how does an Overflow box work?
- Thread starter 1990jpyj
- Start date
natclanwy
Active Member
Sorry, must not have done a good enough job in the other post
You don't have to restart the siphon after the power goes out in fact it never really loses the siphon they are designed so that the ends of the u-tubes stay submerged underwater so that air cannot be introduced in the u-tube causing the siphon to break.
It is the same concept as when you fill a cup with water inside of the sink and the lift the cup out of the water with the opening on the bottom, the water will stay in the cup until you get above the surface of the water letting air into the cup.
You don't have to restart the siphon after the power goes out in fact it never really loses the siphon they are designed so that the ends of the u-tubes stay submerged underwater so that air cannot be introduced in the u-tube causing the siphon to break.
It is the same concept as when you fill a cup with water inside of the sink and the lift the cup out of the water with the opening on the bottom, the water will stay in the cup until you get above the surface of the water letting air into the cup.
cowfishrule
Active Member
Originally Posted by natclanwy
http:///forum/post/2865120
Sorry, must not have done a good enough job in the other post
You don't have to restart the siphon after the power goes out in fact it never really loses the siphon they are designed so that the ends of the u-tubes stay submerged underwater so that air cannot be introduced in the u-tube causing the siphon to break.
It is the same concept as when you fill a cup with water inside of the sink and the lift the cup out of the water with the opening on the bottom, the water will stay in the cup until you get above the surface of the water letting air into the cup.
but you want the siphon to break if the power goes out.
if not your sump will overflow.
http:///forum/post/2865120
Sorry, must not have done a good enough job in the other post
You don't have to restart the siphon after the power goes out in fact it never really loses the siphon they are designed so that the ends of the u-tubes stay submerged underwater so that air cannot be introduced in the u-tube causing the siphon to break.
It is the same concept as when you fill a cup with water inside of the sink and the lift the cup out of the water with the opening on the bottom, the water will stay in the cup until you get above the surface of the water letting air into the cup.
but you want the siphon to break if the power goes out.
if not your sump will overflow.
natclanwy
Active Member
The amount of water in the DT or sump will not have an effect on the siphon, the overflow box will keep the level of water in the DT the same regardless of the amount of water in the system so any evaporation will lower the water level in the sump specifically the return pump section. You do want to make sure that you have enough room in your sump to be able to hold all of the water that will drain from the DT in the event of a power failure. You will get some extra drainage as the tank level drops to the bottom of the teeth on the overflow box and some from the drain and return plumbing. If you return outlet is below the level of the water it will siphon some water back through the return plumbing, and to keep this to a minimum you want to drill a hole in the at the surface of the water so that it will suck air into the return plumbing when power is removed from the return pump and break the siphon on the return plumbing. So you need to make sure that your sump has enough room to accomodate this extra drainage.
natclanwy
Active Member
You don't really need to do this if you set the water level in your sump. The way you do this is to get the system running but don't fill your sump more than half full, you want to leave yourself plenty of room for water to drain back to the sump after you shut the return pump off. Once you have it started shut the return pump off and let the water finish draining from the DT it needs to stop completely before you go on to the next step which may take several minutes. Once the water has stopped draining and with the pump still off fill your sump to the maximum level allowed which is governed by the height of your baffles. Now turn the return pump back on, the water level will drop in the return pump section of your sump until the DT is refilled and starts flowing through the overflow box. Now mark the water level in your return section with a marker or piece of tape this will be your maximum fill point when you are topping off the tank with the return pump running. You may need to lower this level to accomodate a skimmer or other filtration in your sump depending on your design but never fill your sump over this mark. Now if the power goes out you do not have enough water volume to overflow the sump so no worries about flooding. Be sure and test the setup a few times by removing power manually before you leave it unattended to make sure everything works correctly.
aquaknight
Active Member
Bored tonight so I played on MSpaint.
I hope natclanwy doesn't mind me going over what he already said.
How a U-tube overflow works, is pretty simple. You have two boxes filled with water that, when not flowing are equal in water height (the red line in the pic). Since water will ALWAYS try to find it's equal, it's this principle we use. As water spills into the first overflow box (inside the tank), the height of the water will be above that of the box outside of the tank. So there will be a slight positive pressure to force water up the U-tube, and into the outside box. But since there is a drain on the outside box, any extra water in the outside will spill down the pipe and into the sump. This creates a negative pressure and will draw water from inside the tank.
The siphon will never break after it's started because the ends of the U-tube are below the red line. It's impossible for the water in either box to go lower then that red line.
How a U-tube overflow works, is pretty simple. You have two boxes filled with water that, when not flowing are equal in water height (the red line in the pic). Since water will ALWAYS try to find it's equal, it's this principle we use. As water spills into the first overflow box (inside the tank), the height of the water will be above that of the box outside of the tank. So there will be a slight positive pressure to force water up the U-tube, and into the outside box. But since there is a drain on the outside box, any extra water in the outside will spill down the pipe and into the sump. This creates a negative pressure and will draw water from inside the tank.
The siphon will never break after it's started because the ends of the U-tube are below the red line. It's impossible for the water in either box to go lower then that red line.
mboswell1982
Active Member
wow, that is super informative, thanks guys, ive had it all explained to me before on several occasions, but now after seeing that, it makes perfect sense
V
vinnyraptor
Guest
Originally Posted by AquaKnight
http:///forum/post/2865227
Bored tonight so I played on MSpaint.
I hope natclanwy doesn't mind me going over what he already said.
How a U-tube overflow works, is pretty simple. You have two boxes filled with water that, when not flowing are equal in water height (the red line in the pic). Since water will ALWAYS try to find it's equal, it's this principle we use. As water spills into the first overflow box (inside the tank), the height of the water will be above that of the box outside of the tank. So there will be a slight positive pressure to force water up the U-tube, and into the outside box. But since there is a drain on the outside box, any extra water in the outside will spill down the pipe and into the sump. This creates a negative pressure and will draw water from inside the tank.
The siphon will never break after it's started because the ends of the U-tube are below the red line. It's impossible for the water in either box to go lower then that red line.
question? is the flow leaving the tank just done by gravity or does a powerhead pull the water down to the fuge. either way what type of pump is required to return the water back up into the DT? i understand how these filters work on principle but dont really know whats needed to return the water to the DT.
http:///forum/post/2865227
Bored tonight so I played on MSpaint.
How a U-tube overflow works, is pretty simple. You have two boxes filled with water that, when not flowing are equal in water height (the red line in the pic). Since water will ALWAYS try to find it's equal, it's this principle we use. As water spills into the first overflow box (inside the tank), the height of the water will be above that of the box outside of the tank. So there will be a slight positive pressure to force water up the U-tube, and into the outside box. But since there is a drain on the outside box, any extra water in the outside will spill down the pipe and into the sump. This creates a negative pressure and will draw water from inside the tank.
The siphon will never break after it's started because the ends of the U-tube are below the red line. It's impossible for the water in either box to go lower then that red line.
question? is the flow leaving the tank just done by gravity or does a powerhead pull the water down to the fuge. either way what type of pump is required to return the water back up into the DT? i understand how these filters work on principle but dont really know whats needed to return the water to the DT.
natclanwy
Active Member
I don't recomend building a custom overflow, the only plans I have seen are the type that use cast acrylic sheets and bend them into shape. These overflows are notoriusly unreliable. Do a search for Eshopps prefilters or overflow box, they are probably the least inexpensive and they are built very well.
The water leaves the DT by gravity, and is returned with a high pressure return pump. Typical return pumps are Mag 7, 9.5, and 12 or Quietone 3000, 4000, 5000, and 6000. Getting the correct sized return pump is one of the critical steps to having a successful flood free overflow systems. You want to select a pump that is rated for 70-100% of the overflows rating after you subtract for headloss.
The water leaves the DT by gravity, and is returned with a high pressure return pump. Typical return pumps are Mag 7, 9.5, and 12 or Quietone 3000, 4000, 5000, and 6000. Getting the correct sized return pump is one of the critical steps to having a successful flood free overflow systems. You want to select a pump that is rated for 70-100% of the overflows rating after you subtract for headloss.
V
vinnyraptor
Guest
what is headloss?
robertmathern
Active Member
head loss is the amount of resistance the water puts on the pump i.e push the water up any elbows in he plumbing stuff like that. i forget the exact number. but you can google headloss calculator. put in the info and it will tell you the pumps gph after headloss. try to get an overflow for that rated flow
camfish
Active Member
Originally Posted by 1990jpyj
http:///forum/post/2866612
nat- ok so i found those overflows you were talking about at a nice price of $45.00. now my question is, there is a sypon tube at the top of this thing what do i do with that?
a siphon tube? If I'm understanding correctly, you would use this to get all of the air out of the u-tube. If you get all the air out, it fills with water and starts the overflow.
http:///forum/post/2866612
nat- ok so i found those overflows you were talking about at a nice price of $45.00. now my question is, there is a sypon tube at the top of this thing what do i do with that?
a siphon tube? If I'm understanding correctly, you would use this to get all of the air out of the u-tube. If you get all the air out, it fills with water and starts the overflow.