 jig
join:2001-01-05
Hacienda Heights, CA | reply to emptywig
Re: A/C Ductwork Question on the return duct issue, the rooms closest to the return will have the lowest air pressure, especially if the rooms are pretty much sealed from other areas of the house, and those other areas aren't leaky themselves. lower pressure means lower resistance through the supply ducts to the "return" rooms, and so you end up with a kind-of a cycle that somewhat bypasses the rooms that aren't line of sight to the return.
in other words, you can have sections of your distribution system that are blowing air into closed spaces like trying to blow into a full balloon, and other open sections that are like blowing air into a toilet paper tube. the tube sections get more wind.
the fresh air return is somewhere near the suction side of the system, or it'd probably be more like a stale air exhaust. i think fresh air returns are built with a high enough constraint to air flow that they don't make a large difference to the (already small) pressure differentials throughout the house (they rely on the suction of the return). i don't know what the code specifically says, but i seem to remember it's something like 10% fresh air.
side question: when they installed the fresh air return, did they put any kind of separate filter on the return, maybe on the outside, or do you just rely on the main intake filter for everything? my neighbor burns something in his fireplace that sticks to the ground and would ruin our house air if we had much of a fresh air inlet, let alone 10%, filtered or not. |
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emptywigHuh? What?Premium
join:2002-08-05
Pasadena, TX | Thanks for the explanation.
All of the return air (fresh and inside) runs through 5" media filters located just before the furnace. I have to change the filters about once every 5 months or so.
wig
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"There is nothing- absolutely nothing- half so much worth doing as simply messing about in boats." |
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emptywigHuh? What?Premium
join:2002-08-05
Pasadena, TX
1 edit | reply to jig
OK, I think I understand what you're saying here. Unfortunately, the rooms that are having problems are on a hallway with one of the air returns, so those rooms _should_ be getting the good, easy airflow if that was the problem. But they're not.
Thanks,
wig
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"There is nothing- absolutely nothing- half so much worth doing as simply messing about in boats." |
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