Hello everyone,
I would like to get your opinions and assessments on the following topic. We are planning a central controlled residential ventilation system with humidity recovery. I don’t want to discuss the purpose or necessity of this system here, as it might turn into a heated debate.
We are considering a rotary heat exchanger because we like the adjustable humidity recovery and especially the fact that no condensate drain is needed. An Austrian website about comfort ventilation explains different types of rotors and mentions rotors without coating and with coating for humidity recovery (enthalpy or sorption). A query with our preferred manufacturer revealed that “our” rotor is made only from aluminum and has no coating.
Now, on the same site, in a brochure on this topic, there is a passage that says:
The type of surface texture of rotors determines their ability to transfer moisture. There are basically condensation rotors, enthalpy rotors, and sorption rotors, whereby condensation rotors can only transfer moisture when condensation occurs, which is considered to be hygienically questionable. Condensation rotors generally do not allow effective control of indoor air humidity.
I therefore assume that our rotor is a condensation rotor. Does anyone have an idea or understanding of what “which is considered hygienically questionable” might mean or imply here?
Interestingly, I cannot find any other sources linking hygienic concerns with rotor type. Would you ignore this note or take it seriously when selecting the heat exchanger?
Background:
The manufacturer offers the most suitable design for our floor plan regarding the duct system – also with ceiling outlets in the basement, ground floor, and upper floor, which we definitely prefer over floor or wall outlets. Almost every other supplier (of plate heat exchangers) would at least use floor outlets on the upper floor (bedrooms, children’s rooms, bathroom...), so here is the question: what would you do or recommend? Ignore the note “considered not entirely hygienically acceptable” or bite the bullet and go with floor outlets?
Thank you very much and best regards!
I would like to get your opinions and assessments on the following topic. We are planning a central controlled residential ventilation system with humidity recovery. I don’t want to discuss the purpose or necessity of this system here, as it might turn into a heated debate.
We are considering a rotary heat exchanger because we like the adjustable humidity recovery and especially the fact that no condensate drain is needed. An Austrian website about comfort ventilation explains different types of rotors and mentions rotors without coating and with coating for humidity recovery (enthalpy or sorption). A query with our preferred manufacturer revealed that “our” rotor is made only from aluminum and has no coating.
Now, on the same site, in a brochure on this topic, there is a passage that says:
The type of surface texture of rotors determines their ability to transfer moisture. There are basically condensation rotors, enthalpy rotors, and sorption rotors, whereby condensation rotors can only transfer moisture when condensation occurs, which is considered to be hygienically questionable. Condensation rotors generally do not allow effective control of indoor air humidity.
I therefore assume that our rotor is a condensation rotor. Does anyone have an idea or understanding of what “which is considered hygienically questionable” might mean or imply here?
Interestingly, I cannot find any other sources linking hygienic concerns with rotor type. Would you ignore this note or take it seriously when selecting the heat exchanger?
Background:
The manufacturer offers the most suitable design for our floor plan regarding the duct system – also with ceiling outlets in the basement, ground floor, and upper floor, which we definitely prefer over floor or wall outlets. Almost every other supplier (of plate heat exchangers) would at least use floor outlets on the upper floor (bedrooms, children’s rooms, bathroom...), so here is the question: what would you do or recommend? Ignore the note “considered not entirely hygienically acceptable” or bite the bullet and go with floor outlets?
Thank you very much and best regards!
B
Bieber081522 Sep 2017 10:36In a rotary heat exchanger, moisture is transferred directly, with some slip between the exhaust and supply air. An enthalpy heat exchanger is generally more reliable hygienically over the long term compared to a plate heat exchanger. Nevertheless, rotary heat exchangers are also a well-established technology.
How important is moisture recovery to you? In the proposed design, it occurs only during condensation.
In my opinion, floor outlets are not a disadvantage. The ductwork can be shorter (reducing pressure loss), and no one will experience uncomfortable drafts around the neck or head area.
How important is moisture recovery to you? In the proposed design, it occurs only during condensation.
In my opinion, floor outlets are not a disadvantage. The ductwork can be shorter (reducing pressure loss), and no one will experience uncomfortable drafts around the neck or head area.
Bieber0815 schrieb:
How important is moisture recovery to you? In the proposed design, it only occurs during condensation.
Floor outlets are not a disadvantage in my opinion. The duct network can be shorter (pressure loss) and no one will experience unpleasant drafts around the neck or head area. Moisture recovery is very important to us, since both my wife and I wear contact lenses and immediately notice overly dry air. However, our supplier/manufacturer informed us that in their own tests and in many installed houses, the moisture recovery was at least 50% even in winter, which should be more than sufficient.
Now, I don’t want to be more naive than I already am, but due to a lack of information, you inevitably have to trust the “professional,” as there is no contradictory evidence available.
So the hygienic concerns would essentially be due to internal leakage? The manufacturer referred in this context to the leakage rate proven and passed by the PHI institute, which I believe was < 3%. Besides the PHI certification, the device also has the EUROVENT certification, although I’m not sure how much weight that carries...
Regarding the floor outlet: Shouldn’t drafts also be avoidable with proper design of airflow volume and duct cross-section in ceiling valves? On the other hand, there are concerns about possible “cold air pools” with floor outlets. Is there any truth to that?
At least it seems reasonable that objects might fall into floor outlets (liquids, toys), and there might be some restrictions on furniture placement because of them, right?
The outlet is usually placed, for example, in front of or below the window, where there are naturally no furniture items anyway.
Fluids are collected by a "trap," so they don’t just flow directly into the pipe.
Cold drafts... well, with heat recovery over 80%, nothing noticeable should occur, especially since the air is moving.
The only drawback I see is the additional cost of floor outlets (nice stainless steel grilles plus extra effort when installing the floor covering). On the other hand, the piping is shorter and simpler.
Fluids are collected by a "trap," so they don’t just flow directly into the pipe.
Cold drafts... well, with heat recovery over 80%, nothing noticeable should occur, especially since the air is moving.
The only drawback I see is the additional cost of floor outlets (nice stainless steel grilles plus extra effort when installing the floor covering). On the other hand, the piping is shorter and simpler.
Alex85 schrieb:
The outlet is placed, for example, in front of or below the window, where there are naturally no furniture pieces anyway. Maybe desks?
Cold drafts... well, with heat recovery above 80%, you shouldn’t feel anything noticeable, especially since the air is circulated. Hmm... is it different thermodynamically with ceiling outlets? There’s a recommendation not to install them near head level because of possible drafts.
No idea if there’s any truth to that, or if people generally just worry too much about it...
Cleaning floor-level air vents or inlets can be quite unpleasant if you have pets... Something will definitely end up inside (especially with cats). I also think that floor-level installations are more limiting because people tend to place tall furniture in rooms rather than items on the floor. These don’t have to be just cabinets; runners, small furniture, decorative items, as well as changes to the flooring, are all more difficult in that case. Additionally, exhaust air should usually be near the ceiling, so overall you probably won’t save much. Depending on where the mechanical ventilation with heat recovery is located, savings may be even less (for example, if it’s installed in the attic, the ducts to the ceiling are shorter).
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