InsulSeal Web Site,

The characteristics that make rigid Insul-Seal a superior insulator for hot water lines has finally been translated into a flexible version retaining the positive benefits of the original product.

Flexsul-Seal is an elastomeric thermal insulation used to retard heat loss in hot water plumbing and dual hot waterline systems. The Flexsul-Seal system is designed to trap dead air, within an expanded closed cell structure, thus increasing its total R-Value and reducing Heat loss in cold underground burial. Thermal performance is achieved by sealing the 2 5/8" centered air space, in effect reducing the flow of air and increasing the total R-Value of 6 by an additional factor of 5-9.

Flexsul-Seal Performance

The following chart from Flexsulseal.com gives examples of performance at some typical installation parameters. Contact us for expected performance on your particular installations.
Calculations based on the German 'VDI-Richtlinien' VDI 2055, July 1994.