Water Sprinkler on hot roof
Tony Miklos
cool the building, and especially curious how to make it automatic.
Thanks,
Tony
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Bob's Backfire Burrito
"Tony Miklos" <tonym...@planetc.com> wrote in message
news:1187379...@sp12lax.superfeed.net...
> I'm wondering if anyone out there has tried this, how it worked to help
> cool the building, and especially curious how to make it automatic.
>
> Thanks,
> Tony
>
It does NOT work well. It wont pull the heat out of the roof, the Infrared
energy from the sun heats the water before it can run off with the heat it
absorbed.
Besides that, it wastes water,and makes the ground around the place a soggy
mess.
Now if you REALLY want to cool the house, mount solar panels about 4 inches
above the roof, covering the entire roof with shade. The 4 " gap allows air
to
flow between the panels, cooling them and the roof.
Use the power generated by the panels to run the power meter backwards. The
money saved by this can be spent on running the A/C when you really need it.
Cover the windows with "Solarscreens". They are perforated metal covers that
you can see thru, but reflect a lot of the energy so it doesnt heat the
windows more
than the outside airtemp.
There are MANY good ideas, the water trick is not one of them....
nicks...@ece.villanova.edu
>"Tony Miklos" <tonym...@planetc.com> wrote:
>> I'm wondering if anyone out there has tried this, how it worked to help
>> cool the building, and especially curious how to make it automatic.
>
>It does NOT work well. It wont pull the heat out of the roof, the Infrared
>energy from the sun heats the water before it can run off with the heat it
>absorbed.
Woowoowoo. Got any numbers? :-)
Nick
Rod Speed
> I'm wondering if anyone out there has tried this,
Yep, hordes have.
> how it worked to help cool the building,
Its better than nothing, but not as good as real air conditioning. Much cheaper tho.
> and especially curious how to make it automatic.
Completely trivial to do that. The usual thermostat switches
a solenoid valve and that controls the water to the sprinkler.
You can do it with what you can buy in any decent store.
Rod Speed
>> I'm wondering if anyone out there has tried this, how it worked to
>> help cool the building, and especially curious how to make it automatic.
> It does NOT work well.
Depends on how you define well. Works a lot better than nothing.
> It wont pull the heat out of the roof, the Infrared energy from the sun heats the water before it
> can run off with the heat it absorbed.
Mindlessly silly. The reality with roofs is that they get a lot
hot due to the heat absorbed and the water does get rid
of most of that heat even if the humidity is quite high.
> Besides that, it wastes water,
Sure, but there is often plenty of water available.
> and makes the ground around the place a soggy mess.
Nope, not if the roof drainage is designed properly.
> Now if you REALLY want to cool the house, mount solar panels about 4 inches above the roof,
> covering the entire roof with shade. The 4 "
> gap allows air to flow between the panels, cooling them and the roof.
Pity that that costs a hell of a lot more than a sprinkler.
> Use the power generated by the panels to run the power meter backwards.
Pity about the cost of doing that.
> The money saved by this can be spent on running the A/C when you really need it.
Nope, the money saved wont even pay for the solar panels.
> Cover the windows with "Solarscreens". They are perforated metal covers that you can see thru, but
> reflect a lot of the energy so it doesnt heat the windows more than the outside airtemp.
Lot cheaper to have appropriate eaves to stop the sun falling on the windows in summer.
> There are MANY good ideas, the water trick is not one of them....
Wrong if you want a very low cost approach. Its a lot better than nothing.
clams casino
>"Tony Miklos" <tonym...@planetc.com> wrote in message
>news:1187379...@sp12lax.superfeed.net...
>
>
>>I'm wondering if anyone out there has tried this, how it worked to help
>>cool the building, and especially curious how to make it automatic.
>>
>>Thanks,
>>Tony
>>
>>
>>
>
>It does NOT work well. It wont pull the heat out of the roof, the Infrared
>energy from the sun heats the water before it can run off with the heat it
>absorbed.
>
>
Granted, the results are probably marginal, but that makes little sense.
>Besides that, it wastes water,and makes the ground around the place a soggy
>mess.
>
>
You are obviously using way too much water / expecting way too much from
this marginal, but effective method of cooling the roof / attic.
Tony Miklos
> Tony Miklos <tonym...@planetc.com> wrote:
>
>> I'm wondering if anyone out there has tried this,
>
> Yep, hordes have.
>
>> how it worked to help cool the building,
>
> Its better than nothing, but not as good as real air conditioning. Much cheaper tho.
The thing is that I'm not very frugal when summer comes. My bedroom is
at about 66* and the rest of the house 70 - 74*. I'm looking for a way
to make the A/C not have to run as much.
The way I cool is mostly from an little 8k btu window rattler in the
bedroom window. That can run day and night for less than $50/month. I
have central A/C but it's old and costs a lot to run. Part of its
inefficiency is because I don't use about 1/3 of the house and have the
vents closed. I then set the A/C fan speed down one notch since there
are less vents open. The good part is that is also gives me added
dehumidification, and I love it arid! Anyway I set the central at about
76* and leave the bedroom door open. The little window unit with the
door open does a good job up to about 85* outside. The last couple
weeks we have been in a 90-97* heat wave so the central does run on and
off quite a bit.
>> and especially curious how to make it automatic.
>
> Completely trivial to do that. The usual thermostat switches
> a solenoid valve and that controls the water to the sprinkler.
> You can do it with what you can buy in any decent store.
I didn't want to use a thermostat because if I mount it in the attic, it
will respond too slow. I suppose I could figure out a way to put it on
the roof in such a manner that the sprinkler doesn't turn itself off
again in the first pass. From my observations, it may work well if it
just used a timer and turned on for 1 minute every 20 minutes.
Rod Speed
>>> I'm wondering if anyone out there has tried this,
>> Yep, hordes have.
>>> how it worked to help cool the building,
>> Its better than nothing, but not as good as real air conditioning.
>> Much cheaper tho.
> The thing is that I'm not very frugal when summer comes. My bedroom is at about 66* and the rest
> of the house 70 - 74*. I'm looking for a way to make the A/C not have to run as much.
A sprinkler will only help if the roof isnt well insulated. Wont make any difference if it is.
> The way I cool is mostly from an little 8k btu window rattler in the
> bedroom window. That can run day and night for less than $50/month. I have central A/C but it's
> old and costs a lot to run. Part of its inefficiency is because I don't use about 1/3 of the
> house and have the vents closed. I then set the A/C fan speed down one notch since there are less
> vents open. The good part is that is also gives me added dehumidification, and I love it arid!
> Anyway I set the central at about 76* and leave the bedroom door open. The little window unit
> with the door open does a good job up to about 85* outside. The last couple weeks we have been in
> a 90-97* heat wave so the central does run on and off quite a bit.
See above.
>>> and especially curious how to make it automatic.
>> Completely trivial to do that. The usual thermostat switches
>> a solenoid valve and that controls the water to the sprinkler.
>> You can do it with what you can buy in any decent store.
> I didn't want to use a thermostat because if I mount it in the attic,
> it will respond too slow. I suppose I could figure out a way to put it
> on the roof in such a manner that the sprinkler doesn't turn itself off
> again in the first pass. From my observations, it may work well if it
> just used a timer and turned on for 1 minute every 20 minutes.
It'll only make any real difference if the roof/attic isnt insulated.
hchi...@hotmail.com
<tonym...@planetc.com> wrote:
>I'm wondering if anyone out there has tried this, how it worked to help
>cool the building, and especially curious how to make it automatic.
>
>Thanks,
>Tony
Yes, I did it in south Florida. It does help cool the building, but
insulation will do a better job. My primary reason for doing it was
to increase the life expectancy of the asphalt shingles. Shingles
have three main routes to failure - Degradation from UV radiation,
outgassing from excess heat, and expansion contraction cycles creating
cracks. To a lesser extent, mold can be an issue.
Use a single hose end impulse sprinkler and hook the hose to a
programmable water timer. The one I had allowed four sprinkling
events per day. 10 AM, Noon, 2 PM 4 PM 6:30 PM worked for me,
watering for about 15 minutes or less each time. It really was quite
simple to set up. You will need to put a single screw in the base of
the sprinkler to hold it in position. Is it cost effective for
cooling? Marginally, but probably a wash when you pay for the hose,
timer, sprinkler, and water. However... an extra couple of years
life on a roof is a good savings.
You can search the archives for more details on what I did.
Seerialmom
<BLAMP...@pullmyfinger.org> wrote:
> "Tony Miklos" <tonymik...@planetc.com> wrote in message
I like the idea of the elevated solar panels; do any of the companies
actually install them that way? I've invented (in my mind of course)
similar contraptions for the roof like "shades" you could raise to
allow the air flow and shade.
But I agree that sprinkler on the roof would do what you said plus
make the area around the house more humid as well. The bright side
would be if there was a forest fire your house wouldn't burn :)
Tockk
"Tony Miklos" <tonym...@planetc.com> wrote in message
news:1187379...@sp12lax.superfeed.net...
> I'm wondering if anyone out there has tried this, how it worked to help
> cool the building, and especially curious how to make it automatic.
A friend of mine tried this . . . he bought a gizmo that you attached to a
garden hose, and it ran on the roof and had several smaller hoses extending
from it that dripped water on to the hot roof. He couldn't detect any
difference, but it eventually damaged his shingles where the water dripped.
No idea why.
timeOday
I would also worry about hard water stains, a problem often created by
leaky swamp coolers. They can be quite unsightly.
sno
If what you are after is to cool the attic then probably what is best
would be a powered attic fan....cost less then hundred dollars and
easy to install if you use gable mounted one....here is link that talks
about....
hope helps...have fun.....sno
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now.....???
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Tony Miklos
> would be a powered attic fan....cost less then hundred dollars and
> easy to install if you use gable mounted one....here is link that talks
> about....
>
> http://www.atticfans.com/
An attic fan at one end of the house helps but the heat from the roof
still radiates to the joists and ceiling. A fan can't stop that. Then
to make things worse, the living room area is a vaulted ceiling so it
gets very little circulation. A fan at the other end of the house
wouldn't help much either since the rooms there are not used (or cooled).
Tony Miklos
I tried a soaker hose and it just wasn't enough. Also the water liked
to follow certain paths so most of the roof stayed dry.
Rod Speed
If there isnt any real insulation at that level, the joists and ceiling, a
sprinkler on the roof should help significantly and doesnt cost much to try.
Rod Speed
> Tockk wrote:
>> "Tony Miklos" <tonym...@planetc.com> wrote in message
>> news:1187379...@sp12lax.superfeed.net...
>>> I'm wondering if anyone out there has tried this, how it worked to
>>> help cool the building, and especially curious how to make it
>>> automatic.
>>
>>
>> A friend of mine tried this . . . he bought a gizmo that you
>> attached to a garden hose, and it ran on the roof and had several
>> smaller hoses extending from it that dripped water on to the hot
>> roof. He couldn't detect any difference, but it eventually damaged
>> his shingles where the water dripped. No idea why.
> I tried a soaker hose and it just wasn't enough. Also the water liked to follow certain paths so
> most of the roof stayed dry.
Yeah, you really need something with a decent throw like an impulse sprinkler.
Tony Miklos
I'm on a steep hill so it's difficult to see my roof unless I'm up in
the woods, and when I'm up in the woods I seldom look at the roof.
Speaking of woods, I'm letting some "trash trees" grow and that will
give the roof a lot of shade in another year or so. I'm not sure what
kind of trees they are, one person told me that they are Balsa. They
grow like weeds. No joke, some new branches grew 7 foot this summer,
and that is after a late freeze killed the first months growth and it
started over after new buds popped out weeks later.
--
Don K
news:1187397242.7...@i38g2000prf.googlegroups.com...
> I like the idea of the elevated solar panels; do any of the companies
> actually install them that way? I've invented (in my mind of course)
> similar contraptions for the roof like "shades" you could raise to
> allow the air flow and shade.
Spacing a flat panel off the roof, could turn it into an airfoil.
For example, you can get 1120 pounds of lift for a 20x20 foot flat rectangle
in a 100mph airflow at an angle of 1 degree.
Here's a neat applet from NASA that shows the lift you can get from
flat rectangular plate (and other shapes).
http://www.lerc.nasa.gov/WWW/K-12/aerosim/applet/vj402.html
select input to "shape/angle"
change airfoil shape to Plate
change angle-deg to 1
change camber-% to 0
select input to "size"
change chord-ft to ~20
change span-ft to ~20
select input to "flight test"
change speed-mph to 100
set view to show geometry 2D or 3D geometry and streamlines
set output, plot selection to lift vs. speed (or anything)
Then vary the input parameters to see how it behaves.
Don
TKM
"Rod Speed" <rod.sp...@gmail.com> wrote in message
news:5imdeuF...@mid.individual.net...
Not in my experience either. I tried it using a soaker hose at the top of
the roof. The water trickled down the roof, evaporated and, hopefully,
cooled the roof and the rooms below. But the temperature of the rooms below
didn't change after a day and a night and about $10 worth of water.
TKM
>
>
bowgus
the roof does, is shade that insulation in summer, and keep the rain/
snow off, and the attic is vented to get any humidity out in winter,
and the hot air out in summer. Venting the attic space properly is the
reasonable way to go.
hankus
this evaporative affect IS related to humidity...on a triple digit,dry day,a
sprinkler will break but not stop the heat as in AZ at noon....a roof vent
or passive attic ventilator with side vents or good soffit vents will help
in any clime...if one is starting from scratch,'tis better to build a house
with 6" rather than 4" walls and the extra insulation possible pays off.
--
Thanks
Hank (on the Gulf Coast-where it is always humid but seafood is cheap)
Rod Speed
> The ROOF but not necessarily the house gets cooler with a sprinkler...
Yes, like I said, whether the house gets cooler depends on how well the roof is insulated.
> and this evaporative affect IS related to humidity...
It isnt just an evaporative effect.
> on a triple digit,dry day,a sprinkler will break but not stop the heat as in AZ at noon....a roof
> vent or passive attic ventilator with side vents or good soffit vents will help in any clime...
Nope, not if the ceiling is well insulated, the temperature
of the roofspace doesnt necessarily matter at all.
> if one is starting from scratch,'tis better to build a house with 6" rather than 4" walls
Depends on the climate.
> and the extra insulation possible pays off.
And doesnt in some climates.
Tony Miklos
Like I said before, ventilation will not stop radiated heat. Also part
of the ceiling is vaulted so there is only a tiny amount of ventilation
in that area.
I've been turning the sprinkler on and off and it sure makes a
difference. I need a timer to cycle it on for about 2 minutes then off
for about 20.
Tony
Wayne Sallee
That's a cool web ap. And they have it downloadable too.
Wayne Sallee
Webm...@LeesburgNazarene.org
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