Wireless Radiant Infloor Control

I have a unique set of skills that make HVAC a lot of fun for me. I have been a programmer my entire life but I also work in the HVAC industry giving me a unique perspective on all the ‘smart things’ hitting the market.

Taking my knowledge of HVAC and my skills as a programmer I recently began programming my own MCU’s to control my radiant in floor system.

Over the next month I intend to finalize my radiant in floor ‘smart control’ and I will be tracking my progress here on my blog. I should be clear that this is a hobby but when completed it will be as polished as I can make it and hopefully somebody likes the idea so much they take it over and make it a reality for more than just my in floor system.

Design Concepts;

  • Bring the Smart Thermostat trend to Radiant: The company I work for sells one of the premier brands of radiant in floor systems but controls in general for hydronic systems are lackluster at best. Why is there no wireless options? Why cant I control it from my smart phone? My control is both wireless and internet enabled
  • It must have a small footprint. As of right  now my wireless radiant control is the size of a deck of playing cards or slightly larger than my business card.
  • It must be standalone. I feel that a radiant control that requires a computer is a tragedy. My system does not require a computer it is completely stand alone and can be installed anywhere in a building.  Every 3 seconds it reports data to a cloud server which you can access from your smart phone or computer but no computer is needed to power or run the system.
  • It must be mobile. Currently I am powering mine off of a battery and given its tiny size it is VERY portable. Batteries have serious limitations but I have spent a lot of time and research and I should be able to power mine for 2 years based off the power consumption of the system as it stands ( about 3480 milli volts )
  • It must have WiFi access / Local Backup: My system has WiFi access and all the data that it collects is stored securely on the internet. My system also has an onboard SD card which I will in the future use as a local backup for all the data that is currently being stored in the cloud.
  • It Must be Affordable: If you are going to build a smart control for radiant systems it does nobody any good if you can not afford it. My goal is to have a radiant smart control system that can be built by Engineers or über nerds for under $300.

How the System Currently Works

If you are familiar with a Taco ZVC control box my system works on a very similar premise. The system currently has 4 inputs ( temperature readings ) for four separate zones and those in turn energize one of 4 relays which will in turn energize the pumps ( or actuators ) for each zone. The relays for those wondering are rated up to 10 amps at 250volts which is more than competent for my project or yours.

The device is connected to the cloud and I am using JavaScript to render the results into a browser so that I can monitor what the system is doing.  I can see not only the temperatures in each zone but I am also monitoring the power to my device.

I have set up automated email alerts that notify me under the following conditions;

  • If the system looses power or the battery backup is going to die I will get an email
  • If the zones are not heating correctly or loosing temperature drastically I get an email
  • If the zone has lost communication with the server I get an email.
I took this screenshot of my online reporting about an hour ago. It shows an entire days operation for one zone and the systems power usage in Milli Volts
I took this screenshot of my online reporting about an hour ago. It shows an entire days operation for one zone and the systems power usage in Milli Volts

On My Roadmap of ‘Things to do’

I have put a lot of time into my Radiant floor Smart Control and I have already managed to program in some very interesting ‘gadgets’ have no real world value as well as some cool features I think make Radiant in floor system operation more innovative. A few items on the very near roadmap are;

  • Enable Alerts When System Goes Offline: I need to fine tune how I am going to do this portion but when my system looses internet access or does not report any data in a given period it will send an email so you know the system is offline.
  • PID Control: I am going to add a proper PID control to my temperature sensors so that it will efficiently get to the set point. I have the code just need the time to implement it.
  • Max / Min Floor Temperature: I will be adding in min/max floor temperature settings to the controller to make sure that my floor is always comfortable but that it is also not ever going to overheat the floor which can cause damage and discomfort. Nobody likes a hot floor.
  • Launch a Website for the Project: I intend to launch a Site for the online portion very soon so that anyone can see the data that is being collected.
  • Make the System even Smaller: I have already found a smaller MCU which I can hopefully program and achieve what I have done already with an even smaller footprint. The new MCU is just about the size of a small pack of matches which is exciting to me. It also costs half as much as the prototype I built.

That is all I have for now but  I will continue to update and add new blogs on this topic as I make progress.

Radiant Infloor Smart Control up against a blank business card just to show size / scale of the project right now.
Radiant Infloor Smart Control up against a blank business card just to show size / scale of the project right now.


  1. M,
    I’m really interested in your controller project. I would like to discuss your project in more detail if you wouldn’t mind.

    1. Hey Brian ask away. I am long overdue to post an update ( maybe tonight ). The hardware has been running in my house for about 6months now and the mobile app / front end code I polished off this weekend. Up until now it was not user friendly, now it is 🙂

      As of right now I have 1 complete, and 5 to build so I can do more testing in other places.

      Let me know what specific questions you have and I will answer them.

  2. This is great. I have been trying to build something similar. I am using a Nest as the primary control for each floor. Then I have actuators (12) on my manifold that are on: upstairs has 7 actuators, down has 5. I was originally going to embed sensors in the thinset for the tile, but I hear that the radiant feature in the Nest is pretty good. Anyway, I am going to use a sensor in each room for temperature, and a Remotec dry contact at the valve. Setup some logic in SmartThings software to break that contact if the room is warmer than the setpoint. I would still like to see how you are doing your project.

    1. I 100% disagree with using the air temperature to control the system. This article will help explain why.

      I like your idea on using smart things but in my own situation I want a control that follows the principal of KISS ( keep it simple stupid ). The control I have setup monitors room temp, floor temp, zones on or off and also turns the system on and off and monitors run time. Total package size is about a deck of cards ( I will at some point post a new photo ).

      1. Hi, I am also interested in your project. My system is running with in-slab hydronic heating on first floor and radiator panels on second floor. I live in Australia, Canberra, the temperature occasionally goes down to -5 during winter. I have this system for about year and a half. I am looking for a way to monitor and cut my heating bill. It was over 1200$ for a quarter. There might be something I can do to cut the cost. I have been looking at ecobee and come across your web site. So I am interested in the controller if it’s something DIY.

      2. Right off the bat how are you controlling your existing radiant heating system? Air sensing thermostat? What insulation do you have below the slab of your hydronic system? Maybe I can help you improve what you have. Most of the radiant systems I see are poorly installed.

        My control is a DIY that may turn into something more.

      3. My house is 2 story. Downstairs living area around 166 sqm 5 zones with in-slab hydronic heating at 40 degree Celsius. Slab Insulation waffle pod and edge insulation with XPS form. Upstairs around 93.9 sqm, wall-mounted 3 radiator panels and 2 towel racks heating at 70 degree Celsius. Boiler is internal condensing Sime Green Murelle Planet. Thermostat is air sensing only, Honeywell FocusPro 6000 (I wish I read your blog about Rehau dual sensing thermostat before installing the current one)

      4. Is the radiant infloor and the radiators on the same levle? Because if so I will share a really cool way to control it and keep nice and comfortable 🙂

        When you installed the radiant in the slab did you install a floor sensor?

      5. no, they are not the same floor. The radiators are all up-stairs.
        I didn’t know about the floor sensor before until I read your blog 😦 Not sure if there is a way to retrofit it.
        Also I found something about Honeywell evohome last week but the cost of the units are way too expensive. The TwinCo 3000 is installed to distribute water to the downstairs (slab) and upstairs (radiators) at different temperatures.

  3. I’ve got a distribution manifold on the 2nd floor, and we mismanaged the wiring aspect awhile back. now drywall and priming is done, so… i’d love to figure out a system OTHER than Honeywell that will get me 2-3 wifi thermostats, connected a to a few actuators on the manifold to control water flow.

    Does that make any sense, and is this what your system can do? Is it available yet?


    1. Brian.

      Sorry for the late response. I am not releasing my product anytime soon its a blast tinkering with and I just keep making way to many changes.

      For the manifold on the second floor how many wires do you have? I have a solution for you that is completely wireless I just need more specifics on what you have.

      You can put a thermostat upstairs, wired to a WIRELESS zone box that will communicate with the basement. The company I work for sells them and they are really cool.

      Hit me with more specifics I can let you know how to get one. ( an email would help also )

  4. I am currently using a Neptunes Systems Apex controller to control a radiant floor in an alligator house at our zoo along with other things. The Apex system is a pretty mature system but the company is single minded and does not realize that there system could control radiant floor systems. You can add sensors and control relays built in to a box with outlets. I wired a plug/cord to the circulator. There temp probes seem accurate in water and ambient air. With a little tweaking this system could be mainstreamed for hydronic control. It is a bit costly at around $400 bucks. But has an app and a web server as well as a web page account at the company. One good thing the app reads the thermostat not data from the web page.

  5. Hi I have been searching for something like this for months. I have a radiant system installed in my home with 9 loops each Loop goes to a different room. I currently only have one thermostat controlling all the loops. I’m trying to find a solution perhaps using thermal actuators to put a wireless thermostat control in each room to control each of the loops by controlling the flow on the manifold. I know using Honeywell I can do all that I need to do for about $12,000 but there’s no way I can do that. Your system sounds like the perfect solution for me I don’t know if you can point me in the right direction. But I’m a little desperate as the main feed line to the manifold was installed in the wrong size so not all of the loops get sufficient water all have heat at the same time and the house is complete and sealed so would be some serious demo to fix it. Any help or advice would be really appreciated.

    1. Ohavia, where are you located in the world? ( Roughly not exact address ). Key to answering your question is knowing where you are. There are a few new products on the market that could help.

      1. Find a contractor with experience in hydronics and tell them to get you pricing details on the new TEKMAR 561 and the HBX Wifi thermostats. I am based in Toronto and have used both with my customers. These products are 100% available in NY

      2. How does one hook these up to a manifold with 9 zones? And i really appreciate your time. Thank you for any guadance. I had a few plumbers in. they all wanted to use a honeywell system for 15,000

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