Has anyone considered using rainwater collection for roof evaporative cooling to reduce cooling load/costs ?

[ilbebauck]

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.

[Gothumbs]

Shouldn't have moved to Florida if you can't stand the heat.

[ilbebauck]

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I never said i cant stand the heat , now did i ? Just looking for ways to cut some expenses ; what was behind your snide comment ? What brought that on ?

[skeeter]

he has two thumbs up his ass.

[JIMMIE]

Ive tried that but not with rain water. It works but keeping your roof wet all the time is not a good idea.

Jimmie

[RicodJour]

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.

R

[PatM]

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.

[HeyBub]

It would be off at night...

[HeyBub]

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.

[hrhofmann]

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.

[Reed]

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.

[The Daring Dufas]

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:

TDD

[Winston]

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.

--Winston

[ilbebauck]

ide quoted text -

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 !

[Ken]

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Because he must know that you're just a religious braindead asshole

[DerbyDad03]

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?

[hrhofmann]

Hide quoted text -

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.

[ilbebauck]

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RESPONSE >>>>

[Red]

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.

[Duffman]

I think he means the only losses would be evaporation losses as flow would be back into gutter which is your collection point, this would only be effective in dry heat areas though as the heat transfer is mostly into the air through evaporation, which in humid areas is minimal. Best bet is good insulation, light coloured roof, and ventilated eaves with whirlybird type ventilation near peak of your roof