Quote:
Originally posted by Jun41
This should not make a lot of noise because its kind of like a siphon, but not really. There should be no air bubbles or anything coming out of my pipe going to the sump. Am I right or do I have the wrong idea about the noise? I want to know whether I can kill the noise or not.
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I'm no plumber, but here what I've managed to learn, mostly form reading this forum and from trial and error:
1) noise from overflows can come from two different places:
A) the top of the overflow, in the overflow box (where the durso mod goes). Without the durso mod, (i.e. with just an open pipe) this noise sounds like the "sucking" sound that happens when you drain your bathtub, right as it empties, when that whirlpool forms at the drain.
B) the bottom of the overflow. If the return pipe is submerged in the sump (without geoff's mod) then it sounds like an episodic "blurping" as air collects at the bottom of the pipe, obstructing the flow of water down the pipe; the water building up in the pipe then forces the collecting air, all at once, out the bottom of the pipe as a large bubble, causing the "blurping" sound. If the return pipe is not submerged in the sump (i.e. if the end of the pipe is above the water-line) then the sound is simply rushing water hitting the water in the sump. No air collects in the pipe to cause the "blurping", because it just gets washed out the open bottom of the pipe.
Getting rid of all sounds to have a "silent" overflow requires silencing both the TOP and BOTTOM sounds of the overflow.
The durso mod is the most common way to silence the sound at the top. It works in two ways. First, it prevents a "whirlpool" from forming so you don't get that "sucking sound" like when you empty a bathtub. It does this by having the water "poured" down the main standpipe from one side (the side with the L) rather than swirling around a bare standpipe from all sides. the sound you're left with is simply one of rushing water (you can hear this if you remove the cap from the durso). The cap with the small hole on the durso effectively quiets the remaining rushing water sound because not much sound can get out the small hole (if were able to put your ear up to the small hole, you'd still hear the same rushing sound). The small hole DOES allow air in which prevents a siphon. (So there ARE still air bubbles going down the pipe, even with a durso)
Even with a durso mod, you'd still have the sound at the bottom of the pipe. Geoff's mod is the best way to get around this. If you submerge the end of the pipe, the problem is that air builds up in the bottom of the pipe and episodically blurps out the end. Geofff's mod allows that air to escape continuously without building up. the small hole in Geoff's mod just quiets the remaining "rushing water" sound (just like the small hole in the durso cap), while still allowing air out (just as the durso cap small hole allows air in).
It wasn't clear from your earlier post whether you were having noise from the top or bottom of the overflow; hope this helps.
i will try and draw a pic of what i am talking about. my normal program is at work. i am at home now with sick little Reefer Ryan.
