Silent and Failsafe Overflow System

[TheFishMan65]

Area of the inlet is pi r squared circumference is 2 pi r. You need it high enough that the two are equal or the opening may be the limiting factor in water flow. So if my math is right you need in opening r/2 above the glass.

 

[JTL]

Only other reasons to upsize lines was to be sure you kept air in the open channel, and allowing more surface area for water to travel down, reducing noise. The other reason, is there is less chance of clogging the drain at the valve or union, if it makes it past the bulk head.

The only air that gets into my open channel is from the small airline tube. I get no water going into my open channel unless the system is restarting. The full siphon is doing the work.

 

[ram1500]

anyone have any luck finding 1" x 1.25 street elbows? Best I can find is 1" x 1" street elbow.

Thanks
Gus

 

[Names Brucey]

OK. New one. I found what I thought were street elbows at Lowes but they are loose in the bulkhead fitting. Real loose. Any ideas?

 

[CJBROWN]

OK. New one. I found what I thought were street elbows at Lowes but they are loose in the bulkhead fitting. Real loose. Any ideas?

What size are your BH's?
What size is your pipe?
You're putting a fitting directly into a BH? Usually they go onto a short length of regular pipe first, then into the BH. Mine fit snug enough to need nothing but a friction fit to be watertight. Your elbow and BH should be the same ID. They are sized to fit standard OD PVC pipe, whether it be thin-wall, regular or sched 80.

 

[BeanAnimal]

Just build your own "street els". by using a short length of pipe. You can cut the socket down slightly if you need a more narrow profile.

 

[TheFishMan65]

Please correct me if I am wrong. I also maybe mixing folks up.

BUT

If the T is friction fit into the bulkhead you could just use 2 elbows. The T was for cleaning unscrew the cap for cleaning. If the the joint can be pulled out for cleaning then no cap is needed. This may also save a few dollars. This will require that the air line tube be moved for the open channel to some other convenient location.

 

[RocketSurgeon]

Keep in mind, water tight and air tight are two different things. I have heard individuals having air leaks on the siphon line, yet no water leaks. This causes an issue trying to start the siphon.

 

[BeanAnimal]

Air leaking is one issue:

SLIP fittings IN the overflow box tend NOT to leak air simply due to them being submerged, or mostly submerged and the fact that they get gummed up fairly quickly.

SLIP fittings EXTERNAL to the box MUST be solvent welded. They will leak air and/or water, but more importantly, if they ever came loose they would cause a flood.

 

[TheFishMan65]

Yes - I should have specified slip fitting IN the over flow box.

 

[JTL]

Bean, I am still pondering the pipe size issue. Can I use 1" for everything in the overflow box including a 1" BH and then go to 1-1/4" for the down pipes and not sacrifice any flow? I really don't get the dynamics of this but is seems like if you use a 1" BH that is the restrictive part and nothing else matters. Yet everyone seems to agree that it is better to use a larger down pipe.

 

[BeanAnimal]

The larger intake bell simply reduces velocity and helps to ensure that a vortex does not form in a shallow overflow box. The smallest ID of the standpipe is (in theory) the limiting factor. That said, for a high flow strandpipe, the friction of the pipe length comes into play and part of the reason that I increased the diameter of the siphon standpipe. I also wanted to ensure that the growth of tube worms and other high flow, low light creatures did not affect the flow in the siphon to the degree that regular maintenance would be an issue.

Secondly, the open channel standpipe must not be allowed to cross into 2-phase (air mixed with water) flow, or it will create noise and a lot of bubbles. The larger the diameter of the pipe, the less likely this is.

 

[RocketSurgeon]

... I really don't get the dynamics of this but is seems like if you use a 1" BH that is the restrictive part and nothing else matters...

There is another part that matters greatly, if you use a gate valve. Gate valves do not fully open. A gate valve is 20% +/- restricted when fully open.

To get maximum flow from a 1" pipe, you need a 1.25" gate valve.

All this said, there are people that have used the 1" globally, without any issues.

 

[JTL]

Gate valve issue makes sense. I use one but it is only about 1/2 open.

My open channel is not used except for startup because the operating water level in the OF box is lower than the intake. I have the open channel and the full siphon set at the same height. Is this how it is supposed to work?

 

[RocketSurgeon]

Gate valve issue makes sense. I use one but it is only about 1/2 open.

My open channel is not used except for startup because the operating water level in the OF box is lower than the intake. I have the open channel and the full siphon set at the same height. Is this how it is supposed to work?

There should be a trickle of water in the open channel. This ensures you are not siphoning more than your pump can handle.

 

[JTL]

I thought that was a function of the gate valve. If the water level gets too low for the intake of the full siphon I just adjust the flow. In order for me to keep the water level high enough to force some of it down the open channel I barely have any drop into the OF box from the tank. If I had made the box deeper or set the open channel lower this would not have been an issue.

 

[RocketSurgeon]

I thought that was a function of the gate valve. If the water level gets too low for the intake of the full siphon I just adjust the flow. In order for me to keep the water level high enough to force some of it down the open channel I barely have any drop into the OF box from the tank. If I had made the box deeper or set the open channel lower this would not have been an issue.

the gate valve adjusts the flow. the flow should be adjusted so that there is a trickle of water entering the open channel. box size has no bearing on adjustment, although it may determine the length of time it takes to start the siphon.

 

[RocketSurgeon]

Copied from Bean's webpage:

http://www.beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system.aspx

"During normal operation the valve on the Siphon (middle) standpipe is adjusted (as shown in the rendering above) until the water level in the overflow box rises high enough that air is not being sucked into its down-turned elbow. This means that the standpipe is running at full siphon with NO air being sucked in. This is DEAD SILENT. However, it also means that the standpipe is NOT handling all of the flow from the return pump. This is where the Open Channel (right) standpipe comes into play. The Open Channel (right) standpipe is open to the air via the airline attached to it. Because air is allowed in and the overall flow is fairly small (the siphon standpipe is handling the bulk of the flow), the standpipe will not siphon or gurgle. In other words, the small amount of excess flow that is not being handled by the Siphon (middle) standpipe quietly flows through the Open Channel (right) standpipe. Because the flow is very low, very little air makes its way to the sump."

 

[TheFishMan65]

Part of the issue is how much room between the inlet for the siphon and the open. If there is a lot of room it is possible for the siphon to take the full flow of the pump. But if there is any build up then the siphon will take slightly less. This will raise the water level in the over flow. The higher water causes additional head pressure and the siphon can flow more. Eventually the water raises enough and goes down the open. No imagine some water evaporates the pump will pump less due to the additional head pressure the water level will drop and the siphon will take it all. More evaporation and the siphon will start to draw air.

This is why the Herbie system works well on tall stand pipes there is lots of range between the siphon and emergency to allow for changes in pump. The Bean design due to the short box does not allow this as much and need the open drain to be quiet.

 

[CJBROWN]

There should be a trickle of water in the open channel. This ensures you are not siphoning more than your pump can handle.

This could be a bit confusing to the inexperienced.
Yes, you need a trickle in the open channel - this insures that the full siphon is just that, no air in it, at max capacity for the valve setting.

The second part is what's confusing. It isn't what your pump can 'handle', it is the source, so it would be what your pump 'produces'.

If the T is friction fit into the bulkhead you could just use 2 elbows. The T was for cleaning unscrew the cap for cleaning. If the the joint can be pulled out for cleaning then no cap is needed. This may also save a few dollars. This will require that the air line tube be moved for the open channel to some other convenient location.

I did not use a tee and cap on the full siphon, it is slip fit in the BH, used two elbows, works fine.

For the open channel, if you didn't use a tee, where would you relocate it to? Where would you install the vent tube? The rising water and thus blocking the vent tube is what turns it into an emergency full-siphon drain.

So, I'm confused. :spin2: