Pressure vacuum breaker backflow prevent or always engaging

Discussion in 'Irrigation / Sprinkler Forum' started by ColbyJack, May 21, 2015.

  1. ColbyJack

    ColbyJack New Member

    May 21, 2015
    North Carolina

    I am putting in an irrigation system with an Apollo pvb. This is the first time I've ever used such a device and wanted to ask a few questions.

    First: I just hooked up my main line to the PVB and when I turn it on, with the end of the mainline open for free flow, the vacuum breaker is always engaging and spilling water after a few seconds of flow. If I turn the distal valve back to approx 80% with the proximal 100% open, the vacuum breaker will not engage. This doesn't seem to make sense to me and the mainline pressure should be lower than the feeding line from the water main. The water main is 3/4" copper and the mainline is 1" poly. Would any one have an explanation why the vacuum breaker is engaging or if this is a sign of the PVB malfunctioning?

    Second: When the PVB engages and spills water during normal function, will the vacuuming breaker engage and spill water until the line is turned off, or should it turn off on its own when the proximal and distal pressures equalize?

    Thank you for your assistance.
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