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Presently, the potential financial advantages of smart thermostats are garnering rapid interest. To help navigate complex technological jargon, I've developed a complete guide. This handbook aims to deepen understanding of the diverse range of thermostats, breaking down the unique benefits and drawbacks of each through a thorough assessment.

What is a Thermostat?

A thermostat is a device that regulates the temperature in a building, such as a home or office, by controlling the heating or cooling system.

It detects the current temperature using a built-in sensor and compares it to the desired temperature set by the user. If the actual temperature deviates from the set temperature, the thermostat signals the HVAC system to either heat or cool the space to reach the target temperature.

This way, a thermostat helps maintain a comfortable environment while managing energy consumption.

How Do Thermostats Measure Temperature Changes?

Thermostats measure temperature changes using temperature-sensing elements. The most common types of sensors in thermostats are thermistors and bimetallic coils.

  • Thermistors are ceramic semiconductor devices that change resistance with temperature variations. These are commonly found in smart and digital thermostats. When the temperature changes, there's a resistance shift caused by the temperature fluctuation which generates an electrical signal
  • Bimetallic coils are made of two different metals bonded together, which expand and contract at different rates when the temperature changes. Typically found in older mechanical thermostats, this expansion or contraction triggers a switch or moves a needle on the thermostat's scale.

The thermostat then processes this signal, comparing it to the user-defined set point.

If the room temperature deviates from the set point, the thermostat sends an instruction to either the heating or air conditioning system to correct the temperature and maintain a comfortable environment.

Old thermostat
Bi-metallic strips form the fundamental basis for thermostats as we know them today

Different Types of Thermostats

There's a wide variety of thermostats designed to cater to different HVAC systems, power levels, user preferences, and available equipment.

When it comes to low-voltage thermostats, line-voltage thermostats, and millivolt (mV) thermostats, it's important to understand their unique features and capabilities.

In the following sections, I'll explore these different types of thermostats in detail, helping you make an informed decision based on your specific needs and requirements.

1. Smart Thermostats

Smart thermostats are the latest generation of thermostats. Smart thermostats have all the features of previous versions and more.

While the older programmable thermostats have custom scheduling, the new ones have learning technology and auto-scheduling.

Other features of smart thermostats include 

  • Geofencing (adjusting the temperature according to your proximity to your home), 
  • Advanced monitoring with notifications or alerts
  • The option to add remote sensors for “smarter” energy and money savings, 
  • Integration with smart home technologies.
  • Additional functionality to control humidity and ventilation
  • Intelligent or even AI technologies are being added or developed to innovate thermostat technology.


  • Smart thermostats can be controlled from anywhere thanks to remote access and Wi-Fi.
  • They also come equipped with algorithms that can ‘learn' your preferences and apply them automatically.
  • Smart learning and automatic adjustments can enhance your home comfort and help you save up on energy bills. On average, you can expect the system to be 25% more efficient and possibly shave off almost 10% of your energy bill.


  • The cost of a smart thermostat is generally higher than that of a traditional thermostat.
  • This is due to the advanced technology involved, which may not be economically feasible for everyone.
  • Besides, in certain systems, it might be unnecessary or completely incompatible

Check out my list of the best smart thermostats that work with heat pumps here.

2. Wi-Fi & Touchscreen Thermostats

Wi-Fi and touchscreen thermostats offer modern convenience while bridging the gap between traditional devices and smart thermostats.

These thermostats come equipped with Wi-Fi connectivity, allowing homeowners to control their heating and cooling systems through an app on their smartphone.

Although Wi-Fi thermostats lack the advanced learning capabilities and extensive smart home integration found in smart thermostats, their features may be ideal for those seeking a simpler and more cost-effective solution.

On top of that, the programmable modes, and “non-smart” protection and efficiency improvements can work just as well as intelligent thermostats, especially under the right conditions and a small amount of supervision from the user. 


  • Controlling the app via a touchscreen panel is more convenient and accurate than using dials or buttons.
  • WiFi connectivity allows you to log in and see your thermostat profile and settings from anywhere at all.
  • It's easier to monitor how much money you're spending on heating expenses with Wi-Fi thermostats.


  • Much like smart thermostats, Wi-Fi thermostats can also require a sizable investment upfront.
Thermostat Touchscreen
Digital thermostats are more accurate and bring a lot of features to the table

3. Digital Programmable Thermostats

Digital programmable thermostats offer a convenient upgrade from traditional thermostats by allowing users to set automatic temperature changes based on predetermined schedules.

These schedules vary in flexibility, with some models offering basic weekday and weekend (5-2 day) settings and more advanced models providing individual day-to-day configurations (7-day).

This level of customization helps users efficiently manage their home's temperature while potentially cutting down on energy bills.

In a select few, you might also have a remote control or an extra accessory that helps you control the device remotely, adding in a certain amount of “smart” functionality.


  • Offer several settings that allow you to regulate the temperature and save on energy bills.
  • Can be controlled remotely – which allows you to turn the unit on or off according to your needs.
  • Provides scheduling abilities – so that you can plan your heating or cooling according to the changing weather.


  • Initial setup can be tricky and time-consuming for first-time users.

4. Digital Non-Programmable Thermostats

As their name suggests, these thermostats have no scheduling feature on them. They are limited to being manually set to one temperature only.

Unlike the past generation, they’re electronic and equipped with a digital display. Most often with a clock and extra information. 

They can control multiple units including heating, ventilation, and air-conditioning systems and allow you to seamlessly switch between the different temperature modes and fan settings.


  • Are incredibly user-friendly, with a simple button-operated interface.
  • More cost-effective than smart or digital programmable thermostats.
  • Offer all the required components for temperature control without the fuss of complicated features.


  • Digital non-programmable thermostats can only be controlled manually and don't offer scheduling or remote control capabilities.
  • Can be less efficient unless it’s constantly monitored

5. Analog / Manual Temperature Controls & Time Switches

Analog or manual thermostats represent the humble beginnings of temperature control systems.

These early thermostats operated using basic mechanisms, such as bi-metal strips, which relied on metal expansion caused by heat to control switches.

Although they were basic in nature, these analog thermostats were seen as a luxury when they initially entered the market. However, their capabilities were limited to just a few controls, which have since evolved tremendously in modern thermostats.

Time switches also gained popularity for their use in regulating burners, central heating systems, and water heaters.


  • Analog thermostats are the least expensive method of temperature control.
  • Include an ergonomic interface that can be easily managed and controlled.
  • Simple manual operation thanks to an on/off button and a slider button (to control temperature).


  • Not as accurate as smart or digital thermostats when it comes to temperature readings.
Mechanical thermostat
Analog or mechanical thermostats are durable but not very responsive or precise

6. Millivolt Thermostats

Millivolt thermostats serve a specific purpose in heating systems.

They are commonly found in top-vent wall furnaces, direct furnaces, and gas heaters.

Unlike regular low-voltage thermostats, these special devices operate on an ultra-low voltage of just 0.75 volts, making them well-suited for low-energy heating solutions.


  • Offers users the advantage of lower energy bills in comparison to other types of thermostats.
  • These thermostats are energy-efficient thanks to their low voltage use.
  • Offers the advantage of minimizing heat loss.


  • This type of thermostat or HVAC system is no longer used for newly constructed homes.

7. Line Voltage Thermostat

Line voltage thermostats serve as a simple yet effective solution for regulating temperature in rooms with wall, resistance, convection, or radiant heaters.

Their installation process is straightforward since they are directly compatible with the 120V or 240V mains power. 

Besides that, they come in two varieties: single-pole thermostats and double-pole thermostats. 

Single-pole thermostats have two wires and use a single current, while double-pole thermostats have four wires and run on separate currents.

On top of that, line voltage thermostats offer flexibility with options like digital, programmable, and smart models for enhanced convenience and energy efficiency.

For a list of the best line voltage thermostats, click here.


  • Are easy to set up and install.
  • Can effectively control heaters to keep room temperature constant.
  • Can be upgraded to become energy efficient.


  • Are not compatible with low voltage wiring.


Where Should I Locate A Thermostat?

Location, location, location! When it comes to thermostat placement, there are a few things you should keep in mind to ensure your thermostat works at full capacity. 

A thermostat controls your heating/cooling system based on the temperature readings it collects from the surroundings. But, when you place a thermostat in an area that doesn’t reflect the average temperature of the home, it tends to measure incorrectly, causing different rooms to heat up or cool down unevenly.

For best placement:

  • Make sure to include the thermostat in a frequented area such as a living room or hallway. Avoid placing it in kitchens.
  • Don’t install the thermostat facing a window or door, drafts or direct sunlight can cause the thermostat to measure incorrectly.
  • Avoid exterior walls. Outside temperatures can seep in, creating significant differences in the immediate area surrounding the thermostat
  • Don’t place it directly in front of a supply register or incoming air vent. Instead, locate the thermostat somewhat away so you can get an average reading
  • If possible, try installing the thermostat near a return vent as this will help get an average reading of the entire home’s temperature. 
  • If you have a multi-story home, consider setting up a dedicated thermostat for each floor.
  • Don’t install the thermostat in rooms that you rarely frequent, such as guest bedrooms and storage areas. 
Thermostat Location
Location matters so make sure you set up the thermostat where it won't read temperatures that don't reflect the overall feel of the room

What’s a Good Temperature to Set Your Thermostat to in the Summer?

Most people think that one temperature setting on the thermostat can last them the whole of summer. However, that's not how you should be controlling the temperature in your house. 

The weather tends to fluctuate, even during summertime, which means you need to monitor the system regularly to ensure the thermostat is maintaining a comfortable temperature.

That being said if you're still looking for a ballpark figure – the ideal summer temperature should be around 70 degrees Fahrenheit. Energy Star states that this temperature range should give you the cooling relief you require, along with energy efficiency.

What Should I Set My Thermostat to When I'm Not Home

For shorter Intervals (1-3 hours)

  • When you're not at home for short periods of time, say 1-3 hours, adjusting your thermostat isn't really necessary.
  • In such cases, maintaining your regular temperature setting will be the most efficient practice.
  • Changing the settings for such a short period can lead to energy waste when your system has to start up the compressor and heat pumps back up again, which consumes a lot of electricity at once.

For Longer Intervals (4-8 hours)

  • For longer periods of time away from home, like 4 hours or more, changing your thermostat by 5 degrees is a useful strategy.
  • During the summer months, increase the temperature by 5 degrees to reduce the workload on your cooling system.
  • In the winter, lower the temperature by 5 degrees to save on heating costs.
  • This simple act can help save energy and maintain the longevity of your HVAC system.

When Going on Vacation (Couple of days or more)

  • If you’re going to go away on vacation, it makes sense to turn off your HVAC system so you can be absolutely sure that it won’t consume any power. 
  • However, this might not be ideal, especially when you need the house to maintain a comfortable temperature when you return.
  • In such cases, you can try to program a vacation hold in your thermostat, certain thermostats may allow for this setting, counting down the hours until you return and making sure to adjust to a comfortable temperature upon your arrival. 

You can program this hold setting or control the thermostat remotely when you’re returning from vacation. This is where smart and non-smart Wi-Fi thermostats tend to have an edge over the others. 

What Does a Thermostat Do If It Gets Too Cold

When temperatures drop, thermostats play a crucial role in maintaining a comfortable environment indoors especially if it’s a digital thermostat.

When it detects that the temperature has fallen below your preferred setting, the thermostat signals the heating system to kick in and warm up the space.

So, when it gets too cold, the thermostat responds by switching on your heating system.

As the temperature rises and meets your desired setting, the thermostat will then signal your heating system to turn off, ensuring that your home remains at a comfortable level.

However, if you notice your thermostat struggling to maintain the desired temperature, there could be a few reasons for this issue.

  • First, extremely cold weather can potentially cause the thermostat to freeze, especially if it features a touchscreen.
  • In this case, try rebooting the device to resolve the problem.
  • Second, the thermostat might be undersized in comparison to the size of your home, reducing its efficiency in controlling the temperature.
  • Lastly, the thermostat itself could be faulty or in need of maintenance.

In any of these situations, it's important to address the problem promptly to ensure that your home remains comfortable and energy-efficient.

How Do I Make Any Thermostat More Energy-Efficient

Making any thermostat more energy-efficient begins with understanding its capabilities and closely monitoring it. Besides that, you can

  • Turn off your HVAC system when you’re not at home.
  • Or let it run at higher temperatures during summer and lower during winter (closer to the outside temperatures) so it doesn’t have to engage the HVAC system as much.
  • Consider upgrading to a programmable or smart thermostat, as it offers customizable schedules and advanced features that can improve energy efficiency by up to 25%
  • If available, set up remote control features via your smartphone, helping you monitor the thermostat and make changes no matter where you are.
  • Be patient and don’t be afraid to experiment, since optimizing any thermostat to run efficiently could take days or weeks of fiddling around with the settings. 
  • Don't rely entirely on automated features, as extreme situations might require manual adjustments.


With several types of thermostats, catering to different power levels, HVAC systems, and smart capabilities, picking between a smart thermostat or a regular programmable thermostat can seem like a difficult move. 

However, if money isn’t an issue, you can always rely on a smart thermostat to make your HVAC system more efficient and accessible. 

So make sure to consider the pros and cons of each type and drop us a comment if you have any questions. 


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