Centralized and decentralized ventilation, brief experience report

Hello,

after passively reading many posts for 1 year, we moved into a new building a year ago, a subjective report on the question that occupied me for a long time. We live in a flat-roof house, solid construction. Kfw 70, blower door test just at the passive house limit. Inaccuracy about the masonry heater with fresh air supply.

After much consideration, I wanted a ventilation system. Ultimately, we purchased a Comfoair 350 with geothermal heat exchanger for our living area, and due to acoustic decoupling for the granny flat, an inverter twin system (about 25m2). The costs were higher than the average posted here.

My purely subjective assessment after 1 year: central: significantly quieter, more like a flow noise. You can feel the air current well with your hand at the outlet, but it does not draft. Central control option is comfortable. Geothermal heat exchanger is nice to have, I have pushed the temperature limits. On humid midsummer days it is not so "stuffy", air is drier. I have no sufficient experience in winter yet. The air in the first winter was already dry (25-35%), I will buy the moisture-retaining membrane this winter. No malfunctions so far. Maintenance: cone filter at the outlet needs to be replaced every 3 months (no original products), so rather inexpensive. I have both coarse and fine filters, coarse filter is dusted every 3 months, changed every 6 months. F7 once a year. Original products have been expensive so far. I have ordered cheaper ones (German company, 5 letters, starts with S.), I will try these.

decentralized: despite internal soundproofing, unpleasant fan noise for me, hardly any air current felt, coarse filter can be washed out, so no maintenance costs so far. "Swiss cheese" problem, as acoustic opening to the outside.

My conclusion for the house: central ventilation makes sense, geothermal heat exchanger nice to have. High comfort gain (no mosquitoes for example). Decentralized rather for small residential units.

Many thanks for the many helpful contributions I read.

hexentrics

We have had a central ventilation system from Weißhaupt for 3 years and are satisfied with it. We always run the ventilation at the lowest level because we also occasionally open the windows. In summer, it has the advantage that you don't have to open the windows and thus no flies or manure odor come into the house. In winter, you don't waste the good warm air outside. I claim that it would also work without ventilation... but this way it is easier and more comfortable... so also a bit of luxury.

Since when do ventilation systems filter out odors?

We always run the ventilation at the lowest setting since we also occasionally open the windows. In summer, the advantage is that you don't have to open the windows, so no flies or manure smell come into the house.

And there are also fly screens against flies.

Against the heat, it might even be counterproductive to run the ventilation at the lowest level all day. In my opinion, no air exchange during the day and as much as possible in the evening/morning/night. However, open windows with a draft are simply more effective and quieter than ventilation at full power.

Since when do ventilation systems filter out odors?

If needed, activated carbon filters can be used

And there are also fly screens against flies.

But dust and pollen still come through the fly screen, which the F7 filter would otherwise filter out...

Against the heat, it might even be counterproductive to run the ventilation on the lowest setting all day.
In my opinion, no air exchange during the day and as much as possible in the evening/morning/night. However, open windows with cross-ventilation are simply more effective and quieter than running the ventilation at full power.

But I still have to ventilate my house during the day, and there is a bypass for heat recovery in the device (at least there should be).
This also provides cooling at night without the device running at the highest setting. The ground-source heat exchanger supports this additionally by removing moisture from the outside air and (slightly) cooling it. The air is thus significantly more pleasant than the humid outside air that comes in through the window.