What kind of water line plan is mine

[SkeetMan44]

I am rerouting a slab leak in copper lines through the ceiling bay. I am stymied as to why there are two 3/4" pipes entering/emerging from the slab when there is only one 3/4 coming off the cold water supply and then leading up to the hot water tank. They shouldn't be connected under the slab, should they. Anyway, the nearest to the main manifold emerges from the slab in a wall behind the downstairs powder room and a half off of that feed the toilet, before it dives back into the slab. It likely travels under the slab to emerge beneath a manifold in the wet wall of the laundry adjacent to that powder room. I believe I have all the 1/2" lines accounted for as far as to which fixtures they go, but that second 3/4 bugs me. It goes up the perimeter wall on the far side of the laundry and does not appear to have any 1/2" coming off it on the ground level.

There is a 1/2" hot coming down from the two sinks in the bathroom above as well as a 1/2" cold.

If it helps, the hot water 3/4" trunk has been isolated with a sharkbite before it enters the slab in the wall between the garage and the house.

Is this some kind of a loop and why can't I find where the loop connects?

If it helps, when I opened a cold tap for one of the above sinks, cold water gurgled out of the hot line that should be feeding the hot tap for that sink. That line was capped with a sharkbite on the manifold side of the cut. I believe the water gurgled out of the open cut below. Is there some kind of cross over between the hot and cold at the sink. There is a plastic tube that I think may connect the hot and cold tap somehow.

Thanks.

 

[Reach4]

You did not post a photo. Part of what you have may be a water softener loop. Probably not. I did not follow your description much.

 

[Sponsor]

 

[SkeetMan44]

You did not post a photo. Part of what you have may be a water softener loop. Probably not. I did not follow your description much.

I don't have a water softener and am the original owner. I took a picture of a sketch that may help. Where I circled "3/4 cold" is where a 3/4 comes up out of the slab but returns into the slab as a 1/2. That 1/2 also moves up several inches, tees off, tees back down a couple of inches and feeds through the wall to the toilet.

On the far side there is a big blue dot repesenting a 3/4" copper emerging from the slab and going up that wall. I am not sure where it connects, but wonder if it is part of a loop system of some sort. On either side of that 3/4 there is a 1/2. Each run under the slab over to the wall running beneath the top of the page. There is actually a hot manifold and a cold manifold located in a stud bay below the washing machine box at that point.

 

[SkeetMan44]

Here are few pictures of what things are like. The first is what I call the main manifold, which is at the base of the wall shared by the house and garage, The water heater is just on the other side. It shows where the lines for the other side of the house were isolated, when they were routed through the ceiling years ago. The next shows the the lower half of the manifold in the wall of the laundry room.

 

[CountryBumkin]

Your drawing is not readable. Too small and the text is too faint.
I don't think you will get many replies to your question unless you repost with better photos and description. IMO.

I think, many of the Pros that respond here, first respond first to the easy to answer questions - and your issue is complicated and your description is hard to follow (at least to me it is).

Good luck.

 

[SkeetMan44]

Thanks CountryBumkin. Perhaps if I simplify. This is a wood frame and stucco Southern California house built on a slab in 1990 and all water lines are copper.

The hot water side seems simple enough, as there is a single 3/4" trunk line running from the supply line/water heater manifold to a submanifold in the laundry room, which manifold feeds hot water to a sink, the laundry taps, two upstairs lavatory sinks, and the upstairs shower/bath mixer valve via 1/2" copper pipe. The cold water side is what I am trying to figure out.

It is also fed by a 3/4 line from the same manifold and running under the slab , but I see two 3/4 pipes coming up out of the mud sill. One goes all the way over to the far perimeter wall, goes up the wall, and to the upstairs lavatory. Along side it in the same wall is a 1/2" running from the upstairs sinks over to that laundry room wall manifold. 1/2" inch lines from that manifold also feed cold water to the washing machine box, the sink, the upstairs shower/bath mixer valve, and perhaps he downstairs toilet. I say perhaps, because there is a second 3/4" copper pipe coming up out of the slab behind that toilet, which 3/4 reduces to 1/2 and loops back into the slab.

So why is there a 3/4 cold line going up the far wall to the lavatory above and another supplying the downstairs toilet, which is the nearest fixture to the supply line manifold? Is the cold water running in some kind of a loop, in which case I would think that one line is teed into the other beneath the slab and is that a Bad. I know this isn't a water softener loop like some have in their garages.

I realize that his is complicated and I don't describe things so well.

Anyway, I hired a licensed plumber to reroute/ repipe lines.