... than ten yearsVacuum tube: Φ58*1,800mm double-vacuum solar collector tube, the product is a ... of high-temperature resistance, anti-freezing, high heat efficiency, long service life, no leakage of ... , aging resistance, high efficiency, vacuum super heat conduction, one-way heat transfer, etc.Volume (L): 160 to 350LNumber ... Light Gathering Series 30GS18/Φ58--45° double vaccum solar energy heater