KfW 55 - Ventilation system yes/no? - Experiences

I believe I can help you very well with that. My wife, like your fiancée, can hear a flea coughing. I also had great concerns because of that. We have already tried all the variants: no ventilation, decentralized ventilation, and now centralized ventilation.

First of all: definitely go for the centralized system. Both other alternatives are not good. Decentralized is the worst and extremely noisy, no matter how quiet these things are advertised to be!

We have a Zehnder Q350 and it is very quiet. With this system, you have the option to set it to Away mode at night; turning it off is not possible and definitely should not be done (otherwise the system gets dirty!). In Away mode, it only runs at 80 m³, and you definitely won't hear anything. The normal setting, Level 1, is 160 m³ and can only be heard by people like our wives and only at night. But it doesn't bother mine because it is very quiet. From Level 2, it becomes clearly noticeable, 230 m³. Level 3 is then unbearable, especially at night. But you actually never use it at that level.

So in summary, I can only recommend this system and tell you that you won't have any problems if you run the system on Away mode at night with a timer (Zehnder app schedule). The ventilation performance is still sufficient!

I believe I can help you very well with this. My wife is like your fiancée, she hears every flea cough. I therefore also had big concerns. We have already tried all variants, no ventilation, decentralized ventilation, and now centralized ventilation.

First of all: Definitely go for the centralized system. Both other alternatives are not good. Decentralized is the worst of all and extremely loud, no matter how quiet these things are advertised!

We have a Zehnder Q350 and it is very quiet. With this system, you have the option to set it to Away mode at night; turning it off is not possible and should definitely not be done (then the system gets dirty!). In Away mode, it only runs at 80 m³ and you definitely hear nothing anymore. The normal setting, level 1, is 160 m³ and can only be heard by people like our wives and only at night. But it doesn’t bother mine because it is very quiet. From level 2 on, it becomes noticeably louder, 230 m³. Level 3 is then unacceptable, especially at night. But you hardly ever have that on.

So in summary, I can only recommend this system and tell you that you won’t have a problem if you run the system at night with a timer (Zehnder app time program) in Away mode. The ventilation performance is still sufficient!

Thank you very much for the quick feedback!

That definitely gives courage ;)

The general contractor, who is currently our favorite, uses a centralized ventilation system from the company Wolf. I will ask there whether there is a timer function.

Thanks and have a nice Sunday

Or simply dimension the pipe network + plate valves (in number or size) so that you do not exceed about 3m³ air velocity at the highest level, then it is also quiet. Also consider sound attenuators, because the pipe network tends to transmit noises through the house (e.g. during bed sports ;) ).

Many thanks for the quick feedback!

That definitely gives courage ;)

The general contractor, who is currently our favorite, uses a central ventilation system from the company Wolf. I will inquire here whether there is a timer function.

Thanks and have a nice Sunday

I haven’t followed this thread, but a Wolf!

If someone here tells me they hear fleas coughing at night, then they will also hear the system.
Of course it has a timer. And since I know that one should never change a running system, I don’t touch the function either, as it doesn’t bother us and also fits well. I have been at the heating system two or three times and suddenly you stand at the dial (what was that for again?)... the heating actually doesn’t run the next day.
But regarding the controlled residential ventilation: you hear drafts, you feel drafts. If you are sensitive.
I have certainly written once that you don’t hear it. That obviously also applies – to those who can easily block out background noises.
I must mention that I am definitely in favor of controlled residential ventilation.

We have one from Wolf. The display is installed in an inconvenient place. It’s just a general contractor house, where you don’t have influence on everything. The control is sufficient for spontaneous 20-minute full ventilation or full power or reduction. At night, early morning, at 5 p.m. and in the evening at 10 p.m. it goes full throttle. You can hear the humming then. And otherwise? I feel a draft on the sofa. Otherwise all good :)
As already said: the open housekeeping room door with the heating noises bothers me more, a warped floor, or something like that. And I am noise sensitive, often turn off the radio during the day. The ventilation is quite pleasant with its noises. It doesn’t impose itself, I am louder when I write on a sheet of paper or pound on the keys. My timer for the Christmas lights, on the other hand, is extremely annoying.
But I cannot say: you hear nothing!

KfW55 without a ventilation system is not possible anyway. The disadvantages of a central ventilation system remain compared to decentralized systems. (Hygiene costs such as energy consumption.) The noise level in good systems is in the range of a PC or notebook fan.

KfW55 without a ventilation system is not possible anyway. The disadvantages of a central ventilation system remain compared to decentralized systems. (Hygiene costs such as energy consumption.) The noise level in good systems is in the range of a PC or notebook fan.

Certainly, KfW55 works without controlled residential ventilation without any problems. A central system has no disadvantages compared to a decentralized system. What are you writing there? What hygiene costs? The decentralized system is more expensive to operate because more filters are needed and the heat exchanger is not as efficient.