What is thermal expansion in residential water supply pipes, why is it a problem, and what is the solution? Last Update: Sep 03, 2002

Thermal expansion is caused when the supply water entering a building at ambient ground temperature is warmed in a closed residential piping system. With check valves in place at the building entrance (to avoid cross contamination) and all end service valves in a closed (locked) position, the water expands and pressure increases rapidly (again, since water does not compress). The potential result: damage to pipes and fittings. SOLUTION: Installation of at least one pressure-relieving toilet fill valve, preferably closest to the building entrance, should solve the problem. CESCO’s pressure differential ballcocks throughout the building will give added protection for the piping system.