hot/cold pipe identification for new shower


I'm totally re-doing my bathroom and shower. I tore out the old shower 2 months ago, re-routed the plumbing, and capped off the pipes. At this point I am ready to install my new shower mixing valve but I don't know which pipe is hot and which is cold.
Are there any tricks to identify which is which short of uncapping the pipes and letting the water fly??
Thanks! Andy
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ashroyer

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ashroyer wrote:

Hmmmm. Have someone bang on each with a hammer whilst you listen at some junction.
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line)and let the water run through it to see if it is hot or cold.
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You're gonna have to uncap the pipes to hook up the new valve. Can't you decide then?
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Turn off the water to the water heater. Turn off the main water supply to the house. Uncap one pipe. Turn on the house water slightly. If water comes out the pipe, that is the cold. If not, it is the hot.
Bob
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ashroyer wrote:

Isn't the hot usually on the left? cold on the right?
but I have been to a couple hotels where the bathroom faucets worked opposite to that.....
cheers Bob
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You just look where you wrote on them with the magic marker. :)
Run the hot water in the nearest room that has hot water. It may warm the pipe enough that you can feel a difference between the two. If you followed normal conventions, the pipe on the left facing the point of use is the hot.
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Thanks a lot for all the great tips!
I ran the hot water tap closest to the pipe for awhile to get it nice and hot. I then turned off the main water line and drained the pipes (to get the layer of room temperature water out of the pipes). I then turned it pack on, theoretically filling the pipe with fresh hot water.
It worked, I was able to feel the temperature difference in the two pipes.
Now I just have to install the valve, hang the sheetrock, buy the tile....
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ashroyer

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ashroyer wrote:

btw....was it on the right or the left?
cheers Bob
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