Keen vs Flair Smart Vents

I am looking to commit to a smart vent system, as I have a house that is pretty unbalanced. It’s not simply about airflow, though that’s definitely part of it, but is also as much about being rooms with more going on in them as far as heat generating sources. Add to this that it’s a 3 story house with multiple open stairwells between floors and well smart vents seem like they would help a lot actually.

I have certain rooms that are always warmer, regardless of heat or AC and there are certainly times of the year when I go from AC to heat and back again many times within a couple month span. So even just being able to statically adjust vents base on mode would be a huge benefit. I have 2 Central AC units and 2 furnaces BTW, and an Ecobee 4 controlling each.

I really thought I was just going to go with the Flairs when I was researching them, they seemed to have a larger percentage of open area, they’re cheaper, had the ability to hardwire them for power, and were metal and more easily printable. I also thought the puck was kinda cool as I have a couple guest bedrooms and to allow guests some control over “their” room was something useful. So wrote Flair with a couple questions, the most important, for me anyway, was I was looking at the Flair DH on here and saw that it was limited to either fully open, half open or fully closed, which seemed really limiting. So I asked if that was a hardware limitation or software, the answer I got back was that half open is no longer supported because it drained the battery too fast.

Hmmm, I guess I don’t really see how a vent that is only either fully open or fully closed can really be all that useful in regulating a homes HVAC system without really screwing with the static pressure. I almost think this almost eliminates Flair outright, unless I don’t really understand how the algorithms work. I can see where during a blower cycle you could vary the airflow somewhat and even close off vents based on some sort of duty cycle so that one zone or more zones are heated or cooled for the full duration at full open while you do some varying restriction on the others, but I guess I don’t see how that can bee really effective if the options are essentially on or off.

So then there is Keen, it’s ZigBee, and I have a strong ZigBee mesh in my house, so that’s good. Apparently it can be directly paired with a SmartThings hub, and with the right DH can use “other” sensors, also a plus, and can be varied by percentage. All good. The down side is Keen seems to use far more of the insert surface area for mechanism, and a poly-carbonate grill which to me looks like it’d be far more restrictive in overall airflow. Also they’re quite a bit more expensive, like 30% more and even if I didn’t have to buy any of the Pucks that I’d have to buy with the Flair system it’s still hundreds more for a fairly large house. I would need 15 vents to do this house, plus a few more at some point. Some of these are oversize which only complicates things since both Flair and Keen only make 4 sizes, though Keen does sell adapters, they are basically just duct reducer plates, reducing a larger opening to a smaller opening and then further reducing that with the mechanism and a grate with what looks like not much more than about 50-60% open area. Poly-Carb is also not so paint friendly.

But I guess the real question is how well do they work, and in particular how well do they work somewhere where I can have some control over them (IE: SmartThings) as I would also like to supplement climate control with ceiling fan control. Also has anyone hacked the Keen vents with maybe battery eliminators to hardwire them in? Since they use 4 AA batteries it seems like you might be able to power them via an adapted USB perhaps. Am I reading too much into the Flairs fully open, fully closed limitation? Are the Keens as airflow restricted as they appear? Anyway not a lot of comparisons between the 2, just a lot of posts in a lot of places complaining about delivery times, though both seem to be shipping at this point.

For a comparison between the 2 smart vents (Flair vs. Keen), refer to

My zoning smartapps are the most advanced solutions to control smart vents under SmartThings.

Refer to this thread for more details and look & feel:


Right, actually it’s your thread I referenced when I wrote Flair, and and as per their reply they say they no longer support 50% open, only fully closed and fully open. this just seems to me to seriously compromise what you could effectively do with them. I suppose, since you seem to be the one has wrote the DHs for these, I am kind of curious if that is indeed the case, how much do you rely on that 50% setting in your zoning? So the problem I have is that the hottest and coldest rooms in the house are both on the 2nd floor opposite ends of the house. The hotter it gets the greater the difference, the hottest room also has an open stairwell to the first floor which only makes it worse. Oh and although there is significantly more duct area going to that hot room, the length of that duct work is 3 times (at least) compared to the coldest room. The rooms in between (they are on opposite ends of the house are closer in temperature to the colder room than the hotter one and there is a total of 9 ducts associated with this AC/Furnace, 3 of which are in the hottest room. Also the temperature can vary quite a bit, and although you can effectively cool that hot room it is at the expense of over-cooling the cold room. manually closing ducts most of the way in the colder areas helps, quite a bit actually, which is why I feel this is a good solution for me, however that balance changes very frequently by time of day, outside temperature, dry or raining, etc. It really needs an automated solution.

I can see where balancing, under worst case circumstances, could work effectively. Vent openings with a varied percent opened base line depending on some environmental conditions both within the house and outside of it. But I guess I don’t see how you could effectively pull off meaningful zoning, while still maintaining reasonable levels of static pressure, when the vent is essentially an on-off device and the rule seems to be to not close more than a third of your vent area at any one time. This just seems like you’d have to completely subvert any smarts your smart thermostat has and be opening and closing some combination of vents almost constantly during blower cycles, and even then as in my case, still probably be over cooling those cooler rooms. In my case, I’d probably guess, on the hottest days, you’d probably need to send about half the capacity to a third of the vent count for each blower cycle while dividing among the other 2/3rds more reasonably. While this doesn’t sound like it’d be all that complicated if you are starting with a semi-restricted airflow baseline to the cooler areas, I guess I don’t see how you would do that purely on essentially time slicing the blower cycle, which is the only option an on/off vent would give you, and you would probably have to open and close 2/3rds of the vents every single cycle at least once to do that.

Hmm, really makes me wonder why Flair would say that the 50% setting was draining the battery too fast, seems like taking away the mid point would mean that all operations are a full servo cycle, wouldn’t that be worse?

Hi, to my knowledge, the flair vents can still be set at 50%.

It may be a recent change, and this could be limited to the new batch of Flair vents (HW), but mine ( I have the flair vent for more than 2 years now) can still be set at 50%…

I will double check tonight, but I would be suprised that the APIs have been changed to limit the flair vents’ level. This could be a change within the Flair app only (not for the APIs).


Yes, you’re right. Flair has changed the behavior of the vents and they can only be open at 100% or close at 0%…No more intermediary states anymore… I haven’t seen any updates in their forum… I must say that their communication is not outstanding…

Are they still stuck that way? There is no fix?
And do flair vents show as fan/vents in the new smartthings app with your dth?

Yes, that’s the new behavior now, and nothing can be done about it . And, yes, they do appear as switches with dimming capability in the new Samsung Connect app.

Do you have a screenshot? I’m debating these vs. Keen

See my previous post:

Do the keen vents allow intermediary states or are they also full open or full close only?

Hi, yes you can set them at different levels, not only 0 and 100%


I’m very undecided about which one to choose and would like to take the best advantage possible when using your app. Hope you can answer these questions.

  1. Do the Keen vents need the Smart Bridge and/or Temp Sensors when using Ecobee sensors and SmartThings hub?
  2. If any of the two companies were to go out of business … Would it be correct to assume Flair vents would stop working and Keen would still function since connection it’s handled locally?
  3. Which of the two have a better build and in your opinion does the current build affects performance?
  4. Have you seen any impact in your HVAC system when using these vents ( breaking, pressure issue, performance issues over time, etc )?
  5. In your opinion does the capability of doing multiple percentages open/close affects the performance of your application for better zoning/energy savings results?

I don’t expect you to answer this one but … If you were to choose one at this time, which one would it be and why? ( Price not been an issue )

I really appreciate in advance any assistance you can provide about the questions above.


Here are my answers

  • 1.No, with my zoning smartapps, you can use any ST connected temp/motion/contact sensors to adjust the smart vents (including the ecobee’s proprietary remote sensors and Keen temp sensors when connected to SmartThings). And, you don’t need the Keen Hub, only the ST hub.
  1. Yes.

  2. Both smart vents have a good sturdy design. Some of my contributors prefer the Flair vents because their flat design doesn’t protude from the floor after their installation.

  3. My HVAC is 20 years old, and I haven’t seen any impact on its blower or any other component for the last 5 years. Please note that my zoning smartapps have many built-in safeguards to avoid putting too much pressure on your HVAC. Refer to the ST community wiki for details.

  4. It will not affect the zoning smartapps per se, but this means that the zoning smartapps cannot allow proportional control of the smart vents…

Each smart vent has its pros & cons. The best design is probably the Keen Home vents overall; however, the Keen Home vents are prone to some disconnects depending on all your signals at your home (strong zigbee mesh vs. wifi signals and potential interference, etc.).


Are there any in line damper options? I have manual dampers on all of my take offs (6”, 7” and 8” round flex).

Looking to add some smarts in the attic and in the crawl space. Here in NC, the crawl space is mostly comfortable but the attack gets HOT in the summer.

Hi @rontalley, no commercial solution as this probably entails cutting through walls & ceilings to install them contrary to smart vents.

Few people have tried to DYI…


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Thank you sir for the feedback. I appreciate the time you took to reply to my questions.