My question is in reference to HRV duct placement. Is moisture laden air affected by gravity? I know that the warmer air is, the more moisture it can hold, but it’s also less dense, so the warmer air is closer to the ceiling. Most things that I’ve read show removing stale air from the upper walls in rooms, is this because of forced air heat and that’s where the warmer air is? What about radiant heat? The air closer to the floor will be warmer, so is that where the higher moisture will be? So is this where I should pull air from? Please advise. Thanks
Gearhead61
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To answer one question, at a given temperature, as the dewpoint of air increases, the density decreases, believe it or not. For instance 80 degF, dry air has a specific volume of 13.6 cubic feet/pound, 80 degF air with 40% rh (or dewpoint of 54 degF) has a specific volume of 13.8, ie. is less dense.
As far as where to exhaust air from the house, high or low, who can say. Do you have forced air? Do you have exhausts in bathrooms? Do you have areas with little or no air circulation?
If it were my house, I would take exhaust out from the most used bathroom (or all bathrooms if possible), the little powder room with no supply air in it, the den where my aquarium is located and where I smoke and the laundry room.
Edited 3/29/2002 8:26:59 AM ET by Tim
Thanks Tim for your response. I do have radiant heat throughout the entire house. It's about 2000 sq. ft. with a loft and a very open floor plan. I am a self builder and have done all of the mechanical systems my self also, with exception to the Gypcrete poor and central air this summer. As far as venting for the two bathrooms, I wanted to tie the two 50CFM fart fans in to a 4" duct and then "T" that in to the 6" HRV exhaust. The HRV is about 120-140 CFM and when it is running normally, will pull some air through the fans. Then when the fan is on, for showers or other reasons, the room should exhaust quite well.
I'm going to put in double pole switches on the fans and run a switch loop to the basement. I believe the HRV has provisions for a manual override from the normal humidity/timed controls, but I will know more when I get it. Thanks