Hot Water Stockage Tanks Hot Water Stockage Tanks Flowbox on tank The flowbox maintains the hot water temperature in the back boiler for greater efficiency. 54154161 The same tank Hot water stockage tanks can be linked to many heat sources e.g. Solar, heat pumps, oil boilers, electric elements. Meaning your house can be heated many ways! 54154166 Same type of flowbox but in a cave. As they are pumped you can locate them almost anywhere in the system. 54154163 A Gravity fed stockage tank This tank is located in a void directly above the woodburner downstairs. 54154165 An underfloor heating manifold Underfloor heating is very compatible with hot water stockage tanks 54154168