Registered: 1541781819 Posts: 10
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I built a solar water heater about a year ago and I covered it with clear Lexan R-panels. In about 6 months time the lexan had deteriorated from too much heat, most of this was winter. Now I am rebuilding the panel and have discovered the insulation I used that was behind a 7/16" plywood has surcomed to heat as well.
https://photos.app.goo.gl/MJeF8EMYkLpgzXnf7 I am modifying this as a drainback system but would like to know what glazing would be recommended. https://photos.app.goo.gl/MuKQ9STeutkZt6F16 I live in N. Central TX, it does get quite warm here. Thanks, Rick Wilkinson
Registered: 1352940256 Posts: 1,084
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Welcome Rick. Most folks here are using twinwall polycarbonate. Lots of info linked in the first post of this topic
For insulation most use polyisocyanurate rigid foam board https://www.builditsolar.com/Projects/SpaceHeating/Odor.htm .
- Use only high temperature insulation. Polyisocyanurate insulation works well (1). Don't use polystyrene, as it is only good up to about 130F. The pink, blue, and white rigid sheets of foam board are normally polystyrene
(1) Polyisocyanurate (sometimes called polyiso) is a high temperature polyurethane based insulation that works well in collectors. Many lumber yards carry it, but they often don't know it by the name polyiso. Ask the lumber yard person to look at what they carry -- if its polyiso, each sheet will say polyisocyanurate somewhere on the face. This insulation is usual a tan color, and normally comes with face sheets -- often reflective aluminum foil. Its slightly more expensive than the polystyrene, but also has a higher R value per inch. __________________ Both temperature rise and airflow are integral to comparing hot air collectors