... tube solar thermal collector (CE, ISO9001,CGC,Keymark ) Features:1. High Efficient:Excellent selective absorbent coating and perfect combination with high vacuum ... too many rainy days and snowy winter days.Specification:1).Vacuum tube: 58mm*1800mm,High borosilicate glass,hardness 3.3, with ... /(m2. °C) 2012 hot sell heat pipe evacuated or vacuum tube solar thermal collector (CE, ISO9001,CGC,Keymark )