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[Rob <becida AT comcast.net>]

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Date:   Sun, 07 Jun 1998 09:56:15 -0400
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From: tvoivozd <tvoivozd AT roanoke.infi.net>
To: rdodd AT airmail.net
Cc: homestead list <homestead AT listserv.oit.unc.edu>
Subject: Re: Solar powered air conditioners
References: <3577F1CF.3FB45096 AT airmail.net>
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tvoivozhd>>>to make swamp coolers extremely effective and extend life of the
evaporative pads, here's a couple extracts by John Cruickshank, plus another
on which type of evaporator pad is preferable.  Put this in your files,
because if you ever use a swamp cooler (highly recommended) you are going to
need the information desperately and be unable to find it.


>>>Re: Maximizing Evap cooler performance
I don't recall this thread covering the standard industry approach to this
??.  There was a cursory note from one soul that referred to a pre-cooling
coil for the evap water before it goes to the evap pads.  Although this
will do something, it isn't the whole picture, or the best approach.
Currently, and for many years now, the industry has provided a solution
that is designed for small to medium commercial deep cooling requirements
in climate zones demonstrating RH readings in the <40% range.  Basically,
what is done is to pre-cool the *air* and not the water before the *air*
gets to the evap pads.  Now, you are probably thinking: run it through two
sets of pads, one after another.  But, you will soon come to the conclusion
that that is a class one error because the cooling only occurs in the first
because the RH of the air is saturated then, and no cooling will occur in
the second pad.  This is the dilemma.  How to pre-cool the air before it
gets to the main evap unit, do it *with* evap cooling, and *don't* add any
humidity in this 1st stage so the 2nd stage can work.  Well, the way I've
seen it done is with a special pad and separate blower unit positioned
upstream from the air flow going to the main evap unit (2nd stage).  This
special pad is a series of aluminum fins, hollow and fabric lined on the
inside, corrugated on the outside.  Water is distributed to the hollow
fabric cores of the fins, and air is blown through the hollows and
exhausted outside. This induces a delta T of >20deg F in the fins.  As the
air going to the 2nd stage passes between these fins on its way to the evap
pads of the 2nd stage, there is a delta T of >20deg F transferred
*indirectly* through the aluminum fins to this incoming air.  So, in effect
you have cooled the air >20deg F *without* adding any humidity.  Kind of
like an integral HVR unit.  What this means is that after this 1st stage
indirect cooling and then the 2nd stage direct evap pad cooling, you can
easily and with confidence provide a delta T to incoming building air
(originally with <40%RH) of at least 60degF!  I do this on our dining room
here, and, believe me, it is short of miraculous to have cool make-up air
incoming at 60deg F *even when the outside temps are 120deg F*!!  Now, not
being a salesman, or a practicing HVAC engineer in the field, I can't offer
much more info on sales, costs, availability, performance ratings etc but
the concept explained may perk some ingenious angles on the picture and
perhaps open some doors to a simple homeowner system that operates
similarly.  What you need to consider is evaporative based indirect cooling
of incoming air *before* it gets to your main evap pads.



                John Cruickshank
         <<<Hobbit House Sunrise Ranch>>
            5569 North County Road 29
                Loveland CO 80538
                    _/V\_
                    (o~o)
    ~~~~~~~~~~~~oOOo~(_)~oOOo~~~~~~~~~~~~~~~


>Dear Evaporators:
Thanks all for your input regarding the water temperature of evaporative
coolers. I am going to build a passive cooling tower for my patio and
because it is so hot and dry in Las Vegas, I thought I might be able to
eke out a couple of degrees by preheating the water before it goes
through the pads. Where we hover around 15% humidity, evaporative
coolers work wonderfully here, but because there is a maximum drop an
evaporative cooler can offer from the ambient temperature, going from
110 to 85 may not seem like such a good deal to desert climate deprived
individuals. Anyway, I am going to experiment and let you all know what
happens, although I suspect that the collective knowledge of the group
will once again prove superior.
Thanks again,
Andy Anderson




>>>Here's a valuable tip for honeycomb block (and all pad coolers for that
matter.)  Scale buildup is usually attributable to insufficient bleed rates
of the recirculated water.  As is evaporates, the mineral content rises,
the pH rises, and disaster looms.  I have seen side by side units on the
same water and building t'stat, demonstrate just how critical the bleed
rates are.  In this instance, one bleed unit functioned, the other didn't.
In the one that didn't, the pads where blocked solid, the bottom pan peeled
up *all* it's epoxy waterproofing finish, all the paint on the blower, pad
frames, and everything else with paint inside the swamper!!! Right next to
it, the unit with the bleed working was like new at the end of the year!
(and still is after 14 years) That showed me the lesson to learn -
bomb-proof your bleed rates, making sure you dump at least a quart/hour
from the evap unit when it is running, more if your water is hard or from a
well.  Run the bleed *off* the roof, not *on* the roof or you will save
your swamper, and lose your roof instead!  Plant some alkali loving plants
(wine grapes, sedges etc) and run it there.  The best way to bleed?  Use a
.25 to .5 gal/hour *self-cleaning* irrigation drip emitter.  Plug it into
the pumped supply line to the pads.  *Don't* even think about using the
usual manufacturer provided line tee fitting (impossible to control,
*always* plug up.)  This system provides excellent control, reasonable
assurrance against clogs, and is *real* cheap (<50 cents and only a few
gallons a day in extra water use to save the usual >$300 investment).  BTW,
I have a ten hp swamper installed here that uses the honeycomb block
system. Been here for 14 years, in constant use in the summer.  NO BLOCKS
OR CORROSION, EVER!  Works like the day I put it in.  Bleed rates are in
the neighborhood of 2 gals per hour when running. (this is a huge unit, 10
tons in weight for the entire 2stage package.)  Manufacturer was amazed
too.  Only special treatment it gets other than bleed and annual flushing,
is occasionally (once every 5 years) I clean the water pans and pads with a
wash and flush with a little liquid Tide brand *laundry* detergent
(manufacturers suggestion - works like a charm, cleans *and* rinses out
easily)



                John Cruickshank
         <<<Hobbit House Sunrise Ranch>>
            5569 North County Road 29
                Loveland CO 80538
                    _/V\_
                    (o~o)
    ~~~~~~~~~~~~oOOo~(_)~oOOo~~~~~~~~~~~~~~~

   <<<Provider of the "Sunny John" solution>>>



Andy,

All coolers are not created equal...
I've lived under a "swamper" for 8 summers here in Vegas...
I will not push any one brand over another...but I will push a superior
technology.  After using the "aspen" pads... the "plastic" pads and the
cellulose mats... I have discovered "swamper-nervana" in the form of the
cardboard/honeycomb style cooler blocks.  "Mastercool" makes the unit I
use.  Even our hottest summer days are bearable now... for me anyway.
The one drawback (and it applies to all the other cooling pad mediums)
is that the water leaves a scale build up within just 2-3 years.  So,
you should figure on replacement about every other year or so.. It runs
about $75 for a new honeycomb block.  I get about a 30-35 degree
temperature drop when the pads are new and about a 25 degree drop when
they get "scaled" up. Check over at Homebase on Rainbow and Charleston.

Axekicker...