ESP8266 Smart Vents Keep Tabs On Home Temps

Have you ever found that, despite having a central heating and air conditioning system, that not all the rooms in your home end up being the temperature you want them to be? Maybe the dining room gets too hot when the heater is running, or the bedroom never seems to cool off enough in the summer months. If that sounds like your house, then these motorized “smart vents” from [Tony Brobston] might be exactly what you need.

The idea here is pretty simple: an ESP8266 and a servo is built into the 3D printed vent register, which allows it to control the position of its louvers. When connected to your home automation system via MQTT, the vents allow you to control the airflow to each room individually based on whatever parameters you wish. Most likely, you’ll want to pair these vents with an array of thermometers distributed throughout the house.

While [Tony] says the design still needs some testing, he’s released smart vents in a range of sizes from 2×10 to 6×12 inches. He’s also provided excellent documentation on how to print, assemble, and program the devices. It’s clear that a lot of care and thought went into every element of this project, and we’re excited to see how it can be developed further by the new ideas and contributors that will inevitably pop up now that it’s gone public.

Want to add some automation to your HVAC, but don’t have a fancy central unit? Don’t worry, as long as your heater or air conditioner has an infrared remote, you should be able to wedge a WiFi-enabled microcontroller in into the equation.

49 thoughts on “ESP8266 Smart Vents Keep Tabs On Home Temps

  1. Living in a 3000 sq ft 300 year old house…..with two kids 50% of the time, I need this to auto shut down their room and rooms I don’t use. Lower heating in the upstairs during the day…and downstairs at night….mmmm just need round vents for upstairs!

    1. In order for this to work without potentially causing problems for your system, you need to have variable capacity equipment to account for the lower airflow when you have rooms “turned off.” A few vents isn’t a problem, but when you approach 25% closed, you need variable capacity equipment.

      1. I wonder if you could modify a smart vent to “short circuit” part of the flow back into the return plenum when open, to relieve some pressure without wasting the heating/cooling energy.

          1. Except you are dumping cooled air into right back into the evaporator which will drop it below freezing and cause icing. General recommendation is the dump that air into an unoccupied area like a stairway or foyer. That way it can mix with warmer air before it returns to the air handler.

      2. +1 This! AC or Heat pumps in particular but all non variable HVAC systems MUST allow a factory speced minimum airflow in order to prevent damage to coils, compressors, and heat exchangers. Cracking your furnace heat exchange is life threatening and the rest is very expensive. Many systems retrofitted into older homes are already working at bear minimums (one reason for uneven rooms in the first place)

      3. I’ve been thinking about doing something like this for years and every conversation I’ve ever had about it someone brought up this very issue.

        I’m sure there’s a “right” way to deal with it involving an expensive retrofit that is beyond how far most of us would take the project.

        I’m thinking a more reasonable solution is just to control the flaps from a central location and make the code smart enough to never shut more than 25% or whatever number sounds good at a time. Maybe coding the local firmware at each vent to default to the open state if it hasn’t heard from the boss in a while is a good idea too.

        If that means a little compromise, not always achieving quite as much control as was desired… so what? It’s still better than the old way, manual shutters or no shutters at all!

      4. Another approach could be to use a couple of atmosphere pressure sensors to calculate the air pressure in the system. Then use that data to adjust all of the vents a little bit so that you never put too much pressure on the system.

          1. Minimum airflow requirements across the evaporator coil during AC cycles. Minimum pressure drop requirements needed across the furnace heat exchanger

      1. That’s not unusual in Europe. My wife went to an antebellum house in the US and, confused by the way it was being treated as if it were an ancient monument suddenly realised and blurted out “Oh! My house is older than your country”.

        Unusual to have air con in an older property though as there’s not usually anywhere to run the ducts.

      2. Living even in a 600-year-old house isn’t that uncommon in much of the world. In the states, it’s common for your house to be falling over after thirty years (the length of a mortgage, imagine that) and still have green, damp pinewood in the framing.

    1. No, most smaller homes in the US that have forced air heat have a single “zone” (the entire capacity of the system) switched on and off by a centrally located thermostat. Multiple zones are usually only installed in larger homes. And multiple zone systems have always been crazy expensive.

      So if you want to shut off unused areas of the house, manual vent controls are typically the option of choice.

    2. Motorized dampers are quite expensive and not really efficient and robust.
      The dampers we have are triggered by a thermostat that simply open or close a contact: this allows a small bulb of wax to heat and extent, opening the damper. The dampers stays open as long as the power flows to hear the bulb … 3 W.h per damper. It’s not efficient at all, and more over the wax mechanism dies often, requiring time and money to replace.
      Moreover there is not a global view of the house: the HVAC starts according to a temperature sensor in the living room: so if the living room has the right temperature, you can melt in your bed, the HVAC will not give you fresh air :) In some words: it does not priority to the place were air conditioning is needed.
      That’s why I was thinking of such dampers to make my project. I am lucky enough to select an HVAC that can be managed using modbus, so now I have all the parts I will be able to start my project.
      BTW I think that I will not use PLA because I would be affraid that they would deform too fast particularly when using my HVAC to heat my house …

  2. I’ve been wanting to implement something like this for a long time. I think I want to modify this design to add controllable flaps to an existing register, for a more stealth install. I’m also wondering about the possibility of incorporating a modified PC fan and a supercap to make it self-powered.

  3. if you’re doing this on a DX cooling equipment that cannot vary the fan speed you’re going to need to make sure you install a bypass damper to maintain the airflow at the cooling coil or the cooling coil will freeze if the airflow is restricted too much. that bypass damper allows supply air to go directly to the return duct and is typicallycontrolled based on duct static pressure

  4. I attempted this and failed, so congrats. When I tried I did not have 3d printing or ESP chips. I had so many size ducts. I do see that you run external power to the vents which you need to do to power the servo and electronics. Being in Florida with a 3000 sf house it is always was a problem, especially when one room was used as an office with multiple people and computers. We finally solved that by putting in ductless units which are great and make little noise.

    1. I wonder if you could pick up enough power some other way, capacitor and solar panel, or something like that. Wouldn’t take much if the servo isn’t moving often. The nice thing is that the stakes are generally pretty low, if the battery dies you just end up with a less controlled room.

      1. Look for plenum cat6, it’s specifically designed for fire-resistance and use in conduits and vents. Spendy, but worth it. In this case you might want to choose an SBC with a NIC instead of the microcontroller+wifi, and send the data over the same cable that was powering the vent.

    2. Keen Smart Home and Flair have been making these for many years. Go to Lowe’s, Home Depot or wallmart and pick one up. I think you’ll be dissatisfied with them because all it does is turn off a room and cause back pressure into the HVAC. What you want is to turn up and down various rooms and you can’t do that without adjusting the central air. Might as well do a ductless mini split. Easy to install, adjust and super energy efficient.

      1. I have a lot of Flair vents, pucks, working with a Nest thermostat and even an additional in room ac for my studio. They have been a huge life saver and work great together at keeping only the rooms I’m in cool and running the AC less. Battery life on the vents is great with them only needing changed once every 6 months to a year+.

  5. I’ve been daydreaming about doing this for years now!
    It’s a project that my house really needs but never quite gets to the top of my pile.
    Thanks so much for the STLs. That probably will push me over the edge of actually building it.

  6. Several people already commented on this but you need 400CFM per ton of cooling for an air conditioning system to properly operate. On the heat side without proper air flow the unit will shut down on overheat. Two stories: 1) I recieved a call that the persons furnace was shutting down and they would cycle the power switch to get it running and it would shut down again. wash rinse repeat. On site I found the unit shut down on high limit. Reset the unit and watched it run a cycle. About halfway through unit shut down on high limit. I checked all the usual suspects including the filter but eveything looked good. Removed front cover from unit and restarted. When the blower turned on it was as if it was sucking all the air out of the basement. Meanwhile customer tells me that rooms upstairs don’t heat evenly. Just on a whim I asked how they solved the problem. “Well my husband put plastic over the intake in the hallway.” HAHA Show me please. They had covered the return plenum with a plastic garbage bag and NO return air was making it to the furance causing overheating. Removed the plastic let unit run 2 cycles and handed the person a 250 USD$ service call. Story no. 2) Apartment building three stories high smallest apartment heat only works ocasionally. On site I found a 3 room apartment of maybe 300-400 sqft being fed by an 180,000 input BTU furnace. That furnace would easily handle a 2000-3000 sqft house. WWWAAAAAAYYYYYYY TOO BIG!!!!! Repaired by cutting a large hole in the furnace plenum effectively heating the unheated basement of the apt. building. The building was owned by a freind who supplied me with beer for the repair. Be careful when messing with system airflow!

      1. Many gas appliances aren’t efficient. Modulating gas appliances exist and could greatly help this. My water heater and furnace both draw air from my basement and have unsealed flues. I have many co detectors. Can’t wait to get rid of gas appliances and improve room tightness.

    1. Yup. Seen it all. How about the ones trying to save money? I once had the pleasure of visiting an old widow who was having trouble with her system. She figured she’s only using the sunken living room (2400 sq ft split level 1950s era with gas heat) so she blocked all the vents in the unused rooms. I patiently tried to explain to her how her system was built to service the ENTIRE house, and how her thermal investment consisted of the ENTIRE house, and how she was actually costing herself. I then asked when the filter was replaced last.
      “Oh, my husband used to always do that.”
      “I’m sorry for your loss. When did he pass?”
      “Seven years, now”.
      Wow. The filter was so filthy, it looked like an old piece of dark grey, plush carpet with the side torn out from the frame where the fan finally sucked it in. This was going to get costlier.

      Please, please, please, learn how your system works, and don’t let your wife(partner) live her(his) whole life ignorant of the things that you take care of, that you WILL leave them stuck with, following the prevailing life expectancy statistics (Or not. Jeez, you can’t even use typical data anymore without having to rethink everything to keep it PC! )

    2. I work from home and in Oklahoma it would be nice to cool the house only in the parts we need. Because of some of the animals, doors tend to be closed.

      Right now, I’ve been told that our AC unit (Trane) is oversized and we added a return recently to help rectify it. However, its 15 or 16 years old and I’ve been told to start considering a replacement. Average electric bill has gone from $89/month to $170/month since I moved here and work from home as well combined with the summer of hot and a rate increase to boot.

      I’m considering heat pump, variable speed AC and even possibly a geothermal loop system. Pair this with these smart vents and we might have a winner? I’m thinking I might just want to have one or two of the vents set up to be a passive pressure release.

      This is part of a series of upgrades to a 1952 hour including residing with Hardy board, foam insulation in the walls, new windows, replacing the gas tank hot water heater, solar panels on the roof, an EV in the driveway, a new back deck and eventually a light kitchen remodel.

      The new federal tax rebates are mostly out of reach for us because we are above income thresholds but its time.

      Does anyone have any best thoughts and practices.

  7. Years ago I started designing exactly this, with local room temperature sensors. All the vents were going to talk to a central “flow controller” to ensure that air flow was maintained when the system is on, and only on when really necessary etc…
    Unfortunately I discovered it was patented only a few years ago. The company that has the patent has products out in the market.
    So… keep an eye out for the cease and desist !!!

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