ᐅ Central ventilation system – is humidity recovery necessary?
Created on: 30 Dec 2019 16:17
L
ludwig88sta
Hello everyone,
for our planned single-family house with 2 floors and a basement, we have decided on a central ventilation system for all rooms with heat recovery within the thermal envelope. The brand and model are not yet determined.
I have read here on the forum a few times about an additional moisture recovery feature (MRF?), since otherwise the indoor air tends to become too dry (of course, the ventilation system also removes the moisture that naturally occurs in the room, which usually makes the air feel comfortable). I wanted to ask if anyone can confirm these issues and whether this is more common in timber frame houses or also occurs in brick houses?
Did you install additional moisture recovery in your ventilation system? How much extra cost does it involve? I assume there are also additional maintenance costs because it involves another motor and related components.
Best regards
ludwig88sta
for our planned single-family house with 2 floors and a basement, we have decided on a central ventilation system for all rooms with heat recovery within the thermal envelope. The brand and model are not yet determined.
I have read here on the forum a few times about an additional moisture recovery feature (MRF?), since otherwise the indoor air tends to become too dry (of course, the ventilation system also removes the moisture that naturally occurs in the room, which usually makes the air feel comfortable). I wanted to ask if anyone can confirm these issues and whether this is more common in timber frame houses or also occurs in brick houses?
Did you install additional moisture recovery in your ventilation system? How much extra cost does it involve? I assume there are also additional maintenance costs because it involves another motor and related components.
Best regards
ludwig88sta
L
ludwig88sta8 Jan 2020 16:52What I found during my online research on this topic:
Source: all from enbausa.de
Maybe this is interesting for some readers
He therefore regrets that moisture recovery is not yet widely used in practice, even though the technology has been available for some time. According to Müller, there are three technological approaches to moisture recovery: rotary heat exchangers recover not only heat but also moisture. Another option is ventilation units with heat pumps, and the third type are devices with an enthalpy heat exchanger.
Schnieders recommends ventilation units with moisture recovery only for large residential buildings with low occupancy. They might also make sense when the supply air is heated. Basically, one must take a close look: how many people occupy the building, and how much moisture is generated. "Often it turns out that moisture recovery is not necessary. Usually, it is sufficient to slightly reduce the air volume flow to keep the indoor humidity within an appropriate range," says the passive house expert.
Without proper maintenance and care, ventilation systems can become breeding grounds for germs instead of sources of fresh air. Regular replacement of good-quality filters is especially important.
...
It is often forgotten that in certain systems, not only the supply air can cause health issues. This applies, for example, to moisture-recirculating systems. These transfer moisture from the exhaust air to the supply air to prevent the indoor air from becoming too dry in winter. However, this can also transfer germs from one air stream to the other — from exhaust air to supply air. Therefore, filters should also clean the exhaust air. Schaaf even recommends using higher-grade filters for this purpose. "Most manufacturers still overlook this point," Schaaf notes.
The separation of supply and exhaust air is also important for hygiene in heat recovery. Experts like Professor Ulrich Pfeiffenberger from the engineering firm of the same name see the advantages of closed-loop systems (KVS) not only in their status as the most efficient solutions for heat recovery. Since supply and exhaust airflows are separated, no germs, pollutants, or odors are transferred.
Source: all from enbausa.de
Maybe this is interesting for some readers
L
ludwig88sta8 Jan 2020 17:04Oh, so the idea is that your own smell/odor from inside the house is distributed throughout the house?
What generally worries me about controlled mechanical ventilation is that odors/smells from outside are spread inside the house (smoke from fires, accidents, or even just the typical farm smell in rural areas). There are supposed to be activated carbon filters for this, but they are said to be almost unaffordable. For others, the F7 filter has already helped reduce odors coming from outside. Are there any experiences with this here?
What generally worries me about controlled mechanical ventilation is that odors/smells from outside are spread inside the house (smoke from fires, accidents, or even just the typical farm smell in rural areas). There are supposed to be activated carbon filters for this, but they are said to be almost unaffordable. For others, the F7 filter has already helped reduce odors coming from outside. Are there any experiences with this here?
tomtom79 schrieb:
In the meantime, I have also read something about enthalpy heat exchangers. Some people report problems with odor nuisance. Can anyone confirm this? Especially when cooking strongly, the smell spreads throughout the entire house, even into rooms with closed doors.No, that is technically not possible.ludwig88sta schrieb:
Are there any experiences with this here?If it smells outside, it will also smell indoors even with normal ventilation.