I have these valves ( Ventilatieventielen Rozetten Staal voor Afzuiging - Ventilatieshop.com ) for my ventilation system. The ventilation system makes an annoying noise, even at the lowest setting. I want to be able to close the valve in the living room through HA. But I can not find any that can be close remotely.
Anyone have any tips?
Hello!
I have the same problem but have already found some suboptimal solutions I would like to share (and hope that someone will get inspired and find something even better).
Living in Hungary, in a flat build in the '70s, I have very similar air extractor disc valves mounted in my kitchen and bathroom, particularly this [1] model. For those unfamiliar with this kind of ventilation system: a big extract ventilator is mounted on the top of the building, which draws the air from all of the flats below, using a long vertical pipe having openings in everyone’s bathroom/kitchen. Given the 50-150Pa pressure difference, the valves are noisy, and it is hard to regulate the airflow (it takes quite a time to screw it open after taking a shower, and again quite a time to close it properly after the steam has got out), furthermore in their fully open state they generate a noticeable airflow even in the rooms (from where the fresh air is drawn in). So I would like to replace them with something which is 1) quick to open/close and 2) also has good acoustic properties.
Now, in this and this topic they suggest Keen and Flair smart vent covers/grills for the purpose, however, these come with two flaws: first, as I see they are available in rectangular shape only, which is not impossible to mount over the circular duct/hole in the wall, but it would need some tweaking (like insulation on the perimeters, to keep air from going through). Second, I could not find any proper documentation (like airflow in m3/h in their open/close state given the pressure difference, acoustic properties, etc.). Moreover, I already have a bad experience with these kinds of closable vent grills/shuttles: mounting something like this [2] over the duct only made things worst. As it turned out, they (and most closable vent grills) were not designed to effectively stop airflow against a continuously operating extract ventilator (like in my case), but solely to limit the amount of air naturally going through the duct (with the ventilator turned off, which in this case is impossible).
Now, to address the second problem, I tried to look for devices designed specifically for operating along high-pressure differences (ie. continuously operating common extraction fan) and found two possible candidates: Aereco TDA and BXC series [3], or Helios AE series [4]. There are slightly different models available on the Hungarian and German pages, but both companies feature variants that allow only very low ventilation in their closed state (Aereco appr. 5 m3/h at 100Pa, Helios model-dependent), and have a push-button / motion-sensor / IR remote activation for the so-called shock ventilation mode (ie. open state) in which they allow 25-50-60-80-130 m3/h (model and setting-dependent) for quickly drawing out the moist air*. However, they are quite expensive (starting at approximately 75 Euro), and on top of it, you must make it smart on your own (not a big deal with eg. an ESP32, ESPHome, and a relay or IR led, but far from plug-and-play 
).
So here I am in my research, and I would be glad if someone could offer me some already smart alternative (even if it is more expensive), or some proven-to-work cheaper DIY version.
Thank you all in advance and have a nice day! 
*for those inexperienced in ventilation systems (like me), I found that the typical airflow rates needed are around 30m3/h/person in the room and that 5m3/h should be enough if the bathroom is unused. Given that this is a bathroom, I also found that the open-valve flow should be higher (high moisture environment). However, if I am wrong, I would be glad if someone with more experience could correct me.
Edit: upon trying to post (and follow the guidelines to reference my previous works in trying to find a solution), I got the error that as a new user I am limited to two links per post. So here are my references:
[1] https://www.ventilatieshop.com/ventilatieroosters-ventielen/ventilatieventielen/ventielen-rozetten-staal-afzuiging/rooster-ventiel-afzuiging-125mm-wit-staal-met-veer-voor-spirobuis/
[2] https://www.nemesventilatorhaz.hu/de/spd/T36/Awenta-T88-kerek-zarhato-fali-szellozoracs-allitha
[3] https://www.aereco.hu/termekek/legelvezetok/
[4] https://www.heliosventilatoren.de/en/products/mechanical-accessories/air-inlets-and-air-outlets
that is quite the research hope someone has some pointers for us for a good solution
If you are still looking for something, take a look at this:
Open AIR Valve from TheFlamingo on Tindie
They are intended to work inside a Duco Box but he also has external versions that can be mounted in like 125mm Spiro tubing or flex tubing.