Silent and Failsafe Overflow System
- Thread starter JohnL
- Start date
hbash
New member
A 1" builkhead is most often fitted to 1" pvc. As best as I can tell the three pipes only need to be far enough apart that the other attached fittings (sanitary tee and elbow) don't overlap.
So consider the pipe width, and the distance the elbow will protrude plus a bit to allow you to work on the pipes without knocking into an adjacent assembly.
sleepydoc
Team RC
Bulkhead size refers to the PVC pipe size that will fit it. a 1" bulkhead will fit 1" PVC. For determining hole size to drill, refer to the bulkhead specs.
For spacing, refer to this diagram
For spacing, refer to this diagram
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uncleof6
Active member
Pop quiz (sincere and serious
1) What is the definition of the top of the weir?
2) How far down from the top of the weir are the tops of the elbows supposed to be?
uncleof6
Active member
What size are your bulkheads?
hbash
New member
Pop quiz (sincere and serious
1) What is the definition of the top of the weir?
2) How far down from the top of the weir are the tops of the elbows supposed to be?
The top of the weir is the edge where the water overflows into the box.
The distance between the top of the weir is depicted in a diagram I obtained here is 1 7/32".
I miss-measured the top of my elbow this evening as it doesn't make sense I had stated it to be 10 3/8" off the OB bottom. On second closer reading the height is 10" off the OB bottom.
If my calc is correct that would put the top of my elbow 5/8" below the top of the weir and so it would seem that it is too high by 19/32". Also of note is that the water line in the OB doesn't cover the elbow and is at the halfway line of the horizontal section of the elbow.
The Calc: OB Height is 12" - Top of Elbow 10" is 2" - 1 3/8" for Notch Height is 5/8" for distance from bottom of notch to top of elbow.
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Voight
New member
I am taking my 75 gallon in to get it drilled soon, and I'm having trouble finding out exactly where to drill the holes. Specifically I'm not sure how far down from the rim to place my holes. I know they should all along the same plane, but where should the center of my holes lie in relation to the rim. I just want to be able to measure it out exactly for the glass company.
Also if anybody can give me some exact placement of my overflow that would be very helpful. Or do I just have it right up till it th e top hits the rim?
Also for the bean animal & the 1 inch bulkhead do I simply drill 1 inch holes, 1.25, or 1.5 inch?
Also if anybody can give me some exact placement of my overflow that would be very helpful. Or do I just have it right up till it th e top hits the rim?
Also for the bean animal & the 1 inch bulkhead do I simply drill 1 inch holes, 1.25, or 1.5 inch?
uncleof6
Active member
Ok, that can be scratched off the list of possible issues. (1.5" bulkheads + low flow rate = start up issues)
woodnaquanut
Active member
Always better to self-identify than have others point it out to you! :lol:
You are not an idiot. How do I know? Well you knew it wasn't right and kept asking questions and trying things. None of these traits point to idiocy!
We all get stuck, frustrated and confused. When we finally figure it out we can then declare an epiphany! :bounce3:
Yeah, it was how restricted the flow was from my Sicce pump using 3/4". I used 1" pvc and it started up as it should. That 1/4" made a huge difference in the flow. I had to open the gate about half, maybe a touch on the closed side. With the 3/4" tube, the gate was about 1.5 turns from fully closed.
The slow flow did start a siphon but it took a LONG time to purge the air. It would go silent and work as expected though. Just physics takes over and takes 45 minutes to purge the air from 1.5" tube with that little flow. If I used 1" pvc it probably would start as one expects.
It was all about the 1" return piping
uncleof6
Active member
Everything I talk about relates to just about everything else I talk about. I take a system wide view, rather than just looking at one particular sub system. Glad it is working for you now. As a result of your "idiocy" I am ammending my comments on flow rate vs bulkhead size to: Flow rate too low for the bulkhead size, rather than knocking on 1.5" bulkheads alone. Although true idiots do exist, they are relatively rare, and one that searches for answers is anything but an idiot. I, being a typical idiot, can and do overlook the obvious at times... my students catch me at it from time to time, and as a result they get an "F" for the day... ...just sayin.
uncleof6
Active member
The top of the weir is defined as the highest point over which water flows. E.G. on a "combed" or "toothed" weir, that is the low point between the "teeth."
The height of the OB is irrelevant.
The elbows should be 1" below the low point between the teeth.
Sounds like 3/8" high. Significant? Depends on where the inlet of the dry emergency is, and the relationship to the point that water will spill out of the tank. Water line will end up between the elbow centerline and the top of the elbows, so I don't see a problem there.
Recommendation 1: A flat weir (get rid of the teeth and raise it.) Keep the top of the weir a good inch below the point where water could possibly flood out of the system. Function and system health come before keeping fish out of the overflow, and preventing them from taking a ride down to the sump. The improvement in water quality, will make that likelyhood less, as most fish jump for water quality reasons, (unless they are surface feeders by nature.) No matter how many times we say that, seems it just does not "sink in."
Teeth cause problems.Also, make sure the dry emergency inlet is the difference of an upturned elbow, and a down turned elbow, inlet. So you get sufficient head height to purge the air out of the siphon. Make sure the inlet to the open channel air vent line is above the inlet to the dry emergency inlet sufficiently so that during startup, it is not occuluded by rising water level. If you can't get the water line high enough to flow in the dry emergency at startup, your flow rate is too low for the bulkhead size.
Recommendation 2: Live with the mirco bubbles, because it is the teeth that are causing them, IMO. That is barring too much flow in the open channel, or an air leak in the siphon.
mmn
New member
I just drilled mine today. The placement was, from info posted in this thread, top of elbows (horizonta part) one inch below top of weir which I am placing even with the bottom of the trim. There's 1/4 inch between the flange and the rim. The holes need to be a minimum of 1.5 diameters apart (don't know if that means center to center or between edges) and from any edge. Since I'm doing a coast to coast overflow, I went somewhat wider with the spacing. Six and 3/8" center to center. But my holes are 2 3/8" in dia.
With the elbows I'm using that puts the down turned elbows about 4 1/2 inches deep into the box and the upturned 5/8 inch above the water line.
With the elbows I'm using that puts the down turned elbows about 4 1/2 inches deep into the box and the upturned 5/8 inch above the water line.
mmn
New member
I'm building my own box so I'm doing it the other way around. I know where the top will be. I know where the elbows should be in relation to that (I think!). The box is sized to give the proper clearance on the bottom and the width will be just enough to be able to insert and remove the bulkheads with the glued-in elbows.
I'm sure you will get other opinions. This is just what I think I've learned from this thread.
I think I drilled mine 2.75 inches from the bottom of the trim.
Voight
New member
Is that center of hole or top of hole?
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