I belong to little brick bungalow in a midwest city, built in 1954. Shingled roof.
It gets hot as hell here in the summertime (it's already here). Sun pounds down on little house unmercifully.
Outa work for years, I gotta budget so tight it makes the proverbial cat's arse ('scuse my French) look like the Grand Canyon.
I just put my last 3 lbs of R-22 in my 21-year-old condensing unit (which is about to roll over and die a horrible, horrible death).
They don't meter the water supply here.
What (aside from sanity, which I do not possess) would keep po' me from somehow mounting a sprinkler or 2 on the roof, running them with a garden hose, say, from 11 AM to 7 PM (to cool the house, which retains heat like crazy)??
TIA, Puddin'
********************************************************* Puddin' Man PuddingDotMan at GmailDotCom *********************************************************;
A lot depends on the humidity in your area. If it's dry, the roof wet will help a lot.
Might also want to consider a sprayer to spray cold water on the outdoor AC (get your AC guy in on the plans). If there is little evaporation, that might lower the temp of the outdoor unit, and help system that way.
White curtains in the south and side windows to help block out the "greenhouse effect". White exterior paint. Well, maybe not for brick but....
Wish I was closer, I'd offer to come out and look at the system for you.
Lack of a hose or sprinkler? Can you shade the condenser? How about a fine mist on the condenser to remove more heat from the condenser? Do you have a basement? One tirck I use is to put the fan in the "ON" position and I also have cold air returns in the basement. This helps bring the cool basement air upstairs. If you're outa work, how about spending the day at Walmart?
It will work just fine, spray the roof till they come and install a meter! With fine thinking like that, Bush is gonna come knockin at your door when Greenspan retires but you'll be watchin stolen cable tv or too drunk to answer the door and accept the appointment. I love the comment about spending the day at wallmart but he prob already does, as an employee get paid next to nothing in sinking american dollars. This guys represents all that is great about americans! Lazy, broke, cunning. Anyone want to ad to the list?
That scheme is unlikely to be efficient, with lots of thermal resistance (insulation) between the living space and the roof, and it's the wrong time of day to collect coolth, but Harry Thomason did something like this in the 60's for hundreds of houses, including his own in Washington, DC (a bad climate for evaporative cooling) pumping water over the roof at night and storing and distributing coolth during the day. He also ran an AC at night, when ACing is more efficient.
In "Solar Space Heating and Air Conditioning in the Thomason Home" (Solar Energy Journal, Vol 4, No. 4, Oct. 1960, pp 11-19), Dr. Thomason wrote "...the water on the north sloping roof flows slowly in an almost perfect thin sheet from top to bottom. The granules of sand in the asphalt shingles help to spread the water evenly and to retard the rate of flow... On the night of 14 July the rate of cooling was 25,700 Btu/h at the peak when the sky was overcast, but there was a breeze of about 15 mph. Outside air was at 68 F, water to the roof was at 73 F, with a return temp of 65.5 F and a flow rate of 5 gallons in 41 seconds. Humidity was about 65%."
Thomason used a 1600 gallon steel tank surrounded by rocks for heat and coolth storage and distribution. A homeowner with a basement might cool a house by pumping water over a roof at night and collecting it in a gutter and letting it flow back into some 4" thinwall PVC pipes or poly film water ducts tucked up between basement ceiling joists and circulate air between the house and the basement during the day.
NREL says an average 75.6 day July day in Sterling, VA (close to DC) with an average daily 64.1 and 87.0 min and max has a humidity ratio w = 0.0136 pounds of water per pound of dry air and an average V = 6.2 mph windspeed.
With average night temp Ndbt = (75.6+64.1)/2 = 69.9 F and vapor pressure Pa = 29.921/(1+.62198/w) = 0.640 "Hg and dew point Tdp = 9621/(17.863-ln(Pa))-460 = 65.5 F, the approximate wet bulb temp Twb = (Ndbt+Tdp)/2 = 67.7 F. With lots of T = 70 F water flow, Phil Niles says A = 0.002056*Tdp+0.7378 = 0.8725 for a radiation loss Qr = 1.63E-09*((T+460)^4-A*(Ndbt+460)^4) = 16.5 Btu/h-ft^2 plus convection loss Qc = (0.74+0.3*V)*(T-Ndbt) = 0.3 Btu/h-ft^2, with B = 3.01*(0.74+0.3*V)*((T+Twb)/65-1) = 8.753 and evaporation loss Qe = B*(T-Twb)-Qc = 19.8 Btu/h-ft^2, for a total Q = Qr + Qc + Qe = 36.6 Btu/h-ft^2, or 12Q = 440 Btu/ft^2 per night.
A small 1000 ft^2x8' house with 200 Btu/h-F of thermal conductance and
0.5 air changes per hour with 600 kWh/mo of indoor electrical use that's 80 F with w = 0.012 indoors would need about 70K Btu/day of cooling, which might come from 70K/440 = 160 ft^2 of roof.
It would need about 7100 Btu/h of peak cooling. If that comes from 1000 ft^2 (about $150) of ducts in the basement ceiling, the min duct water temp would be about 80-7100/(1000x2x1.5) = 77.6 F. If the house needs
350K Btu for a warm humid week, with no significant cooling at night,
350K = (77.6-70)C makes C = 45,851 Btu/F, eg 23 tons of water in 8.8" deep ducts (a good ballast foundation :-) More roof or basement ceiling surface would reduce the water depth.
As an alternative, we could cool static basement ducts without plumbing or pumping with a whole house fan on cool nights. Dr. Thomason also used a small dehumidifier.
Couple thoughts: Why bother cooling off the whole house when the only thing that really needs cooling is _you_? With that in mind, leave the cold water running in the shower and stay in there during the hottest part of the day.
Or - a looping configuration of copper pipes encircling the La-Z-Boy with constant cool water circulation?
The house fries mostly 'cause of the sun on the dark-brown shingles.
Thanks, but there's not much to it. Just a little brick bungalow in the sun.
Puddin'
********************************************************* Puddin' Man PuddingDotMan at GmailDotCom *********************************************************;
1.) It's a Carrier, circa 1984, with long lines from the A-coil. I tried for years: it don't fix.
2.) Can't afford the elec. bill. I can run it a tiny bit, but now way all day/evening.
Puddin'
********************************************************* Puddin' Man PuddingDotMan at GmailDotCom *********************************************************;
down in his la z boy, and connect one copper tube to his neck, another one at his foot. Route the one coming out his foot to a floor drain, and the one going in his neck to the water supply; turn water on.
More like I haven't figgered how to mount sprinklers/hose on the roof.
Wouldn't hep' that much. Can't afford to run the AC much ...
Si, senor.
Interesting. I don't have any returns in the bsmt, but I 'spose I could cut some.
Tell the truth: are those folks human?? :-)
Seriously, I'm pushing 60 and have some physical problems. Can no way stay on my feet all day.
Puddin'
********************************************************* Puddin' Man PuddingDotMan at GmailDotCom *********************************************************;
I've seen horse stables here (Idaho) cooled with a similar system. Works OK, although our humidity is a lot lower than the Chicago area.
My *guess* would be that you might cause the roof to fail prematurely -- asphalt paths that are watered (sprinkler) on a daily basis wear out a lot faster than paths that are kept dry most of the time. Of course, keeping the roof cooler may more than make up for keeping it wet all the time.
It's a strong function of the temperature of your water coming out of the hose, which is probably a bit under 70F if your lucky. But it will take ALOT of water, and flowing pretty quickly. It will also tend to cool the peak of the roof the most. It's also hard as heck on the shingles. Do you have any roof ventilation? That's gonna help the most.
Planting grass up there would probably do more, but the roof probably can't take the weight.
Actually, just coiling the copper pipe around Puddin's neck - much like the rings worn by certain African tribeswomen- would probably keep him cool. Fitting the copper to a lengthy flexible hose would also allow him the mobility to leave his La-Z-Boy to make sandwiches and such.
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