Silent and Failsafe Overflow System

[uncleof6]

Read what I made bold. I was under the impression that the air line, or in this case, the top part of the p-trap was supposed to be above the emergency. At least that has been my understanding.

You are correct. The inlet to the air vent to the open channel needs to be above the inlet to the dry emergency. This is what I keep talking about, people not understanding how the system is supposed to work, yet giving advice concerning it. They are free to say whatever they wish, however, saying it should be below, is absolutely wrong! It does not matter whether it is a p trap or an air vent line as the original design.

Having the air inlet below the dry emergency does not allow the system to start properly. The open channel takes too much flow, and the siphon does not purge all the air. This is at the top of the list of reasons the system does not start properly. The air inlet needs to be high enough, that during start up, the water level cannot reach the air inlet, which means it needs to be above the inlet to the dry emergency, as if you are getting sufficient head height to start the system properly, water will flow in the dry emergency.

The emergency trip order is and has been all along:

If the siphon plugs --> dry emergency takes the flow.

If the open channel plugs --> dry emergency takes the flow.

If the siphon plugs, and then the dry emergency plugs (both bean and I have had this happen) --> air vent line gets occluded due to rising water level, and trips the open channel to siphon mode, that will quickly pull the water level down from the flood zone. The open channel is the last chance, drop dead fail safe.

Whenever you have an issue with this system look at the way you (collective) have it set up, and compare it to how it should be set up, and you will know exactly why it is not working.

 

[uncleof6]

Yes, that is how it was originally designed. With the original design, as the water level rises the following happen:

1. Siphon channel kicks in (noisy d/t air)
2. Open channel kicks in
3. Emergency channel kicks in
4. Air line occludes, converting open channel from a Durso to a full, unrestricted siphon. The flow dramatically increases and rapidly empties the overflow.

On startup, the water level normally stops rising between 3 & 4. This maintains a head of pressure on the siphon channel, allowing it to purge the air bubbles. As this happens, it gets quieter and more efficient d/t the lack of air bubbles and the water level then drops below the E channel and stabilizes.

If the OC kicks over to a full siphon, it will frequently drain the overflow to the point that the siphon starts entraining air. The OC will then switch back over to a lower flow Durso once the airline is not under water, but the siphon never fully purges.

Depending on the configuration, some systems may purge air before the E channel kicks in. In the system Floyd has with the p-trap, the OC does not instantly convert over to a full siphon the way it does with Bean's original design, so having the emergency above the air inlet for the OC may work since the OC does not totally purge the overflow; I don't know for sure on this point.

Not really.

Normal start up:

Water rises in the OFB, starts flowing in the siphon.
Water continues to rise, and flows into the dry emergency, while the siphon purges the air. This can take several minutes. The water level should drop close to the inlet of the siphon.

The valve is then adjusted raising the water level till water just flows in the open channel.

The open channel should never engage during start up, though there may be a small amount of flow in it, till the siphon drops the water level. If it does, the system is built wrong, and needs to be made right.

Emergency trip order is dry emergency first, and open channel drop dead last chance fail safe.

 

[thejuggernaut]

Makes sense. If the OC engages into a siphon before the siphon has a chance to purge, then it will just keep cycling. Not giving the siphon line enough head pressure to push all the air out of the line and equalizing. I tried mine today with the OC's air vent below the emergency and it still worked fine at flows ranging from about 700 all the way to 3000. It purged and equalized in about 10 seconds. Although I think it would give you trouble setting the OC air inlet lower if you set it up like the original design, with the OC and siphon at the same height. I think this is one of those instances where the rear mounted box gives you more adjustment and can run with a much wider set of perimeters. It sounds like the original system require a very precise setup to run properly. I've tried about 10 different variations in my box, and the only one I couldn't get to run was using a 1.5" pipe on the main siphon for flow less that 1000 GPH. The water didn't have enough velocity to push the air down the pipe with the gate valve so closed off.

 

[sleepydoc]

Not really.

Normal start up:

Water rises in the OFB, starts flowing in the siphon.
Water continues to rise, and flows into the dry emergency, while the siphon purges the air. This can take several minutes. The water level should drop close to the inlet of the siphon.

The valve is then adjusted raising the water level till water just flows in the open channel.

The open channel should never engage during start up, though there may be a small amount of flow in it, till the siphon drops the water level. If it does, the system is built wrong, and needs to be made right.

Emergency trip order is dry emergency first, and open channel drop dead last chance fail safe.

Thought that's what I said!

When you say the OC should never engage during startup, do you mean as an open channel with low flow, or as a full siphon? By design the system has a small amount of flow in the OC at steady state. If the water level rises to the emergency inlet, the OC must have some flow, but it should still be an open channel, not a full siphon, unless the air line is too low and gets occluded.

 

[adova]

The OC is going to start siphon if the emergency kicks in (because the air line gets occluded) from what I understand. OC air line should be right at or just above the emergency pipe. That is the whole idea - if water ever gets high enough to use emergency then OC should convert to full siphon. In my system the emergency never kicks in during normal start up.

 

[mmn]

The OC is going to start siphon if the emergency kicks in (because the air line gets occluded) from what I understand. OC air line should be right at or just above the emergency pipe. That is the whole idea - if water ever gets high enough to use emergency then OC should convert to full siphon. In my system the emergency never kicks in during normal start up.

No. If water gets high enough to flow in emergency, the oc should not convert to full siphon unless and until the water gets high enough to submerge the airline. This will only happen if the emergency is occluded.

 

[adova]

well, for me, I put the air line just above the emergency so that it will start the siphon in the OC. Why wouldn't you want the OC full siphon to occur in that instance?

 

[thejuggernaut]

I personally think that I would like the emergency line to be the last line of defense. My idea system would be Siphon fills and OC trickles under normal conditions. If siphon clogs, then OC rises and if need be triggers a siphon. Continually rising and falling until I hear it and can fix the clog. If the siphon and OC clogs, then it would rise and start flowing through the emergency. I guess it doesn't really make a difference as long as it starts properly. It might not be an option to run it that way depending on how your personal system is setup.

I may even setup my sump to where the emergency would flow into a separate box with a float switch, so that it would trigger the apex and shut off the return pump and notify me. That wouldn't be possible with the normal setup where the emergency takes on water during start up.

 

[sleepydoc]

See my and Uncle's posts above. The issue is with the startup - once the air line gets occluded, the OC converts to an unrestricted full siphon and rapidly drains the overflow. When this happens, the water level frequently drops below the full siphon inlet so it starts entraining air. If you have the air line set too low so it occludes as the water rises during startup, you end up with a cycle that never allows the siphon to fully purge the air.

During startup, you need the water level to stay up long enough for the siphon to purge all the air. If you have the air line above the emergency drain level, the water level rises to the level of the emergency drain. At that point, the E drain handles the flow and the water doesn't rise appreciably higher. At this point you have the siphon purging air, the open channel functioning as a durso, entraining air from the air line, and the emergency channel handling the excess.

Once the siphon purges all the air, it becomes more efficient and handles more flow so the water level drops. Depending on the configuration, pipe/bulkhead sizes, flows, etc, the emergency may not actually kick in before the siphon completes its startup purge, but if the OC kicks over to a full siphon before it does it will generally prevent a proper startup.

 

[thejuggernaut]

See my and Uncle's posts above. The issue is with the startup - once the air line gets occluded, the OC converts to an unrestricted full siphon and rapidly drains the overflow. When this happens, the water level frequently drops below the full siphon inlet so it starts entraining air. If you have the air line set too low so it occludes as the water rises during startup, you end up with a cycle that never allows the siphon to fully purge the air.

During startup, you need the water level to stay up long enough for the siphon to purge all the air. If you have the air line above the emergency drain level, the water level rises to the level of the emergency drain. At that point, the E drain handles the flow and the water doesn't rise appreciably higher. At this point you have the siphon purging air, the open channel functioning as a durso, entraining air from the air line, and the emergency channel handling the excess.

Once the siphon purges all the air, it becomes more efficient and handles more flow so the water level drops. Depending on the configuration, pipe/bulkhead sizes, flows, etc, the emergency may not actually kick in before the siphon completes its startup purge, but if the OC kicks over to a full siphon before it does it will generally prevent a proper startup.

I understand all that, but in my instance, my system is setup to where the emergency doesn't even see any water. The water rises about half way up the OC and the siphon purges in about 3 seconds and the water level starts to lower. It never gets near the emergency or near the OC top. But like I said, it may not be practical to set it up like that with every system.

 

[mmn]

And here we go off on another tangent...

 

[sleepydoc]

And here we go off on another tangent...

yes and no - this is all quite relevant to the Beananimal overflow system

I understand all that, but in my instance, my system is setup to where the emergency doesn't even see any water. The water rises about half way up the OC and the siphon purges in about 3 seconds and the water level starts to lower. It never gets near the emergency or near the OC top. But like I said, it may not be practical to set it up like that with every system.

In the 'standard' setup, the water will frequently rise to the level of the emergency during startup, so having the air line lower creates start up problems. If yours starts up properly, it would probably be ok, unless I'm missing something.

The normal backup sequence is:
1. Full siphon
2. Open channel
3. Dry emergency
4. Open channel converted to full siphon by occlusion of air line.

In your case it would be:
1. Full siphon
2. Open Channel
3. Open channel converted to full siphon by occlusion of air line.
4. Dry emergency

Going through the possible scenarios:
1. Siphon occlusion - open channel takes excess, converts to siphon if water level rises
2. open channel occlusion - water level rises and occludes air line. If occlusion isn't cleared or the open channel can't handle the flow with the air line occluded, the open channel kicks in.

Essentially, the dry emergency is the last line of defence rather than the open channel with the occluded air line

 

[thejuggernaut]

I agree that this isn't a tangent. Discussing variations is relevant in the fact that not all people want their systems the same way.

You are correct, and just to be clear, that wouldn't work in all instances. But because on startup, my system doesn't rise to the level to occlude the OC or to let water run down the emergency, then I could rig it up with a float switch. Because the only time the emergency would see water would be in the event of a clog of one or both of the other drain lines. Immediately shutting off the return pump, and notifying me so that I can fix it. Having the ability to monitor if any water comes down the emergency, is the only reason I can see it being a benefit over the original design.

 

[JACOXVIII]

So I have a 300 DD that I was about to set up but do not think I will be happy with the flow. So with not wanting to drill holes in the back of the Marineland. I started to sketch up this the rear glass is cut down 1.5" to act as a coast to coast over flow. the dimensions would be as close to the 300 DD 72"x 36"x27"

 

[uncleof6]

So I have a 300 DD that I was about to set up but do not think I will be happy with the flow. So with not wanting to drill holes in the back of the Marineland. I started to sketch up this the rear glass is cut down 1.5" to act as a coast to coast over flow. the dimensions would be as close to the 300 DD 72"x 36"x27"

Watch the height on the external. Insure that the external is tall enough both above the elbows and below the elbows, so there is room to "tune" the system, or you will end up with problems. Don't try to cram it all in the shortest external box possible. ~ 8" tall should work, but it depends.

 

[JACOXVIII]

yes it is 8" tall 5" wide

 

[rlinusc]

hello all,

I have read the original post a few times over and beananimal's explanation on his site.

I have a couple of questions:

1) Bean mentions that he originally had 1" bulkheads and then used a reducer with 1 1/2' standing pipes.

How much is adversely affected if one were to stay with 1" pipes? Would it just be a lower flow, or would it make it more difficult to create a full siphon? Would 1 1/4 bulkheads and standing pipes be all right?

I have the option of going forward with 1 1/2' bulkheads, but the piping will be quite large and the holes as well.

2)the original design used elbows with strainers, but i can't figure out where to get them, or how to make them.

3) I am getting a custom internal overflow box made (for a 125 gallon tank, and a full 72" coast to coast overflow seemed a bit much) and asked for dimensions of 24"L x 3" W x 6" H.

If i were to use a 1 1/2 inch bulkhead holes, and started 2.75" 'inches from the top, my bulkheads would fit, but only barely right? (the top of the hold would be 2" from the top and then there is the 1.75" rule).

Sorry if these questions have been answered ad nauseum, i have tried to read as much as i can.

Thanks!

 

[Camien]

hello all,

I have read the original post a few times over and beananimal's explanation on his site.

I have a couple of questions:

1) Bean mentions that he originally had 1" bulkheads and then used a reducer with 1 1/2' standing pipes.

How much is adversely affected if one were to stay with 1" pipes? Would it just be a lower flow, or would it make it more difficult to create a full siphon? Would 1 1/4 bulkheads and standing pipes be all right?

I have the option of going forward with 1 1/2' bulkheads, but the piping will be quite large and the holes as well.

2)the original design used elbows with strainers, but i can't figure out where to get them, or how to make them.

3) I am getting a custom internal overflow box made (for a 125 gallon tank, and a full 72" coast to coast overflow seemed a bit much) and asked for dimensions of 24"L x 3" W x 6" H.

If i were to use a 1 1/2 inch bulkhead holes, and started 2.75" 'inches from the top, my bulkheads would fit, but only barely right? (the top of the hold would be 2" from the top and then there is the 1.75" rule).

Sorry if these questions have been answered ad nauseum, i have tried to read as much as i can.

Thanks!

I used 1-1/4" bulkheads and pipe. I reduced siphon to 1" pipe. It works perfect. My box is 18" long, 5" wide, and 6" high. With the bulkheads and elbows, the width was just barely doable (I used internally threaded bulkheads and threaded street elbows). You may not be able to fit the elbows with 3" width.

You can make the strainers using elbows on a table saw. I just used the elbows with no strainers and have had no problem.

I drilled my holes 4" on center down from the top. I have been very happy with this setup.

 

[sleepydoc]

1) Bean mentions that he originally had 1" bulkheads and then used a reducer with 1 1/2' standing pipes.

How much is adversely affected if one were to stay with 1" pipes? Would it just be a lower flow, or would it make it more difficult to create a full siphon? Would 1 1/4 bulkheads and standing pipes be all right?

Depends on your system and how much flow you want. For most setups, a 1" siphon can easily handle over 900 gph. If you need more flow, you can use 1" bulkheads and upsize the pipe after the bulkhead like Bean did. Larger systems needing higher flows can benefit from the larger bulkheads, but most of the time you can use 1" bulkheads. The limiting factor ends up being the open channel standpipe. The amount of flow it can silently handle depends on the pipe, and a 1.25" pipe can handle significantly more than a 1" pipe.

2)the original design used elbows with strainers, but i can't figure out where to get them, or how to make them.

Bean made them on a table saw, but actually doesn't recommend them. They're not necessary and are dangerous to cut if not done properly. You can buy strainers to put on your elbows, but if you design the system so the downturned elbows are about ¾" from he bottom it will keep most critters out and still allow adequate flow.

3) I am getting a custom internal overflow box made (for a 125 gallon tank, and a full 72" coast to coast overflow seemed a bit much) and asked for dimensions of 24"L x 3" W x 6" H.

Have you already ordered your tank? If not, hold off until you have the system designed. The full coast to coast is generally recommended and is actually easier to install. 3" deep may be too narrow, depending on your plumbing. the 6" height should give you plenty of height.

If i were to use a 1 1/2 inch bulkhead holes, and started 2.75" 'inches from the top, my bulkheads would fit, but only barely right? (the top of the hold would be 2" from the top and then there is the 1.75" rule).

See this post. A 1" Bulkhead needs a 42mm/1.65" hole, 1.5" bulkhead needs a 59mm/2.32" hole. the minimum is 1 hole diameter edge to edge, 1.5 diameters preferred. In general, the frames and plumbing requirements put you past these minimum requirements.

 

[rlinusc]

thank you sleepy,

Can i get one piece of clarification?

When you say below-

A 1" Bulkhead needs a 42mm/1.65" hole, 1.5" bulkhead needs a 59mm/2.32" hole. the minimum is 1 hole diameter edge to edge, 1.5 diameters preferred. In general, the frames and plumbing requirements put you past these minimum requirements.

I bought diamond hole saw bits, and they come in sizes from 3/4, 1', 1 1/4, 1.5 etc, does this mean i need to find a different bit type of 1.65" in order to drill for a 1' bulkhead?

I understand the minimum distance between the holes and the rims looks at the diameter of the hole, is that what you mean in terms of calculating the minimum distances? You should use 1.65 instead of 1.5 for purposes of distance? or do I need to get a different drill bit sizes for my bulkheads?

I bought the tank and plan to drill the holes myself. As for a coast to coast overflow, i can't find anyones that would fit a 72" tank and the coast to make one seems to be exorbitant. I know that a longer overflow box means a better skimming capacity, but i figured 24' was pretty good. Should i go for longer?

for space saving, i think i am going to try for 1 1/4" bulkheads and standpipes.