Abstract: A flexible fluid-filled circulation conduit is selectively and removably connectable to a portable hot water heating system. The conduit is configured and arranged so that prior to connection to the hot water heating system, the conduit carries its own fluid supply under pressure within the conduit for circulation through the hot water heating system. Upon removable connection of the fluid filled conduit to the hot water heating system, fluid from the conduit immediately circulates under pressure with fluid from the hot water heating system through both the conduit and hot water heating system. Upon selective disconnection of the conduit from the hot water heating system, fluid within the conduit is retained under pressure within the conduit and fluid continues to circulate through the hot water heating system but is prevented from circulating through the conduit.