DIYbanter - View Single Post - Has anyone considered using rainwater collection for roof evaporativecooling to reduce cooling load/costs ?

The Daring Dufas[_7_]

hr(bob) wrote:
On Jun 22, 9:12 pm, "HeyBub" wrote:
RicodJour wrote:
On Jun 22, 6:14 pm, " wrote:
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
more viable.
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.
Not evaporative cooling so much as transfering the heat from the roof to the
water and letting it drain away, taking the heat with it.- Hide quoted text -

- Show quoted text -

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:

http://www.flatplate.com/

TDD