internal overflow plumbing setup - 55 gal with small internal overflow box

[Mrramsey]

In short yes you can drill a vent hole in the cap of the emergency drain. This will aid the emergency in flowing smoothly if and when it is needed. And yes the main siphon drain into the sump should just penetrate the water level by an inch or so. The 5 inches you have will be difficult to start. I did the same thing on my first BA build.

 

[uncleof6]

In short yes you can drill a vent hole in the cap of the emergency drain. This will aid the emergency in flowing smoothly if and when it is needed. And yes the main siphon drain into the sump should just penetrate the water level by an inch or so. The 5 inches you have will be difficult to start. I did the same thing on my first BA build.

I have to say that the hole in the cap of a pipe that needs to be capable of "siphon" performance is bad advice. With a hole in the cap, under any conditions, the drain will not achieve siphon. rather durso performance, which is not what is wanted here. These systems are based on head pressure, not anything else. If there is insufficient head pressure to start the emergency in case of need, the system is not designed as it should be. Since the emergency is not supposed to have water flow in it, under normal operation, there is no reason or need to smooth the flow through it.

Siphon systems are a case of not everything works, and they are very predictable. These two traits make them very easy to troubleshoot, when they don't work.

 

[Mrramsey]

internal overflow plumbing setup - 55 gal with small internal overflow box

Uncle just to be clear I am talking about the upturned emergency. That would never even become a full siphon, I don't really see how it could. It would suck air before it could start. If it is supposed to siphon then what is the practice purpose for the upturn? From my understanding that is all the upturned elbow would ever achieve. (Durso performance) correct. Not arguing here just making sure we are talking the about the same thing.

 

[uncleof6]

Uncle just to be clear I am talking about the upturned emergency. That would never even become a full siphon, I don't really see how it could. It would suck air before it could start. If it is supposed to siphon then what is the practice purpose for the upturn? From my understanding that is all the upturned elbow would ever achieve. (Durso performance) correct. Not arguing here just making sure we are talking the about the same thing.

We are on the same page. What will happen with the emergency is a function of the head height. It may or may not go siphon depending on the head height. What will determine the head height will be the actual flow rate. So far so good?

We know that an open channel cannot handle the flow that a same size siphon can. Why? Because an open channel cannot become a siphon, because there is no way to stop the inflow of air. However, for back up for a siphon, the "backup" must be capable of flowing the same amount or more than the siphon. So far so good?

Now comes the tricky part with open channels. (aka dursos, etc.) The amount of water that can be in the pipe is inversely proportionate to the amount of air in the pipe. E.G. the less air, the more water can be in the pipe, and the more air in the pipe, the less water can be in the pipe. This is where most folks get off the boat. By putting an additional air inlet in the pipe, you reduce the amount of water that can be in the pipe, by increasing the amount of air in the pipe, and exacerbate the issue you are trying to solve.

The DRY emergency will go to siphon, once the head height is sufficient, to not suck in air. We know that is only a couple inches at the most. (basic operation of the system.) What will happen is the water level will rise, till the emergency is handling an equal flow to that of the siphon before the siphon became occluded. It will not be a stable siphon as the water level will drop, (the dry emergency has higher capactiy in most cases, unless you follow the fractured method of a "trickle of flow" in the dry emergency,) and the siphon will break. The process will repeat. If the dry emergency cannot handle the flow period, either due to insufficient head height (implementation error) or "normally having" flow in the dry emergency, or adding an air hole to smooth out the flow, what the emergency pipe cannot handle, will go over the top of the tank, and on the floor.

Despite the hobby standard of "anything works," siphon systems are fairly close tolerance. There are right ways and wrong ways to implement them. If implemented the right way, there is seldom any problem with them, (other than air leaks) if implemented the wrong way, there are problems with them. The nice thing is due to their predictability, they are very easy to troubleshoot. The list is very short, and they are all implementation errors.

The short answer is, you don't need a hole in the top of the dry emergency, and you don't want one. The ops problem was the emergency was airlocking, because it could not purge the air out. The reason was it was too deep in the sump. Adding more air, would have made the problem worse, not better.

 

[Mrramsey]

We are on the same page. What will happen with the emergency is a function of the head height. It may or may not go siphon depending on the head height. What will determine the head height will be the actual flow rate. So far so good?

We know that an open channel cannot handle the flow that a same size siphon can. Why? Because an open channel cannot become a siphon, because there is no way to stop the inflow of air. However, for back up for a siphon, the "backup" must be capable of flowing the same amount or more than the siphon. So far so good?

Now comes the tricky part with open channels. (aka dursos, etc.) The amount of water that can be in the pipe is inversely proportionate to the amount of air in the pipe. E.G. the less air, the more water can be in the pipe, and the more air in the pipe, the less water can be in the pipe. This is where most folks get off the boat. By putting an additional air inlet in the pipe, you reduce the amount of water that can be in the pipe, by increasing the amount of air in the pipe, and exacerbate the issue you are trying to solve.

The DRY emergency will go to siphon, once the head height is sufficient, to not suck in air. We know that is only a couple inches at the most. (basic operation of the system.) What will happen is the water level will rise, till the emergency is handling an equal flow to that of the siphon before the siphon became occluded. It will not be a stable siphon as the water level will drop, (the dry emergency has higher capactiy in most cases, unless you follow the fractured method of a "trickle of flow" in the dry emergency,) and the siphon will break. The process will repeat. If the dry emergency cannot handle the flow period, either due to insufficient head height (implementation error) or "normally having" flow in the dry emergency, or adding an air hole to smooth out the flow, what the emergency pipe cannot handle, will go over the top of the tank, and on the floor.

Despite the hobby standard of "anything works," siphon systems are fairly close tolerance. There are right ways and wrong ways to implement them. If implemented the right way, there is seldom any problem with them, (other than air leaks) if implemented the wrong way, there are problems with them. The nice thing is due to their predictability, they are very easy to troubleshoot. The list is very short, and they are all implementation errors.

The short answer is, you don't need a hole in the top of the dry emergency, and you don't want one. The ops problem was the emergency was airlocking, because it could not purge the air out. The reason was it was too deep in the sump. Adding more air, would have made the problem worse, not better.

Thanks for explaining that uncleof6. I misunderstood. I think my logic came from that misunderstanding in my first build. I think my emergency drain in that system was/is a few inches below the water level so when I built the new one I added a 1/4" vent hole in the cap. However on my new build the drain is at the 1/2 below weather level.

I will make the necessary corrections to both systems.

 

[cjdesign]

Need to catch up on some reading it think!! Thanks!