Abstract: A fluid coil includes a tube bundle having a series of straight tubing runs and a series of return bends extending between and fluidically connecting ones of the straight tubing runs, an expansion header fluidically connected to at least some of the return bends and a polymeric material disposed in the expansion header. The polymeric material has an initial shape and is compressible to repeatedly expand and contract between a first volume in which water is present in the tube bundle and a second volume in which the water undergoes a phase change. Contraction of the polymeric material absorbs an increase in volume as the water undergoes the phase change to prevent stressing and rupture of the tube bundle and upon an opposite phase change, the polymeric material returns to its initial shape. The polymeric material can be a pressurizable bladder. A system and method to prevent the rupture of a tube bundle in a fluid coil are also disclosed.