Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

If air is leaking in one direction into the living area, installing a fan to suck air out seems like it would be pulling air from the living space. I would get down there and start plugging holes and sealing gaps and maybe install some sort of vapor barrier under the floor joists.

On Wednesday, February 10, 2016 at 3:24:42 PM UTC-5, John G wrote:
On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

If air is leaking in one direction into the living area, installing a fan to suck air out seems like it would be pulling air from the living space. I would get down there and start plugging holes and sealing gaps and maybe install some sort of vapor barrier under the floor joists.

+1

Must be some unusual construction or circumstances where this "dirty
air" is somehow noticeable. And what makes it dirty?

trader_4 wrote:
On Wednesday, February 10, 2016 at 3:24:42 PM UTC-5, John G wrote:
On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

If air is leaking in one direction into the living area, installing a fan to suck air out seems like it would be pulling air from the living space. I would get down there and start plugging holes and sealing gaps and maybe install some sort of vapor barrier under the floor joists.

+1

Must be some unusual construction or circumstances where this "dirty
air" is somehow noticeable. And what makes it dirty?

Single dimensional thinking. No insulation on the ceiling of crawl
space? Dirty air? Maybe Radon gas build up? I just got the Radon gas
level in our basement after 6 months sample collection sent in. Way
below UN or government set limit of safe level. We were told nothing
needs to be done.

Bob writes:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

Why is the crawlspace vented into the living area in the first place?

On 2/10/2016 12:07 PM, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) {this part removed due to stupidity.}


You ignorant arsehole American stoopid ****pig! "Rising up..." Give me
a ****ing break.
Stoopid ****z.
LOL

On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

first you want to seal the floor as well as possible to minimize air from the CS
getting into the house.

Then putting an exhaust fan in the crawl space exhausting to the outside will help to prevent air flow from the CS to the house. But two bad things may happen.
You may pull air from the house into the CS which would waste warm air. Also you may pull more radon up out of the ground.

So..
1) seal as best a possible between the house and the CS
2) vapor barrier on the ground to minimize moisture and radon into CS
3) small exhaust fan to the outside on the lee side of the prevailing wind
4) small opening on the opposite side to let some fresh air into the CS. You don't want the pressure to be too low in the CS, just low enough to minimize air from flowing from the CS into the house.

M

John G wrote:
On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

If air is leaking in one direction into the living area, installing a fan to suck air out seems like it would be pulling air from the living space. I would get down there and start plugging holes and sealing gaps and maybe install some sort of vapor barrier under the floor joists.

Ditto.
Dirty air? May be Radon gas? High level of this gas is
major cause of lung cancer. I had our house basement
Radon gas level checked and it is well below safety limit
of 200Ml/m3.

trader_4 posted for all of us...



On Wednesday, February 10, 2016 at 3:24:42 PM UTC-5, John G wrote:
On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

If air is leaking in one direction into the living area, installing a fan to suck air out seems like it would be pulling air from the living space. I would get down there and start plugging holes and sealing gaps and maybe install some sort of vapor barrier under the floor joists.

+1

Must be some unusual construction or circumstances where this "dirty
air" is somehow noticeable. And what makes it dirty?

Farts and other odoriferous parts of his body.

--
Tekkie

Scott Lurndal posted for all of us...



Bob writes:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

Why is the crawlspace vented into the living area in the first place?

"Dirty air" Can't you read? 8~)

--
Tekkie

No one here mentioned sealing any gaps/cracks in the highest
ceilings in that place, plus the minimum insulation r-value for
your area of the country. That, plus sealing the floor, will stop
the up-drafts in a heartbeat.

On Wed, 10 Feb 2016 16:26:44 -0700, Tony Hwang
wrote:

John G wrote:
On Wednesday, February 10, 2016 at 3:07:14 PM UTC-5, Bob wrote:
Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent) and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace, and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

If air is leaking in one direction into the living area, installing a fan to suck air out seems like it would be pulling air from the living space. I would get down there and start plugging holes and sealing gaps and maybe install some sort of vapor barrier under the floor joists.

Ditto.
Dirty air? May be Radon gas? High level of this gas is
major cause of lung cancer. I had our house basement
Radon gas level checked and it is well below safety limit
of 200Ml/m3.

Goody for you. There is no reason to think that what he calls dirty
has radon in it. Radon is colorless, odorless, tasteless, and
soundless. People don't notice it, so they don't consider it dirty.

I agree with those who thought the crawl space could be sealed from
the rest of the house.

And iiuc you mostly called the crawlspace dirty, not so much its air.
But for your specific questions:

On Wed, 10 Feb 2016 12:07:08 -0800, Bob wrote:

Is it possible to stop the stack effect (rising up of warm air causing
dirty crawlspace air to be sucked into living area) by installing an
exhaust fan in the crawlspace (obviously all vents are covered except
the exhaust vent)

These days, "obviously" has become a very popular word. It's not
obvious to me!! I'd leave one other basement to outside vent
uncovered, at the opposite end of the house. Otherwise what you fear
will indeed happen, and maybe anyhow.

and creating a negative air pressure?

Or would this just create a convection effect where in cooler part of
the house, air migrates down into the crawlspace,

I dont' think it would even have to be cooler if the air pressure in
the crawl space is lower.

and in warmer area of
the house, air rises upwards and pulls the crawlspace air into the
living area?

No, it won't create this. But you've said it already exists. Your
plan would lessen it and maybe eliminate it. It would not increase
it. And your plan is something you can do in the winter, while all
the suggestions for sealing leaks seem best left for the spring or
summer.

!!! But wait a second. Isn't the air in the crawl space colder than
any of the air in the house? Is it really rising from the crawl
space, or is it only a tiny whiff of the smell?

Especially if this only happens in the winter, before you do anything,
you might want to take steps to find those openings that could use
sealing. Do you have any friends who smoke? The could crawl
aroudn the floor etc. puffing out their smoke and you could see if it
rises faster in some places. If it's not too cold, they could crawl
around the crawl space, where it might be more obvious. If not
cigarette smoke, maybe there's a substitute??

If it happens in the spring too, you could turn the fan off and do the
testing when it's warmer in the crawl space, if you're sure you'll get
it done then.

First we need to know if the crawl space is also open to a partial basement, if there is plastic covering the ground in the crawl space, any insulation in the crawl space ceiling or plastic on the underside of the upper level floor joists. Also what is meant by "Dirty Air"? Is it visibly dirty or is it smelly, or what??
More information would make it possible to give more detailed suggestions!!!!!