A pipe-in-pipe fast installation structure comprises: an outer pipe; a pliable inner pipe, disposed in the outer pipe; a connector, connected to the outer pipe; and a C ring, formed integrally with an end of the connector. Wherein, the pliable inner pipe penetrates through the outer pipe to extend out from the connector, while an end of the pliable inner pipe is fastened into the C ring. The C ring used for fixing the pliable inner pipe is formed integrally with the connector. As such, the pliable inner pipe can be fastened into the C ring of the connector by making use of the radial compressibility of the pliable inner pipe. The inner pipe and the outer pipe are fixed together through using a special design connector. Therefore, the installation structure is simple in structure, low in production cost, and fast in installation.

A connection assembly is disclosed for connecting a magnetic separator into a central heating system circuit, the magnetic separator including a housing, a separation chamber within the housing, and externally threaded inlet and outlet ports extending from the housing. The connection assembly comprises: a fitment adapted to be received within at least one of the ports of the separator, the fitment including a bore for carrying fluid from/to the central heating circuit to/from the separator; a threaded connector disposed around the bore for securing the fitment to the or each port, the threaded connector having a hand grip area for facilitating tightening of the connector by hand; and a removable force transfer element receivable between the fitment and the threaded connector for transferring force between the threaded connector and the fitment.

A nipple that includes: a fluid passage; a housing; a valve for the fluid passage; and a relief valve for the valve. The relief valve may include: a first sleeve axially movable for sealing against a first seal of the housing; a second sleeve for sealing against a second seal of the housing; and a third seal for sealing between the first sleeve and the second sleeve. Relative axial movement between the first sleeve and the second sleeve opens or closes, respectively by the direction of the axial movement. The relief valve, the first seal, and the third seal are arranged at a set radial distance from a central axis of the fluid passage.

A fluidic connection system for connecting two two-phase pipes includes two coaxial sleeves defining a central flow flowing through the inner sleeve and an annular flow flowing through the space between the inner sleeve and the outer sleeve. The connection system includes a second complementary connector that is configured to be fastened to the end of one of the two-phase pipes and a first complementary connector that is configured to be fastened to the complementary end of the other of the two-phase pipes.