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Old 01-30-13, 07:28 PM   #12
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Originally Posted by Exeric View Post
Well, that answers that. It seems to imply the humidity filtering only occurs in one direction - outside to inside. Too bad.
Well, the way it works is that as the higher temperature air, with it's load of water vapor, moves across a higher-to-lower temperature gradient, as the air temperature changes, if it crosses the dew point, will causes the vapor to condense and become water.

If you have a HRV, the water stays on the side of the barrier on which it condenses, and exits, usually through a tube to be disposed.

If you have an ERV, the barrier is permeable, and the water crosses through the barrier and evaporates into the air in the lower-to-higher temperature gradient.

I was very careful with my language to avoid words like "inside" and "outside" so that the description would be valid when read for heating as well as air conditioning.

* * *

So, if you wanted to ventilate AND save heat in a bathroom/shower, you would NOT use a ERV, as that would send the water vapor back into the loo. So in that case the proper choice would be a HRV.

I'm not an HVAC technician. In fact, I'm barely even a hacker...

Last edited by AC_Hacker; 01-30-13 at 09:54 PM..
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