Just removed a shower and found this plumbing. Any one know what the function is of the pipe that comes off the T connection from the pipe between the mixer valve and the shower head. It has a length of 1/4 copper pipe that has been almost crushed in 3 places, and connects to another 1/4 inch pipe that comes up through the floor and back down again. I have tried to trace where it goes from below, but cant and no other appliances, or fossets have 1/4 pipe attached to them 
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Looks like someone was out of pex
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No there was all kinds of pex pipe left over in the basement when we moved in. I used it to plumb in the bathroom I built in the basement and still have about 30ft left over. I think it does something to the pressure in the shower head, as our other upstairs bathroom has plenty of pressure as well as the bathroom I built in the basement. This one has always had low pressure in the shower.
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The white pipe looks half the size of the blue and red and it is supplying the cold water? That short chunk of copper is ‘interesting’.
Where is the blue line (from above the valve) going?
I thought is was a lower shower faucet but Nope…
Cheers
G
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Yeah that’s quarter inch pipe, and no the cold water and hot water comes from the mixing valve lower down. Its a deceiving pic. The T connection above the mixing valve curls around behind the cold water pipe going into the valve. The pipe coming off the T and having the copper pipe on the end and connecting to the white 1/4 inch piping is what is perplexing as it seems to serve no purpose. If it draws off water from the mixer as it travels up to the shower head, it will be warm to hot depending on what the mixing valve is set to. So whatever it feeds at that moment is getting anything from cold to hot water. I am thinking of just cutting the blue pipe from the T above the mixing valve and terminating both ends just to see what happens lol.
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Your plumber gave your shower an appendix?
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Yeah they did a crappy job, no support behind the mixer valve to screw it to, I had to cut the stud deeper that the hot water runs through and staple it as its just flopping about in the gap. The power point that is in the bedroom should not be that close to a water pipe either, and is not to code. I am going to spray that with expanding foam to stop any potential moisture getting in it and may change the socket for an RFI so if it shorts it will trip out. I found a similar problem under the bath which is a water jet bath, no RFI socket on the pump connection under the bath, so that’s not to code either. Cowboy plumbers and electricians.
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it could just be a pressure outlet. Maybe they thought that there was excessive water pressure above the mixing valve, and added in the t junction above that to bleed off excess pressure?
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Previous owner DIY job?
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Thats what I was wondering, but the water pressure would be the same throughout the house and in the other shower, but I have not seen behind that so it may have the same thing going on.
Nope, he lives next door. Whenever I ask him about the weird shit I find when doing stuff, he just says no idea, why the contractor would do that.
They split the land plot in half and his son had the house built, and then separated from his wife 2 years later and we bought it. Neither the son or the father would have plumbing or electrical knowledge to attempt doing the work. Even if its still done badly lol.
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Also if there was any water pressure in the 1/4 inch white pipe connected to the pipe going up to the shower head it would be constantly having water coming out the shower head, wtf is it all about.
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I’m no plumber, but I’ve run plenty of pipes. Done a few shower valves. Wouldn’t make any sense for that to be connected to anything outside of the shower, you wouldn’t get constant water to it. As for being a siphon of sorts, doubtful, its not a venturi setup, and opening the shower valve would pressurize it as such.
I’m really curious now where the white goes / ends up…
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I have pulled out every appliance that has water attached to it, I can’t see anything else that has 1/4 inch pipe. I can only assume it is T’d back into something else somewhere. Why would they almost crush the copper pipe 3 times, I can only assume its pressure related.
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but it makes no sense… its on the line going FROM the valve TO the shower head, right?
So, it should only be pressurized when the valve is open / mixing water being sent to the shower head (and hitting that T).
Otherwise, if it was pressurized, you would always have water from your showerhead regardless of the valve being open or closed.
Maybe just unscrew both sides of the T with the white pipe, and blow in one side, see if you feel it from the other (shows a loop).
certainly wouldn’t have much effect to bleed off pressure then or act as a water hammer arrestor…
I bet its a loop… for no reason…
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and 1/4" line typically only feeds a few things. Icemakers, automated top-off valves, RO/DI systems. You wouldn’t see a 1/4" feed line going to a sink (unless its RO water, separated from the tap), certainly not to a dishwasher or washing machine (those take 3/4").
The location of it being on the showerhead side of the valve is perplexing too…
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Exactly why its confusing me. I will go and see if I have any 1/4 inch pipe terminators, I dont think so, I have only installed half and 3/4 pex pipe here. I think I will give blowing through it a go and see if its looped.
Another trip to home depot 
Maybe they have someone there who has seen something like this, worth asking I guess.
Cheers.
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I’m have minimal plumbing experience but that’s pretty sketchy. There has to be SOME reason but damned if I know.
I once overheard two Home Depot employees talking - “if I knew anything about plumbing I wouldn’t be working here.”
Good luck.
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It’s definitely an odd install. It just seems like the 1/4inch tube would go to an ice maker , water cooler, or bidet maybe.
It’s probably just a pointless loop though. 🤷
I take that back. The line is after the valve so only would have pressure when on. Idk
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This looks like I made it. Too often I do something unequipped, without the necessary parts …
In this case I used a T piece because I didn’t have the required one. But the problem is I have nothing to plug it with. So I put a tube on a T piece, on it another copper tube. I try to crush the copper to plug the line. I see that I will not succeed, so I put a T-piece on it and close the white tube in a circle
I’m in a hurry because I’m thirsty. Satisfied I go to the bar
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Lol. Sounds right. But it seems to split into 2 and go into the floor? That’s what seemed weird to me. Have some jets in the back of your shower? 
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