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

["Phil Scott" <philscott@xxxxxxxxxxxxx>]

"Chas Hurst" <hurst1@xxxxxxxxxxx> wrote in message
news:pMGdnT7ZIrKcylzfRVn-2A@xxxxxxxxxxxxxx
>
> "Phil Scott" <philscott@xxxxxxxxxxxxx> wrote in message
> news:d9quua$l83$1@xxxxxxxxxxxxxxx
> >
> > "Chas Hurst" <hurst1@xxxxxxxxxxx> wrote in message
> > news:0uednRz508PCbCLfRVn-1w@xxxxxxxxxxxxxx
> > > Don't cooling towers use evaporative cooling?
> >
> >
> > 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
>
> 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.

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
>
> Chas Hurst
>
>
>
> > > "Phil Scott" <philscott@xxxxxxxxxxxxx> wrote in message
> > > news:d9ocdq$2hf$1@xxxxxxxxxxxxxxx
> > > >
> > > > "Some Guy" <Some@xxxxxxx> wrote in message
> > > > news:42BF3E57.659FD057@xxxxxxxxxx
> > > > > Phil Scott wrote:
> > > > >
> > > > > > > Doesn't a mister waste water by atomizing it and
> > then
> > > > the
> > > > > > > wind will blow it away?
> > > > > >
> > > > > >      The latent heat of evaporation for water ...
> > > > >
> > > > > 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.
> > > > >
> > > > > > Evaporative cooling would be limitlessly popular
if it
> > > > > > did not add an equal amount of humidity in the
form of
> > > > > > 'steam' to the air it was cooling to *sensibly
lower
> > > > > > termperatures.
> > > > >
> > > > > 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 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/
> > > >
> > > >
> > > > >
> > > > > 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.
> > > >
> > > >      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.
> > > >
> > > >
> > > > >
> > > > > 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).
> > > >
> > > >   Oh please.
> > > >
> > > >
> > > > Phil Scott
> > > >
> > > >
> > >
> > >
> >
> >
>
>