Has anyone ever installed a pvc siphon system in the more northern states where it is subject to freezing? Is it even feasible to do so?

Bob

I might add that the freezing concern is with the intake air vent and not the main part of the system which can be deep enough under ground so as not to freeze. As I understand it if the air intake vent becomes blocked either with debris or ice it can cause the pond to drain accidently.
Any advice or experience with this would be appreciated.

Old Bob, that is a great question, but my curiosity leans back to the main water feed line.
If the water surface of the pond freezes 6" thick, why wouldn't the same 6" freeze within the pipe, thus creating a 6" thick ice plug?

Brettski

The reason I believe that the main drain will not be a problem in freezing weather is because of how it can be installed under ground far enough to prevent it. Check out this website for a diagram from easywayplastics, a company that sells supplies for the siphon system.
http://www.easywayplastics.com/page/page/1478349.htm

Bob

hmmm...that creeps me when I know that the frost line can be at 36" + in the midwest

I think many siphons use a Y with a clean out port where the suction pipe goes into the water. How about putting the clean out port at the desired high water level so in winter you just leave it open like a traditional overflow pipe then plug it back up at ice out. It won't have the capacity of an active siphon when in "winter mode" and this should be considered during design.

Ryan that is a good idea. I had been thinking about a similar type of fix using a pvc ball valve. If you look at the siphon system diagrams that they have on the pond dam piping website they show a 3 or 4 inch tee on top of the riser for the vent pipe with a plug in the top. I had thought about putting a pvc ball valve there and just opening it when we have freezing weather. Usually when it is freezing the water flow really slows down so I believe that may work to prevent accidental siphoning of the pond.

Bob

Brettski, Here in my area of Virginia the frost line is 24 inches so we would not have to go as deep as in your area.
Bob

Here's what I had in mind. Remove the "plug" at the left for winter. This way it would be nearly impossible to plug with ice. The bottom of the left "plug" hole would preferably be at the desired high level mark.

That is certainly one option to consider. I noticed on your drawing that there was a rubber coupling on the siphon pipe in the pond. Is the purpose for that so the pipe can be disconnected and removed for cleaning. On all the drawings I have seen they show a trash guard on the intake and I have been wondering if they have to be cleaned periodically.

Bob

For cleaning, assembly, shock absorbtion, ice movement, etc. A trash guard is a good idea too. Siphons can develop a tremendous amount of power. I started a siphon with a 2"id sandblast hose once to lower my pond for some bank work and it sucked onto my waders. I had pull the outlet line out of my overflow pipe to break the suction because I couldn't get it off. Good thing I had on waders or I would have had a heck of a hickey on my leg.