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Energy saving idea?

  • Thread starter JimmySchmittsLovesChocolateMilk
  • Start date
J

JimmySchmittsLovesChocolateMilk

Jan 1, 1970
0
John Harlow said:
What would be the problem with ducting cool air from under a house to the
attic in warmer months to help with cooling, and just the opposite in the
winter to help with heating?

woudln't Your floor would get cold from the cold attic air, cooling the air
above it, and forcing your furnace to run more often?

Once you cyled the air completly once, the radiant heating from the earth
would take a while to warm the air under the house again,
more likely it would be the heat escaping thru the floor that would be
warming the air under the house,
so I think the net benifit would be little to none, ...
 
J

John Harlow

Jan 1, 1970
0
What would be the problem with ducting cool air from under a house to the
attic in warmer months to help with cooling, and just the opposite in the
winter to help with heating?
 
E

Edwin Pawlowski

Jan 1, 1970
0
John Harlow said:
What would be the problem with ducting cool air from under a house to the
attic in warmer months to help with cooling, and just the opposite in the
winter to help with heating?

I'd be concerned about the quality of air from under the house. Mold spores
could cause problems.
 
J

John Harlow

Jan 1, 1970
0
Edwin said:
I'd be concerned about the quality of air from under the house. Mold
spores could cause problems.

Interesting - wouldn't they also cause problems under the house?

How about a filter, or a heat exchanger made with some ductwork?
 
E

Edwin Pawlowski

Jan 1, 1970
0
John Harlow said:
Interesting - wouldn't they also cause problems under the house?

How about a filter, or a heat exchanger made with some ductwork?
Sure, mold is a growing problem in homes.

OTOH, bringing in fresh air may help the problem. The filter and heat
exchanger would help.
 
M

Melodie de l'Epine

Jan 1, 1970
0
John Harlow a écrit :
What would be the problem with ducting cool air from under a house to the
attic in warmer months to help with cooling, and just the opposite in the
winter to help with heating?


Depends what "under a house" means. Is the house elevated? Is the house
on a concrete foundation? etc etc..

Do you mean taking cool air from an existing cavity or laying a couple
of pipes under the house and getting air from there? If its the second,
it's reasonably common (it's called a Canadian Well here in France). If
it's the first, it would depend on the air temperature, the thermal
mass's capacity and fan running costs (cold air won't rise on its own...)


Mel
 
E

Edwin Pawlowski

Jan 1, 1970
0
Robert Barr said:
For this to be remotely feasible, you'd have to have woefully inadequate
insulation. In that case, the obvious solution would be to insulate.

Good point, but there are attics and there are attics. If the attic is the
unoccupied space above the rooms and the insulation is between the joists,
you are correct. If the attic is the livable space above the second floor
and the insulation is in the ceiling, the idea would work to some degree.
 
J

John Harlow

Jan 1, 1970
0
Melodie said:
John Harlow a écrit :


Depends what "under a house" means. Is the house elevated? Is the
house on a concrete foundation? etc etc..

I'm thinking of the somewhat typical house here in the US (like mine of
course ;) with a small crawl space over dirt.
Do you mean taking cool air from an existing cavity or laying a couple
of pipes under the house and getting air from there? If its the
second, it's reasonably common (it's called a Canadian Well here in
France). If it's the first, it would depend on the air temperature,
the thermal mass's capacity and fan running costs (cold air won't
rise on its own...)

I am thinking about moving the air from the existing cavites using a blower.
It seems to me, for the price of running a couple hundred watt blower, there
could be substantial energy savings at least in the summer months.
 
M

m II

Jan 1, 1970
0
Chet said:
A couple hundred watt blower? How much air do you think you're going
to move from below the house into the attic with that?

It's only a matter of time. A low 'cubic foot per minute' fan will
just take a bit longer to do the job. As cold air is heavier per cubic
foot, he just has to overcome the density difference caused by the
temperature variation and whatever resistance to flow may be in the
ducting. Large ducts = less resistance.

A one or two ampere motor (approx. 100 to 200 watts) can
deliver/remove a lot more energy in heated air that it uses up. That's
just a guess for an average bathroom fan motor.

all in my humble opinion, of course..




mike
 
G

Gymy Bob

Jan 1, 1970
0
A bathroom fan motor would never push hot air down ten feet or cold up ten
feet.
 
M

m II

Jan 1, 1970
0
Gymy said:
A bathroom fan motor would never push hot air down ten feet or cold up ten
feet.


I respectfully disagree. I stand by my statement that it would only be
a matter of longer time. The amount of air will vary a bit per time
period, but it WILL keep moving.



===================================

A fan is a "constant volume" device where the transported volume is
the same, no matter air temperature and density, if all other things
are equal. Only the mass flow through the fan varies with air
temperature and air density.

http://www.hvac-toolbox.com/37_144.html
===================================



mike
 
G

Gymy Bob

Jan 1, 1970
0
Bathroom fans have a hard time pushing 55 cfm through a 3-4" pipe 20
horizontal feet. They are made to vent smells and humid air horizontally
only.

Do the research and think!
 
Gymy Bob said:
Bathroom fans have a hard time pushing 55 cfm through a 3-4" pipe 20
horizontal feet.

Awww. Do they complain?
Do the research and think!

You might do this and find that the density difference between hot and
cold air in houses creates a negligible pressure difference compared to
the static pressure rating of the fan or the friction loss of a long duct.

Nick
 
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