Page 16 RAIN August/Septcmbt:r 1979 Put aSunbeam inYour~nk Early last year we asked RAIN readers for suggestions on booking up solar collectors to honze hot water systems. In the confusion after our house burned, the responses got buried and forgotten. I finally got to them last month, much to my delight at the good things lying there. j ohll Broberg's recommendations mesh beautifully with tbe feedback we 've gotten on demand water heaters. People we 've talked to using gas demand heaters are well satisfied. The units are well designed, competitive in cost, and can deliver adequate heat. As gas water heaters are difficult to convert to solar, adding a separate solar prebeat tank to an existing gas water beater, or onverting the present heater to solar storage and lIsing a demand beater for backup heat seem sensible. Electric units are a different picw re. Most electric water beaters can, according to julm and others, be easily cOl/verted tI) do both solar storage alld backup heating by procedures outlined below. As we don 't recomme~ld any of the electric demand heaters presently on the market, that seems to be the way to go. We have tested tbe Instant-Flo unit (Lbe only UL approved electric demand heata on the market> arId our experie1lce paralleled that of other people we've beard from. The units, with no direct competition, are highly overpriced ($120 each). The heating elements, which seem to blow out frequently, are IIOt your standard $5 replaceable element, but require replaceme1Jt of the elllire unit at 80 percent of retail cost (or $961). Their performance seems erratic, they don't seem to deliver as much heat as tbey ure supposed to, tbeir J70 w is limited (114" tubing), and tbe:v require wiring as heavy as a kitchen range. Like all electric demand units, they add to peak load generatillg conditiO/IS rather tban Lessefling them. all electric units, tank c01lversion seems to be tbe wa.y to go rigbt now. My apologies for being so slow in passing this all 011 to you. Thallks. john. and everyone who sent all the good information to us. --TB Dear RAIN; I insta!l solar systems here in Florida, and have plumbed many conventional tanks for solar. Most hot water heaters here arc d tetric, and it is fairly easy to do with an electric heater. Conver.sion takes a little longer, but you get the use of your old tank until it wears out. With natural gas heaters, the situation is a little different, as I will explain. Basically a solar tank needs four fittings: one pair for the collector loop (to and from collector) and one pair for the house (cold water supply in a-nd hot water out). Fortunately, every electric HW heater has 4 or 5 holes in it. These arc: CW in, HW out, drain, pressure relief valve, and lower heating element. Lower heating elements can be removed and replaced with an adaptor to pipe. The upper heating element is retamed for backup. The supply to'the collector should be taken from a point near the bottom of the tank, where the water is coldest. Since tank bottoms scale up, the supply should be taken out about four inchcs above the bottom to prevent dirty water from going through the collector loop. The return from the collector should not be at the top of the tank. Instead, the return should be just below the upper heating element ( suggested 4-8" below). In a solar tank thi! would be through a side entrance. When adapting, we can use a modified dip tube to bring the return to where we want it (see drawings). Doing this will minimize the use of back-up electricity. E.L.6GffZJC MO£)IFIEO ~O~ 'SoL.-Mi!... -n-- 3M~ " '\ I fIf:rtIUV -+ _ UlH\I~GIU£oTlI.I6 \ .1<",. ~wl."Rft ~f'f'VI ~ , ..,-u It etWIN !-tOT"",AtEIt M~OO I " ~''''''~I.A6F f«.Qt..&~~ l- (C;:::::::;:;"==(1I":;:l2n-5!t ~~ '"'~~1.14' f\&l.0Uf PI/f 1'\AeE . " .':O'lfll Fi1166A. acT :'J:L":~~~ ~_••· lfVOU~J..~ ~~", ' . 3:: 4,~t:e.(~Ac;.) c o t • .. '-' c.. \c. ..' " -, IIIIUWIIOII 5 :~~"""'()fl.. III • I '.....;,. Net - " --' ~~N6 ~1It'~~RlR CAA>~SCMIH 1D~ I ENERGY I County Energy Plan Guidebook Creating a Renewable Energy Plan, Alan Okagaki and Jim Benson, July 1979,192 pp., S7.50 individuals and public interest groups, S15 all others from: going to bt:. The goal of thc People's Energy Plan is to compost: county-wide reports which will examine the total energy used, how much can be saved through conservation, and what percentage of the remainder ca..'l be replaced by uSing renewable energy sources. Jim Benson and Alan Okagaki's guidebook is a vcritable cookbook on how to preproduct. Although no one has had an opportunity to sec if this guidebook works (to the best of my knowledge) it appears that if you follow the suggestions in the book, your plan will be a vital part of this ambitious and needed project. Let me know how it works out. - YL Weatherization Materials Handbook, Institute for Ecological Policies 9208 Christopher St. Fairfax, VA 22031 703/691-1271 In tb~ May 1979 Issue of RAIN, I mentioned the People's Energy Plan and that a guidebook was availablc to help write thesl:. plans. I have finally received my copy of the guidebook and it appears to ht: t:verything it said it was pare these plans. Not only docs it conraj n specific recipes for calculating total energy use for various sectors of society and what ways that energy can be reduced, it also contains many charts and figures which will he helpful in preparing your local plan. The book also contains s~ctions on why we need such an cnt:rgy plan and what methods to use to write and implement the completed 1979, $6 from: Institute for Local Self-Reliance 1717 18th St. N.W. Washington, DC 20009 This handbook dOl'Sn't attempt to cover the already well-done area of how or how mlteb ti> weatherize a house. What it docs, and docs well, is give a clear and solid explanation of the properties of various insulation, caulking, storm
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