Ive read some articles where people have collected rainwater pumped up
to the roof and fed into either 180 degree sprinklers, or, into PVC
piping with holes drilled in the sides to soak the roof thereby
drastically cooling the roof tiles, deck, and hence reducing cooling
load on the inside of the home. In order to maximize savings, a 12
vdc high head pump can be used which is fed off of a small solar
collector or DeepCell batteries (which are periodically recharged) .
One article says his water flow amounts to approx. 50 gallons in just
a couple of hours ; this would require a HUGE quantity of collected
rainwater in order to have it operate for a full day.
I suppose if one lived next to a lake , pond, or stream...it would be
Comments ? Thanks.
It's a wasteful way of getting evaporative cooling. The time, effort
and money would be better spent on better insulation, better attic
ventilation, solar film on the windows and having the correct amount
of solar shading (awnings and/or roof overhang) for your area.
I would use the water to help the compressor run cooler by dripping
the water across the condensor coils. That way there is no need to
pump the water up. The only drawback is that you would have to clean
out the condensor coils once a year to get rid of any build-up. It
could be done with a 120 Volt solenoid from an old wahing machine,
Just put it in parallel with the condensor fan motor, also usually 120
V. That way the water only drips out when the fan motor is running.
You'd be better off using a flat plate stainless steel
heat exchanger because I will bet the rain water will
eat away the aluminum fins of the condenser unless it
is treated. A rain shower isn't going to bother an air
conditioner condenser but a constant spray or drip will,
unless it is designed for it. I've seen coils eat up
when a fellow decided to install a water spray system
on his air conditioners. I had a customer who owned a
restaurant who wanted a water spray on his condensing
units so I asked the manufacturer and it was not recommended.
The city water in my area would cause lime deposits very
quickly and the rain water is acidic. The HVAC supply
houses around here sell these heat exchangers:
Funny you should bring this up, cause in extreme outdoor temps, i put
the hose on a fine spray and cover as much of the condensor coil as
possible...turning it into an evaporative condensor. I may hookup an
inline water filter to eliminate the sediment buildup issue. It does
drop the amps when water is being sprayed on it. I like your idea of
having a solenoid valve open when the a/c turns on ...and if i had the
rainwater collection barrel on my deck which is 2' higher than the a/c
unit on the ground...then the water would drain by gravity. Should I
opt to have the water go into 90 or 180 degree sprinkler heads to
diffuse the water ??? Would the gravity pressure be adequate ?
Again...filtering would be a requirement. Thanks much !
The pressure would be low, but you could enlarge the holes to get more
flow. But do you have an infinite supply of water?? Even in Florida
there are days when it doesn't rainat 3 pm in the afternoon like
clockwork. I used to install TV antenna towers in Fort Pierce, before
WestPalmBeach came on the air, so we used 40' towers to hold antennas
to get very weak signals from Miami. Early 1950'sera. Never planned
to work on antennas after 12 noon in the summer. Too dangerous.
For some publicly funded grants for house, you get extra points for
things like rainwater control. They want you to keep the first 1" of
water or something like that for re-use. The re-use is generally for
watering plants or toilets or something like that. You also get
points for plants on roof, etc., to shed heat load.
In Colorado, at least, you cannot trap rainwater from your own roof.
Some farmer downstream always has more senior "water rights" to the
runoff. There are "Water Courts" that control the allocation of water
across the entire state.
I tried that once.
The interior of the house changed from unpleasant hot and dry,
to *very* unpleasant hot and wet.
I suspect however that one could filter and use the rain water in a
conventional swamp cooler, where the saturated air is directed away
from the house instead of enveloping it.
re: One article says his water flow amounts to approx. 50 gallons in
just a couple of hours ; this would require a HUGE quantity of
collected rainwater in order to have it operate for a full day.
I'm confused...wouldn't you be recycling this water over and over,
other than the evaporation loss?
Let's say I take a little over 2 minutes to pour a gallon of water
from one bucket to another. If I do this 25 times an hour for 2 hours
wouldn't my _flow rate_ be "approx. 50 gallons in just a couple of
hours" but my _quantity_ be only 1 gallon?
We had a guy in our neighborhood try that with city water some years
back. Our city water has very minute traces of minerals in it so he
thought he was safe to use it. Two years later his roof had major
white streaks & splotches that were permanent - looked like the floor
of a chicken house.
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