Article 31292 of alt.solar.thermal: Path: news.misty.com!not-for-mail From: nicksanspam@ece.villanova.edu Newsgroups: alt.solar.thermal Subject: Plug-and-play sunspace house and water heating Date: 16 Sep 2008 12:52:20 -0400 Organization: Villanova University Lines: 58 Message-ID: NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: max.inside.misty.com 1221583942 27716 153.104.44.130 (16 Sep 2008 16:52:22 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Tue, 16 Sep 2008 16:52:22 +0000 (UTC) Xref: news.misty.com alt.solar.thermal:31292 M writes (re inexpensive 100% solar house heating): >Is the plan to have this eventually be a manufactured, packaged, >plug-and-play sort of system (definitely the way the market is going) >or does it always need to be custom designed? Plug-and-play sounds good, with the same radiator and controls, but different amounts of sunspace glazing and heat storage, depending on the house and the climate. >Boulder is doing a big retrofit push to meet the goals of the local >Climate Action Plan. This might be one way to go if it's simple to >understand, engineer, and install. God knows we have lots of sun. When last She spake to NREL, 750 Btu/ft^2 fell on the ground and 1030 fell on a south wall on an average 29.7 F January day with a 43.2 F high in Boulder. So a well-insulated house with a 200 Btu/h-F thermal conductance and no window or internal heat gains would need about 24h(65-29.7)200 = 169K Btu/day of heat, or 847K for 5 cloudy days in a row. A 1000 Btu/h-F radiator with water temp Tmin (F) could keep the house 70 F if (Tmin-70)1000 =3D (70-29.7)200, which makes Tmin =3D 78 F. If the heat storage tank contains P pounds of water at 140 F on an average day and (140-78)P =3D 847K Btu, P =3D 13661, ie P/62.33 = 219 ft^3 of water, eg a 3'-tall x 219/3 = 73 ft^2 tank, eg a 3'-tall x 9.6'-diameter folded cylindrical polyethylene film liner inside insulation inside a $200 3'-tall x 15'-diameter inflatable EZ-set swimming pool. With a dark mesh curtain to keep a sunspace more efficient and comfy and an average 36 F daytime temp, a $2 ft^2 of R2 south sunspace glazing could gain 0.8x1030 = 824 Btu and lose 6h(70-36)1ft^2/R2 = 102, for a net gain of 722 Btu/ft^2-day, so we could collect 169K Btu with 169K/722 = 234 ft^2 of sunspace glazing, eg an 8'x32' or 16'x16' transparent wall. A 200 Btu/ft^2 house in Rochester NY (560 Btu/ft^2 on a south wall on an average 29.1 F December day) would need 172K Btu/day, so the same pool could store heat, but if 1 ft^2 of sunspace glazing only gains 335 Btu, we might need 172K/335 = 513 ft^2 of glazing, eg a south house wall with 16'x32' of R2 solar siding (we could refine this with a simple TMY2 simulation.) A frugal 600 kWh/mo (68K Btu/day) of internal electrical use would reduce the glazing requirement to 104K/335 = 310 ft^2 and shrink the tank to a 4'x8'x4'-tall plywood box or a 3'-tall x 7.6' diameter pool or a few vertical 55 gallon drums in a ring with a liner inside and insulation outside the drums. With more care, we might stack drums to make a 6'-tall x 5.3'-OD ring. >And BTW, I have a cracked radiator in my Honda CRV, which will cost far >more than $35 to replace. Where do you get a radiator for $35? From a junkyard, with a short guarantee and no installation labor, if you can use any of several years and makes, eg Japanese radiators with 4-peg mounts. I've bought 1984 Dodge Omni and 1997 Mitsubishi radiators with their 12 volt electric fans (20 watts in series) for $35. Nick