Not a heating, but a plumbing question

Gordy

Finally replaced my 60 year old crane shower valve this weekend after gutting the shower that could have served as a bomb shelter.



  Upon cutting the old valve out I noticed that the hot pipe was clean as a whistle, and the cold pipe had a green patina on the inside of the pipe.



 I have replace a few faucets in the house, and I guess I never noticed if this was the same condition in the other supply pipes.

Mark Eatherton

Precipitants...

When you heat hot water, it causes the lime that is in suspension to come out of suspension. The cold water must have a slightly depressed pH, which causes the copper patina to form. If you had a water softener, I'd expect to see both the hot and the cold greenish in color. Or, if your softener is bypassed for the DHW system, THAT could be the reason you see green on the cold, but not the hot.



If memory serves me correctly, your ladies LOVE soft water for their hair, no?



DHW tanks, especially those with anodes in them HATE soft water. It causes the anode to dissolve quickly and exposes the steel tank to high concentrations of oxygen. Certain stainless steel tanks dislike sodium as well...



ME

Gordy

Yes the ladies

 Well Mark I bypassed the cold water supply with the softner only the Hot water gets softened. And yes the ladies notice immediatley when we are out of salt. Our city water is 28 grains so rather hard........Good pressure though. So I guess what is going on is opposite of what you are saying unless you meant the opposite of what you were saying. Being that the DHW only gets softened so thats why there is no patina on the hot side.



 Was kinda concerned at first about film for legionella, but once the pipe dried what I thought was biofilm was patina.



Thanks Mark!



Gordy

Mark Eatherton

Well, that blows holes in my theory...

My previous experience tells me that soft water will not allow a slight (protective) lime scale to accumulate on the inside of the pipes, thereby avoiding cuprous oxides, which is the green stuff.



I will have to defer to a more qualified water quality expert to figure out why the hot looks white. Salt cake?1



Do your water lines come from above or below?



ME

Gordy

From Below Mark

 There is not any deposits on the hot side of the valve just looks like ole type L copper.  I should also note that shower has been idle for about 7 months till construction commenced, maybe no use played a role also. Weep holes in the old drain were plugged for the mud bed causing the lead pan to back up in one corner, and the valve.



 And I did verify that the DHW is only softened. Its been a while since I plumbed in the waterboss.  Don't care to cook, or drink the stuff.  Funny I had a water softner sales man tell me the whole house should be softend so you get clearer ice cubes, and when you wash the car it won't spot as bad.



Gordy

Mark Eatherton

Now THAT makes sense based on my previous experience...

Un softened = lime scale deposits.



Softened = Cuprus oxides, no lime scale.



I must have been thinking backwards, or upside down, or upside down/backwards :-)



It's a dyslexic plumber thang ;-)



Thanks for the clarity Gordy.



ME

BearCreekNick

Powers Mixing VAlves

Hey these are kind of new to me but can someone tell me the temp. Gauge on top of the mixing valve. Is that the hot temp coming into the valve or the temp of the tempered water leaving the valve???

Wesman

Powers #11 mixing valve

The gauge was an expensive but worthwhile adder to the mixing valve.  Pretty sure that would display the mixed or "leaving" temperature.  If you adjust the mixed temperature while it is in use,  you should observe a corresponding  change on the dial face.  The high and low dial degrees represent the highest and lowest temperatures you would be able to adjust to.