shop-talk
[Top] [All Lists]

Re: Two items (HVAC Ducting and follup to Screws)

To: Matt <mattmahony@attbi.com>, shop-talk@autox.team.net
Subject: Re: Two items (HVAC Ducting and follup to Screws)
From: "Kai M. Radicke" <kai@radiohead.net>
Date: Mon, 17 Mar 2003 16:11:12 -0500
Matt wrote:

> Looking at the picture, I think I see a register with 2 grilles
> aimed  180 degrees from each other, blowing parallel to the
> exterior wall.  Correct me if this is wrong.

Matt, this pic should clear it up:

http://astro.temple.edu/~kmr/images/duct2.jpg

You're right that the register has a divided grille, each blowing 180
degrees from the other side.  But you'll see in the pic that the one half is
directed at the wall (with all the window space) and the other half out
towards the middle of the room.

> You generally want the air flow to "wash down" the exterior
> wall and not directly into the conditioned space as that's
> where objectionable drafts come from.  Your biggest heat
> gain or loss is through exterior walls and windows. The
> "usual" way to mount ceiling registers for forced air
> heat/cool systems is a 2 way with the long axis parallel to
> the exterior wall and the vanes 180 from each other and
> directing the air along the wall. It does seem a bit far out into
> the room and a low pitch or obstructions in the attic could
> account for this. But it's not the type register/boot I would
> normally use in this application. Depending on CFM I would
> expect to see a 6X12, 6X14 or similar.

Thanks for the confirmation, every forced air installation I've seen in
friends' and relatives' homes, has been the way you described.  Blowing
along the axis parallel to the wall also makes the most sense to me for
practical reasons, as you mentioned, such as draftiness.  There are two 6X10
outlets on that wall, about 10 feet apart from each other.  The crawl space
directly above that area is rather small, so I wasn't too concerned with how
far out from the wall they installed the registers, as the rafters and
insulation cut down the work area in the crawl space considerably.

> If he can't or won't explain it to you, get very suspicious. Poor >
installations cause more problems and complaints than all
> other causes combined.

Well there are a few things on my list at the moment to ask about.
Obviously the orientation of the registers, but now that I have a bit more
knowledge about how it should be done, I can make a reasonable assessment of
their reason for doing it their way.  Also, a few of the registers are
crooked, which really bothers me... I have a severe dislike for things that
aren't at near-perfect right angles.

The HVAC contractor will be back tomorrow, so he will be quizzed about the
work he has done so far.  Thanks for the info Matt, I needed another opinion
about how I thought it should be done.

Kai

///  unsubscribe/change address requests to majordomo@autox.team.net  or try
///  http://www.team.net/mailman/listinfo
///  Archives at http://www.team.net/archive/shop-talk


<Prev in Thread] Current Thread [Next in Thread>