The No Good, Bad & the Ugly

                     “Here is an improper installation with multiple deficiencies.”

1) System has an unprotected bypass, this is not allowed.

2) Backflow assembly is not mounted per manufactures written specifications; mounting bracket blocks the ability to repair this assembly.

3) The Wye strainer is installed downstream of the backflow preventer. In order for the Wye strainer to perform its job and prevent debris from impeding check valve operation it must be installed upstream of the backflow preventer per manufacturer’s written  instructions.

4) Both check valves leaked on this DCVA because the internal assembly was filled with gravel, the contractor did not follow manufacturers written installation instructions and flush the lines before installing the backflow preventer.

It’s important to note: if the Wye strainer was properly installed upstream of the backflow preventer per manufacturer’s suggestion, it would have blocked the gravel from entering the assembly and jamming the check valves  in the fully open  position consequently leaving the city water supply unprotected.

Below is off of Watts basic installation instructions found on the 774 series:

Check with local authorities for installation requirements. Install valve in the line with arrow on valve body pointing in the direction of flow. Pipe lines should be thoroughly flushed to remove foreign material before installing the unit. A strainer should be installed ahead of the backflow preventer to prevent discs from unnecessary fouling.

CAUTION: Do not install a strainer when a backflow preventer is used on seldom-used water lines which are called upon during emergencies, such as fire sprinkler lines, etc.