[Greenbuilding] forced air heating vent placement

[Alan Abrams]

you still might be able to get the best of all the above by blowing the air
from high registers from a central location. depending on velocity and the
width of the room, you may be able to move the air all the way across the
space by means of the coanda effect (akin to laminar flow), where in turn
it would prevent frosty windows and warm the exterior wall, etc.

-aa

Alan Abrams

*certified professional building designer, AIBDcertified passive house
consultant, PHIUS*
*certified passive house builder, PHIUS*
cell     202-437-8583
alan at abramsdesignbuild.com
HELICON WORKS *Architecture and Education*
<http://www.heliconworks.com/index2.html>

On Tue, Mar 29, 2016 at 10:20 AM, RT via Greenbuilding <
greenbuilding at lists.bioenergylists.org> wrote:

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> ---------- Forwarded message ----------
> From: RT <ArchiLogic at yahoo.ca>
> To: Green Building <greenbuilding at lists.bioenergylists.org>
> Cc:
> Date: Tue, 29 Mar 2016 10:17:48 -0400
> Subject: Re: [Greenbuilding] forced air heating vent placement
>
> Reuben;
>
> As WatJohn has pointed out moving the supply air registers to the core
> partitions works for buildings with high-performance walls & windows and
> although doubling the R-value of the farmhouse walls and windows is a Good
> Thing, I have doubts whether the improvement will be sufficient to move the
> registers back to an interior partition parallel to the exterior walls.
>
> The increased depth of the window wells will almost certainly create still
> air pockets at the bottom portions of the windows and that still air
> lingering against the R-2 or R-3 equivalent of the exterior-stormed windows
> (depending upon whether the original windows were single or double-glazed)
> can result in very serious condensation issues and possibly ice
> accumulation on the bottom edges of the vision glass and bottom sash &
> sills.
>
> Since the existing registers will be buried by the added wall thickness,
> when you shorten the supply ducts to move the registers away from the new
> walls, it would be possible to run a smaller wide/thin duct extension from
> the end of the shortened duct/new end boot just beneath the interior wall
> finish under the window sill to a long,skinny slit-type register in the
> window sill that would provide enough upwards air movement against the
> glass surface to prevent the air against the glass from cooling down to the
> dew point.  You'd probably want to install a damper in that duct extension
> so that the volume can be adjusted to minimise noise (imagine the
> phenomenon of a whistle).
>
> For an old farmhouse reno, it's likely that the budget would not allow for
> the storebought skinny registers that are more typically used in commercial
> work so you might make one out of wood. Easy to do on a table saw by
> ripping the slots on the top face with the blade set at half depth and then
> cross-cutting on the backside for the remainder of the depth.
>
>
>
> On Mon, 28 Mar 2016 18:29:36 -0400, <jfstraube at gmail.com> wrote:
>
>
> Suffice it to say, walls with better than code insulation , good
>> airtightness (way better than 5 ACH and usually below 3) ‎, reasonable
>> window areas with very good to exceptional performance do work.
>>
>
>
> home-nrg at dnaco.net
>>
>
> with all of the ducts in a central wall cavity
>>>
>>
>
> From: Reuben Deumling <9watts at gmail.com>
>>
>
> I'm in the process of adding four inches to the inside of
>>> the exterior walls on a 140 year old farmhouse and blowing
>>> a ton of cellulose into those deeper cavities. There will
>>> be exterior storm windows
>>>
>>
> --
> === * ===
> Rob Tom  .  .  . T60BOM
> Kanata, Ontario, Canada
>
> A r c h i L o g i c  at  Y a h o o  dot C A
> (manually winnow the chaff from my edress if you hit "reply")
>
>
>
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