or cooling and adjusts accordingly, giving you maximum comfort.

Why We Love It:

  • Installation is simple and easy to do, thanks to the UWP Mounting System.
  • You can schedule your heating and cooling cycles to rhyme with your lifestyle.
  • It has a crystal-clear T5 Touchscreen display that is stylish and functional. Reminders to change air filters will appear on the screen.
  • It is compatible with most HVAC systems.
  • It has an indoor humidity readout.

Lux Products TX9600TS 7-Day Programmable Thermostat

This is the most compatible programmable thermostat in the market. It is compatible with basically all North American heating and cooling systems except for electric baseboard heat systems.

Why We Love It:

  • It is pretty affordable.
  • It is relatively easy to install.
  • It has a large backlit touchscreen.
  • It can be used for two-stage and one-stage cooling.
  • It has a seven-day programmable feature with 2 or 4 periods per day.
  • It is user-friendly, and Lux provide you with a detailed manual in case you are stuck. You can download it from their website.
  • It is universally compatible with all systems apart from electric baseboard heating.


Question: What Is A 3H 2C Thermostat?

Answer: A 3H 2C thermostat indicates that it can control three heating stages and two cooling stages.

Question: How Should I Set My Thermostat In Winter?

Answer: During winter, we recommend that you set your thermostat temperature at 68 degrees Fahrenheit when at home. If you feel cold, you can try to keep warm by layering your clothing. However, when you go to sleep or are away, it is best to lower it. Lowering the thermostat 10-15 degrees for around eight hours will reduce your heating bill up to 15 %. According to Energy Hub, you save up to 3% or more on heating costs for every degree of heat you lower.

However, in the summer, it is recommended to set your thermostat to 78 degrees Fahrenheit while at home. Here, programmable thermostats will come in handy to ensure that the proper temperatures are set and adjusted according to the temperature changes.

Question: How Do I Get the Most Out Of My Programmable Thermostat?

Answer: There are several tips to follow to ensure that your programmable thermostat gives you service for many years. They include the following:
Set your ideal temperature for hours when you are home and awake.

Plan for the events where you will want to adjust the temperature, such as when going to work, returning from work, waking up, and going to bed.
Adjust the thermostat to reduce your energy usage while you are not at home.

Override the regular temperature programming for when you will be away from home for a long time.

Set the temperature adjustments before any events. For example, reduce the heating and cooling 30 minutes before leaving the house or 10 minutes before bed. You can also set the thermostat to the preferred temperature around 30 minutes before you return home.

Question: When Is The Best Time To Buy A Thermostat?

Answer: The best time to buy a new thermostat is between October and December, as there will be the holiday and end-of-year sales that you can take advantage of. You can also watch out for Amazon Prime Day in the middle of the summer for lucrative deals. However, if you desperately need a thermostat, get it as soon as possible to help you save on your energy bills as soon as possible.


When it comes to saving money, being more energy-efficient, and having a comfortable home, HVAC thermostats are the way to go. They will help you control your home’s temperature effectively while still giving you value for money. With the above guide, you will choose the best thermostat for you, based on your needs. Try one today, and let us know your experience.

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