Best Smart Thermostat Reviews and Guide 2021

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Our 2020 Best Smart thermostat reviews guide meticulously lays out the need-to-know details about the highest rated Smart thermostats on the market. So, if you’re searching for a Smart thermostat for your home, you made a good choice coming here.

You should know that Smart thermostats are not typically reviewed in high numbers. In fact, most Smart thermostats have fewer than 20 customer reviews. However, we found some exceptions to this rule!

The smart thermostats we included in our list get high marks for quality, ease of use and performance. Most offer easy installation and benefits like WiFi connectivity and the ability to reduce your heating and air conditioning bills by up to 15%.

Brief Smart Thermostat Overviews

The purpose of this section is to give you the highlights of the best smart thermostat models on the market today. So if you’re ready to make your selection, choose one with the features you prefer, and make a purchase if you’d like.

Other readers will want to read the full reviews below for a complete understanding of how each 2020 best smart thermostat works to determine which will best fit their needs and lifestyle. In either case, select a thermostat with the number of heating and air conditioning stages you need.

      Image                              Product

Emerson Sensi ST55

Emerson Sensi ST55

  • Alexa, WiFi, Geofencing
  • Digital display with backlighting
  • Programming options: 7-day or non-programmable
  • Conventional heating: 2H/2C; heat pump: 4H/2C
  • Dimensions: 3.75 H x 5.88 W x 1 inch D
Honeywell Home RTH9585WF1004

Honeywell Home RTH9585WF1004

  • LCD touchscreen with WiFi compatibility
  • 7-day programming
  • Conventional: 2H/2C; heat pump: 3H/2C
  • Works with Alexa
  • Dimensions: 3.5 H x 4.5 in W x 0.88 in D
Ecobee Smart Thermostat

Ecobee SmartThermostat

  • Touchscreen with dual-band WiFi
  • Built-in Alexa & Geofencing
  • Conventional: 2H/2C; heat pump 2H/1C/2 Aux heat
  • SmartSensor Keeps Occupied Rooms Comfortable
  • Dimensions: 3.25 H x 5.5 W x 1 D
Glas SIO2-10000

Glas SIO2-10000

  • Translucent OLED touchscreen with WiFi
  • Universal HVAC system compatibility
  • 7-day programming
  • Conventional: 2H/2C; heat pump: 2H/2C/2 Aux heat
  • Dimensions: 5 H x 5.51 W x 1.18 D
Nest T4000ES

Nest T4000ES

  • WiFi compatible; works with Alexa
  • 24-bit color LCD, high resolution display
  • Universal HVAC system compatibility
  • 1H/1C with possible 2H or 2C (all systems)
  • Dimensions: 3.19 Diameter x 1.14 D

2020 Best Smart Thermostats Full Reviews

Alright, here’s more depth to differentiate one smart thermostat from another.

1. Emerson Sensi ST55 Smart Thermostat

This good-looking smart thermostat was rated a Best Value by USA Today, and we agree. You get a lot of thermostat bang for your buck here. It is Energy Star certified to use less power than most thermostats, and its intuitive adjustments can help you reduce heating and air conditioning costs by 15% or more. Sensi claims “23%,” but we think that’s a little bit of a stretch. Most homeowners will see a reduction of 10-15%.

This is a highly rated thermostat that gets excellent reviews from nearly 90% of verified users. Homeowners praise its Smart features, temperature control, and Alexa compatibility.

Emerson Sensi ST55


Here’s what you’ll like:

  • Usage reporting (monitoring HVAC system through the Sensi app) allows you to track your energy use
  • Geofencing (must have Android 5.0 or above) allows you to set up a geographic boundary around your home, so that when you pass in or out of the boundary, the system will adjust to your settings. For example, if you want the house cooler in summer when you arrive, set up a boundary 15 minutes from your home. When you cross it on your route home, the thermostat will automatically lower the set temperature to the setting you programmed.
  • Keypad lockout, so nobody messes with your temp settings!
  • Seasonal auto changeover from heating to AC and back.
  • Filter change reminder.
  • Optimal indoor comfort with Humidification/dehumidification settings.
  • WiFi compatible: It can connect through iPad (IOS) 10.0 or above and Android 4.2 or above.

The Smart Part of this Thermostat:

Because of the WiFi feature, you can remotely access your ST55 from anywhere. The thermostat sends “smart alerts,” which notify you of extreme temperature or humidity levels in your home, and it works with Smart Home platforms such as Google Assistant, Apple HomeKit and Samsung SmartThings.


  • Energy Star certified and outstanding package of features for the price. Using the 7-day flexible scheduling, geofencing, and remote access, you can save quite a bit on energy use.
  • Universal HVAC system compatibility – that is, it works with almost all types of HVAC systems. Also compatible with aux heat on heat pumps.
  • Has a temporary temperature hold when you set the schedule to “on.” Using the Sensi app, you will see “Temporarily set to,” which you can press to hold your new temperature until the next scheduled set point. The temperature hold will last up to 2 hours.


  • Works only with standard 24-volt systems, as most thermostats do.
  • A C-wire is needed for some HVAC system types, which most homes are already wired with, so you likely won’t have an issue. Systems requiring a C-wire include a furnace with no AC and all heat pump systems. Additionally, the WiFi radio will work only intermittently without a C-wire. See our C Wire Guide for details.
  • Can have WiFi connectivity issues – and this is one of the bugaboos of all smart/WiFi thermostats.

Note: If you plan to wire your thermostat rather than hire an HVAC tech to do it, you might want to bookmark our Thermostat Wiring Guide for future reference.

Additional Information:

For your backlight to run continuously, you will need to have a C-wire.

See this link to sign up for the Sensi app on your Smartphone device.

Requires Alkaline batteries.`

Bottom Line: This Emerson model will serve you and your home well if you are particularly interested in being eco-friendly.

2. Honeywell Home RTH9585WF1004 Smart Thermostat

This unit is different than most on the list because of its touchscreen user-friendliness.

Most customers give excellent reviews to this Honeywell smart thermostat. They appreciate most the RTH9585WF1004 Smart features, as well as its touchscreen and straightforward installation process. It’s a good DIY option.

The RTH9585WF1004 was Energy Star certified in 2019 and 2020. In short, this model is incredibly energy-efficient.

Honeywell Home RTH9585WF1004


  • Intelligent Alerts including:
  • Change reminders for air filter & humidifier pad
  • Hi/Lo temperature notifications
  • Loss of internet connection/internet restored indicators
  • Language preference option
  • Color customizing touchscreen
  • 12- or 24-hour clock
  • Auto changeover

The Smart Part of this Thermostat:

The RTH9585WF1004 is compatible with your iPhone and/or Android Smartphone, as well as your IOS and/or computer, providing opportunity for remote access to your heating and cooling. Its Intelligent Alerts keep you in the loop on your HVAC system without needing to worry yourself about system checking on your own time.


  • You are able to view the local weather via your thermostat and the Honeywell app, seeing the daily forecast on the thermostat and the five-day forecast on the app.
  • flexible temperature hold option for conventional HVAC systems. This hold option allows you to choose between permanent, temporary, or vacation adjustment schedules for whatever is most comfortable and suitable for the circumstance.
  • Listens to voice commands through the Honeywell app, acting on the commands within 3 to 5 seconds.


  • The temperature hold option does not work with heat pump or electric baseboard heating systems.
  • The wall plate is flimsy. Some customers have complained that it could break on them should they move it.
  • Will not work with either millivolt systems, such as a gas fireplace, or 120/240 VAC systems.

Additional infomation:

You must have a C-wire for this thermostat for both conventional HVAC and heat pump systems. Honeywell provides an alternative adapter, which can be found here.

Some customers have experienced issues with two-stage heating/cooling.

This item is IFTTT compatible. If you are unaware of IFTTT, or If This, Than That, it is a free platform that will connect all your apps and devices. For more info, see

Bottom Line: If you’re hoping for a reliable thermostat and don’t mind having only a small sample of Smart thermostat luxuries, the RTH9585WF1004 is a safe choice.

3. Ecobee SmartThermostat

The ecobee SmartThermostat has Alexa built into it! Users like the ecobee for its energy efficiency, easy installation and battery life. Many also mention the unit’s touchscreen design and how responsive it is. In our opinion, and the ratings show it too, the ecobee SmartThermostat is an improvement on the former model, the ecobee4.

Ecobee Smart Thermostat

Additional Features:

  • Far-field voice allows you to control the thermostat using voice from a significant distance without shouting.
  • SmartSensor – If you have zoned heating and air conditioning, sensors in each room will determine whether they’re occupied. Dampers to zones that are not occupied can be closed. This function is available in the Settings.
  • Remote access through a mobile app that connects to your Smartphone, tablet, computer, or Apple Watch.
  • Compatible with Smart Home systems (Google Assistant, Apple HomeKit, Samsung SmartThings, IFTTT).
  • Ecobee mounting plate.
  • Smart Home/Away – It is designed to “know” when you leave, i.e., when the sensors aren’t triggered for a period of time, and go to Away Mode that saves energy by reducing heat in winter and AC in summer.

The Smart Part of this Thermostat:

This model can detect when you are home and away to adjust your inside temperature according to your pre-set preferences. With a built-in Alexa, you will be able to voice command your thermostat on and off, as well as voice command other controls or internet searches. The ecobee SmartThermostat also has an advanced “reverse staging” setting, in which you can enable it to transition from stage 1 heating/cooling easily and automatically to stage 2, then back to stage 1 until your set preference temperature is reached again.


  • Energy Star certified. You can save up to 15% on annual energy cost. Again, ecobee says “23%,” but we think 10-15% is more realistic. Still, the thermostat pays for itself in a year or two through energy savings.
  • If you are interested in using Alexa technology but don’t have an Alexa device, this model has a built-in Alexa.
  • Smart Home/Away with sensors. You will have two set schedules—one for when you’re around and one for when you’re gone—that the ecobee SmartThermostat will automatically switch between. 


  • The Home/Away setting doesn’t kick in very readily.
  • A few of these thermostats cause fan issues – the fan sometimes comes on when it shouldn’t, and this can increase energy costs.
  • Ecobee’s new feature, free software called “eco +” that is designed to maximize energy efficiency, has been known to mess with otherwise healthy SmartThermostats. Our recommendation is to wait to download eco+ software until you research it to determine whether bugs or updates are available to fix the issues.
  • The model’s WiFi connection can be spotty, true of all WiFi thermostats.  

Additional information:

This model requires Lithium batteries.

You should receive a “Power Extender Kit” (PEK) in the thermostat box. The PEK is a C-wire alternative freely provided by ecobee. Again, see our C-wire guide if you care to learn more about this issue.

For more on ecobee connectivity via IFTTT, see

Bottom Line: The SmartThermostat may cost more upfront, but its state-of-the-art design and abundant features will compensate for that. You’ll save a lot of money on monthly energy bills with this model.

4. Glas SIO2-10000 Smart Thermostat

This is certainly the most stylish smart thermostat on this list. It features modern design and intuitive operation using cutting edge technology. It also monitors indoor air quality, which is a major concern in today’s tightly built homes. There’s little air exchange, so indoor air becomes polluted.

One user had this to say about the monitoring: “My wife has some health conditions…We have been trying to create a healthier air environment for her at home, [so] the added air quality monitoring is amazing!”

While the unit doesn’t purify the air, there are many quality air purifiers available. PickHVAC has created a library of Air Purifier Guides and Reviews of top brands and specific types of air purifiers. For example, good places to start exploring how to clean the air in your home might be our Best Air Purifiers Reviews and Guide or our Best HEPA Air Purifier Reviews and Guide.

Glas SIO2-10000

Additional Features:

  • Indoor air quality monitoring (for humidity, VOCs, and CO2).
  • Outdoor air quality reporting (allergens, air quality index, UV index).
  • Google Assistant.
  • Remote access through Johnson Controls’ app.
  • Broad HVAC system compatibility: Conventional, single stage up to 2H/2C, Heat pump, up to 2H/2C/2 Aux Heat. GLAS is compatible with the following HVAC configurations- Gas Heat, Oil Heat, Electric Heat, Ground-source, Air-source, and Water-source heat pumps, Dual-fuel support for Heat Pump

The Smart Part of this Thermostat:

It monitors outside air conditions to determine how to give you the best inside air quality. This is particularly useful if you have a whole house air purification system. See our Guide to Whole House Air Purifiers for more details. You can monitor the thermostat remotely and adjust your home temperature accordingly with the click of a few buttons. 


  • You can control multiple Glas thermostats at once with the app.
  • Works with all conventional heating and cooling systems, as well as ground-, air-, and water-source heat pumps that use aux heat.
  • Stylish – It has a stunning touchscreen and looks good in a room.


  • The SIO2-10000 is not compatible with high voltage systems, such as 110-240 volts (V). The thermostat will work with most 24 VAC systems, however, and that’s what most HVAC systems are.
  • Terminals won’t fit extra-thick wires.
  • Occasional issues with scheduling heating/cooling events and with randomly shutting down.

Additional Information:

Glas can function with most 24VAC HVAC systems, but to ensure your system is compatible, see

If you only have one R wire, you will need to plug the wire into the RC terminal. Additionally, if you are replacing an existing thermostat, you will need to remove any jumper wires between R and RH or RC and RH.

If you do not have a C-wire, you will need to purchase a C-wire adapter like the PEK mentioned above or use a JC adapter to power your Glas thermostat.

If you have known about this model for some time, you may be aware that it was once compatible with Microsoft’s Cortana. The company decided to get rid of that compatibility in its most recent updates. 

Bottom Line: The Glas SIO2 is a great fit for homeowners with bad allergies or air-related medical needs plus built-in air purifying equipment.

5. Nest T4000ES Thermostat E

The Nest E is an upgrade in energy efficiency. It comes with programmed temperature parameters that keep your heating and air conditioning within Energy Star recommendations. However, you’re free to keep your home as comfy as you want it, and the Nest Thermostat E will soon learn your preferences and automatically adjust to them.

Nest is the original learning thermostat, and it is now in its 4th generation. Competition from Honeywell, ecobee, lux and other manufacturers have driven Google, the manufacturer of nest thermostats, to improve its performance and functionality of the Nest T4000ES. Homeowners enjoy the user-friendly design, integration with Alexa and Google Home and how easy it is to install and set up.

The frosted display allows the T4000ES to conveniently blend in with the rest of the wall and room layout. Unlike many thermostats, it will not stick out like a sore thumb.

The T4000ES is a 6-wire capable thermostat that has universal HVAC system compatibility. While it is always safe to ensure a thermostat works with your system before making a purchase, you will likely find this model fits what you have.

Nest T4000ES

Additional Features:

  • Ambient lighting.
  • Utilizes local weather data through WiFi.
  • Built-in Lithium ion battery.
  • Energy history (through Nest app) allows you to monitor daily energy use.
  • Home/Away assist learns through sensors when you are gone, and it automatically adjusts to use less energy.
  • Nest Learning monitors and “learns” your heating and cooling preferences and automatically adjusts temperature settings – and it can be overridden at any time.
  • Nest Thermostat E is a built-in energy-saving feature.

The Smart Part of this Thermostat:

This thermostat uses the available WiFi to locate weather data for optimal indoor heating and cooling, while also providing a simple means of remotely controlling the thermostat schedule and set temperature through the Nest app. You can browse your energy history through the app to navigate how much energy you saved and how the energy saving occurred.


  • Heat pump and aux/em heat compatible up to one stage of aux heat. The T4000ES is also compatible with dual systems (heat pump and furnace) through “Pro Setup” in the settings.
  • If you are replacing a wide thermostat with the T4000ES, you can purchase a Nest thermostat wall plate that will cover the full space left by your former thermostat. Here’s the plate for the Nest E.
  • You can set up a basic heating/cooling schedule and adjust it at any point. Through the Home/Away assist feature, the T4000ES will turn the temperature down after you leave your home to reduce energy waste.
  • This thermostat can be purchased with a sensor bundle to optimize indoor comfort and efficiency. Choose just the thermostat or the bundle option.


  • If you have an HVAC system that can go up to 2H/2C, then this thermostat won’t be able to power your system to its fullest extent. The Nest T4000ES only allows a second stage for heating or cooling, but not both.
  • Like most smart thermostats, this one will not work with a 120/240 VAC system, just standard 24 volt systems.
  • A common problem is that customers who purchase a T4000ES from third-party suppliers receive their thermostats with no battery charge. When the thermostat sits in a warehouse for a while, it loses its charge. You can recharge the thermostat by using a mini-USB cable.

Additional Information:

Occasional software updates will occur whenever the thermostat is connected to the internet. Each update will take a few minutes, depending on your internet speed.

While a C-wire is optional for this thermostat, you will find it difficult to adequately use the Smart features on this device on battery power alone. Adding a C-wire will be in your best interest. Many times, one of the wires not being used for another purpose can be used as the C wire.

Bottom Line: If you are familiar with Google’s Nest brand, you will find that this model is a nice improvement from former models and will serve you and your household well. We recommend, however, that if you purchase it from Amazon, you use the link provided because it will be sold and shipped by Amazon. This will help to ensure that the battery is charged when it arrives.

Best Smart Thermostat FAQs

Here are questions we commonly hear along with answers that are accurate and to the point.

Can you explain how to install a smart thermostat?

Unfortunately, there is no direct answer for this question, as every brand has its own unique installation style. However, there are a set of general rules you can follow that will help you with most Smart thermostat brands.

Tools/supplies needed:

  • Small screwdriver or power drill
  • Approximately 4 small screws (may need more)
  • Level
  • AA or AAA batteries (Alkaline or Lithium ion)
  • C-wire or adapter (if applicable)
  • WiFi router password
  • Smart thermostat and wall plate
  • Smart thermostat installation manual

First, follow these steps if you’re replacing an old thermostat:

  1. Switch off the circuit breaker for your HVAC system.
  2. Remove the thermostat’s faceplate and take a photo of the wire placement. You will need to know which wire color and terminals are connected when installing the new thermostat. If it helps, you can even use tape to label each wire.
  3. Use your small screwdriver to unfasten the terminal screws that hold the wires in place.
  4. Loosely band the wires together, as with tape, to make sure they don’t slip back into the wall. (Depending on how far the wires stick out of your wall, you may not need to do this step.)
  5. Unscrew and remove the wall plate. If you have paint still holding the wall plate in place, use a utility knife to cut along the perimeter. Otherwise, you will take off some of the wall paint when removing the wall plate, damaging the immediate area.

Now, the basic steps for your Smart thermostat installation:

  1. Keep the circuit breaker off.
  2. If you do not already have it in, add a C-wire or adapter.
  3. Slip the wires through the hole in the new thermostat wall plate.
  4. Screw the wall plate in place. As you do this, make sure of the following: (a) that you use a level to ensure the wall plate is properly mounted, and (b) that the screws you are using are not stripped.
  5. Plug in each wire in its respective terminal. If the wires are not straight, you will need to straighten them.
  6. Add batteries to the back of the thermostat.
  7. Attach your thermostat’s faceplate to the wall plate.
  8. Turn the circuit breaker back on.
  9. Program your new Smart thermostat according to your preference(s).

To see what these steps are like in action, refer to this video: 

Where can I find the installation manual for my smart thermostat?

The manual and installation videos are available on their websites. However, we’ve made the manual part easy for you.

Here are the specific installation manuals for the five thermostats in our list. Refer to any of these, which will also be in its respective thermostat box, when installing your particular model:

Emerson Sensi ST55

Honeywell RH9585

To see the ecobee SmartThermostat guide, download it here

Glas SIO2-10000

Nest T4000ES

Is a Smart thermostat worth it in terms of the higher cost?

This is a question we’ve been asked several times before. Our short answer is, Yes! But, of course, this depends on what your particular preferences are. Some homeowners prefer a no-frills thermostat that performs its basic job well, and we can’t argue with that.

What we can say is that Smart thermostats are intentionally designed to save energy through their various Smart features, such as geofencing, zoning, multiple stage heating/cooling, and energy history/monitoring. In other words, basic thermostats give you control over your heating and cooling, but Smart thermostats allow you to manage your entire HVAC system.

Monitoring your entire system allows you not only to save money on utility bills and to actively protect the environment.

Smart thermostats are incredibly convenient, as well. You no longer have to worry about over- or under-heating or cooling throughout the year, as many of the WiFi-capable thermostats “learn” your daily routine, adjusting your temperatures according to what is most comfortable and affordable for you when you are home or away. You can even get a reading on the local weather forecast ahead of time to best prepare your thermostat settings each week if you have a WiFi model like the Emerson Sensi ST55 or the Ecobee SmartThermostat. And with each company now providing Smart phone apps, what’s more convenient than controlling your thermostat remotely?

If you don’t care about the extra components found in a Smart thermostat, then you will be most satisfied with a non-programmable or basic programmable thermostat. We’ve provided Reviews and Buying Guides for both types.

2020 Best Non Programable Thermostats

2020 Best Programable Thermostats

I keep seeing 7-day, 5-1-1, and 5-2 programming with these thermostats. What do they mean?

In short, these options indicate how flexible your Smart thermostat is with its programming. 7-day programming, for instance, is the most flexible of the three options, as it allows you to plug in different temperature settings for each day of the week, including weekends. 5-1-1 and 5-2 programming, on the other hand, limit the number of times you can set up your preferred temperature schedules.

For 5-1-1 programming, you plug in a series of temperature settings for the coming weekdays, then a different temperature setting for Saturday and another for Sunday. You don’t set up your preferred temperatures on each new day, but rather at the beginning of the week.

5-2 programming is similar; you plug in one series of temperature settings for weekdays and a different series for weekends.

What is geofencing?

Geofencing is an app feature for Smart thermostats that use WiFi. Through this app, you can set a boundary around your home that uses GPS to sense when you’re within the boundary or leaving it. Depending on what thermostat model you own, this boundary can be as wide as a three-mile diameter.

While inside the set boundary, your HVAC system runs on your preferred, programmed settings. Whenever you leave the area, the system will automatically switch to your pre-programmed “away” temperature settings. This way, you won’t have to worry about remembering to change the settings before leaving the house.

This feature is most ideal for homeowners who have unpredictable schedules.

Keep in mind that some Smart thermostat brands use different names for geofencing, such as “Smart Home/Smart Away.” Don’t be tripped up by the names; they may be different, but the technology is the same.

What is a C terminal wire, and what is it used for?

The “C” stands for “common” and is used to complete the circuit that runs 12 to 24 VAC through the heating and cooling wire(s). Put in different terms, the C-wire allows your thermostat to be powered without disrupting the other wires, preventing thermostat glitching and malfunctioning.

Smart features are also typically dependent on the C-wire, as it provides the extra and necessary power for WiFi connectivity.

Some manuals or homeowners will suggest that the C-wire completely replaces the use for putting batteries in your thermostat: this is not true, however. It is true that you do not technically need batteries when you have a C-wire, but batteries act as backup power for low-voltage thermostats during power loss. Therefore, when you lose power, both your thermostat and your HVAC system will stop running if you do not use batteries.

Is the C-terminal/C-wire necessary for my Smart Thermostat?

It is necessary to enjoy the full features of your thermostat. The C-wire is significant for low-voltage thermostats/HVAC systems.

Even if the C-wire is said to be optional, the reality is that all Smart thermostats perform better with them. Battery power alone will limit the Smart feature technology, assuming the Smart technology can work at all without the C-wire.

If you do not have a wire available to use as a C-wire, you can purchase an alternative. Most thermostat brands provide C terminal wire adapters that act as C-wire replacements. They are typically simple to install and efficient. You can find some adapter options here.

What does it mean to say a thermostat is “Energy Star Certified”?

Energy Star certified products are more energy-efficient than standard market products, having to follow a strict set of criteria to earn the certification. These products will save you money on your monthly utility bills while also protecting you from harmful environmental factors, such as power plant emissions.

What are some of the specific criteria that Smart thermostats must follow to be Energy Star?

They function as basic thermostats when WiFi is absent.

They have to meet the minimum threshold of HVAC energy savings (approximately 8% on heating/cooling bills, or $50 per year).

They must be able to work with utility demand response programs.

Each Smart model has to demonstrate annual savings based on installation in homes across the country, ensuring that the collected data is based on true customer interaction with the product.

They have to be programmable.

If you are interested in knowing more criteria, visit Energy Star’s website.

If you are confused on what a few of these criteria mean, this page provides some clear and concise explanations.

What’s the difference between the stages of heating and cooling?

As you have seen throughout this article, there are a number of heating/cooling stages:

Single-stage, which is abbreviated to “1H/1C”

Two-stage, abbreviated to “2H/2C”

Variable capacity, abbreviated to “3H/2C,” “4H/3C,” or anything above two stages.

The main difference between all three stages is the capacity intensity. 

“Single-stage” systems work at 100% capacity only. Utility bills are higher with this system.

Comparatively, a “two-stage” system has two modes of operation: it can either work at 100% capacity or at “low” capacity. In other words, the system can work up to two-stage heating/cooling if you have the necessary terminals and wiring for it. It is more energy efficient and quieter.

Variable capacity means the gas valve in the furnace or the compressor in the AC or heat pump modulates in tiny increments up and down. Heating and air conditioning are very precise, so more efficient than the other type. Variable capacity systems are best considered only in climates with extreme heat or cold. Otherwise, you might not recoup the higher equipment cost through lower energy  bills.

For more nuanced information on this topic, see our comprehensive article here comparing the three performance options.

Where should I install my new thermostat?

Of course, if you’re replacing an old thermostat, the most appropriate response could be, “Where your old thermostat is located.” However, this may not always be the best answer.

Whether you’re replacing an old thermostat or installing the first one in your home, the thermostat’s location has a profound effect on the thermostat’s accuracy. To answer where you should install your new thermostat, you’ll have to first know where you shouldn’t.

You will want to make sure that you AVOID these areas/circumstances:

  • Exterior walls. If your new thermostat is installed on a wall connected to the outside, it will read higher or lower than room temperature due to the effects of outside weather.
  • Near exterior doors. Drafty hallways tamper with thermostat accuracy. Your new thermostat won’t have an accurate reading if it’s by a door that leads to the outside, especially if the door is frequently used.
  • In a room with a fireplace, stove, or heat-oriented appliances. Where there is excessive heat, the thermostat will always read higher than it should.
  • Where the sun rises/sets. If the thermostat is exposed to direct sunlight, especially in long intervals, it will read a higher temperature than the room.
  • Above or near air vents. Similar to the issues above, the constant gusts of heat or cool air from air vents will skew the thermostat’s readings.

The best place to install your new Smart thermostat would be on an interior wall in a room that is most used/occupied. We also suggest that it is located near the WiFi router and away from exterior doors. Make sure the thermostat is unobstructed by items, such as bookshelves or decorations, and that it’s in a particular spot that rarely or never experiences direct sunlight.

What are “aux” and “em” heat?

Heat pump systems can have a supplemental heat source, known as auxiliary heat (aux heat). Aux heat, powered by one or more radiant heat strips, assists the heat pump when the pump cannot extract enough heat from the air outside to warm your home. The heat pump begins to experience this trouble when the outside temperature drops between 35F and 40F.

Em heat, on the other hand, is a safeguard for your home and heat pump when the outside temperature drops to freezing (32F) or below. It’s used for emergencies, such as if your heat pump malfunctions, and/or extreme weather conditions.

For a more information on aux and em heat, check out our other articles.

What is Auxiliary Heat?

What is Emergency Heat?

What do you mean by a “low voltage” HVAC system?

90% of all HVAC systems these days are considered “low voltage,” which refers to their wiring and the number of volts they need to function. Low voltage systems run on 12 to 24V (and sometimes 30V).

Comparatively, line voltage systems run on 120V to 240V (and sometimes 110V).

For more on this topic, including the difference between low voltage and line voltage, see our article on thermostat wiring.

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