5 ms·

This is the last thing you want to do. By creating a low pressure zone in your home humid outside air will seep in through every crack, gap, and uncaulked seam

by zionic 4y ago

This is the last thing you want to do. By creating a low pressure zone in your home humid outside air will seep in through every crack, gap, and uncaulked seam in your house. Such a system is basically a mold incubator. The correct method is to: 1) have central HVAC 2) have an energy recovering ventilator (ERV), zhender is a good brand. #2 Constantly cycles fresh air throughout your home and it’s intake is controllable and filtered.

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eru 4y ago
I think you might be misunderstanding? My suggestion was for situations like London or Germany in summer. The air cools down a lot in the evening there, and people typically don't have any A/C there nor humidity problems in summer. The point-fan-out-the-window technique is for rapidly bringing your home down to ambient temperatures (and humidities). There will be no condensation, and thus no mold, because the ambient night air is above its dew point, and your own walls start out hotter than the ambient air, and they only approach its temperature _from above_ as you ventilate the house. What you are describing sounds like it might be more appropriate for something like Florida. In places like Germany or London, people have mold problems in winter, when the walls are colder than the air in the home. (You can also get mold problems, when you are running an AC.)
- zionic 4y ago
  The humidity in London is currently 69%. Your indoor humidity should never exceed 60%, and you should target 40%-45%. If you have no way to control this then you are essentially running a mold incubator. From my travels around western europe I also noticed a SHOCKING number of bathrooms lack any form of bathroom fan, so hot showers spike the indoor humidity and it stays there. >The point-fan-out-the-window technique is for rapidly bringing your home down to ambient temperatures (and humidities). Sure, but the goal is to do that in a controlled manner. Every outlet needs an inlet, and that inlet can either be a dedicated one with a filter (via ERV) or cracks, crevices, and air leaks around your house that you can't see. By puling in uncontrolled outside air you risk moisture buildup in those areas that can lead to mold and rot. >There will be no condensation, and thus no mold, because the ambient night air is above its dew point, and your own walls start out hotter than the ambient air, and they only approach its temperature _from above_ as you ventilate the house. Unless your interior air is humid, because the house lacks even the most basic form of humidity control. Then those air leak spots cool the area they're leaking in around which then makes condensation from your interior humidity. >(You can also get mold problems, when you are running an AC.) Oh for sure. My point is that a house with proper AC, humidity control, and ERV will be extremely resistant to mold growth. It will also feel fresh, comfortable, you'll sleep better etc.
  - eru 4y ago
    Where do you get your 60% humidity ceiling from? I live in Singapore these days, we currently have 80% humidity (and that's fairly normal). We have much less problems with mold here than in Britain or Germany. (In Germany, problems with mold were usually in winter, anyway.) Yes, bathrooms with neither windows nor fans are annoying. > Sure, but the goal is to do that in a controlled manner. Every outlet needs an inlet, and that inlet can either be a dedicated one with a filter (via ERV) or cracks, crevices, and air leaks around your house that you can't see. By puling in uncontrolled outside air you risk moisture buildup in those areas that can lead to mold and rot. Eh, the air will mostly be pulled in either through another open window (good), or through the same window you are blasting the hot air out of (slightly less good), because your fan doesn't form a seal. I don't really see how you are getting your moisture build-up. You only really get condensation on the walls, when your walls are colder than the air. > Unless your interior air is humid, because the house lacks even the most basic form of humidity control. Then those air leak spots cool the area they're leaking in around which then makes condensation from your interior humidity. I never heard of anyone having that problem in summer, and never had it myself. I have no clue where you are taking your worries from.

by zionic 4y ago

deleted 4y ago

[deleted]

eru 4y ago

I think you might be misunderstanding? My suggestion was for situations like London or Germany in summer. The air cools down a lot in the evening there, and people typically don't have any A/C there nor humidity problems in summer. The point-fan-out-the-window technique is for rapidly bringing your home down to ambient temperatures (and humidities). There will be no condensation, and thus no mold, because the ambient night air is above its dew point, and your own walls start out hotter than the ambient air, and they only approach its temperature _from above_ as you ventilate the house. What you are describing sounds like it might be more appropriate for something like Florida. In places like Germany or London, people have mold problems in winter, when the walls are colder than the air in the home. (You can also get mold problems, when you are running an AC.)

zionic 4y ago
The humidity in London is currently 69%. Your indoor humidity should never exceed 60%, and you should target 40%-45%. If you have no way to control this then you are essentially running a mold incubator. From my travels around western europe I also noticed a SHOCKING number of bathrooms lack any form of bathroom fan, so hot showers spike the indoor humidity and it stays there. >The point-fan-out-the-window technique is for rapidly bringing your home down to ambient temperatures (and humidities). Sure, but the goal is to do that in a controlled manner. Every outlet needs an inlet, and that inlet can either be a dedicated one with a filter (via ERV) or cracks, crevices, and air leaks around your house that you can't see. By puling in uncontrolled outside air you risk moisture buildup in those areas that can lead to mold and rot. >There will be no condensation, and thus no mold, because the ambient night air is above its dew point, and your own walls start out hotter than the ambient air, and they only approach its temperature _from above_ as you ventilate the house. Unless your interior air is humid, because the house lacks even the most basic form of humidity control. Then those air leak spots cool the area they're leaking in around which then makes condensation from your interior humidity. >(You can also get mold problems, when you are running an AC.) Oh for sure. My point is that a house with proper AC, humidity control, and ERV will be extremely resistant to mold growth. It will also feel fresh, comfortable, you'll sleep better etc.
- eru 4y ago
  Where do you get your 60% humidity ceiling from? I live in Singapore these days, we currently have 80% humidity (and that's fairly normal). We have much less problems with mold here than in Britain or Germany. (In Germany, problems with mold were usually in winter, anyway.) Yes, bathrooms with neither windows nor fans are annoying. > Sure, but the goal is to do that in a controlled manner. Every outlet needs an inlet, and that inlet can either be a dedicated one with a filter (via ERV) or cracks, crevices, and air leaks around your house that you can't see. By puling in uncontrolled outside air you risk moisture buildup in those areas that can lead to mold and rot. Eh, the air will mostly be pulled in either through another open window (good), or through the same window you are blasting the hot air out of (slightly less good), because your fan doesn't form a seal. I don't really see how you are getting your moisture build-up. You only really get condensation on the walls, when your walls are colder than the air. > Unless your interior air is humid, because the house lacks even the most basic form of humidity control. Then those air leak spots cool the area they're leaking in around which then makes condensation from your interior humidity. I never heard of anyone having that problem in summer, and never had it myself. I have no clue where you are taking your worries from.