Two Cold Water Pipes at Shower and Tub

[zdman]

Hi All. I am new here as a member, however I have come to the site many times when searching for plumbing problems.
I am re-modeling my bathroom, not moving things, just updating them. When I took down my shower walls I noticed that I have two cold water pipes and one hot water pipe coming out of my cement slab. The two cold pipes (both 1/2 inch) T into one and then go the shower fixture (again just a 1/2 inch tube). I looked under my tub and see the same thing - one hot water pipe and two colds coming out of the slab that then T and go to the tub cold water supply line.
My question is does anyone know why they would run two cold water lines and then T them together just before the tub and shower faucets?

Thanks

 

[IFIXH20]

Zdman, are you sure it's the cold side -- could be recirculating lines if it's the hot side. Do you have a recirculating pump at your water heater ?

 

[zdman]

Interesting, I had not thought of that. When I took down the shower wall I just assumed that the right side pipes were cold and the left were hot. I just looked under the tub again and sure enough, the two pipes coming up go to the hot side. That probably means that my plumbing in the shower is backwards.
Here is the thing though, I know my hot water is not recirculating because it takes a long time to get hot water to the bathroom. Could it be that the house is plumbed for recirculation but it is not enabled? Guess I need to read up on that one.

 

[phishfood]

If the pipes are copper or polybutylene, you probably have a looped system. In order to keep from having joints under the slab, the branchoffs to individual fixtures are done above the slab, then the branch is looped underneath the slab to the fixture.

So, a larger line, usually 3/4", will be ran to the wall behind a single fixture, for example, your shower. Then it will be tied into the branches to the other fixtures in that area, and also to the shower valve.

 

[zdman]

Thanks Phishfood. I think you are right. The T in the shower is off the cold line and the T at the tubis off the hot line. I suspect they both run under the slab over to a nearby sink.

 

[IFIXH20]

If the pipes are copper or polybutylene, you probably have a looped system. In order to keep from having joints under the slab, the branchoffs to individual fixtures are done above the slab, then the branch is looped underneath the slab to the fixture.

So, a larger line, usually 3/4", will be ran to the wall behind a single fixture, for example, your shower. Then it will be tied into the branches to the other fixtures in that area, and also to the shower valve.

Good job Phishfood. I haven't seen a looped system in years -- didn't cross my mind.