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

["Chas Hurst" <hurst1@xxxxxxxxxxx>]

"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.

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
> > >
> > >
> >
> >
>
>