Line Voltage Thermostast

I live in a 62-unit mid-rise condo building in Chicago, and my thermostat is a line-voltage thermostat. My thermostats (two of them) are old, and I’d like to replace them with z-wave capable versions. Is anyone aware of any z-wave, line-voltage thermostats? Thanks in advance for your help.

I have been looking for the same thing for some time now. No luck so far.

Do you mean to switch a three phase powered device or do you want to switch one of the phases ?

In my case… I have some 220v radiant heaters in my rental cabin bedrooms, need to switch both legs of that. Single phase though.

Heatmiser in the UK have a 240v wi-fi thermostat (live, neutral and switched live) which works well. It doesn’t talk to Vera yet but folks are working on it. Meanwhile you can control it remotely via browser, iPhone app etc.

From what I can see from their site the wifi 230v models only switch 3amps. I would need to check but I am sure that those beasts are pulling more power than that. Was I looking at the right model? Wifi would be better than nothing and would give me some remote control which would make me happy.

They’re designed to switch pumps and boilers, so I guess you’d need an interposing relay to handle the currents you’re talking about.

Now that I am thinking, it may be easier to pick up a 24vac heater relay such as
to allow me to use a regular thermostat. Not as pretty as I would prefer but still would be using parts that are designed to do just what I need, allow a normal thermostat to switch a 15-20amp heater circuit.

@ Les F

I have never used the brand of relay you posted, but I have used the RIB branded relays for years. I didn’t see on their website that they had one with a built-in 24v transformer, like the Aube, but I’m not so sure I would necessarily want to have both the relay and transformer built into one device. If the relay contacts were to go bad, or the transformer, you would have to replace the whole thing. A separate transformer and relay would be more reliable, and easier to repair.

I’m not sure if you live in the USA or not, but I couldn’t find where the Aube products were manufactured, but I’m a little worried about their manufacturing origin. This is all they say about it on the website.
“Designed in Canada, Aube products…”

RIB on the other hand is made in the USA, and has been around a while. And like I said I’ve been using them for a lot of years now.
“Functional Devices, Inc. has been designing and manufacturing quality electronic devices in the United States of America since 1969.”

It would be a neat project if you can get it all wired up. Like I always say there’s nothing I can’t fix with enough relays!hehe

@mundyb .

Yeah, I am in Maryland.

Thanks for the tipoff! I had googled around and found the aube, but I prefer something someone has actually used and can tell me that it has held up for them. I’ll look at those.

Wow! that’s a great site… .all kinds of good ‘stuff’ thanks again!

Horstmann HRT4-ZW + ASR is also able to switch single phase up to 230V, 3Amp. For more Amps a relay can also be switched directly by VERA for which plug-ins are available ( but you would need a temperature sensor and run the thermostat algorithm in VERA.

I am looking at doing the same thing only I am finishing my basement off. I have Geothermal forced air that heats and cools my whole house but I want to put some electric heat in the basement to boost it up a little bit. I am looking at radiant cieling panels and I am thinking of controlling it with the Aube TH115-A-240D Thermostat and I will use an appliance module and relay to switch the stat between vacation and standard mode when I am in the basement was thinking of using the HSM100 on motion sensor and than leaving heat on for 2 hours but not to go above a certain level but affraid I will get to many false call because it will turn on whenever someone walks through. I was thinking of using the HSM 100, appliance module, and Aube RC840T relay/transformer but am worried I will not get it to work how I want and not have precise temperature control. . I just want the heat to come on when I am down there otherwise it can stay at the temp the geothermal keeps the basement. Any better Ideas? Thanks.

Side note about Aube I am an Electrical contractor and have been installing Aube products for a few years with no problems Aube is owned by Honeywell if you were wondering if there stuff is good. RIB is a great product also just thought I would mention that about Aube.

Hello folks,
This “line-voltage” thermostat thing has been haunting me for quite a while. I’m an integrator from Quebec, where 80% of homes are heated with baseboard heaters… Let me save you hours of Googling : there is nothing out there. Not only have I looked far and wide, I have talked on the phone with some of the most obvious companies, to no avail. Their say there is not enough of a market for them out there… Your alternative is to use a relay. I can certainly vouch for Aube products. Aube is a Honeywell company who’s factory is 10 minutes out from my office, their product outfit a very large number of Canadian houses. Having the transfo built-in is a plus to my ears, but feel free to disagree :slight_smile: What you need to worry about is both footprint (inside the wall or near the unit itself) and cooling. This thing can heat up quite a bit. Work your numbers out and make sure it’s placed where it can breathe. Also know this : this will be a full on / full off setup. With most modern line-voltage thermostat, you’ll get “pulsing” or the ability to slow down the unit once near the setpoint. The disadvantage of not doing that is that you’ll heat it up red until it reaches the setpoint, then the relay clicks and stops it, but it will radiate a lot more before beginning cool down, so it’s not exactly an “energy wise” method since it’ll produce a lot of unwanted heat.

We have taken it upon us to come up with a solution : we are in the early stage of a working Z-wave line-voltage, triac-controlled, thermostat. If it’s something you need, let me know. I’m pretty sure we’ll be looking for a bunch of people to use/abuse it once it’s ready… Certification is a pain, but there’s hope yet, bear with me :slight_smile:

Cheers !

Not sure if this helps, but TimAlls is working on a plugin for a device that has three relays and 8 temp inputs.,9386.0.html

Might be an option.

  • Garrett

I have been leaning towards taking a zwave thermostat and adding on a relay made just for heating (high amperage) purposes. A lot of the solutions don’t handle that kind of load so you would have to piggy back another relay on top of the outputs of the device.

@T1000, let me know what you come up with, I would be interested in testing/trying your solution.

Yes, the solution offered with the ControlByWeb unit is a good one. I’m actually more familiar with this stuff as this is the usual solution for “simple” systems (read, when Crestron is not warranted), but I really think that what most people are on the lookout for is a retrofit unit rather than anything involving fishing, holes in walls and whatnot. At least that’s where the frustration has been coming from. We started looking into Zwave for simpler, more cost effective solutions, but the lack of a product for such a simple use has really been a setback. The people we offer Zwave to don’t want to hear about re-wiring their houses… That’s why we decided to do one ourselves ! I’m new to this forum, but if there is interest, I’ll post our progress here.

Hi T1000,

I will be interested in your thermostat solution as I live in Québec too (Laval) and I cannot believe that there is not enough market here in the north for that… They do dimmer, switch and outlet z-wave or zig-bee compatible but no line voltage thermostat… Also the challenge will be the price, because having to buy 1 HVAC thermostat at around 200-300$ for a whole house is not bad, but with line voltage you need 1 for each room so the price must be under 100$ each (even less) to be appealing to do a whole house project. I might need as much as 10 for my house to control all baseboard heater…

@mathieuc : I hear ya ! I find it hard to believe as well, hence the decision to look into it. Above the pricing issue you mention, the certification issue is a big pain as well. Any high voltage stuff requires rigorous specs and testing and I sure hope we won’t sink our boat with that. It’s pretty hard to say who would be interested, I know that Quebec and these parts are big on baseboards, but I don’t know how big… I’ll eventually start a thread on here to probe the interest of fellow zwave users. In the meantime, we’re good, summer’s here :slight_smile:


I set up a line voltage baseboard zwave controlled house in Charlevoix Québec years ago (Vera 1 now on a Vera 2) using 18 Aube relays placed in the baseboard heaters. I used the now discontinued Intermac CA8900 thermostats (I assume the 2gig thermostats can replace them). It is used in a rental property so I can turn up before client arrive and down when they leave (or set them at ridiculously high settings/ people think by setting it at 30 the room will heat up faster…). My electrician been very familar with Aube had no issues with my configuration.



Salut Richard !
That’s a great setup, but it did require re-wiring between the wall thermostat and the Aube relay. That works great in a build/renovate context, but it’s not very efficient as a retrofit solution. The other issue, albeit a small one, is that the relay is either opened or closed. It won’t “cycle” or “pulse” your baseboard as a regular electronic thermostat would, thus overshooting the target temperature every time. It’s not huge, but it will eventually end up costing more on the long run as a bit of electricity is wasted on every cycle.
We are still working on this, even got a working prototype running, but it’s an absolute pain. There is red tape everywhere I look and the “ZWave alliance” does not look keen on helping the small guys get started. The worst red tape comes from CSA, as it should. If anyone knows of an electronic, line-voltage thermostat OEM manufacturer, we’re having the hardest time locating one. I’m about to board a plane to China and knock on doors !