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H.reidi.MN
08/06/2013, 05:52 AM
Just curious if anyone has seen or heard of this. So obviously when the pumps go out we deal with drainage down the intake and back through the return until the siphon is broken.

Even though my returns are just under the water line I noticed on the tank I bought used they had tiny holes drilled in the elbow on each return in the top of the overflow... I'm assuming its to break siphon instantly, what I don't like is the loss on pressure and added salt creep as there is constantly a tiny stream pouring out these holes...

downbeach
08/06/2013, 05:56 AM
Very common. If you didn't have those siphon breaks, the water in the DT would drain down to a point that the surface would reach your return discharge, and would most likely overflow your sump.

RocketEngineer
08/06/2013, 07:04 AM
Very common. If you didn't have those siphon breaks, the water in the DT would drain down to a point that the surface would reach your return discharge, and would most likely overflow your sump.

I think you missed something:

Just curious if anyone has seen or heard of this. So obviously when the pumps go out we deal with drainage down the intake and back through the return until the siphon is broken.

Even though my returns are just under the water line I noticed on the tank I bought used they had tiny holes drilled in the elbow on each return in the top of the overflow... I'm assuming its to break siphon instantly, what I don't like is the loss on pressure and added salt creep as there is constantly a tiny stream pouring out these holes...

While I understand the point of siphon break holes, I would rather the return lines are right at the surface. It is easy to plug a small hole but it is much harder to plug two 3" wide slots.....

Both work, I just prefer the less risky solution.

thegrun
08/06/2013, 07:15 AM
It helps to drill them on a downward angle so the water does not spray upward and slightly towards the back of the tank against the water flow. You can seal the old holes with a dab of Weld-On #16 glue.

spieszak
08/06/2013, 07:18 AM
I think you missed something:



While I understand the point of siphon break holes, I would rather the return lines are right at the surface. It is easy to plug a small hole but it is much harder to plug two 3" wide slots.....

Both work, I just prefer the less risky solution.
Its a used tank right? The preference of having the returns right at the surface obviously didn't apply to the previous owner. I agree its a pretty common practice to drill the holes. Mine are in the loc line, since if I needed to make a change the loc line is easier to replace than the return plumbing.

H.reidi.MN
08/06/2013, 08:09 AM
Thanks guys for clarifying that. Ya they had them drilled on each one on the underside of the 90 so it sprays or drips into the overflow not in the air. I keep my returns at the surface so when I move the tank I'm replacing those 90's anyway as they are to high and need to be cut off and lowered.

Thanks

downbeach
08/06/2013, 08:42 AM
You may find that the elbow is just dry fit onto the stand pipe. If so, you can simply cut a piece of the stand pipe to lower it. I don't know if I'd replace it, unless you can come up with a different method of providing a siphon break. That little hole really doesn't lower your pressure much, and it would be best to add other pumps for circulation it that's your goal.

H.reidi.MN
08/06/2013, 10:08 AM
Its glued . And I keep my returns just under the surface so after only 1/4" or so of normal drainage siphon breaks.. I was mostly just curious if the drilled hole thing was normal or not?

jerpa
08/06/2013, 10:30 AM
Siphon breaks are normal when the returns are placed deep in the tank. In your situation it sounds like an unnecessary redundancy since they are only submerged 1/4". I designed my return the same way Rocket Engineer stated and for the same reason.

Palting
08/06/2013, 10:42 AM
I have a tall tank at 27" and need to have vertical flow. So, my returns point deep and go deep. That hole is an absolute necessity. Water constantly runs through the hole, so it's unlikely to clog. BUT, I pass a toothbrush across the hole every so often, anyway. Has not clogged in over 3 years.

jimmyj7090
08/06/2013, 11:54 AM
Still, Mr.Murphy and his law love those little siphon holes when we are relying on them :(

H.reidi.MN
08/06/2013, 12:09 PM
That's why I would only use it as a back up, relying on my outlet to be properly set to break siphon on its own..

downbeach
08/06/2013, 12:39 PM
I keep my outlets just below the waters surface when the returns are off, so when I restart the pumps, I'm not getting a lot of splashing, etc. That means, when the pumps are on, and the water level is at it maximum height, the outlets are about two inches below the surface. In my case that would mean my sump would need to hold an additional 14 gallons of water if I was relying on the openings in the discharges to cause the siphon to break. My sump will hold that much more, but it's a little too close for comfort for me.

H.reidi.MN
08/06/2013, 12:41 PM
That's a lot of water to have flow in your sump. For me I have 2 gal of back flow maybe 4 tops depending on where my returns are.

downbeach
08/06/2013, 12:50 PM
That's a lot of water to have flow in your sump. For me I have 2 gal of back flow maybe 4 tops depending on where my returns are.

You're right, my math was flawed, I already have about 4 gal. of back flow, so another inch below the current siphon break, would mean another 7 gallons.

Palting
08/06/2013, 05:39 PM
Still, Mr.Murphy and his law love those little siphon holes when we are relying on them :(

I hear 'ya. To be honest, the sump has a 55 gallon capacity, but only contains 30 gallons in running trim. Worst case scenario if the siphon holes clog is that the water will go up almost to the rim. I think? Maybe I'll test it :eek:

Savant
08/07/2013, 05:50 PM
I have anti-siphon holes on my 3/4 returns that came with the plumbing kit, I found they were NOT adequate to break the back-flow siphon to my basement sump. Several factor contributed to this I believe:
1) the 8' of 1" pvc return line that the 3/4" lines join to immediately after the tank bulkheads draining vertically to the basement creating a very strong siphon
2) the return loc-lines were deep in the tank allowing the siphon to run for a longer period than if they were closer to the surface
3) lol the anti-siphon holes were of an inadequate size to work with the setup in #1

So my lesson was learned when I was stress testing the system for full power failure. Luckily my sump can handle the volume so I didnt bother increasing the size of the anti-siphon holes. So if your gonna be counting on them, as others have said you might want to test for absolute worst case scenario :spin1: