Cooling attic (and home) by spraying water on roof (shingles) - good/bad? - Page 2

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Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


Phil Scott wrote:

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I still don't see an effective way to arrange a residential cooling
system based on the evaporation of water.

I don't think you can concentrate and deliver a substantial amount of
heat to a surface you can cool via evaporation.  Evaporative cooling
would be effective if the heat inside a house could be brought to an
out-door device who's surface temperature is well above boiling and
the application of water would result in evaporative cooling.  

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So what you're saying is to mistify the air circulating in a house in
order to cool it.  I don't think that would work once you've saturated
the air (ie humidity > 75%) not to mention the effects of saturated
air on items in the house, the wood, the machinery, etc.

I think only the roof makes a workable item to cool with a water
cooling.  It's designed to get wet, to collect runoff, and gets very
hot in the summer, and cooling it can lead to reduction in cooling
requirements of the house.

The only thing that makes more sense is a temporary tarp or canopy to
cover the roof during the summer (to be taken down during nasty
weather, storms, etc).


Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?



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the
cooling
amount of
cooling
brought to an
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boiling and
cooling.
house in
saturated
saturated

I am a mechancal engineer doing these sorts of calculations
and systems for over 40 years.. and you are entirely correct
if the humidity is say 50% and the outside air is 90F... you
can cool the air to 75 or so but the humidity is then up into
the 80% range and all the problems you mention manifest.
Thats why evaportive cooling is not used in many cases.

However in areas where the relative humidity is in the 20 to
30% range, and the outside air is over 90F... then the supply
air can be cooled to 70F and 50% relative humidity..that works
very well/


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water
gets very
cooling

     Its workable...but there are problems ..its seldom used
because of those problems.   You get to do whatever you wish
though its yer house.  Have fun.


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canopy to
nasty

  Oh please.


Phil Scott




Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


Don't cooling towers use evaporative cooling?

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Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?



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Yes they do... but they discharge 100% relative humidity
air...but its outside so its fine...the water in the process
is cooled and that cool water is used to cool most often the
condensers on large tonnage refrigerated AC systems.  that
water typically runs 65 to 80 degrees F... sufficiently cool
to cool condensers but not cool enough to be used directly for
conditioning air  (below 40F is required)

Phil Scott
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then
residential
substantial
Evaporative
in a
you've
of
calculations
correct
you
into
to
supply
works
a
and
in
used
wish
or
during




Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?



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Well you really lost me now. Hasn't this suggestion of water ON the roof
been about water on the outside of the house?
So the humidity created by a watered roof would be outside, just as with a
cooling tower.

Chas Hurst



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Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?



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process
the
cool
for
ON the roof
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just as with a
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correct...thats why your plan WORKS....that is...it is
VIABLE....in other words...you are NOT wrong.... said another
way...your plan to cool the roof and thus reduce attic temps
will fly like an eagle...  its FLAWLESS....

to elaborate... water cooling works GREAT... your plan it
water cooling the roof... very very good.


  Its just that an attic fan works better without whatever
problems are incurred by wetting the roof...that is why so few
people on planet earth, including the worlds best engineers
use the strategy.

  Its workable you see.... just not practical in context with
other approaches.

Phil Scott
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be
above
if it
form of
lower
circulating
once
effects
etc.
90F...
up
manifest.
cases.
20
humidity..that
with
runoff,
reduction
seldom
you
tarp




Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


Phil Scott wrote:

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Would you care to mention what those problems are?


Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?



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runoff,
to

Water is a corrosive.  Would mildly wear the roofing but with
your limited use not much...

Mineral deposits with your limited usage would be minor but
still a negative factor.

The net benefit of water cooling the roof would be close to
the benefits of attic air ventilation..attic air ventilation
would not have that set of minor problems though.

Your suggestion is workable  just not the optimum as I see it.
It would be optimum however say in the deep south west with
air temperatures over 110 in the shade...  but then mineral
content of the water is higher there and could be a very
significant problem one would have to look at...  it is
typically not done.

I might be inclined to put a spray misting system in the attic
air make up stream.  that would work.

However misting companies will not sell into a high mineral
content water area because the minerals destroy their PD pumps
and clogg the micro nozzels....thus...we see swamp coolers
used in the south west.



Phil Scott






Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


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Are you sure about that?  I use much less than that, even with lawn
sprinklers and a 15,000 gallong in-ground pool to maintain.

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Where I live it's a good deal more costly than that.

--

Regards,
Robert L Bass

=============================>
Bass Home Electronics
2291 Pine View Circle
Sarasota Florida 34231
877-722-8900 Sales & Tech Support
http://www.bassburglaralarms.com
=============================>



Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


"Robert L. Bass" wrote:
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15000 gallons is about 2005 cubic feet.  It would cost me $77 CDN ($63
USD) for that much water.

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http://www.azcentral.com/specials/special26/articles/0122drought-waterrates.html

Cheap water could become thing of past as supplies dwindle
The Arizona Republic
Jan. 22, 2003

"It may not seem like it when you write the check to pay the bill
every month, but water is cheap in the West.  Not only do Arizonans
pay some of the lowest residential rates in the nation - in one survey
of big cities, only San Antonio charged less - the state's farmers tap
into reliable, subsidized sources that allow them to survive a
shifting economy.  The Salt River Project collects about $10 per
acre-foot from its municipal customers, a rate that hasn't changed
much in years. The Central Arizona Project, a $4 billion canal that
brings water to Phoenix from the Colorado River, charges cities about
$105 per acre-foot.  An acre-foot is about 326,000 gallons, or enough
to supply a five-person household for one year.  Tribes have been
reluctant to talk price publicly, but one attorney told a group of
city officials that the cost could start as high as $1,100 per
acre-foot."

$10 per acre foot is practically free.  Are there no carrying or
pipe-line charges?  That wouldn't even support routine maintenance.

An acre-foot is 326,000 gallons, or about 43580 cubic feet.

$100 per acre foot is 0.23 cents per cubic foot.
$1000 per acre foot is 2.3 cents per cubic foot.  That's still almost
half of what we pay (but then some of our costs include sewer surtax).

So what does the average home owner in San Antonio pay for his water?

Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


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Corrosion.  Air doesn't eat at the coil nearly as bad as chlorinated pool
water would.



Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?



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cooling with water
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I do between
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drop in
system is a 6:12
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reduction in the
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panels, down from
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yards,
figuring that I
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worried about
days over
panels because
claims, and
years of
usually, since
panels that
use a
available
temperature
degrees.  This
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reduced the
those 100 degree
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the first
lost
any day over
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since we had
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$108.00 worth of
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reduction in A/C
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not running it.


Misting is a vastly under used technology... sounds like you
have a great application there.    Ive been trying to sell it
to super markets with air cooled refrigeration for years... a
tough sell..but it would save them a bundle and cut repair
costs.  There are commcl systems on the market for that
application but they dont sell well.

They sell for chicken ranches and misting public areas the
desert mostly.

Phil Scott

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can't put a
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a value on
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you'll probably find it's
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anything, put in an
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might imagine.
algae other
consider.  Enough
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it not only a bad
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some people
here if I
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Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?


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Nice bit of explanation Jim.

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True, I suppose dangerous isn't the right word.  I was thinking more along
the idea of some DIY nightmare oversaturating the roof (somehow) and
introducing problems well beyond the roof's design.  Weight, saturation,
downspout overflow, etc.



Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


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Jim Baber's expanded comments:

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   1. The average humidity in Fresno CA is generally quite low in the
      daytime during the summer.  Right now it is 8:30 in the morning
      the humidity is 66%, and the temperature is only 62.8 with an
      expected high of 92 @ 17:00 pdt.  The humidity will probably drop
      to about 25 - 35% if it performs as usual.
      This is really ideal for misting as a cooling device.
      I just wish these temperatures would continue all summer, but we
      are supposedly going to hit 100's next week (the latest in several
      years by the way).
   2. Wind does severely reduce the effectiveness of the misting as far
      as cooling, but one of the major problems with the weather in
      Fresno is the LACK of wind in the summer. At best we can maybe get
      a 3 - 6 mph breeze and that will usually be after 7 PM. I just
      looked at my weather station again, the highest wind speed over
      the pas 24 hr was a gust to 4 mph most of the rest at 2 - 3 mph.
      with long periods without any at all.  Rather typical and boring.
      <>
      By the way, in the 5 min. I've been typing, the Relative humidity
      dropped to 62 and the temperature went up to 64


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Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?


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There's one method of using water to cool the roof/attic that can help.  I
use solar panels to heat my pool.  The pool holds ~30,000 gallons.  There
are eight 4'x10' solar panels on the roof.  Sunlight hitting them warms the
pool -- not the attic.  I've noticed a significant improvement in cool-down
cycle (time it takes to get the house cool again after we've been away) with
the pool heater running.  Since the pool water is being circulated by the
filtration pump during the day anyway, there's almost no *extra* cost to use
the solar panels.

--

Regards,
Robert L Bass

=============================>
Bass Home Electronics
2291 Pine View Circle
Sarasota Florida 34231
877-722-8900 Sales & Tech Support
http://www.bassburglaralarms.com
=============================>




Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?


Robert L. Bass wrote:
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The solar heating system should be a required part of any pool
installation.  It should be written into the code and rebates should be
offered by the utility companies.

But that would make sense...

R



Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?


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True, so don't count on any incentives coming from the present
administration either.  :)

--

Regards,
Robert L Bass

=============================>
Bass Home Electronics
2291 Pine View Circle
Sarasota Florida 34231
877-722-8900 Sales & Tech Support
http://www.bassburglaralarms.com
=============================>




Re: Cooling attic (and home) by spraying water on roof (shingles)- good/bad?


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RicodJour wrote:

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I really have to agree, but I feel the government already has too much
to say in how I do things at my home.  I can't even REPLACE a bad water
heater without getting a building permit.  Dealers will not sell the
heater without the permit, and it is just a way to extract a $35 fee
from the homeowner. Supposedly it is to provide inspections to insure
proper installation, but when I insisted that the inspectors actually
come out and inspect my installation they got very upset, and claimed it
would cost them a lot more than the 35 would cover.  The did come out,
since I told them my next call was to the newspaper.

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Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?


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Given the risk of damage to property and loss of life due to improperly
installed water heaters I'd say it's perfectly reasonable to insist a permit
be issued.  As for your permitting people being lazy, that's certainly worth
a call to the newspapers.  Call them anyway, if just to give the Metro
section reporters something to write about.



Re: Cooling attic (and home) by spraying water on roof (shingles) - good/bad?


Jim Baber wrote:

Jim, watch what you're doing.  I don't need your posted response as an
email with an attachment.  Reading the newsgroup is just fine.

R



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