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Air admittance valve vs. venting

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frodo

Just call me Macgyver
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I understand how siphon works very well
And that is NOT what I am talking about
BACK SIPHONAGE/BACKFLOW as pertains to plumbing drain/vent systems
is not the same.
 

frodo

Just call me Macgyver
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If the atmospheric pressure pushes water out of a vessel
then please explain how the water in this vessel is overcoming gravity

Let me explain this to you, to Begin the process of siphoning
first you must have negative pressure to PULL the water up and out of the higher vessel
This is called backflow or backsiphonage in the plumbing industry.
This action is what PULLS the water out of the trap.
After, the initial negative pressure has pulled the liquid out of the trap [vessel]
THEN, the weight of the water and atmosphere pressure can PUSH the water .
WHICH. Does not happen because only a small amount of water is in a p trap
So to re-cap
A vacuum [negative pressure] is what pulls the water from a trap






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