On Fri, 10 Dec 2010 08:03:57 -0600, Vic Smith
wrote:

On Fri, 10 Dec 2010 03:57:10 -0800 (PST), wrote:

On Dec 9, 9:45Â*pm, Vic Smith wrote:
On Thu, 09 Dec 2010 21:03:33 -0500, Home Guy wrote:

And I still say that having the ability to draw return air totally from
a dedicated outside duct in the summer and force the normal return air
out of the house through another duct is more energy-efficient at
cooling your house vs using an AC during those times when the outside
air temp is lower than the current inside air temp, which frequently
happens in the late afternoon and evening in the spring and late summer.

I totally agee with that. Â*
Probably isn't done because of issues with ducting to the outside.
For my basement furnace it wold take a up window, not counting the
ductwork and diverters.
So we open the windows when it's cooler outside than in.
But if there's no breeze you really need fans in the windows to make
that work well.

--Vic

I'd say it depends on how much cooler the outside air is. And even
then, you have
the issue of humidity which is a major concern in many climates.
Pulling humid
air from outside that happens to be 5 deg cooler than the house inside
wouldn't
seem to make a lot of sense to me. And here in the NYC area, the few
days of the
year you would do that, ie some Spring and early Fall days, it just
isn't worth it comared
to the addional ducting. Besides, I thought Home Guy was all about
simplicity. At a
minimum such a system would require actuators, more controls, etc. To
do it right
you'd have to measure outside temp, outside humidity, inside temp,
inside humidity and
then have a mircrocontroller decide what to do. Sounds exactly like
the complexity that
HG wants to rip out of a new high efficiency furnace.

If you want to go that route, a whole house fan to pull air in from
outside is an option. But
it too has the above problems and being in the upstairs ceiling/attic
interface, you now
have something difficult to seal and insulate perfectly for the entire
winter. Meaning what
you gain in a few days that you use it could be more than lost.

You don't need microcontrollers. Just go to the basement and pull a
lever or crank on a chain fall (-:
Where I live, and the house I live in, it makes sense to draw in
outside air at night about 10-30 days a year, depending.
My house is brick, with little or no insulation.
Haven't torn off any drywall on the exterior walls, but I know from
drilling the drywall is on furring, maybe 1", not 2x4's.
Never picked up any fluff when drilling.
Surprisingly, my gas bill isn't bad.
But it can absorb a lot of heat during the days of high sun and the
heat migrates in if the nights aren't sufficiently cool.
Better to have the night air working on both sides.
Adds up to 10-30 days a year, depending.
The same was true of my last brick house.
Besides, if it's not too humid, outside air is good.

--Vic



Up here in Central Ontario when it is hot enough that you would want
to draw in the outside air, the humidity is way too high to make it an
acceptable alternative most days.