11-04 Thermal expansion

Question: 11-04Code Section: 7Date: 28 February 2011OBC 2006 Reference:;;

Question Submitted: Could the committee provide various methods of acceptable protection against
thermal expansion.

Interpretation: Protection against thermal expansion shall be required when a check valve is
required by Article, a backflow preventer is required by Article, or a pressure
reducing valve is required by Article

Suitable protection can be achieved by;

a) the installation of an adequately sized diaphragm expansion tank designed for use
within a potable water system,

b) the installation of a thermal expansion relief valve conforming to CAN/CSA-B125.3 (ie.
the only approved T.E.R. Valve presently is used as a shut off valve on the cold supply
to a hot water tank and must be set to a pressure of 550 kPa or less and designed for
repeated use).