Best Z-Wave Thermostats for 2021
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While many connected devices can offer clear benefits to the smart home, it’s hard to find many that are a better fit than the smart thermostat. These devices integrate well with other sensors in the home to offer easier management of comfort levels while providing genuine energy savings.
In an effort to appeal to the broadest market many devices go with WiFi for compatibility, but due to no integration standards that means they have to rely on cloud services to power their apps. I’m really not a fan of that model as it causes all sorts of issues around privacy, security, and reliability. As a Z-Wave user you’d know that there is a better way, and that’s the local control offered by a dedicated smart home hub.
I’ve taken a deep look at dozens of Z-Wave thermostat models, and narrowed the field down to the best in a handful of categories; Overall compatibility, those for the budget conscious, ease of integration, and specialist uses like line-voltage models.
Given we’re relying on Z-Wave for control here, software is not a factor as that’s determined by your chosen Z-Wave Controller, so I’ve looked at on device features, wiring options, and a wide range of customer reports for quality and reliability.
What is a Z-Wave Thermostat?
A Z-Wave Thermostat is a wall mounted electronic device that manages the operation of a home HVAC, boiler, or furnace, and connects to compatible home automation systems using the Z-Wave communications protocol. This protocol allows for efficient, reliable control of the thermostat via smartphone apps, or through the use of automation rules that can be linked to other sensors and smart home devices. You may also be able to use voice commands to query and control the thermostat, depending on the Z-Wave controller you have.
best Z-Wave Thermostat Overall
The Honeywell T6 Pro is the latest z-Wave iteration from the venerable electronics manufacturer, and is my best overall pick. It presents well in a sleek form factor with a nicely detailed touch screen control panel that reports temperature down to tenths of a degree, and includes humidity sensing and a good selection of configuration options. The panel is backlit when in use, which is always helps with usability outside of brightly lit positions.
The T6 Pro supports 2 stage heating and cooling in conventional system, with auxiliary heating and dual fuel systems. It also supports 3 stage heating/2 stage cooling heat pumps, so you have a good range of configurations this will work with. For matching your existing system, the available terminals are:
Y, Y2, G, C, O/B, W2(Aux), W, R, Rc
Honeywell includes a clean terminal block on the back where the wiring terminals use push clips instead of screw terminals, making for a nicer install experience. Pairing to Z-Wave is easy and provides a solid connection using either C-wire power or 3 AA batteries. Temperature control is very accurate, and you can set a differential in single degree increments down to 0.
Reports indicate it works well with most Z-Wave hubs, including SmartThings, Hubitat, and HomeSeer. You’ll pay a bit more for this model, but it’s not the highest price in the field. The Honeywell units are solid and reliable and there’s really nothing to strike against them, so I consider the price to be well worth it.
Best Z-Wave thermostat on a budget
The GoControl Z-Wave Battery Powered Thermostat is made by Z-wave device maker Nortek and is specifically designed to integrate with Z-Wave powered security systems like 2GIG GoControl, Alarm.com, TelGuard and Uplink, but will also work with any Z-Wave controller.
This model gets down to business in a fairly no-frills fashion. It’s fairly generic to look at and the LCD display offers limited information, however it gets the job done, is easy to install, and supports some enhanced wiring configurations for multi-stage heating, cooling and heat pumps. For matching your existing system, the available terminals are:
Y2, Y1, G, Rc, C, Rh, W1, W2 (single transformer systems can use Rc or Rh)
You can power it from a C-wire if you have one, and this is the preferred option from a reliability perspective, but if you only have a 4 wire system, you can still use it by powering it off 4 AA batteries. The specs claim 2 year battery life, but real life usage suggests it’s much less than that, and this is the biggest complaint against it in the field. I expect the battery life claimed is purely for manual use, not when connected to Z-Wave which will get you around 3 months instead.
It’s not officially support by SmartThings, which limits monitoring of the battery life, but it connects easily and works as expected. It also reportedly works well with Vera, Wink and HomeSeer.
Best Z-Wave thermostat for integration
Alarm.com’s ADC-T3000 is a popular brand of smart home security systems that have been expanding into ever more device categories. The current model offers a modern, stylish presentation with a clean integrated display. This is sufficient for day-to-day status checks and basic control, but most of the (fairly extensive) feature set is only accessible through the Alarm.com app.
In spite of that it’s a full Z-Wave Plus device, so you should be able to use it just fine on any other hub, but the power of this model comes from it’s deep integration with Alarm.com’s system. This makes it easy top tie into smoke alarms, door and windo sensors and other temperature sensors through out the home. You’ll also get the benefit of their geo-location services to help adjust things based on who is home. Of course, these are all things you can do with any good smart home hub, but this tight integration makes it all very easy
You can support for 2 stage conventional system and heat pumps, with configurable terminals for some third stage features as well. Available terminals are:
RC, RH, W, W2, C, Y, Y2, G, O, B, Z1, Z2 (the last two are configurable options)
In addition to these, there is support for non standard features such as external sensors, a dehumidifier function, emergency heat, and some others. There’s quite a lot to like here, but you do pay a premium for it. If you’re primarily controlling things through Z-Wave it’s a very good unit, but the lack of on-panel control might be off putting for some.
Best Z-Wave thermostat for line voltage
The Stelpro KI is from an HVAC manufacturer out of Canada that offers a handful of smart thermostat models in addition to a wide range of other systems. Most of these are WiFi and ZigBee based, but the Stelpro KI has a Z-Wave offering as well. The big selling point of the KI is that it is billed as the first line voltage thermostat in North America, and is the only such model in this list.
The use of Line voltage thermostats is a lot more specific than most, and this one is specifically designed to control electric baseboard heating units without fans, so if you want cooling control as well you’ll need something else. For those who want smart control of such a system, though, this is your go to device.
The KI supports 2 and 4 wire heaters (no c-wire is applicable because it’s a line voltage system) up to 4000W. The display is simple, but there’s less to look at with a system like this. Even so, it offers everything you could need, including Z-Wave signal strength, ambient temperature and the ability to show either the set point or the value of an external Z-Wave sensor connected to the same network.
It’s a full Z-Wave device, so it has good support for virtually any hub with positive reports for SmartThings, Vera, Wink, Vivint, HomeSeer and others.
The biggest issue with it is that you can’t turn off the heat completely. The best you can do is set it to the minimum 41F. This is OK for a home, but not for a vacation property that will be empty for extended periods. An update is supposed to be coming to add this, but it’s best not to base decisions on what may be.
Z-Wave thermostat alternatives
Trane is a big name in industrial and commercial HVAC systems, and they naturally have a line of consumer products as well. The TRANE XR524 is a mid range model in their smart thermostat line up which offers a solid, if basic, solution. It’s a fairly standard 5 wires model with support for 2 stage heating, but only single stage cooling. You might find it unsuitable for your setup as a result. For matching your existing thermostat, the available wiring terminals are:
C, R/Rc, W1, W2/O, Y1 and G
It doesn’t have any battery backup, which can be an issue if you lose power. The system will reset and not retain any settings. You can mitigate this somewhat by managing schedules and so forth in your Z-Wave system instead. The XR524 reportedly works well with SmartThings, Nexia, HomeSeer, and Vera without issues, and the Vivint Z-Wave control panel.
Outside of that criticism, the XR524 is a solid performer, holding temperature reliably and is fairly easy to set up, providing your system is supported by the limited wiring options.
The CT101 from Radio Thermostat offers a decent alternative with easy installation. Radio Thermostat has had a wide range of WiFi and Z-Wave thermostats for some time, but seem to be switching focus to WiFi at the moment. Many of the Z-Wave models are discontinued, and can only be found from third parties.
The CT101 is the top end model of the Z-Wave range, and offers a good range of wiring configurations, humidity sensing, and can be programmed on the device or via Z-Wave, but only one or the other. It’s best to power it off the C-wire, but it can run on 4 AA batteries as well, or use these as backup. There’s support for conventional HVAC and heat pump systems, with various options including multi-stage auxiliary heat.
For compatibility checks with your existing thermostat, the available wire terminals are:
C, B, O, W, W2, Y, Y2, RH, RC, G, A
Access to the wiring terminal and the battery compartment is via the front. The top and bottom section of the face plate clip off for easy access. This seems like a good thing, but it does mean the wires have to come over the top of the unit, and the panel cover can have trouble going back on if the wires are not firmly pressed down and behind.
Additionally, while support for SmartThings is good, other Z-Wave hubs have reported issues with the implementation of the protocol they’ve used. If you’re a SmartThings user, this may be a good option, but other hub owners may want to look elsewhere.
Frequently Asked Questions
What are the HVAC wires for?
The thermostat you choose needs to support the wiring of your HVAC (Heating, Ventilation, and Air Conditioning) system. While there are standards for wiring, these vary somewhat for different types of systems. It’s important to note that the colors of the wires are NOT standard, and can vary between manufacturers. Use the labels on the terminals to identify the correct wires.
Most retail thermostats support a 4 or 5 wire system, typical for a furnace plus A/C configuration. If you have a heat pump system it’s going to be more complex and this will narrow your options, but some will still support the required extra wiring. You can’t fudge this, the thermostat wiring has to match your system.
A 4 wire system will have:
G - Fan control
R - 24 VAC input
Y - Compressor (cooling) control
W - Heat control
A 5 wire system will include an addition wire, the C-wire, or Common wire:
G - Fan control
R - 24 VAC input
Y - Compressor (cooling) control
W - Heat control
C - Common 24 VAC
Checking the existing wires and the terminal labels they go to on your current thermostat is the best way to get this right.
Why use Z-Wave?
Z-Wave is a communication protocol specifically designed for IoT devices, and offers a secure, resilient private network specifically for those devices. Z-Wave is specifically designed to be light weight and efficient, and thus has much lower power requirements. This not only means better energy efficiency in general, but allows for small battery powered devices, such as wireless sensors, that can last for years.
Z-Wave provides resilience by using mesh networking technology, allowing each Z-Wave device to act as a repeater for others and providing the potential for multiple redundant communication paths around the home. This is all handled by the Z-Wave controller, so the user doesn’t need to deal with network configuration and connectivity issues. Z-Wave also uses a lower frequency than most consumer wireless devices, which helps to reduce the effect of interference and provide better penetration coverage in the presence of physical obstructions.
Z-Wave is also a completely private, local network. This means all your smart devices using Z-Wave do not require the internet. This is both more secure and more reliable as you won’t be subject to outages of your internet connection or the device makers servers (because there aren’t any).
Check out our comprehensive guide to Z-Wave to learn more.
Do you need a hub for Z-Wave?
Yes. Z-Wave is rooted on a single Controller device. This device ‘owns’ the network and manages security and routing information for all devices paired to it. Often the controller is also a complete smart home hub and provides the software features to allow for creating automation rules and a control interface for your Z-Wave devices.
There are some controllers which are simpler, and just provide the network management function. These are used to add Z-Wave connectivity to other devices, such as modular smart home hubs and DIY solutions running on a conventional computer. See my recommendations for hubs in each of these categories.
What is a Z-Wave Thermostat?
These devices communicate via the Z-Wave protocol and provide the ability to control heating and cooling systems in the home. They typically contain a temperature sensor like a typical thermostat, and may include other sensors such as humidity for more holistic comfort management.
By connecting the thermostat functions to Z-Wave, these devices can integrate with a range of sensors and other devices like ceiling fans, motorized blinds, and smoke detectors to enable smarter control of the home and response to varying scenarios without the need for human intervention.
The Wrap Up
Choosing a Z-Wave thermostat is as much about matching the compatible wiring as it is about the features of the device itself. Thankfully the better picks in this line up support a broad range of options which goes a long way to making it easy to recommend them. For the budget conscious, the GoControl battery powered thermostat will get the job done, although battery life isn’t great that’s less of a concern if you do have a C-wire to power it instead. The key point is broad HAVC support for a good price and solid Z-Wave support.
I’d strongly recommend stepping up a bracket to the Honeywell T6 Pro, though, as you’ll get even more wiring support, a host of extra features and a nicer on-wall presentation, as well as the backing of Honeywell’s solid reputation in this market.
A special mention I’d like to note is the Alarm.com ADC-T3000. While this unit is tailored for Alarm.com’s system, using it there gives you a whole lot of bang for the buck in terms of integration features. Yes, you can do those things with other Z-Wave hubs, but you’ll have to set it up manually. For power users that won’t be an issue, and it’s an excellent thermostat in it’s own right, but the Alarm.com app makes this all very approachable for the less tech savvy.