What's a Siphon Break!? OR Teach Me Plumbing!

jonnybravo22 · 05/11/2009, 10:25 PM

so i'm setting up my first sump. i dont understand a) the need to have a siphon break, or b) why everyone is scared of creating a siphon on the drain.

seems to me that a siphon is cool b/c it's silent but there's no danger b/c the worst that could happen is that it tries to pulls out water until the water level drops below the drain pipe.

but isnt the drain pipe level where you want to set your water level anyway? so if it sucks all the water out to that level it will automatically stop when the water level drops below the drain's opening, leaving just as much water in your tank as you planned when you set the drain height? what am i missing here?

and why do people put siphon breaks on return pipes? so lost.

jbird69 · 05/11/2009, 10:35 PM

the siphon break is a hole in the return line just at or below the waters surface. If power is cut to the return pump this hole will suck air and break the siphon. What happens is your water coming out of your return plumming will begin to flow back down into the sump until air is sucked into it breaking the syphon. If your return plumming nozzle is 4" under the water surface in your DT, that 4" will all back-syphon down into your sump if you do not have a "syphon break", causing the sump to overflow.

The other term used for syphon break is with an external overflow...not like the type of drain youre describing. Syphon breaks on drainlines occur with incorrectly designed external overflows with weirs or utubes.

BLKTANG · 05/11/2009, 10:37 PM

r u setting up a RR tank?

The reason for a siphon break in the return line is because if you loose power,& dont have a siphon break then the water will overflow your sump.

HTH

Sisterlimonpot · 05/11/2009, 10:40 PM

A siphon break is on the return line just below the surface of the water.. the reason for the siphon break is because some hobbyist put their return lines (usually loc line) lower in the tank to get the right flow that they seek and this is sometimes 2-3 inches below the surface of the water so if for some reason the power is lost or you shut the pumps off, all that water (3 inches deep) will be siphoned back to the sump and on a tank that is 6'X2'X2'... 3inches of water would roughly be 22 gallons and usually the sump couldn't handle that extra 22 gallons so what people do to avoid that is add a hole on the loc line right below the surface to break the siphon if or when the power goes out.

EDIT: I type slow... but it looks like you got 3 same answers. Redundancy... You gotta like that

jonnybravo22 · 05/12/2009, 09:26 AM

got it. thank you all. i understand that a siphon break really only applies to return lines.

still confused.

when i read the threads for BeAnAnimal and Herbie re: the silent overflow systems, they are all sooooo concerned about the DRAIN siphoning water. the benefit is that it's silent, but they are scared it will somehow overflow? that's the part i dont get. how can a drain siphon be bad? if the return pump power goes off, it will stop siphoning when the water level reaches the drain level. right?

firemedic0135 · 05/12/2009, 09:37 AM

Its not a problem until your sump overflows. If there is adequate room in your sump then no problem. You should set the normal operating level in your sump so that when the power goes off you dont overflow before you have a siphon break( in your return line or water level dropd below overflow box)

ataller · 05/12/2009, 12:18 PM

I am pretty new at this, though I think I can help out. If anyone notices a mistake with what I am about to explain please chime in.

In a standard durso, you drill a holl in the top to prevent a siphon from forming. The reason why you want to do this, is that since the siphon will drain water so fast, you will constantly be emptying your overflow and filling it back up again. Which can create a lot of noise.

In a herbie method, or the method with three drains. One is a small siphon. Since it is small, you can keep a full blown siphon through it and still be able to keep up with the drain via your return pump. Since the siphon is undersized, you have a secondary drain that acts like a normal durso with a siphon break drilled in the top. This seconardy takes care of any excess flow that the full blown smaller siphon can't handle. Then the third is an emergency drain incase one of them gets clogged.

In a small tank without much flow through the sump, the full siphon in the herbie will be too much flow unless you are using a really small diamter drain.

I hope that is right.

Adam

Quote:

Originally posted by jonnybravo22
got it. thank you all. i understand that a siphon break really only applies to return lines.

still confused.

when i read the threads for BeAnAnimal and Herbie re: the silent overflow systems, they are all sooooo concerned about the DRAIN siphoning water. the benefit is that it's silent, but they are scared it will somehow overflow? that's the part i dont get. how can a drain siphon be bad? if the return pump power goes off, it will stop siphoning when the water level reaches the drain level. right?

jonnybravo22 · 05/13/2009, 06:56 AM

oooooh. that makes sense now ^^. its because the siphon pulls water too fast so it would gurgle when the level constantly drops and refills. unless the siphon is undersized.

05/11/2009, 10:25 PM	#1
jonnybravo22 Registered Member Join Date: Dec 2008 Posts: 1,128	What's a Siphon Break!? OR Teach Me Plumbing! so i'm setting up my first sump. i dont understand a) the need to have a siphon break, or b) why everyone is scared of creating a siphon on the drain. seems to me that a siphon is cool b/c it's silent but there's no danger b/c the worst that could happen is that it tries to pulls out water until the water level drops below the drain pipe. but isnt the drain pipe level where you want to set your water level anyway? so if it sucks all the water out to that level it will automatically stop when the water level drops below the drain's opening, leaving just as much water in your tank as you planned when you set the drain height? what am i missing here? and why do people put siphon breaks on return pipes? so lost.

05/11/2009, 10:35 PM	#2
jbird69 Registered Member Join Date: Dec 2008 Location: The beautiful State of Jefferson Posts: 2,751	the siphon break is a hole in the return line just at or below the waters surface. If power is cut to the return pump this hole will suck air and break the siphon. What happens is your water coming out of your return plumming will begin to flow back down into the sump until air is sucked into it breaking the syphon. If your return plumming nozzle is 4" under the water surface in your DT, that 4" will all back-syphon down into your sump if you do not have a "syphon break", causing the sump to overflow. The other term used for syphon break is with an external overflow...not like the type of drain youre describing. Syphon breaks on drainlines occur with incorrectly designed external overflows with weirs or utubes. __________________ Broke Back Mountain is not a movie, its the pile of dead ninjas in Chuck Norris' back yard

05/11/2009, 10:37 PM	#3
BLKTANG Registered Member Join Date: May 2005 Location: Never,Never Land Posts: 7,061	r u setting up a RR tank? The reason for a siphon break in the return line is because if you loose power,& dont have a siphon break then the water will overflow your sump. HTH __________________ We the few have done so much,for so long,for so little.That we are now qualified to do anything with nothing. ____________________________________________________________________________ Current Tank Info: RR 90 Maganvore sump,250w Hamilton fixture,VorTec's ASM skimmer.

05/11/2009, 10:40 PM	#4
Sisterlimonpot R.C. Fraternity President Join Date: Dec 2008 Location: Litchfeild Park AZ Posts: 11,490 Blog Entries: 2	A siphon break is on the return line just below the surface of the water.. the reason for the siphon break is because some hobbyist put their return lines (usually loc line) lower in the tank to get the right flow that they seek and this is sometimes 2-3 inches below the surface of the water so if for some reason the power is lost or you shut the pumps off, all that water (3 inches deep) will be siphoned back to the sump and on a tank that is 6'X2'X2'... 3inches of water would roughly be 22 gallons and usually the sump couldn't handle that extra 22 gallons so what people do to avoid that is add a hole on the loc line right below the surface to break the siphon if or when the power goes out. EDIT: I type slow... but it looks like you got 3 same answers. Redundancy... You gotta like that __________________ Jimmy MASVC President Dishes are done man! Current Tank Info: 300 in progress

05/12/2009, 09:26 AM	#5
jonnybravo22 Registered Member Join Date: Dec 2008 Posts: 1,128	got it. thank you all. i understand that a siphon break really only applies to return lines. still confused. when i read the threads for BeAnAnimal and Herbie re: the silent overflow systems, they are all sooooo concerned about the DRAIN siphoning water. the benefit is that it's silent, but they are scared it will somehow overflow? that's the part i dont get. how can a drain siphon be bad? if the return pump power goes off, it will stop siphoning when the water level reaches the drain level. right?

05/12/2009, 09:37 AM	#6
firemedic0135 Registered Member Join Date: Mar 2009 Location: East Tx. Posts: 147	Its not a problem until your sump overflows. If there is adequate room in your sump then no problem. You should set the normal operating level in your sump so that when the power goes off you dont overflow before you have a siphon break( in your return line or water level dropd below overflow box)

05/13/2009, 06:56 AM	#8
jonnybravo22 Registered Member Join Date: Dec 2008 Posts: 1,128	oooooh. that makes sense now ^^. its because the siphon pulls water too fast so it would gurgle when the level constantly drops and refills. unless the siphon is undersized.