08-09 PEX at hot water tank

Question: 08-09Code Section: 7Date: 22 February 2008OBC 2006 Reference:

Question: How close to the HWT do you allow PEX piping? We ask for 18” copper from HWT to basically mixing valve; now some inspectors are asking for 36” copper, on both the inlet and outlet, past the mixing valve, before the PEX tubing can be used (?). Supposedly this is based on manufacturer’s specs (?). Is it necessary to have copper in this instance? Is there a code reference to back this up?

Interpretation: The installation of PEX piping systems shall be in accordance with the manufacturer’s specifications and, therefore, the distance to the hot water tank must satisfy the conditions imposed by the manufacturer. It is not necessary to have copper specifically. One manufacturer specifies the use of a metallic connector to be used between a gas water heater and the PEX piping with a minimum length of 18 inches. Another standard refers to “components covered by the specification may not be suitable for use with the instantaneous type water heater. They are suitable for use with storage type water heaters with connections made in an approved manner.” The code reference to support the above statements is which specifically references Appendix A- which references the installation information within CAN/CSA B137.5.

Approved at AMES 2008