... pool, sub district; 2. Economic cost; 3. High efficiency Solar water heater projectWorking principle:1) Many-tubes-connected makes the ... stainless steel, the inner tank is produced by argon arc welding, which is very durable with high density;b) Outer ... steel / aluminum alloy, durable and stability performance, well wind resistance solar vacuum tubea) Size: Φ47x1, 500mm / Φ58x1, 600mm / Φ58x1, 800mm ...