Why does my cold water turn warm? Delta Shower Valve

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newowner

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I am in the middle of a master bath remodel. Ever since the plumber came out and extended my pipes so that my sink could be shifted over about 2 feet, whenever we turn on the cold water in our other faucets it will fluctuate between cold and warm water. The master bath plumbing is not hooked up yet. The same day the sink plumbing was extended he also moved our toilet plumbing over about a foot (I could figure out exact inches everything moved if needed). Why is the cold water changing to warm and then going cold and then often back to warm and then finally cold again in our other baths and kitchen? This did not happen before the plumber worked on the master bath.
 

Jadziedzic

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Was a new shower valve installed when the plumber worked on the bath? If so, it's possible he did not install the cartridge yet - and if there's a cover plate over the area where the cartridge is installed that's a cross-connection between hot and cold lines.
 

newowner

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Was a new shower valve installed when the plumber worked on the bath? If so, it's possible he did not install the cartridge yet - and if there's a cover plate over the area where the cartridge is installed that's a cross-connection between hot and cold lines.
He installed a new diverter but didn't put a cover over it because the shower has to be tiled. I am sorry but I don't know what a cartridge is.
 

Reach4

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The cartridge controls the water. It has the knob on it.
 

newowner

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The face of the diverter is plastic, so I am assuming that is the cover plate jadziedzic mentions. The cartridge isn't on (thanks, Reach4) so that must be my answer. Considering it is several weeks before the plumber comes back to complete the job, I wish he had told us to expect that. I asked my general contractor why and he didn't know, so thanks for the help!
 
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Terry

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Was a new shower valve installed when the plumber worked on the bath? If so, it's possible he did not install the cartridge yet - and if there's a cover plate over the area where the cartridge is installed that's a cross-connection between hot and cold lines.

This happens with some valves. Delta now has a stopper that can be used to prevent crossover during the construction mode.
Before that, we used to go back and install the cartridge if it was homeowner occupied.

delta-rp46079.jpg
 
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newowner

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This happens with some valves. Delta now has a stopper that can be used to prevent crossover during the construction mode.
Before that, we used to go back and install the cartridge if it was homeowner occuppied.
The diverter is actually a Delta, model R10000UNWS. There is a light grey plastic piece on the front of it.​
 

Terry

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There is a stopper that can go behind the rough in cover to prevent the crossover. Or you need to insert the cartridge.

delta_multichoice.jpg


multichoice_d1.jpg


As you see, the water passes between those two ports. At least one of them needs to be plugged.
Or since you have individulal stops, you can shut those off.
On both sides of the rough valve, there are two places to put a screw driver. Just turn those closewise to the off position and it's fixed.
Just remember to open them back up when you trim out the valve.

rp50366-stops.jpg


Or since you have stops on your valve, just use a flat blade screwdriver and turn them clockwise to shut off the water to the valve.
Before it's used, and with the cartridge in place, you can open them up again, counter-clockwise.
 
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newowner

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image.jpg


Ok, I know everyone is now going to slap their heads when I ask this because I am obviously so clueless, but isn't the black plastic square shown in my photo the stopper already installed?

If it isn't, then I can't fit the flat head of a screwdriver into the screw on the left side unless I force the black plastic square away because the slot on the screw is touching it. Then what if the plastic breaks?
 
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Jadziedzic

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The black plastic "square" is called a plasterguard; it is used to position the rough-in assembly the correct distance behind the finished surface of the wall. Any "stopper" would be installed behind the gray plastic cover, inside the metal rough-in body in the holes that align (horizontally) with the stops. You should be able to gently push the plasterguard away from the surface of the tile while you rotate the stops with a small screwdriver (use one with a 1/8" wide tip). If you *do* break the plasterguard that's not an issue - in fact, some installers leave the plasterguard out entirely (see the picture Terry posted above).
 

Jadnashua

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Once the valve is installed, in most instances, you can remove the black plastic mudguard.
 

newowner

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Thank you everyone for such wonderful explanations! I appreciate you all taking the time to post.
 
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