Solar hot water heater, 30m copper coil inside of tank, which could bear ... ×18m.Accessories: Water auto-feeding tank, electrical heater. Copper coiler: For heating exchanging, Ø12mm×30m, inside of ... vacumm tube. Higher heat absoption effciency. 2) Copper coil inside of tank could bear high hydraulic pressure, ... hot water out from the coiler. Solar hot water heater& 30M copper coil for heat exchange