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<DIV><FONT face=Courier>"Nick Pyner" <npyner@tig.com.au>
wrote:<BR> <BR>>> I suppose there are situations where climatic
conditions are such that trying to get all-solar is really a hopeless
cause...<BR><BR>Barrow, AK is hopeless, with 0 Btu/ft^2 of sun on the ground on
an average -13.4 F January day.<BR><BR>larencorie@axilar.net
wrote:<BR><BR>>... A good sizing for a Solar water heating system is that it
supplies all the hot water during the easiest few months, and functions as a
pre-heater the rest of the year.<BR><BR>Maybe not, if we build our own. Thom
Styles and I bought a 12'-diameter x 30" deep Intex metal-frame pool </FONT><A
title="http://www.amazon.com/gp/product/B000BVKO0E/ref=s9_simh_gw_p86_d0_g86_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0FXTG7053CFDZNAAHG2W&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846
CTRL + Click to follow link"
href="http://www.amazon.com/gp/product/B000BVKO0E/ref=s9_simh_gw_p86_d0_g86_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0FXTG7053CFDZNAAHG2W&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846"><FONT
title="http://www.amazon.com/gp/product/B000BVKO0E/ref=s9_simh_gw_p86_d0_g86_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0FXTG7053CFDZNAAHG2W&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846
CTRL + Click to follow link"
face=Courier>http://www.amazon.com/gp/product/B000BVKO0E/ref=s9_simh_gw_p86_d0_g86_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0FXTG7053CFDZNAAHG2W&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846</FONT></A><FONT
face=Courier> and a 15' diameter clear solar pool cover for $160 from Amazon
and an $80 1"x300' NSF black plastic pipe from Home Depot <A
title="http://www.homedepot.com/Plumbing-Pipes-Fittings-Valves-Polyethylene-Pipe-Fittings-Pipe/h_d1/R-100124369/h_d2/ProductDisplay?catalogId=10053&langId=-1&productId=100124369&storeId=10051
CTRL + Click to follow link"
href="http://www.homedepot.com/Plumbing-Pipes-Fittings-Valves-Polyethylene-Pipe-Fittings-Pipe/h_d1/R-100124369/h_d2/ProductDisplay?catalogId=10053&langId=-1&productId=100124369&storeId=10051">http://www.homedepot.com/Plumbing-Pipes-Fittings-Valves-Polyethylene-Pipe-Fittings-Pipe/h_d1/R-100124369/h_d2/ProductDisplay?catalogId=10053&langId=-1&productId=100124369&storeId=10051</A></FONT></DIV>
<DIV><FONT face=Courier></FONT> </DIV>
<DIV><FONT face=Courier>We plan to coil the 13-gallon pressurized pipe around
the inside perimeter of the pool near the top and suspend the cover from the
frame and take it to a few summer festivals. <BR><BR>Phila gets 1890 Btu/ft^2 of
sun on the ground on an average 76.7 F July day, so the pool would gain about
0.8x113ft^2x1890 = 170.9K Btu/day at the Phoenixville Green Earth festival on
August 4, where it could provide hot water for a benefit car wash... <A
href="http://www.pxvgreen.org/2012-Green-Earth-Festival/index.html">http://www.pxvgreen.org/2012-Green-Earth-Festival/index.html</A></FONT></DIV>
<DIV><FONT face=Courier><STRONG><FONT color=#4b0700></FONT></STRONG><BR>With no
sidewall insulation and a 113ft^2/R2+94ft^2/R1 = 151 Btu/h-F thermal
conductance, 170.9K = 24h(T-76.7)151 makes T = 124 F, approximately. (Or less,
with significant radiation loss.) With 3 wraps of a 12'x24' $46 solar pool cover
cut in strips around the outside and no hot water use and a 113ft^2/R2+94ft^2/R6
= 72 Btu/h-F thermal conductance, 170.9K = 24h(T-76.7)72 makes T = 176 F,
approximately. With C = 113x30/12x62.33 = 17608 Btu/F, it could make (176-110)C
= 1.16 million Btu of hot water for car washes on the first day. The water temp
would initially increase by about 170.9K/C = 10 F per day. At
(110-81.4)x1.25gpmx10mx8.33 = 2978 Btu/wash, it could provide 390 10 minute 1.25
gpm car washes on the first day, with 8 car washers working continuously for 8
hours. At 110 F, it would lose about 24h(110-76.7)72 = 57.5K Btu/day, for a net
gain of 113K Btu/day in July.<BR></DIV></FONT>
<DIV><FONT face=Courier>This year's PA Renewable Energy Fest </FONT><A
href="http://www.paenergyfest.com/"><FONT
title="http://www.paenergyfest.com/
CTRL + Click to follow link"
face=Courier>http://www.paenergyfest.com/</FONT></A><FONT face=Courier> has
a DIY emphasis. The heater might provide hot showers for 200
campers on 9/23.</FONT></DIV>
<DIV><FONT face=Courier> <BR>The winter version could have a
12'x12' Styrofoam cover under a 12'x12' piece of EPDM with a greenhouse
containing a north reflector on top and a pump </FONT><A
href="http://www.pexsupply.com/Grundfos-59896341-UPS15-58FC-3-Speed-Circulator-Pump-1-25-HP-115-volt-4701000-p"><FONT
title="http://www.pexsupply.com/Grundfos-59896341-UPS15-58FC-3-Speed-Circulator-Pump-1-25-HP-115-volt-4701000-p
CTRL + Click to follow link"
face=Courier>http://www.pexsupply.com/Grundfos-59896341-UPS15-58FC-3-Speed-Circulator-Pump-1-25-HP-115-volt-4701000-p</FONT></A><FONT
face=Courier> that moves pool water over the shallow pond drainback cover
during the day. The controller <A
title="http://www.sun-pump.com/controller.htm
CTRL + Click to follow link"
href="http://www.sun-pump.com/controller.htm">http://www.sun-pump.com/controller.htm</A> </FONT><FONT
face=Courier>could run the pump at night to protect the Styrofoam from
overheating.<BR><BR>20 PI=4*ATN(1)<BR>30 TA=31.8'average December Allentown temp
(F)<BR>40 TM=39.2'average daily max<BR>50 TD=(TA+TM)/2'average daytime
temp<BR>60 LC=12'cover length (feet)<BR>70 WC=12'cover width (feet)<BR>80
RCU=2'upper cover US R-value (F-h-ft^2/Btu)<BR>90 RCL=10'lower cover
R-value<BR>100 GCU=LC*WC/RCU'upper cover conductance (Btu/h-F)<BR>110
SUN=3.01'Dec sun on 60 degree south wall (kWh/m^2-day)<BR>120 LS=12'south wall
slant height (feet)<BR>130 SGAIN=.8*LC*LS*SUN*317'solar gain (Btu/day)<BR>140
LDAY=6'solar collection day (hours)<BR>150 DLOAD=41000!'SRCC OG-300 DHW load
(Btu/day)<BR>160 TW=TD+(SGAIN-DLOAD)/LDAY/GCU'average day cover temp (F)<BR>170
DS=12'heat store diameter (feet)<BR>180 HS=30/12'heat store height (feet)<BR>190
TS=2'wall/floor thickness (inches)<BR>200 RS=3'wall/floor R-value per
inch<BR>210 AP=PI*(DS/2)^2'pool surface area (ft^2)<BR>220 CS=AP*HS*62.33'heat
store capacitance (Btu/F)<BR>230 GS=(AP+PI*DS*HS)/(RS*TS)'conductance<BR>240 FOR
CDAY=1 TO 10'cloudy days<BR>250 TW=TW-DLOAD/CS'hot water loss (Btu/day)<BR>260
TW=TW-(TW-TA)*GS/CS'conductance loss (Btu/day)<BR>270 PRINT
500+CDAY;"'",TW<BR>280 NEXT CDAY</FONT></DIV>
<DIV><FONT face=Courier><BR>01 192.396
F<BR>02
189.7591<BR>03
187.1275<BR>04
184.501<BR>05
181.8797<BR>06
179.2636<BR>07
176.6525<BR>08
174.0466<BR>09
171.4458<BR>10 168.8520 </FONT></DIV>
<DIV><FONT face="Courier New"></FONT><FONT face=Courier></FONT> </DIV>
<DIV><FONT color=#4b0700 face=Courier>The cover could hold 6 240 watt PV
modules that each make about 320 watts when water-cooled under 2
suns.</FONT></DIV>
<DIV><FONT face=Courier></FONT> </DIV>
<DIV><FONT color=#4b0700 face=Courier>Nick</FONT></DIV></BODY></HTML>