BCAB #1370 - Water Hammer Arrestor Location, Article 6.1.8., B.C. Plumbing Code

December 16, 1994

BCAB #1370

Re: Water Hammer Arrestor Location, Article 6.1.8., B.C. Plumbing Code

Project Description

The project in question is a four storey residential condominium. A single water hammer arrestor has been installed at the top of each hot and cold water riser.

Reason for Appeal

Article 6.1.8. requires provision to be made to "...protect the water distribution system from the adverse effects of water hammer by the installation of manufactured air chambers.".

Appellant's Position

The appellant contends that one water hammer arrestor at the top of each hot and cold riser should be sufficient so long as the number of fixture units for which the device is approved is not exceeded. In this case a Type A water hammer arrestor approved for 11 fixture units serves only 9 fixture units and a Type B water hammer arrestor approved for 32 fixture units serves only 18 fixture units. The appellant also contends that if the distance between the water hammer arrestor and the fixture served is a factor then one at the top and the bottom of the riser should be sufficient.

Building Official's Position

The building official maintains that water hammer arrestors are required on each fixture branch line. This requirement is based on the manufacturer's installation instructions which state that the water hammer arrestors should always be installed as close to the source of shock as possible. Also, the water hammer arrestors standard PDI-WH 201 sizes water hammer arrestors for fixture branch lines and there is no evidence in the standard to indicate they can be installed only at the top of a four storey riser.

Appeal Board Decision #1370

It is the determination of the Board that Article 6.1.8. is not specific as to the number or location of water hammer arrestors. Water hammer arrestors are required where water hammer exists and must be installed as and where required to "...protect the water distribution system from the adverse effects of water hammer...". The water hammer arrestors installed at the top of the risers may be adequate but if they prove to be insufficient additional units must be installed.

George R. Humphrey, Chair