Herbie Overflow Fail

[Seth81]

So I have been testing my setup for my new 190 Gallon bow front tall deep tank, and I just realized that I made a really bone head mistake in my Herbie style overflow. I wanted to post this so that others do not make the same mistake that I did.

Here is my current over flow setup ( I don't show it but the sump is in the basement):



Two 1.5" standpipes one has a gate valve to control flow and is meant as the primary and the second as the emergency flow just incase the primary gets plugged. The basic theory is that the water line will be somewhere between the two pipes and the primary will be fully submerged and in full siphon but the second will not be submerged at all. In theory this setup should be completely silent because no air gets sucked in.

The big mistake I made was combining the two drain lines after the gate valve. The reason why this is a mistake is because due to the Venturi effect the flow of water down stream of the valve will create a vacuum on the backup stand pipe and will suck in air along with the water from the primary, which then breaks the full siphon causing the water to flow less quickly. Eventually the water level in the overflow will raise to the emergency level and water will then flow with air down the emergency line causing a horrible sucking and gargling sound.

The only reason I combined the lines in the first place is because my sump is in the basement and I wanted to limit the holes I made in the wall. I am now considering making another whole and making the emergency a completely separate line. Does anyone have other suggestions?

[sphelps]

Yeap two completely separate drains are key although I've never seen it reduce flow but only create the annoying water echo type noise through the back up. It's interesting it had that effect with you.

[RuGlu6]

Thanks for sharing

[reefgirl189]

I did the same exact thing as you did. My sump is also in the basement. I eventually had to change it to a separate line to avoid that awful gurgling sound.

[gregzz4]

And to add something many will notice ...

If the drain plugs up downstream of the 'T', you have no emergency, so it's not really a Herbie, per se

Thanks for sharing and def run a second line

[Seth81]

Originally Posted by reefgirl189

I did the same exact thing as you did. My sump is also in the basement. I eventually had to change it to a separate line to avoid that awful gurgling sound.

Thanks for the reply, are you happy with the end result?

[Seth81]

Originally Posted by sphelps

Yeap two completely separate drains are key although I've never seen it reduce flow but only create the annoying water echo type noise through the back up. It's interesting it had that effect with you.

The reduction in flow I mentioned is becuase when the water is above the primary drain a true siphon isn't achieved becuase air is being drawn in from the secondary pipe. The other kinda crappy thing about this is becuase soo much air is being drawn in the water splashes like crazy in the sump! I've seen the water spalsh up 2-3 feet as air bubble makes its way to the sump!

[gregzz4]

Originally Posted by Seth81

The other kinda crappy thing about this is becuase soo much air is being drawn in ...

Not to worry
Once you run 2 separate lines and submerge the main line between 1 and 2 inches below the sump level, all will be good
Only thing that happens is a lot of air gurgling when you first fire it up as the air is purged, splashing water everywhere
I solved this by adding a splash guard around my drain lines

[Seth81]

Originally Posted by gregzz4

Not to worry
Once you run 2 separate lines and submerge the main line between 1 and 2 inches below the sump level, all will be good
Only thing that happens is a lot of air gurgling when you first fire it up as the air is purged, splashing water everywhere
I solved this by adding a splash guard around my drain lines

Yeah, currently my return in the sump is submerged about 6" in cylindrical acrylic tubes...yet still continuous 2- 3 foot geysers!

I'm sure you are right that once I run the seperate lines and eliminate the air intake my sump should settle down (after startup of course)