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zientm
01-13-2010, 05:57 PM
I am planning on installing a backwash filter (neutralizer) and am looking for some advice on plumbing the drain. The unit will be installed in the basement and I would like to discharge the backwash into a storm water drain I have outside (maybe 4 feet above the filter and 10 feet away). My concern is making sure the pipe outside the house (and the first 18" inside) drain at the end of the backwash cycle to keep water in the pipe from freezing and damaging the pipe. I can make sure that I plumb that section of pipe at a downward angle, but am concerned about vacuum lock. Now, if this was outside plumbing, a vacuum breaker would do the trick, but I have not seen ones that do not discharge some water after a while and am concerned about any granular material in the discharge keeping the vent open and winding up with a mess. Also, since it would have to be mounted up between the joists, I would not be able to inspect the seals on it without completely removing it.

My "Plan B" is to rely on manually initiated backwashes (at least in the winter) and install a drain valve inside that I can use to drain/vent the pipe.

I would appreciate any advice on this.

Akpsdvan
01-13-2010, 07:25 PM
How do you think that it would vacuum lock?

If the line that is running out side ends open and is lower than inside it will drain back to the highest point that you have inside the house.

drick
01-13-2010, 08:44 PM
I have over a 100 foot underground run to daylight and it has never been a problem up here in NH. A few things about it 1) It slopes downhill all the way. 2) It is rather large (4 inches) mostly because it handles several downspouts from the roof as well. 3) The pipe exiting the house from the filter is 1.5 inches in diameter and it leads into the 4" underground pipe without a physical connection to it. (Picture the 4 inch making a 90 degree bend and going up the side of the house about a foot above ground, then the 1.5 inch pipe coming out of the side of the house, making an immediate 90 and then down inside the 4 inch pipe.) I added a reducer so there is less of a gap between the two pipes to help keep dirt and leaves out, but there is still an air gap. You probably don't need a 4 inch lateral pipe for just the filter, but I would go at least 2 inches for the lateral and maybe a one inch coming out of the house.


Also make sure the pipe inside the house starts to slant down a foot or so before exiting through the wall to the outside so it doesn't freeze just inside the wall, but it seems like you already considered that possibility.

-rick

drick
01-13-2010, 08:56 PM
I just reread your post. If your only going 10 feet I wouldn't even worry about an air gap. If it is sloped decently it will drain back quickly if you oversize the pipe a bit.

-rick

zientm
01-14-2010, 05:16 AM
Just to clarify - I am concerned about the backwash drain line freezing, not the stormwater drain. I was planning on a 3/4" line for it, I could go up to 1". It will end with an elbow pointed into the 4" stormwater drain.

zientm
01-14-2010, 09:14 AM
How do you think that it would vacuum lock?

If the line that is running out side ends open and is lower than inside it will drain back to the highest point that you have inside the house.

Yes, I agree, as long as the pipe diameter is large enough it should. I am probably just being too paranoid....

Akpsdvan
01-14-2010, 11:15 AM
There is nothing wrong with having conserns about what might or might not happen and asking questions on how to get to a point that works.

zientm
01-16-2010, 06:19 PM
Thank you all for your replies. I will plan on just sloping the line down and we will see how it goes. Does anyone feel there is a need for a check valve to prevent any possible contamination, or is the backwash valve good enough? Any idea on what would be required by code?