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The invention of the smart thermostat is a great step forward in temperature control technology and makes it much easier to keep our homes at the right temperature. Despite many new products, there are certainly many limitations in today’s systems that buyers need to be aware of. For instance, many big brands only manufacture smart thermostats for low voltage systems, not compatible with high voltage heaters, baseboard heaters, convectors and forced fan heaters still in use in many homes. A separate line voltage thermostat is required to control these high voltage systems. In this article, we review the line voltage smart thermostat, which was created as a solution to the high-voltage issue.

A line voltage smart thermostat can regulate the heating and cooling systems that run on the direct electricity of 240V of 120V. In addition, smart systems can stay connected through  Wifi connectivity and compatible mobile apps. In the United States, if your home uses electric baseboard heater, a line voltage smart thermostat might be required.

Quick Links to the Products Reviewed

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What is a Line Voltage Thermostat?

Also known as two-wire thermostats, these thermostats have 2 high voltage wires that come out at the base and connect directly to your high-voltage line voltage. The thermostat is connected in series within the exiting circuit and can then regulate baseboard heating systems.

It is also simple to install. After switching off power on your breaker panel, the thermostat can be added the circuit that provides power to the heating system. At that point, the basic ON/OFF functionality of the thermostat should already be controlling your heating. Thermostats can detect the temperature in the room and automatically cut off power to the heaters when the required temperature is reached. Of course, when the temperature starts dropping again, the heater turns back on.  The Honeywell multi-zone thermostat is among our favourite smart thermostats for a high-voltage heating systems. If you’re interested in purchasing a smart thermostat for your home we recommend you read through that articles as well.

Now, before making any decision, you need to ensure that the thermostat you are looking to buy is compatible with your heating equipment. Most high voltage smart thermostat are used for the following:

  • Baseboard heaters (or any resistance heaters)
  • Forced Fan Heaters & Convectors
  • Radiant Ceiling Heaters

If your heating system is composed uniquely of the above, most thermostats will work for you, but review the information of each manufacturer before making your purchase, as there are exceptions. Take a note, that when replacing your old thermostat if you find more than two wire coming from the base,  you are not using a line voltage system.

In the next section of the article, we list out three of the best smart line voltage thermostats currently on the market. We will be updating this article as changes are made to product availabilities.

You might be interested in our recent post on the Honeywell Multi Zone Thermostat Review  as well as our articles on other smart devices to upgrade your home, such as our piece on the 3 Best Ovens With Slide Away Doors.

Stelpro STZ402+ ki Smart Thermostat (WiFi & ZigBee Ready)

high voltage smart thermostat

Key Features

  • Zigbee compatible
  • Controls electric baseboards and convectors up to 4000W
  • Compatible with forced fan heaters
  • Equipped with humidity sensor

The Stelpro STZ402+ ki WiFi Ready Smart Thermostat is fully compatible with the Zigbee hub, which enables users to get  access to whole lot of additional functionalities. One of the key differentiators of this device is its compatibility with high wattage circuits. Depending on how your heating system is wired, baseboards and other appliances, such as window air conditioners, create high-wattage, which many modern smart thermostat cannot handle.

This thermostat can safely be integrated to any larger home which might have larger heating systems, while in addition providing smart device features and wifi connectivity.

Unlike on the Misa thermostat, the Stelpro STZ402+ requires users to connect through the Zigbee hub. If you’re already using other smart devices connected to a Zigbee hub this thermostat will work great for you, however is this isn’t your case you will need to do some additional setup. For this reason, I usually only recommend this thermostat to those who have had a good experience with the Zigbee Hub and know how it works.

Just know that if you’re willing to put a little more time in setting up your smart home, learning how to pair your smart thermostat with a Zigbee controller can pay off.  You will be amazed that from one centralized system, you’ll be able to adjust the lighting, home alarm systems and entertainment system, the temperature and much more.

Zigbee hubs are not as popular as other solutions, but it is as user-friendly as any. I used this system for a very long time to automate my own forced air unit system, and it worked great.

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Stelpro ASMC402 Smart Home Thermostat

Key Features

  • Designed for baseboard, convectors, and fan heaters
  • Works with Alexa, Google Assitant, Maestro and Zigbee controllers
  • Controllable through a mobile app
  • Many unique features focused on energy savings

The Stelpro ASMC402 Smart Home Thermostat is one of the best thermostats for energy saving. It is one of Stelpro’s newer products and according to the manufacturer, you can save up to 25% using some of this device’s unique energy saving features.

This smart device is packed with compatibility with both Maestro and Zigbee hubs, which leads to many additional features available within those hubs. Unlike the Stelpro STZ402+ mentioned earlier, this thermostat is compatible with the more popular smart home assistants like Alexa and Google Assistant. With remote access to all your thermostat’s settings through an app on your phone, this smart thermostat will provide all the features you’re likely looking for in your next purchase. In addition to the automatic heating schedules, one unique feature we appreciate is this device’s energy-consumption reports.

Part of what makes this one of the best thermostats for energy saving is how easy it is for you to you to track your energy costs. If you’re anything like us,  easy access to energy usage reports keeps us more aware and in the process allows us to save more money.

If if you’re already using either the Maestro or Zigbee hubs in your home, this thermostat one you should consider purchasing. With the compatibility with larger-scale systems up to a maximum power of 4000 watts, it’s sure option that very likely going to function within all of the rooms in your home.

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Honeywell Home RLV4305A1000/E1

Key Features

  • Lower price point
  • Simple to use for all users
  • Favours traditional control systems over use of an app

The Honeywell Home RLV4305A1000/E1, is the smart thermostat we recommend if there are people in your home that prefer controlling their thermostat using the buttons on the device. Not only is the among the best cheap thermostats, it’s also one of the best non wifi thermostats currently available by a trusted brand. Apart from the low price point and the 1 yer Honeywell warranty, this thermostat offers clear controls that won’t take any time to get used to.

This thermostat, isn’t as “smart” as the others featured in this article, but makes up for it with its simplicity of use. The digital display with large and readable numbers offers a backlight for easy use at all time of the day or night. The thermostat also has back up batteries, which ensure that the thermostat will stay correctly programmed even during power outages.

5-2 day programming is a feature that allows for two separate heating schedules. A 5 day schedule to align with your work week and a 2 day schedule to align with your heating needs during the weekend. Each day can be split up into 4 different temperature periods. For example, you could split up a day into these 4 sections with different temperature settings:

  • 7am-9am: Warm up home every morning
  • 9am-4pm: Keep cool while away
  • 4pm-11pm: Keep warm while at home in the evening
  • 11pm-7am: Keep cool while sleeping

The thermostat capable of reaching the temperatures in your schedule gradually. This means that you will not feel unpleasant temperature swings and in addition save on your energy bill. The Honeywell Home RLV4305A1000/E1 works with fan-forced heaters, electric baseboards, radiant ceilings and convectors.

We mentioned that we believe this system to be one of the best no wifi thermostats available. While we usually prefer smart devices with multiple connectivity options, we are also aware that not everyone is comfortable with using a smartphone. In many homes, especially with children or senior citizens, this thermostat will be preferred. If your home thermostat will be used by many different people this is one of the best available options.

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Nuheat SIGNATURE Programmable Dual-Voltage Thermostat

Key Features

  • Built-in circuit leakage protection
  • Unique floor heater temperature sensors
  • Works with Nest thermostats
  • Nuheat mobile app available on both Apple and Android

The Nuheat Signature Programmable Dual-Voltage Thermostat is our 5th pick and a thermostat that has a lot of fans with unique features that aren’t found in other smart devices. The most interesting of these features is the Class A GFCI (Ground Fault Circuit Interrupter) protection, which protects you and your family against risks of electrocution caused by a current leakage.

The reasons these systems exist is because the possibility is current leakage from your heating appliance does pose a risk. A  the case of a flood or heavy rain coming through a window, water can get in contact with hot wires within the heating appliance and cause a short-circuit. If this happens, the the GFCI will detect that electricity is leaving the circuit and automatically cut the power. While this type of protection is not often associated with smart features, we believe that such innovative features should be considered when making the decision for a smart device.

This Nuheat thermostat also has a unique compatibility with floor heaters and can be attached to your floors to detect their temperature. Since customers usually like to set different air and floor temperatures, a thermostat with this feature is the ideal when controlling a combined baseboard and floor heating system.

The Nuheat app has great scheduling and energy-saving feature, which can be controlled remotely from inside or outside of your home. As a wifi-connected thermostat you will be able to use your smartphone for all of your temperature control needs, as well as connect this thermostat with existing Next thermostat systems.

The touchscreen display allows you to easily control all heating appliances from the device, while keep a small design that is discreet when attached on a wall. Depending on your heating needs or potential needs in the future, this thermostat is might be the better smart thermostat option for you.

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Mysa Smart Thermostat for Electric Baseboard Heaters (Currently Unavailable)

line voltage smart thermostat

Key Features

  • High line voltage compatible 
  • Wifi connectivity 
  • IOS and Andriod App
  • Easy to install device

The Mysa Smart Thermostat for Electric Baseboard Heaters comes as our first choice system for controlling the temperature of baseboard heaters.

Its high voltage compatibility provides remote access through Wifi connectivity. When connected to the Wifi, this thermostat can be fully controlled from anywhere using the Mysa mobile app, which is available for both Apple and Andriod phones. The app contains great features that allow you to easily create temperature schedules, save money using the ‘eco-mode’ or manually set the temperature. The app even has a useful feature called ‘vacation mode’. It allows you to lower heating costs, while you’re away and bring the temperature back up as you return from your trip. These nice features, also make this one of the best thermostats for energy saving.

What we mean by full control is that you will never have to actually use the device itself, since everything can be done remotely through the mobile app. In addition to temperature control, Mysa is a thermostat with humidity control features.

It’s easy to install and should take you less than 20 minutes from start to finish.

Smart features of this device goes beyond wifi connectivity. In addition to controlling the temperature from an app, this thermostat is compatible with Amazon Alexa, Google Home, Apple HomeKit, and IFTTT. What this means is that the Mysa smart thermostat allows you to control heating using voice commands. You no longer need to stop what you’re doing to change the temperature on your thermostat if you’re feeling a little cold, just ask your voice assistant to raise the temperature. We found that because the thermostat works with Alexa (and other smart speakers), it can be just as easy to use Alexa as it is to use the Mysa app itself.

The Mysa thermostat also supports geofencing. In other words, if you’re in and out of your home at different times every day you can program the app to tell your thermostat to reduce the temperature when you leave you house and increase it when you’re back. Take note, that last time we checked the geofencing feature was located in the ‘experimental features’ of the app, so it might not be available to all users just yet.

Finally, we find that the design of the thermostat to be both elegant and minimalist, which is ideal for keeping it not too visible on your walls. The dot-matrix display and capacitive touch-sensitive buttons also make the use of the device itself very user-friendly.

While the price point might be slightly higher than some of the competing products, we believe it to be a worthwhile investment that will likely not have to be replaced for at least 10 years.

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A line voltage thermostat is a good solution for fan coil heating unit, but keep in mind it that these heating units a require multi speed fan, which many thermostat models do not support.

Line voltage thermostats are not compatible with the central forced air furnace systems. Your cannot use these thermostats with electric furnaces, gas furnaces, boilers and heat pumps.

The line voltage thermostat only works with the control heaters, you cannot run your cooling devices through the smart thermostat. On the other hand, many smart hubs will provide ways for you to connect with your cooling systems.

Final Thoughts

While there have been different smart thermostat solutions available on the for a number of years, there are still many things we wish thermostats could do. For instance, there are no thermostats that can deal with low voltage, high voltage heating and cooling systems all together.

We hope you’ve enjoyed this article on the best thermostats in the market. The entry of many new manufacturers and the continuous improvements they bring to products has really improved the experience of using smart devices for many people. The above picks are our favorites and since nearly 10% of homes in the US use line voltage heating systems, new and improved solutions are having a great impact on a very large number of people. Perhaps one day we’ll also have smart thermostats built for handling all of our heating and cooling needs.

Product ImageStelproPrimeEligibleBuy Now
Product ImageStelproPrimeBuy Now
Product ImageHoneywell HomePrimeEligibleBuy Now
Product ImageNuheatPrimeEligibleBuy Now
Prices pulled from the Amazon Product Advertising API on:

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