BCAB #1712 - Protection of Potable Water System, Subsection 7.6.2.

June 14, 2012

BCAB #1712

Re: Protection of Potable Water System, Subsection 7.6.2.

Project Description

The project in question is an apartment building with a hydronic heating system using two indirectly fired domestic hot water tanks with single wall heat exchanges as the heat source.

Reason for Appeal

Sentence 7.6.2.1.(1) stipulates that connections to potable water systems shall be designed and installed so that non-potable water or substances that may render the water non-potable cannot enter the system.

Appellant's Position

The appellant contends that double wall heat exchangers are not required by the Code in order to conform with Sentence 7.6.2.1.(1). Other than a boiler water make-up connection protected with a reduced pressure backflow preventer there is no direct connection between the heating water medium and the potable water system.

Building Official's Position

The building official maintains a single wall heat exchanger clearly is an apparatus that may introduce substances into the system that may endanger health. The potential hazard introduced through the use of a single wall heat exchanger is a cross connection between the chemically treated heating medium and the potable water in the storage tank. The double wall heat exchanger with leak path provides a degree of protection that limits the potential hazard.

Appeal Board Decision #1712

It is the determination of the Board that its decision in Appeal #1524 also applies to this appeal:

“The Code does not prescribe specific protection requirements for this type of application. While the Code does not require double wall, nor prohibit single wall heat exchangers, all installations must comply with good engineering practices as required in Sentence 7.6.1.1.(1).

The Board feels good engineering practice should include analysis of the product certification and testing information to determine suitability for the intended use. Confirmation from a Professional Engineer that the design, fabrication and installation complies with good engineering practice in accordance with Sentence 7.6.1.1.(1). is an acceptable method of determining compliance.”

George Humphrey, Chair