# Which one is hot, which one is cold?



## 422 plumber (Jul 31, 2008)

I cut these out of existing water lines to add a break room sink at a Catholic school today. Which one is what, and why? Sent from my iPhone using PlumbingZone


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## titaniumplumbr (Jun 11, 2014)

Electrolysis caused by dissimilar metals. Usually it's on the cold pipes but in some instances it can be in the hot pipes as well possibly brought on by improper grounding


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## justme (Jul 4, 2012)

The one with green is hot and the bottom is cold, as to the why it has to do with hot dissolving the minerals and then they stick to the wall of the pipe. Can anyone say Lime build up.


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## 422 plumber (Jul 31, 2008)

Not quite, I will see if there are many posts. 









Winner gets a Porter Pipe bandanna.

Sent from my iPhone using PlumbingZone


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## SchmitzPlumbing (May 5, 2014)

the one connected to the outlet of the water heater is hot because thats how a water heater works


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## Nathan901 (Feb 11, 2012)

Water treated before entering the heater?


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## 422 plumber (Jul 31, 2008)

This is in Manhattan, IL. The village has deep wells, pretty hard, but it is either R/O or softened at their water plant. The water is actually pretty decent.


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## KoleckeINC (Oct 22, 2011)

The lack of oxygen in hot water proves difficult for copper oxide to form in Hot water pipe..

For an added bonus.if you've ever forgotten which pipe is which, the darker pipe is usually the cold due to excessive sweating and dust attraction. Except for that one time when the light colored one was just newer...Doh!


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## Redwood (Sep 8, 2008)

The cold has the green. it is Copper Oxide also referred to as Patina...


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## 422 plumber (Jul 31, 2008)

Both Kolecke and Redwood are correct. Since Kolecke chimed in first, he gets the bandanna.


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## budders (May 19, 2013)

SchmitzPlumbing said:


> the one connected to the outlet of the water heater is hot because thats how a water heater works


 hahahHha burn ***** LOL


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