missing one big factor there.

If there is no pressure difference the leakage is zero.

wrote in message
...
Abby Normal wrote:

In sealed homes, built to Canadian Codes, probably 40% of the heat loss
would be infiltration.

A 2400 ft^2 house built to the Canadian IDEAS standard would only leak 2.5
cfm.

To be realistic, 400 would have to be conductance only

Are you talking about igloos again? :-)

Nick

On 15 Feb 2005 09:41:13 -0800, (Nagliar) wrote:

In this case GimmieButt is totally correct. The type that uses heat,
as he stated, to evaporate the water are called "vaporizers", not
"humidifiers". Some may call them kettles also :)

Why would you feed that brainless troll M II? He never has anything of
value to add or even wants to discuss the topic.

There is a also forth type that has live electrodes in the water and
creates steam that way.

Anthony Matonak wrote in message news:YbhQd.31216$uc.3762@trnddc03...
m II wrote:
Gymmie Bob wrote:

Portable humidifiers do not typically use heat to evaporate the water.
The
heat from the room is used.
...
They DON'T use the heat in the room. Well, maybe in Gymmy Land, but
nowhere else.

http://www.hc-sc.gc.ca/english/iyh/p...umidifiers.htm

Well, surprising as it is, GB is 2/3 correct. As that webpage
indicates, there are three types of humidifiers. One uses a
hot coil to boil water and create steam. One uses an ultrasonic
driver to suspend tiny water droplets in the air and one uses
an atomizer to spray tiny water droplets into the air. The
last two rely on the fact that the tiny water droplets will
evaporate. This evaporation uses heat from the air.

There are also the swamp cooler style humidifiers where air
is blown through/past a wet pad. These also use the heat in
the air to evaporate the water. Typically they aren't portable
though.

Anthony

You mention ANY type of humidifier and I can tell you that I have
tryed them all, My stainless kitchen sink has black spots from the
type that uses the conductivity of the water to generate steam. Call
them vaporizers humidifiers or super life savers if you want.

Large humidifiers use mainly steam because it adds vapor generated by
distilled water into the rooms. Most of the unwanted garbage that
comes on the water, bacteria included, stays on the boiling container
and must be cleaned, usually, once a year.

The type that stores the water on the surface of some material and
them operates like your clothes dryer is probably the worse for
bacteria grow and distribution. Your dryer does a good job because
you replace the wet material every time it dries.

There are the so called vaporizers that use an ultrasonic transducer
and a small blower, but they also disperse the unwanted garbage in
the water. Same people use distilled water but the cost and
inconvenience are too much trouble.

The first thing to do is removed the top of the cover . We don't need
it and we must have room to install the a water level sensor, wich is
the main problem with the kettle. We need a mechanism tah will
maintain the water level at the proper level, not a trivial task since
the water is in constant ebullition. At the present I am using an
encapsulated mercury switch attached to a lever with a floating bulb
at the end. That operates an electric valve connected to the water
supply. The bulb breaks if simultaneously exposed to different
temperatures like cold water. By making a loop on the copper tube
that supply the water inside of the kettle, to raise the water
temperature before it's release and reducing the water flow to a
trickle the problem is solved.

I had two minor floods during the last 5 years. The first was caused
by a cracked bulb caused the system to "think" that the water was at
low level and continued to supply water until the problem is
corrected. The second was caused by a rusted component on the same
mechanism.

Kettles have their on safety system that protects them from over
heating if there is no water. Late models use a sealed popping sensor
that does a good job. Easy to test. If you power a kettle without
water, it will click on and off for days and will not likely create
any problem.

As a extra precaution I have installed a larger tray under the kettle
with a drainage tube that exhausts the water if the float fails.
Of course, since I installed this, the system never failed.

Sorry for my poor English but it isn't my mother's language.
Some times and don't even understand it myself.

Vlad

Your English is perfect to me! Not even a spelling mistake!

Evere notice those electrode steamers will not work with distilled water as
it is an insulator to electrical currents? You have to clean them. No way
around it.


"Vlad" wrote in message
...
On 15 Feb 2005 09:41:13 -0800, (Nagliar) wrote:

In this case GimmieButt is totally correct. The type that uses heat,
as he stated, to evaporate the water are called "vaporizers", not
"humidifiers". Some may call them kettles also :)

Why would you feed that brainless troll M II? He never has anything of
value to add or even wants to discuss the topic.

There is a also forth type that has live electrodes in the water and
creates steam that way.

Anthony Matonak wrote in message
news:YbhQd.31216$uc.3762@trnddc03...
m II wrote:
Gymmie Bob wrote:

Portable humidifiers do not typically use heat to evaporate the
water.
The
heat from the room is used.
...
They DON'T use the heat in the room. Well, maybe in Gymmy Land, but
nowhere else.

http://www.hc-sc.gc.ca/english/iyh/p...umidifiers.htm

Well, surprising as it is, GB is 2/3 correct. As that webpage
indicates, there are three types of humidifiers. One uses a
hot coil to boil water and create steam. One uses an ultrasonic
driver to suspend tiny water droplets in the air and one uses
an atomizer to spray tiny water droplets into the air. The
last two rely on the fact that the tiny water droplets will
evaporate. This evaporation uses heat from the air.

There are also the swamp cooler style humidifiers where air
is blown through/past a wet pad. These also use the heat in
the air to evaporate the water. Typically they aren't portable
though.

Anthony

You mention ANY type of humidifier and I can tell you that I have
tryed them all, My stainless kitchen sink has black spots from the
type that uses the conductivity of the water to generate steam. Call
them vaporizers humidifiers or super life savers if you want.

Large humidifiers use mainly steam because it adds vapor generated by
distilled water into the rooms. Most of the unwanted garbage that
comes on the water, bacteria included, stays on the boiling container
and must be cleaned, usually, once a year.

The type that stores the water on the surface of some material and
them operates like your clothes dryer is probably the worse for
bacteria grow and distribution. Your dryer does a good job because
you replace the wet material every time it dries.

There are the so called vaporizers that use an ultrasonic transducer
and a small blower, but they also disperse the unwanted garbage in
the water. Same people use distilled water but the cost and
inconvenience are too much trouble.

The first thing to do is removed the top of the cover . We don't need
it and we must have room to install the a water level sensor, wich is
the main problem with the kettle. We need a mechanism tah will
maintain the water level at the proper level, not a trivial task since
the water is in constant ebullition. At the present I am using an
encapsulated mercury switch attached to a lever with a floating bulb
at the end. That operates an electric valve connected to the water
supply. The bulb breaks if simultaneously exposed to different
temperatures like cold water. By making a loop on the copper tube
that supply the water inside of the kettle, to raise the water
temperature before it's release and reducing the water flow to a
trickle the problem is solved.

I had two minor floods during the last 5 years. The first was caused
by a cracked bulb caused the system to "think" that the water was at
low level and continued to supply water until the problem is
corrected. The second was caused by a rusted component on the same
mechanism.

Kettles have their on safety system that protects them from over
heating if there is no water. Late models use a sealed popping sensor
that does a good job. Easy to test. If you power a kettle without
water, it will click on and off for days and will not likely create
any problem.

As a extra precaution I have installed a larger tray under the kettle
with a drainage tube that exhausts the water if the float fails.
Of course, since I installed this, the system never failed.

Sorry for my poor English but it isn't my mother's language.
Some times and don't even understand it myself.

Vlad

Gymmie Bob wrote in message
...

missing one big factor there.

Nope, its only a small factore.

If there is no pressure difference the leakage is zero.

Yes, but there usually is a pressure difference. The only time
there isnt is when its dead calm outside and that isnt that common.

wrote in message
...
Abby Normal wrote:

In sealed homes, built to Canadian Codes, probably 40% of the heat loss
would be infiltration.

A 2400 ft^2 house built to the Canadian IDEAS standard would only leak 2.5
cfm.

To be realistic, 400 would have to be conductance only

Are you talking about igloos again? :-)

Nick

On Thu, 17 Feb 2005 11:51:17 -0500, "Gymmie Bob"
wrote:

Your English is perfect to me! Not even a spelling mistake!

Evere notice those electrode steamers will not work with distilled water as
it is an insulator to electrical currents? You have to clean them. No way
around it.

Yes, I had to place some salt on the water in order to get some
conductivity. Not very convenient. Rain water wasn't dirty enough

Regards
Vlad


"Vlad" wrote in message
.. .
On 15 Feb 2005 09:41:13 -0800, (Nagliar) wrote:

In this case GimmieButt is totally correct. The type that uses heat,
as he stated, to evaporate the water are called "vaporizers", not
"humidifiers". Some may call them kettles also :)

Why would you feed that brainless troll M II? He never has anything of
value to add or even wants to discuss the topic.

There is a also forth type that has live electrodes in the water and
creates steam that way.

Anthony Matonak wrote in message
news:YbhQd.31216$uc.3762@trnddc03...
m II wrote:
Gymmie Bob wrote:

Portable humidifiers do not typically use heat to evaporate the
water.
The
heat from the room is used.
...
They DON'T use the heat in the room. Well, maybe in Gymmy Land, but
nowhere else.

http://www.hc-sc.gc.ca/english/iyh/p...umidifiers.htm

Well, surprising as it is, GB is 2/3 correct. As that webpage
indicates, there are three types of humidifiers. One uses a
hot coil to boil water and create steam. One uses an ultrasonic
driver to suspend tiny water droplets in the air and one uses
an atomizer to spray tiny water droplets into the air. The
last two rely on the fact that the tiny water droplets will
evaporate. This evaporation uses heat from the air.

There are also the swamp cooler style humidifiers where air
is blown through/past a wet pad. These also use the heat in
the air to evaporate the water. Typically they aren't portable
though.

Anthony

You mention ANY type of humidifier and I can tell you that I have
tryed them all, My stainless kitchen sink has black spots from the
type that uses the conductivity of the water to generate steam. Call
them vaporizers humidifiers or super life savers if you want.

Large humidifiers use mainly steam because it adds vapor generated by
distilled water into the rooms. Most of the unwanted garbage that
comes on the water, bacteria included, stays on the boiling container
and must be cleaned, usually, once a year.

The type that stores the water on the surface of some material and
them operates like your clothes dryer is probably the worse for
bacteria grow and distribution. Your dryer does a good job because
you replace the wet material every time it dries.

There are the so called vaporizers that use an ultrasonic transducer
and a small blower, but they also disperse the unwanted garbage in
the water. Same people use distilled water but the cost and
inconvenience are too much trouble.

The first thing to do is removed the top of the cover . We don't need
it and we must have room to install the a water level sensor, wich is
the main problem with the kettle. We need a mechanism tah will
maintain the water level at the proper level, not a trivial task since
the water is in constant ebullition. At the present I am using an
encapsulated mercury switch attached to a lever with a floating bulb
at the end. That operates an electric valve connected to the water
supply. The bulb breaks if simultaneously exposed to different
temperatures like cold water. By making a loop on the copper tube
that supply the water inside of the kettle, to raise the water
temperature before it's release and reducing the water flow to a
trickle the problem is solved.

I had two minor floods during the last 5 years. The first was caused
by a cracked bulb caused the system to "think" that the water was at
low level and continued to supply water until the problem is
corrected. The second was caused by a rusted component on the same
mechanism.

Kettles have their on safety system that protects them from over
heating if there is no water. Late models use a sealed popping sensor
that does a good job. Easy to test. If you power a kettle without
water, it will click on and off for days and will not likely create
any problem.

As a extra precaution I have installed a larger tray under the kettle
with a drainage tube that exhausts the water if the float fails.
Of course, since I installed this, the system never failed.

Sorry for my poor English but it isn't my mother's language.
Some times and don't even understand it myself.

Vlad

"Gymmie Bob" wrote in message
...
missing one big factor there.

If there is no pressure difference the leakage is zero.

The only time that occurs is a dead calm *and* the outside temperature is
the same as inside. In that case, who cares? If there is a temperature
difference, then there is a difference in pressure that can cause leakage.

daestrom

wrote in message
...
daestrom wrote:

If it only leaks 0.4x2400x8x0.075 = 576 lb/h (128 cfm, vs ASHRAE's 15
cfm
per occupant fresh air standard), humidification expends 5.3X the
savings.

US houses leak way too much air. Air-sealing raises indoor humidity and
actually saves heat energy.

Probably true, but doesn't ASHRAE have a minimum recommended ventilation
level to control pollutants?

That's the 15 cfm/occupant above...

Just looking at the '400 Btu/hr-F' figure, to get that with 0.7 ACH, we
have
about 244 Btu/hr-F to warm up the fresh air coming through, and 156
Btu/hr-F
actual conductance. For a 49x49x8 house, that would be something like
R-40
in the ceiling and R-16 in the walls. Over half the energy is lost
through
the air leakage portion.

US houses leak way too much air, enough for 244/15 = 16 full-time
occupants
on a cold day, with no fresh air at all on a mild day.

Even the 'tight' 160 cfm for the theoretical house we've been discussing,
that's still 160/15 = 10+ full-time occupants.


Is there any practical way to measure a house's air leakage? I've seen
the
'fan-in-the-doorway' trick used to find drafts, but does it actually
*measure* the leakage?

Yes. They pressurize or depressurize a house to 50 Pascals using a $50
Magnehelic gauge and measure the leakage as a pressure difference across
a calibrated orifice in the door. Natural air leakage is about 20X less
than the measured leakage at 50 Pa.


I was looking for something that would measure *actual* leakage, not some
number at 50 Pa. To get an idea of how much leakage actually occurs on a
typical winter day. 'Natural air leakage is about 20X less....' doesn't
sound as accurate as some sort of direct measurement under typical winter
conditions (in winter, I try to keep the windows and doors closed, not open
with some fan deliberately drafting on the house ;-).

daestrom

"Gymmie Bob" wrote in message
...
That's just nonsense and is probably just a troll from a person like you.

tit for tat?

All the skin is in parallel to the arc circuit. If you understand parallel
and series electrical circuits at all you will know the voltage is excatly
the same. I agree with what you are saying. However, I think you mean the
**current** is lower by being spread out throughout a larger area of flesh
and feels less. The cureent in the arc is no less though. The voltage
doesn't change because of the area or other external factors to the arc.

The distance it jumps does determine the intensity or heat created by the
spark. High voltage corona theorum tells us that a pointed object will
"bleed" or discharge smaller sparks more easily and a blunt object (your
finger or flesh) will tend to build up the charge and snap a much more
intense zap. This is the principle of lightning rods used on farmer's
barns.
The sharp points in the air tend to "bleed" the static electrical
difference
from the air in an attempt to keep the big zap from happenning.

I doubt your key is going to "bleed" the static charge as it just isn't in
proximity long enough. This isn't enough difference to feel safe
discharging
static around a flammable/volatile substance. Highly not recommended and
very dangerous to practice and/or recommend.


All your theory and 'doubts' aside, try it. Walking across a carpet and
touch a door knob directly (assuming the humidity is low enough and you have
the 'wrong' kind of shoes). Then repeat the experiment with car keys and
touch the knob with them. Unless your central nervous system is shot, you
*will* notice a difference.

daestrom

"daestrom" wrote in message
...

wrote in message
...
daestrom wrote:

If it only leaks 0.4x2400x8x0.075 = 576 lb/h (128 cfm, vs ASHRAE's 15 cfm
per occupant fresh air standard), humidification expends 5.3X the savings.

US houses leak way too much air. Air-sealing raises indoor humidity and
actually saves heat energy.

Probably true, but doesn't ASHRAE have a minimum recommended ventilation
level to control pollutants?

That's the 15 cfm/occupant above...

Just looking at the '400 Btu/hr-F' figure, to get that with 0.7 ACH, we have
about 244 Btu/hr-F to warm up the fresh air coming through, and 156 Btu/hr-F
actual conductance. For a 49x49x8 house, that would be something like R-40
in the ceiling and R-16 in the walls. Over half the energy is lost through
the air leakage portion.

US houses leak way too much air, enough for 244/15 = 16 full-time occupants
on a cold day, with no fresh air at all on a mild day.

Even the 'tight' 160 cfm for the theoretical house we've been discussing,
that's still 160/15 = 10+ full-time occupants.


Is there any practical way to measure a house's air leakage? I've seen the
'fan-in-the-doorway' trick used to find drafts, but does it actually
*measure* the leakage?

Yes. They pressurize or depressurize a house to 50 Pascals using a $50
Magnehelic gauge and measure the leakage as a pressure difference across
a calibrated orifice in the door. Natural air leakage is about 20X less
than the measured leakage at 50 Pa.


I was looking for something that would measure *actual* leakage, not some
number at 50 Pa. To get an idea of how much leakage actually occurs on a
typical winter day. 'Natural air leakage is about 20X less....' doesn't sound
as accurate as some sort of direct measurement under typical winter conditions
(in winter, I try to keep the windows and doors closed, not open with some fan
deliberately drafting on the house ;-).

The short story is that it isnt possible to measure what you want
to measure without rather extreme measures like say special
isotope tracer gas and monitor the isotope ratio as it leaks away.

daestrom wrote:

Even the 'tight' 160 cfm for the theoretical house we've been discussing,
that's still 160/15 = 10+ full-time occupants.

Too much... And too little, on a mild day with no wind.

Is there any practical way to measure a house's air leakage?

...pressurize or depressurize a house to 50 Pascals using a $50 Magnehelic
gauge and measure the leakage as a pressure difference across a calibrated
orifice... Natural air leakage is about 20X less than leakage at 50 Pa.

I was looking for something that would measure *actual* leakage, not some
number at 50 Pa.

A tracer gas technique. Raise the level of some odd gas like UF6 or water
vapor inside the house, then measure the concentration as it decays over
time. I did this accidently last year with a woodstove, shoveling ash out
into a bin before going to bed. As it turned out, some of the ash was live,
so my digital CO detector woke me at 3 AM. I *could* have quietly sat beside
it and recorded the concentration as it decayed, but I opened the windows
instead. At any rate, these techniques depend on the weather, a confounding
variable, if we really want to measure the house....

All new low-income housing in Phila is blower-door tested, by law. Middle
and upper-class people don't get this treatment, unless they buy an energy
star electrically-heated house.

Nick

Well that can't be measured very easily then. Figures would have to be
established on each side of the house and maybe the bisecting angles in
between. Now who knows which way the wind blows and for how long and the
answer is:

A big ****ing guess!

"Rod Speed" wrote in message
...

Gymmie Bob wrote in message
...

missing one big factor there.

Nope, its only a small factore.

If there is no pressure difference the leakage is zero.

Yes, but there usually is a pressure difference. The only time
there isnt is when its dead calm outside and that isnt that common.

wrote in message
...
Abby Normal wrote:

In sealed homes, built to Canadian Codes, probably 40% of the heat
loss
would be infiltration.

A 2400 ft^2 house built to the Canadian IDEAS standard would only leak
2.5
cfm.

To be realistic, 400 would have to be conductance only

Are you talking about igloos again? :-)

Nick

You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?

"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
missing one big factor there.

If there is no pressure difference the leakage is zero.

The only time that occurs is a dead calm *and* the outside temperature is
the same as inside. In that case, who cares? If there is a temperature
difference, then there is a difference in pressure that can cause leakage.

daestrom

Can't you people read at all here?
I total agreed with that and it wasn't the argument.


"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
That's just nonsense and is probably just a troll from a person like
you.

tit for tat?

All the skin is in parallel to the arc circuit. If you understand
parallel
and series electrical circuits at all you will know the voltage is
excatly
the same. I agree with what you are saying. However, I think you mean
the
**current** is lower by being spread out throughout a larger area of
flesh
and feels less. The cureent in the arc is no less though. The voltage
doesn't change because of the area or other external factors to the arc.

The distance it jumps does determine the intensity or heat created by
the
spark. High voltage corona theorum tells us that a pointed object will
"bleed" or discharge smaller sparks more easily and a blunt object (your
finger or flesh) will tend to build up the charge and snap a much more
intense zap. This is the principle of lightning rods used on farmer's
barns.
The sharp points in the air tend to "bleed" the static electrical
difference
from the air in an attempt to keep the big zap from happenning.

I doubt your key is going to "bleed" the static charge as it just isn't
in
proximity long enough. This isn't enough difference to feel safe
discharging
static around a flammable/volatile substance. Highly not recommended and
very dangerous to practice and/or recommend.


All your theory and 'doubts' aside, try it. Walking across a carpet and
touch a door knob directly (assuming the humidity is low enough and you
have
the 'wrong' kind of shoes). Then repeat the experiment with car keys and
touch the knob with them. Unless your central nervous system is shot, you
*will* notice a difference.

daestrom

"Vlad" wrote in message
...
On Thu, 17 Feb 2005 11:51:17 -0500, "Gymmie Bob"
wrote:

Your English is perfect to me! Not even a spelling mistake!

Evere notice those electrode steamers will not work with distilled water
as
it is an insulator to electrical currents? You have to clean them. No way
around it.

Yes, I had to place some salt on the water in order to get some
conductivity. Not very convenient. Rain water wasn't dirty enough

Regards
Vlad


This water is pretty dirty www.tubgirl.com

"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot. Of course a temperature difference between the oven and
the kitchen doesn't develop a large difference in pressure to 'implode the
oven'. But a 20 ft tall house heated 50 to 60 F warmer than the outside
will generate enough of a pressure difference to cause air leakage if the
house isn't sealed up properly.

The difference in pressure created by a temperature difference is easily
calculated as the density of the fluid on one side (inside the house) times
the vertical distance, minus the density of the fluid on the other side (the
outside air) times the same vertical distance.

With an indoor temp of 70F and outdoor of 0F over a 20ft height would be
about 11 Pascals. Not the 50 that Nick mentioned in the test he described,
but enough to cause significant in-leakage at the ground floor. A 400F oven
that is 2 ft high in a 70F kitchen could generate a pressure difference of
only ~3 Pascals from the bottom of the oven.

Leave the damper open in a fireplace with no fire in the grate. In winter
time there will be a strong draft as this modest pressure difference forces
heated air from the room up the chimney.

Look up 'natural convection' or 'natural circulation'. It is caused by a
density difference that is brought on by a temperature difference, acting on
two columns of fluid. A layman explains it by saying 'hot air rises', but
that isn't quite true. 'Hot air' only rises if there is some 'cold air'
that can get underneath and push it up; and the fact that air changes
density with temperature and gravity acting on the two masses.

daestrom

You are lacking some basic physics there
Later

"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot. Of course a temperature difference between the oven
and
the kitchen doesn't develop a large difference in pressure to 'implode the
oven'. But a 20 ft tall house heated 50 to 60 F warmer than the outside
will generate enough of a pressure difference to cause air leakage if the
house isn't sealed up properly.

The difference in pressure created by a temperature difference is easily
calculated as the density of the fluid on one side (inside the house)
times
the vertical distance, minus the density of the fluid on the other side
(the
outside air) times the same vertical distance.

With an indoor temp of 70F and outdoor of 0F over a 20ft height would be
about 11 Pascals. Not the 50 that Nick mentioned in the test he
described,
but enough to cause significant in-leakage at the ground floor. A 400F
oven
that is 2 ft high in a 70F kitchen could generate a pressure difference of
only ~3 Pascals from the bottom of the oven.

Leave the damper open in a fireplace with no fire in the grate. In winter
time there will be a strong draft as this modest pressure difference
forces
heated air from the room up the chimney.

Look up 'natural convection' or 'natural circulation'. It is caused by a
density difference that is brought on by a temperature difference, acting
on
two columns of fluid. A layman explains it by saying 'hot air rises', but
that isn't quite true. 'Hot air' only rises if there is some 'cold air'
that can get underneath and push it up; and the fact that air changes
density with temperature and gravity acting on the two masses.

daestrom

"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot.

Its too late

Heating only causes expansion, and maybe a pressure difference, as a factor
of the temperature change not from temperature itself. In other words, the
static temperature doesn't matter whether your house is 70 deg or 400 deg F,
the temperature difference between inside and outside does not make
pressure. This can only happen if the temperature of the air changes and
expands or contracts. Now the house has to breathe to equalize. Since my and
most other houses stay at a constant 72F +/- a few there is no pressure as
you put it.

This is all just nonsense and not enough of a factor to consider for heating
or ventilation purposes. relying on the wind or atmospheric pressure changes
is not a very good engineering practice, cannot be relied upon, and it just
insignificant on a house built in the lat 20 years.

Your logic on pressure due to column height is just plan nonsense also.
Column height of air does not change pressure significantly inside a house
or oven. A ceiling fan changes the pressure of air much greater than the
difference of the top to bottom of a 30 foot column of air.

The updraught on the chimney you speak of is from two factors. The heated
air being lighter than the outside air causing convection (as you spoke of)
and the venturi action of a cross wind passing the opening of the flue.

This is all basic grade 9 physics where I was raised.


"Gymmie Bob" wrote in message
...
You are lacking some basic physics there
Later

"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot. Of course a temperature difference between the oven
and
the kitchen doesn't develop a large difference in pressure to 'implode
the
oven'. But a 20 ft tall house heated 50 to 60 F warmer than the outside
will generate enough of a pressure difference to cause air leakage if
the
house isn't sealed up properly.

The difference in pressure created by a temperature difference is easily
calculated as the density of the fluid on one side (inside the house)
times
the vertical distance, minus the density of the fluid on the other side
(the
outside air) times the same vertical distance.

With an indoor temp of 70F and outdoor of 0F over a 20ft height would be
about 11 Pascals. Not the 50 that Nick mentioned in the test he
described,
but enough to cause significant in-leakage at the ground floor. A 400F
oven
that is 2 ft high in a 70F kitchen could generate a pressure difference
of
only ~3 Pascals from the bottom of the oven.

Leave the damper open in a fireplace with no fire in the grate. In
winter
time there will be a strong draft as this modest pressure difference
forces
heated air from the room up the chimney.

Look up 'natural convection' or 'natural circulation'. It is caused by
a
density difference that is brought on by a temperature difference,
acting
on
two columns of fluid. A layman explains it by saying 'hot air rises',
but
that isn't quite true. 'Hot air' only rises if there is some 'cold air'
that can get underneath and push it up; and the fact that air changes
density with temperature and gravity acting on the two masses.

daestrom

Gymmie Bob wrote:
Heating only causes expansion, and maybe a pressure difference, as a
factor
of the temperature change not from temperature itself. In other
words, the
static temperature doesn't matter whether your house is 70 deg or 400
deg F,
the temperature difference between inside and outside does not make
pressure. This can only happen if the temperature of the air changes
and
expands or contracts. Now the house has to breathe to equalize. Since
my and
most other houses stay at a constant 72F +/- a few there is no
pressure as
you put it.

This is all just nonsense and not enough of a factor to consider for
heating
or ventilation purposes. relying on the wind or atmospheric pressure
changes
is not a very good engineering practice, cannot be relied upon, and
it just
insignificant on a house built in the lat 20 years.

Your logic on pressure due to column height is just plan nonsense
also.
Column height of air does not change pressure significantly inside a
house
or oven. A ceiling fan changes the pressure of air much greater than
the
difference of the top to bottom of a 30 foot column of air.

The updraught on the chimney you speak of is from two factors. The
heated
air being lighter than the outside air causing convection (as you
spoke of)
and the venturi action of a cross wind passing the opening of the
flue.

This is all basic grade 9 physics where I was raised.


"Gymmie Bob" wrote in message
...
You are lacking some basic physics there
Later

"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot. Of course a temperature difference between
the oven
and
the kitchen doesn't develop a large difference in pressure to
'implode
the
oven'. But a 20 ft tall house heated 50 to 60 F warmer than the
outside
will generate enough of a pressure difference to cause air
leakage if
the
house isn't sealed up properly.

The difference in pressure created by a temperature difference is
easily
calculated as the density of the fluid on one side (inside the
house)
times
the vertical distance, minus the density of the fluid on the
other side
(the
outside air) times the same vertical distance.

With an indoor temp of 70F and outdoor of 0F over a 20ft height
would be
about 11 Pascals. Not the 50 that Nick mentioned in the test he
described,
but enough to cause significant in-leakage at the ground floor.
A 400F
oven
that is 2 ft high in a 70F kitchen could generate a pressure
difference
of
only ~3 Pascals from the bottom of the oven.

Leave the damper open in a fireplace with no fire in the grate.
In
winter
time there will be a strong draft as this modest pressure
difference
forces
heated air from the room up the chimney.

Look up 'natural convection' or 'natural circulation'. It is
caused by
a
density difference that is brought on by a temperature
difference,
acting
on
two columns of fluid. A layman explains it by saying 'hot air
rises',
but
that isn't quite true. 'Hot air' only rises if there is some
'cold air'
that can get underneath and push it up; and the fact that air
changes
density with temperature and gravity acting on the two masses.

daestrom






Is someone trying to re-invent the wheel here or is infiltration due to
stack effect being argued?

"Gymmie Bob" wrote in message
...
Your logic on pressure due to column height is just plan nonsense also.
Column height of air does not change pressure significantly inside a house
or oven. A ceiling fan changes the pressure of air much greater than the
difference of the top to bottom of a 30 foot column of air.

The updraught on the chimney you speak of is from two factors. The heated
air being lighter than the outside air causing convection (as you spoke
of)
and the venturi action of a cross wind passing the opening of the flue.

This is all basic grade 9 physics where I was raised.

Maybe you shouldn't have stopped at grade 8 then. You seem to have a warped
idea of what 'change pressure significantly' means. Trouble with using such
inexact terms as 'significantly' is you have to put them in context. In the
context of ventilation in a house, the 11 Pascal pressure difference I
calculated *is* 'significant'. If we were discussing the air pressure in
all four tires of your car, then an 11 Pascal pressure difference would not
be 'significant'.

Here, try some physics...

ideal gas law, gives us the density of 1 ft^3 of dry air at a given
temperature....
At 70 F...
density = 14.696*144 / ((70+460)*53.3) = 0.074913 lbm/ft^3
At 0F...
density = 14.696*144 / ((0+460)*53.3) = 0.086313 lbm/ft^3

The difference in the pressure exerted by gravity on two 20 ft columns of
air at these densities is approximately....

delta pressure = 20 ft*( 0.086313 - 0.074913) lb/ft^3 = 0.228 lbf / ft^2.

0.228 lbf/ft^2 is about 11 Pascals

So if the pressure at the top of the house is the same inside the building
envelope as it is outside, then the pressure at ground floor level inside is
0.228 lbf/ft^2 *less* than the pressure outside at the same elevation. Cold
air pushes in down low, near the foundation and pushes warm air out near the
roof.

Now, do you have *any* idea how much air flow that 11 Pascal pressure
difference can develop if it is pushing air through a combination of cracks
and crevices that add up to a total cross-section of about 0.4 ft^2 (similar
to a crack about 1/8 inch wide totaling 40 ft in length)?????

Here, try this if the math is too much for you....
http://chuck-wright.com/calculators/stack_effect.html
Just enter 0.4 for area, 20 for height difference, 70 for indoor temperature
and 0 for outdoor temperature. Voila!

ASHRAE's stack effect formula is for a deliberate opening with something
near circular shape ( Cd of 0.65). A very long and narrow crack would not
provide this much flow because of its very different hydraulic diameter.
Can you compensate for the difference in hydraulic diameter from an
unobstructed circular opening and a very long and narrow rectangular
opening? Here's a hint, for openings where the length width, just use
the length for the hydraulic diameter, and for circular openings, use the
diameter of the opening. So the correction factor for the different shape
would be 0.714 / 40. Now, if you just knew how to apply it....

You don't need a *changing* temperature to develop this pressure difference,
you just need gravity, a fluid that is a different density at different
temperatures (like air) in the two columns, and a vertical distance over
which the density difference acts.

Regarding ovens, most gas ovens rely on this same effect to move the
combustion products from where the gas is burned, out of the oven (no
'venturi action' inside the kitchen). The developed pressure difference is
less, but since the openings are deliberately made to encourage this flow,
it works just fine. Of course there is a trade off, because you want the
combustion products to be vented out effectively, but too much flow and the
oven cools rapidly between burner cycles, wasting energy and heating up the
kitchen.

daestrom
P.S. A chimney that relies on it being a windy day in order to draw
properly is a waste of stove pipe.

Is someone trying to re-invent the wheel here or is infiltration due to
stack effect being argued?


Well, we're not trying to 're-invent' it, but that is exactly what we're
discussing. Old 'Gymmie Bob' doesn't believe that a temperature difference
between the air inside the house and outside creates any 'significant' sort
of pressure difference. But he seems to grasp at some level that such a
temperature difference can cause a draft up a chimny (i.e. 'stack effect').

But apparently his physics education stopped before he got to grade 9 where
,"This is all basic grade 9 physics where I was raised."

daestrom

"Noon-Air" wrote in message
...

"daestrom" wrote in message
...

"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot.

Its too late

Sigh....

Apparently so.... :-)

daestrom

"Gymmie Bob" wrote in message
...
Heating only causes expansion, and maybe a pressure difference, as a
factor
of the temperature change not from temperature itself. In other words, the
static temperature doesn't matter whether your house is 70 deg or 400 deg
F,
the temperature difference between inside and outside does not make
pressure. This can only happen if the temperature of the air changes and
expands or contracts. Now the house has to breathe to equalize. Since my
and
most other houses stay at a constant 72F +/- a few there is no pressure as
you put it.

This is all just nonsense and not enough of a factor to consider for
heating
or ventilation purposes. relying on the wind or atmospheric pressure
changes
is not a very good engineering practice, cannot be relied upon, and it
just
insignificant on a house built in the lat 20 years.

Your logic on pressure due to column height is just plan nonsense also.
Column height of air does not change pressure significantly inside a house
or oven. A ceiling fan changes the pressure of air much greater than the
difference of the top to bottom of a 30 foot column of air.

The updraught on the chimney you speak of is from two factors. The heated
air being lighter than the outside air causing convection (as you spoke
of)

Gee, one minute it's 'all just nonsense', or 'just plan[sic] nonsense...' or
'can only happen if the temperature of the air changes', and the next minute
you're using the same phenomenon to explain the 'updraught on the chimney'.
Can't make up your mind?? Using what you call 'nonsense' to explain
things??

If this is all 'just insignificant on a house built in the lat[sic] 20
years', then I guess every house built over that time period has 0 air
leakage on a calm winter day?? How silly of you to even suggest that.

So, how much does a ceiling fan change the pressure of air in a room???

daestrom

daestrom wrote:

Is someone trying to re-invent the wheel here or is infiltration
due to
stack effect being argued?


Well, we're not trying to 're-invent' it, but that is exactly what
we're
discussing. Old 'Gymmie Bob' doesn't believe that a temperature
difference
between the air inside the house and outside creates any
'significant' sort
of pressure difference. But he seems to grasp at some level that
such a
temperature difference can cause a draft up a chimny (i.e. 'stack
effect').

But apparently his physics education stopped before he got to grade 9
where
,"This is all basic grade 9 physics where I was raised."

daestrom

Stack effect is temperature driven.

On Sun, 13 Feb 2005 19:21:28 -0500, "Gymmie Bob"
wrote:

After getting a nasty poke under a 230kV line some investigations started to
occur. Before the investigators could get my vehicle back to the spot on a
nice sunny dry day the tires got changes and they could not duplicate the
potential hazard. I registered 760Vac to puddle and they could only get 150
or so.


230kV AC? AC?


Another utility bloke told me radial tires have less problem with it. It may
have something to do with the bands of steel going full to the rim in
radials.

"daestrom" wrote in message
. ..

"wmbjk" wmbjk@remove_this citlink.net wrote in message
...
On Sun, 13 Feb 2005 16:57:05 GMT, "daestrom"
wrote:


"wmbjk" wmbjk@remove_this citlink.net wrote in message
. ..

It happens to me *every* time I get out of the car (AZ). I sort of
smack the window frame as I get out, which lessens the effect, and
eliminates the surprise. Strangely enough, it *never* happens to my
wife, who wears very similar clothing.

Wayne

Perhaps it's her shoes. Similar clothing would *generate* similar
charge,
but a different kind of shoe could dissipate the charge faster.

Similar shoes most times as well.

Or maybe she holds onto the door when getting out?

We both get out while opening the door by its plastic handle. She's
usually on the passenger side, so I just asked her if she gets a shock
when getting out after driving. She says she might have. So maybe the
charge builds through the steering wheel? Still, it seems like there
must be some other difference. One more thing... I can't remember ever
getting zapped when driving the truck. So, same guy, same clothes,
same (or similar) cloth upholstery, same route, yet a major difference
in the shock frequency. Is it possible that the vehicles could be
getting charged up from driving on dusty roads, and that the lower
ground clearance of the car makes for more charge?


IIRC, most modern tires have enough carbon in the rubber that they can
dissipate static charge through them. I do remember old gas tankers that
would drag a short length of chain under them to keep them 'grounded', but
haven't seen that in years.

Maybe the upholstery or foam cushions underneath?

daestrom