Hi Bean,
Great system but I do have a few questions for you before I start mine. 1. What is the purpose of the John Guest fitting? IS it just to make the connection airtight? 2. You used the tees with a cap I would assume because your system is external. Mine will be internal so could I just use elbows? 3. You state in your original article that all three drains are at the same height (with execption of the emergency being an upturned elbow) I've seen so many people on You Tube setting all 3 at different heights, why are they doing this?
Bean hasn’t posted in a couple months but I will see if I can help.
1. The fitting is mainly so the airline is airtight. If the syphon & emergency get clogged & the open channel becomes a syphon, u want it airtight. There are easier ways to do it rather then tapping a cap. The easiest way would to be to use 1/2” threads on airline fitting & use a bushing that goes from your plumbing size to 1/2”. Then the airline fitting will screw straight into the bushing.
2. Bean has a internal overflow on his setup that he had when he made this thread. With a internal box all u have inside the overflow box is the 90’s. His tees are on the outside of the tank at the bulkheads. U can use 90’s instead of the tees with caps on them, but I prefer to use the tees. I believe his reasons for the tees is to make connecting the airline fitting on the open channel easier. I think his main reason was if he ever needs to clean out the plumbing he could unscrew the cap & have access.
3. With a backdrilled tank & a interior overflow box, I have never had issues with the holes being drilled at the same height. I drill them all as high as possible without compromising the structural integrity of the glass. If u drill the syphon lower then the other two it’s just that much taller u have to make the overflow box. On a exterior box I make the syphon standpipe lower then the other two, but not a interior box with the bulkheads in the back glass. Of coarse it wouldn’t hurt to drill the syphon 1/2” or so lower then the other two holes & may help in some instances. The reason for the syphon to be a little lower then the other two is so the syphon has a chance to purge the air on startup. What happens in some instances is the open channel takes all of the water & causes the water not to build up enough to purge the air from the syphon. If plumbed correctly then this usually isn’t a issue. Using 90’s in the drain line instead of 45’s, have horizontal runs in the pipe or submerging the end of the pipe to far into the sump all make it more difficult for the syphon to purge the air. So if u do one or all of these things it may help to have the syphon drilled 1/2” or so lower then the other two drains.