ᐅ Decentralized residential ventilation, exhaust air heat pump – any experience?
Created on: 17 Jan 2014 08:02
C
Chris1984C
Chris198417 Jan 2014 08:02Hello everyone,
My wife and I plan to start building our single-family house near Bonn later this year. After numerous consultations (both in the area of prefabricated and solid construction), the company V***Haus is currently one of our top choices as a developer. Unlike many other developers, V***Haus installs a decentralized ventilation system instead of a centralized one. Fresh air is supplied directly through sound-insulated vents in the walls, rather than being drawn in at a single point like in central systems, warmed via a heat exchanger using exhaust air, and then distributed through ductwork; however, the heat stored in the exhaust air is still recovered efficiently through an exhaust air heat pump from Nibe that feeds the underfloor heating system. From my perspective, this system (like many others) has several advantages and disadvantages:
Pros:
+ Air does not need to be supplied through a maintenance-intensive duct system
+ Higher air quality as a result
+ Growth of germs and mold inside ductwork is not a factor
+ Waste heat can be utilized more efficiently in the exhaust air heat pump than in the heat exchanger of a central ventilation system
Cons:
- Air supplied to the rooms is at outside temperature (warm in summer, cold in winter)
- If the vents do not seal properly, drafts can occur
- Possibly similar to the effects of "tilt window ventilation"
Overall, I really like the concept, and I also prefer the operation of the exhaust air heat pump compared to a conventional air-water heat pump. My concern (or fear) is that during the deep winter, I might find myself sitting there while (exaggerating intentionally) -20°C (-4°F) cold outside air flows in through the vents, and the underfloor heating below at 50°C (122°F) struggles desperately to keep the room warm. It is generally agreed nowadays that permanent tilt window ventilation is harmful to the building fabric. So what is the difference here? Is it the air volume flow, which in this kind of ventilation is simply much lower (and above all, controlled)???
My question is therefore: Has anyone here had experience with this type of decentralized ventilation system? What do you think about it? Where do YOU see advantages and disadvantages??? I would appreciate hearing some of your thoughts on the topic.
Best regards,
Chris
My wife and I plan to start building our single-family house near Bonn later this year. After numerous consultations (both in the area of prefabricated and solid construction), the company V***Haus is currently one of our top choices as a developer. Unlike many other developers, V***Haus installs a decentralized ventilation system instead of a centralized one. Fresh air is supplied directly through sound-insulated vents in the walls, rather than being drawn in at a single point like in central systems, warmed via a heat exchanger using exhaust air, and then distributed through ductwork; however, the heat stored in the exhaust air is still recovered efficiently through an exhaust air heat pump from Nibe that feeds the underfloor heating system. From my perspective, this system (like many others) has several advantages and disadvantages:
Pros:
+ Air does not need to be supplied through a maintenance-intensive duct system
+ Higher air quality as a result
+ Growth of germs and mold inside ductwork is not a factor
+ Waste heat can be utilized more efficiently in the exhaust air heat pump than in the heat exchanger of a central ventilation system
Cons:
- Air supplied to the rooms is at outside temperature (warm in summer, cold in winter)
- If the vents do not seal properly, drafts can occur
- Possibly similar to the effects of "tilt window ventilation"
Overall, I really like the concept, and I also prefer the operation of the exhaust air heat pump compared to a conventional air-water heat pump. My concern (or fear) is that during the deep winter, I might find myself sitting there while (exaggerating intentionally) -20°C (-4°F) cold outside air flows in through the vents, and the underfloor heating below at 50°C (122°F) struggles desperately to keep the room warm. It is generally agreed nowadays that permanent tilt window ventilation is harmful to the building fabric. So what is the difference here? Is it the air volume flow, which in this kind of ventilation is simply much lower (and above all, controlled)???
My question is therefore: Has anyone here had experience with this type of decentralized ventilation system? What do you think about it? Where do YOU see advantages and disadvantages??? I would appreciate hearing some of your thoughts on the topic.
Best regards,
Chris
D
DerBjoern17 Jan 2014 09:17+ Air does not need to be supplied through a maintenance-intensive duct system Maintenance-intensive is hardly an accurate description. When the systems operate with filters, hardly any buildup occurs.
+ Higher air quality as a result No, see the previous point. In addition, the air is filtered in a central mechanical ventilation system with heat recovery.
+ No risk of germs and mold forming in the duct system This is generally not an issue with a central mechanical ventilation system either. However, it is often used as a selling point by vendors of decentralized systems.
+ Waste heat can be utilized more efficiently in the exhaust air heat pump than in the heat exchanger of a central ventilation system This claim still needs to be proven. If you research online, you will also find user experiences regarding the mentioned exhaust air heat pump, including the "efficiency" of the system.
The air being supplied to the rooms is at outdoor temperature (warm in summer, cold in winter) For me, this point would disqualify the system.
DerBjörn has already written quite a bit: I agree with that.
How could anything get into the ductwork that would cause mold? And no moisture should develop inside, otherwise it would be a construction defect.
We have a central ventilation system and would not want to miss it for anything in the world. Currently, when it is close to 0°C (32°F) outside, the supply air being blown in is about 15–18°C (59–64°F), which already lowers the room temperature a bit if the heating is switched off at night.
Well, if you already have the option to choose, I would only install a central system in a new build and not anything else...
As others have already mentioned, the arguments are unfounded...
+ Air does not need to be supplied through a maintenance-intensive duct system
As already stated... not more maintenance-intensive than a decentralized system.
+ Air quality is therefore higher
I strongly doubt that!
+ Germ and mold growth in the duct system is not a factor
With both options and proper installation, the conditions are the same.
+ Waste heat can be used more efficiently in the exhaust air heat pump than in the heat exchanger of a central ventilation system
Well, that sounds more like a statement from a glossy brochure without evidence...
- The air supplied to the rooms has outside temperature (warm in summer, cold in winter)
Yes, that is true and it is clearly noticeable.
- If the valves do not close properly, drafts can occur
Yes.
- Possible analogy to "tilt window ventilation"
Yes, that too.
Additionally:
- More openings in the façade, leading to higher potential for installation errors, thermal bridges, etc.
- Increased soiling of the façade around the valves
- Higher filter costs, since “special” filters are required which have specific shapes and a higher quantity compared to a central mechanical ventilation system
and so on and so forth
As others have already mentioned, the arguments are unfounded...
+ Air does not need to be supplied through a maintenance-intensive duct system
As already stated... not more maintenance-intensive than a decentralized system.
+ Air quality is therefore higher
I strongly doubt that!
+ Germ and mold growth in the duct system is not a factor
With both options and proper installation, the conditions are the same.
+ Waste heat can be used more efficiently in the exhaust air heat pump than in the heat exchanger of a central ventilation system
Well, that sounds more like a statement from a glossy brochure without evidence...
- The air supplied to the rooms has outside temperature (warm in summer, cold in winter)
Yes, that is true and it is clearly noticeable.
- If the valves do not close properly, drafts can occur
Yes.
- Possible analogy to "tilt window ventilation"
Yes, that too.
Additionally:
- More openings in the façade, leading to higher potential for installation errors, thermal bridges, etc.
- Increased soiling of the façade around the valves
- Higher filter costs, since “special” filters are required which have specific shapes and a higher quantity compared to a central mechanical ventilation system
and so on and so forth
B
Bauexperte17 Jan 2014 11:57Hello Chris,
As you can already see from the previous answers, the topic of decentralized versus centralized ventilation is a bit of a sensitive issue.
I can tell you about our construction project, where a decentralized system was installed, that our clients are very satisfied with this ventilation system and the "cons" you described do not occur. However, it depends on the chosen supplier and the location in the room where the fans are installed, so that hardly any draft sensation occurs. The same satisfaction applies to our clients who have installed centralized systems. So it’s not just a matter of personal preference but also of the available budget. You have the difficult choice; but generally speaking, in my opinion, it is always better to have a decentralized system than no ventilation system at all.
The red colleague builds quite a few houses – why don’t you ask them for references? Even better, visit a housing development nearby and ask existing customers of this provider about their experiences (you can also find some online). You should be able to recognize their houses even without signposts. Additionally, you might want to inquire about the ongoing operating costs of the installed exhaust air heat pump.
Regards, Bauexperte
Chris1984 schrieb:
My question is: Does anyone have experience with this type of decentralized residential ventilation system? What do you think about it? Where do YOU see advantages and disadvantages??? I would appreciate hearing some of your thoughts on the subject.
As you can already see from the previous answers, the topic of decentralized versus centralized ventilation is a bit of a sensitive issue.
I can tell you about our construction project, where a decentralized system was installed, that our clients are very satisfied with this ventilation system and the "cons" you described do not occur. However, it depends on the chosen supplier and the location in the room where the fans are installed, so that hardly any draft sensation occurs. The same satisfaction applies to our clients who have installed centralized systems. So it’s not just a matter of personal preference but also of the available budget. You have the difficult choice; but generally speaking, in my opinion, it is always better to have a decentralized system than no ventilation system at all.
The red colleague builds quite a few houses – why don’t you ask them for references? Even better, visit a housing development nearby and ask existing customers of this provider about their experiences (you can also find some online). You should be able to recognize their houses even without signposts. Additionally, you might want to inquire about the ongoing operating costs of the installed exhaust air heat pump.
Regards, Bauexperte
Hello,
I have already prepared expert reports on this topic! Talk to disappointed homeowners! There is even a dedicated forum for dissatisfied customers!
Best regards,
NB: Note regarding reference addresses. Many general contractors pay well for such information! So look up the address yourself, rather than relying on the supplier to provide it!
Chris1984 schrieb:An underfloor heating system optimized for heat pumps typically has a supply temperature of around 35°C (95°F) at most! Besides, your concerns are justified!
...Basically, I think the concept is very good, and I also like the way the exhaust air heat pump works compared to a conventional air-to-water heat pump. However, my concern (or fear) is that in the middle of winter, I might end up sitting there and (I’m deliberately exaggerating) -20°C (−4°F) cold outside air flowing in through the valves, while the underfloor heating below me is struggling at 50°C (122°F) trying to keep the room warm...
Chris1984 schrieb:With the overall setup, yes. First of all, it must be clarified whether such an exhaust air heat pump is even suitable! Otherwise, besides this odd supply air, there will be significantly excessive energy costs.
...My question is therefore: Does anyone here have experience with this type of decentralized residential ventilation system? ...
I have already prepared expert reports on this topic! Talk to disappointed homeowners! There is even a dedicated forum for dissatisfied customers!
Best regards,
NB: Note regarding reference addresses. Many general contractors pay well for such information! So look up the address yourself, rather than relying on the supplier to provide it!
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