# Weird issue during "winterization" yesterday



## Glen_Cove_5511 (Jun 13, 2020)

My irrigation vendor came by yesterday to blow out my lines. Something really odd happened.

Let me explain and see if anyone has an idea of what may have happened.
A = Is the water input to the removed backflow
B = Is where the backflow valve is during the season
C = Is the water output from the backflow
D = Is a shut-off valve to the manifold/zones

The tech removed the backflow and then we blew each zone one at a time. Once all zones were blown out and fogging, he removed his air hose and coupling from location C. To our surprise, there was still water in C. Really at loss as to how that could be. I ended up manually vacuuming out the water.


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## Factor (Oct 10, 2019)

Air like water takes the path of least resistance. As long as the water can spread out inside the diameter of the pipe. The Air will never push it all out. You would have to leave the air running for a extremely long time for it to actually dry it out. Some people use lateral drains. King Innovation Plastic Lateral Line Drain 1/2 in. MPT | 22163
Watch the video.
They do fail and you have to dig them up to replace them.


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## FailedLawn (5 mo ago)

Factor said:


> Air like water takes the path of least resistance. As long as the water can spread out inside the diameter of the pipe. The Air will never push it all out. You would have to leave the air running for a extremely long time for it to actually dry it out. Some people use lateral drains. King Innovation Plastic Lateral Line Drain 1/2 in. MPT | 22163
> Watch the video.
> They do fail and you have to dig them up to replace them.


Yup, would be virtually impossible to remove all water with air. I just installed irrigation this season and placed 2 manual drain valves on low(er) parts on the poly lines. I’m curious as to how empty is good enough to prevent freeze damage. Obviously water expands when frozen, but if there’s enough room in the pipe, it shouldn’t damage anything. Water expands around 10%. 

Water lying in the pipes will seek level. What one really need to be concerned with is low spots that would allow water to pool after blowing it out. If too much water is in a given area, that’s where damage can occur. If this isn’t a new system, there’s a good chance that everything should be ok.


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## Victor Von Lawn (5 mo ago)

Try to figure out where is the lowest spot on your property. (excuse to buy a laser level) If "C" is the lowest you are very lucky, as that is where the residual water pools.


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## Glen_Cove_5511 (Jun 13, 2020)

Victor Von Lawn said:


> Try to figure out where is the lowest spot on your property. (excuse to buy a laser level) If "C" is the lowest you are very lucky, as that is where the residual water pools.


C is not the lowest point on my property and not the lowest point for my irrigation. I have one zone out of 5 that have heads lower than C. The rest of the zones/heads are higher.


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