Silent and Failsafe Overflow System

[Floyd R Turbo]

well, i just got back from my LFS and Lowes and im glad i checked this before i started cutting the bulkheads out but i must say, im still confused as always.

I'm in the process of draining the tank of fresh water should i just stop where im at and regroup again?

I bought new bulkheads and p-traps but if i dont have to change them then the better

I would start by taking Uncle's advice and fis the two simplest issue first - cut the pipes in the sump to 1" under the water line (easy), move the airline all the way up on the E drain (easy) and swap out the siphon plumbing for 1" (not as easy)

Then try it out. With a reduction in necessary water volume to fill up the 1" siphon line, this may solve the water volume issue...

 

[ChrisQ]

I would start by taking Uncle's advice and fis the two simplest issue first - cut the pipes in the sump to 1" under the water line (easy), move the airline all the way up on the E drain (easy) and swap out the siphon plumbing for 1" (not as easy)

Then try it out. With a reduction in necessary water volume to fill up the 1" siphon line, this may solve the water volume issue...

sounds good, i'll give it a go, haha too bad i just drained the tank and sump but i did just buy some pvc cutters so that should make it easier if i can cut it in place.


If i can get it running with the water in the box just at the top of the elbows for long enough is it safe to say that will be the "running water level" for the drains in the sump? I'm trying to figure out how best to accurately cut the drains.

 

[Floyd R Turbo]

I have some suspicions concerning some "small box syndromes" but nothing I can make a case on yet.

Just thinking about this - I did some calculations after talking to bean about the external box on a high flow system.

What I figured is the rate of rise of water in the box based on the footprint of the external box and the influent water flow rate. This actually cause me to make the external box larger for a system running a higher flow rate.

One thing that I had to take into consideration was the relative level of the external box. For a rimmed tank, you have to put spacers on the box to allow it to clear the trim and be level with the tank. Otherwise, the top of the box is below the trim and this can set you up for an issue. Say the siphon line clogs and the water starts to rise. If the E and OC kick in fast enough, you're fine. If not, the external box can overflow if it is built too shallow.

With the external box even with the top of the tank the water level in the box will rise quickly, but when it reaches the water level in the tank, it will slow because the tank water level is now rising with it. With the E drain 2" from the top of the box, this allows plenty of time for it to kick in and take on the excess flow not taken up by the OC before it kicks in. With the P trap hole open (plug removed) as soon as you get a good amount of water over it, that will quickly purge and flush, then the process will repeat (as the OC is not tuned, it will likely cause a cyclic flushing)

So the issue of the small box must be accounted for by total water volume of the box, i.e. height. This can also be done by making the box deeper, and putting the plumbing down low, but this is really hard to do because placing pass-thru bulkheads higher relative to the operating water level required with such a setup means the water is crashing out of them into the box and this doesn't work. I know this from experience. The result is that you have a deep box with high bulkheads and the timing of the water level rise to a level necessary for the start-up process to happen and result in quiet operation is too fast, and the box overflows. I'll let you guess at how I found that out.

The pass-thru bulkheads must be underwater for the system to be silent and have a bubble free operation on the siphon line in the sump. This generally means you have to have the external box tall enough to cover the necessary rate of rise, which means it has to have the top even with the rim of the tank.

 

[ChrisQ]

oh btw, the air line was just a hair under the bottom of the cap. Was that too low?

 

[Floyd R Turbo]

sounds good, i'll give it a go, haha too bad i just drained the tank and sump but i did just buy some pvc cutters so that should make it easier if i can cut it in place.


If i can get it running with the water in the box just at the top of the elbows for long enough is it safe to say that will be the "running water level" for the drains in the sump? I'm trying to figure out how best to accurately cut the drains.

I'm not sure I'm following you.

The other thing that you will want to do while you are replacing the siphon line is to put the gate valve at the lowest point possible. A long vertical run under the gate valve will let the water free-fall and could be letting air intrude or rather prevent air from quickly purging out. This also causes a long start-up cycle.

 

[Floyd R Turbo]

oh btw, the air line was just a hair under the bottom of the cap. Was that too low?

I believe you want the airline to be just below the maximum water level that you want in the DT.

So if you have a desired water level of say 3/4" from the rim, put it at 1" below the rim (1/4" below the maximum). So when the water level in the tank starts to get to the point where it will start rising, that's your "oh-cr-p" point and you want the OC to convert to a siphon before that happens.

But check the OP just to make sure....or Uncle will correct me

 

[uncleof6]

Air vent line should be attached just below the trim lip inside the tank. Look back through a few pages, and you will find an image that shows said lip. Trying to translate that to an external box could be a bit tricky. Again, it is not rocket science, you just don't want it occluded during start up, ever, but you want it to trip before the tank/external box starts overflowing, (with some wiggle room,) which ever would occur first.

Easy way to set it, is to run the system without it, until you get the system up and running properly. Then when you restart it, note the high water level and set the air vent line inlet a little above that.

 

[Floyd R Turbo]

you just don't want it occluded during start up, ever,

Never caught this, but in the one I set up I just snaked the airline down the emergency drain. It stablizes so fast though, and since I have the OC about 1" higher than the siphon, even if it does kick over to siphon it won't suck the box dry which allows the siphon to continue purging and the OC opens back up again.

Uncle can you see a potential issue with doing it like that?

 

[uncleof6]

Yes I can see it occluding before the siphon purges. Water should flow in the dry emergency during start up. (Usually anyway, every system is different to a point.)

 

[thejuggernaut]

Yes...glad you agree. I think that additional plumbing is the cause of the problem. If the system isn't really high flow, then the water going through the siphon line is not going to be turbulent enough to churn all that air up and suck it out. So the result is that you have an airlock type of situation, and in order to resolve that the water level has to rise higher relative to the air bubble and compress it to get more water to flow. The more water flows, the more the bubble is purged, the more water flows, and the effect cascades until all the air is vacuumed out of the siphon line.

The other problem I see is that the OC is very close to the level of the siphon line, when looking at the horizontal cross-section of the pipe for both of these relative to each other. You don't need these to be close, you don't want these to be close. You want the siphon line in the bottom of the box, as low as it can go because it doesn't control the the operating water level of the box. The OC does. So IMO the horizontal center of the OC must be no lower than the top of the siphon elbow in order to work right. If you have the space, higher.

I made this, if this helps visually explain what I'm trying to describe

Why even put a p-trap on the submerged line. I ran one without it for years and honestly I never understood why anyone puts one on it. Mine never surges when starting back up. The water level just slowly rises to the open line. Maybe I am missing something.

 

[adova]

Good morning all!

I cranked up my new system for the first time last night and I need a little help troubleshooting my drains. My problem is that I am getting some "running water" noise from the gate valve on the full siphon line. Everything is glued except the connection into the male adapted that is screwed into the bulkhead.

I have some theories as to what may be wrong, but I wanted to check before i start chasing fixes if they are not related:

My siphon line is too high in the overflow. Just made some poor calculations here. I can switch to slip bulkheads and reduce the height significantly.

The gate valve for the 2nd drain is full open - I only adjust the main siphon. I realize now that I did not need the extra gate valve, but whatcha gonna do

The main siphon line runs straight into the sump. It is submerged about 2 inches. I realize that 1/2" is optimal (just did not pull it yet). Could this be the culprit?

Thanks in advance!

Shawn

 

[adova]

Here is a quick vid - it doesn't sound as loud in the video, but I swear it is, lol.

http://youtu.be/JubuTYv8YaU

 

[Floyd R Turbo]

Yes I can see it occluding before the siphon purges. Water should flow in the dry emergency during start up. (Usually anyway, every system is different to a point.)

Well as I mentioned, the OC is about 1" above the siphon, so even if it does occlude the opening fully on start-up, it doesn't drain the box down to the point where the siphon line opens up so it doesn't interfere with start-up.

Now that I understand that you can run the OC and Siphon at the same level, I can see how this variant is different though.

Why even put a p-trap on the submerged line. I ran one without it for years and honestly I never understood why anyone puts one on it. Mine never surges when starting back up. The water level just slowly rises to the open line. Maybe I am missing something.

If you do the original design (internal box only) then no, you wouldn't need a P trap, just a downturned elbow. But with all the plumbing in an external box (variant design) and the bulkhead in the bottom of the box, you need to have a 180 elbow hence a P trap or 2 90s together so that the siphon intake faces down. Otherwise it would face sideways.

 

[Floyd R Turbo]

My siphon line is too high in the overflow. Just made some poor calculations here. I can switch to slip bulkheads and reduce the height significantly.

I don't think you need to switch bulkheads, but you could. this falls under the variant design (external box, bottom bulkheads). Should we start calling it that?

So you could friction fit a P trap into the thread/slip fitting and reduce the height a little, but not much. With the external box you don't need the cap for cleaning access, you can just remove the plumbing part (For reference, 3 years and I haven't had to do this yet).

What you could do is cut the slip side of the fitting down bit so that the double-elbow can be lower in the box. Again it doesn't have to be water-tight but does need to be air tight (so seal with TFE paste is fine) because the siphon line can pull air in through a loose joint (resulting in air in the sump outlet, not a big deal, just an annoyance)

Or, you could change the BH to slip on flange and friction fit everything in.

The gate valve for the 2nd drain is full open - I only adjust the main siphon. I realize now that I did not need the extra gate valve, but whatcha gonna do

You only need a gate valve on the siphon line, no where else. And the gate valve should be as close to the outlet/sump as you can possibly get it. Otherwise the air in the line below the gate valve can take a long time to purge, it will be noisy, and it might even shake quite a bit as the air tries to rise in the pipe against the falling water.

My latest trick - which works fantastic if you are using 1.5" pipe, is a single-union ball valve from Lowes. 100% plastic (no metal screw) Best part, it's less than $10.

http://www.lowes.com/pd_146171-185-024+LBVUS-112_0__?productId=3130791

This one has a nut on one side that works just like the internal nut on a dual-union $40 valve like you get at BRS. The difference is that the nut both tightens down on the ball, and serves as the means to take apart the device. This valve is completely useless in any other application except maybe hot tubs from what I understand, because you can't shut it off and then disconnect it with water on the other side - the ball slides out when you take it apart. BUT - we don't need it for that! We just need fine control and the ability to lock it down. So you set it up nut-down and submerge the bottom outlet (which sticks out 1/2" or so) and loosen the nut. Start things up, adjust the ball (which spins freely) then tighten the nut when you get it tuned, and it won't budge at all. If you ever need to fine-tune it, loosen it a good amount, make your adjustment, then tighten it down again.

The main siphon line runs straight into the sump. It is submerged about 2 inches. I realize that 1/2" is optimal (just did not pull it yet). Could this be the culprit?

Yes, that is a problem. 1" max under the surface. Any more and the air can't easily purge out of the line

 

[woodnaquanut]

Good morning all!

I cranked up my new system for the first time last night and I need a little help troubleshooting my drains. My problem is that I am getting some "running water" noise from the gate valve on the full siphon line. Everything is glued except the connection into the male adapted that is screwed into the bulkhead.

Everything Floyd said is right on!

One other thing I noticed...
There seems to be some small bubbles being created as water goes over the weir. If these are sucked into the siphon they could be the source of the noise. As the system matures and grows some slime coat the bubbles might go away. Smoothing the weir path would also help.

You should be able to see which drain is getting the bubbles. Might be easier to see w/o the socks. BTW you really only need one sock - on the siphon. It will carry 95% of the flow.

I like Floyd's P trap but you can also use two street ells. If you trim some off the male end of a street ell, it will sit lower in the OF box. That plus a small trim on the slip side of the slip-thread adaptor will lower the siphon if you need to.

And lastly, my pet peeve...
Video doesn't like 'portrait' mode. You just loose lots of visible area. Turn your camera 90 degrees!
End of peeve...

 

[thejuggernaut]

Mine was a corner overflow with the holes drilled through the bottom. I didn't have anything screwed into the bulkhead. When I would turn the water off the entire drain would empty, and when I would turn it back on, it would slowly rise the water level over around 60 seconds till it reached the open drain. What was nice, was if I ever got crud settling in the bottom of the overflow, I would just open my main drain all the way and the water level would lower, stirring the bottom and sending it down the drain into the filter sock. I could see where this wouldn't work with a normal C2C where it is drilled through the back and the water barely covers the bulkhead, but with one of the bottom drilled bulkheads it would be fine if not preferable to not install anything on that bulkhead. The only advantage I can see to installing a P is that when you shut off the pump, the water won't completely drain out of the box in a power outage. But ya'll are advising against gluing the p traps anyways, so over time it will still drain down.

 

[thejuggernaut]

As far as what to name the different variants of overflows, I vote for:

Internal C2C (Original Bean Design)

External C2C (Type used by adova)

Dual Chambered Overflow (Ghost style)

All with a 3 piece drain system of course!

 

[adova]

Everything Floyd said is right on!

One other thing I noticed...
There seems to be some small bubbles being created as water goes over the weir. If these are sucked into the siphon they could be the source of the noise. As the system matures and grows some slime coat the bubbles might go away. Smoothing the weir path would also help.

You should be able to see which drain is getting the bubbles. Might be easier to see w/o the socks. BTW you really only need one sock - on the siphon. It will carry 95% of the flow.

I like Floyd's P trap but you can also use two street ells. If you trim some off the male end of a street ell, it will sit lower in the OF box. That plus a small trim on the slip side of the slip-thread adaptor will lower the siphon if you need to.

And lastly, my pet peeve...
Video doesn't like 'portrait' mode. You just loose lots of visible area. Turn your camera 90 degrees!
End of peeve...

Thanks to both! My weir and I are very frustrated. Not only did I miss drill one of the holes before I started routing it out (making one side 1/4" too low), the bearing on my flush trim bit came loose and - well - you can imagine. I am going to work on some repairs in that arena as well.

And, yes - I am no videographer, lol

 

[Floyd R Turbo]

Ah, I see what you are saying jug

On the external box with nothing in the siphon bulkhead, the issue is that makes it easy for a snail to go down and block the line. Also an open drain at 3000 GPH will likely vortex the surface and you will get a sucking sound unless you have to 'just right'

The P trap or double elbow allows you put the inlet very close to the bottom of the box it is in, which reduces what can get into the siphon line, as well as eliminates the vortex issue.

 

[thejuggernaut]

That makes sense. I don't really like snails walking on my glass and my bulkhead was 21" below the water surface, so I didn't have issue with either at the time. This new system might draw in air with only 3 " of water over it.