Which fitting gives allowance for thermal expansion in PVC systems?

In PVC systems, thermal expansion can cause significant issues if not properly accounted for. The use of expansion fittings is specifically designed to accommodate the changes in length that PVC materials may undergo due to temperature fluctuations. These fittings function by providing a flexible connection that allows for movement, ensuring that the system can expand and contract without putting stress on the joints or causing potential failures.

Unlike other fittings such as couplings or end caps, which are rigid and provide no flexibility to account for expansion, expansion fittings are engineered for this very purpose. Elbow fittings, while they facilitate direction changes in the piping, do not offer any allowance for the thermal expansion stresses that occur in the system. Thus, the expansion fitting is the correct choice for managing thermal movement in PVC installations.