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Can't Get Enough Cold Water in Shower

3K views 4 replies 5 participants last post by  Seattle2k 
#1 ·
My house is almost 18 years old (including original shower, gas hot water heater, plumbing, etc.). I have been having problems from time to time with the shower in that I can’t get much, if any, cold water from the faucet/shower head. A couple of time I have been able to somewhat remedy the situation by adjusting the water heater setting. Since, at least from memory, this seems to happen when the weather would start to get warmer I have just chalked it up to that. Today I was experimenting somewhat and the issue appears to be isolated to the shower. I would crack the shower valve (single valve for hot & cold) barely open and could only get warm water……a little more and it would appear to get cooler (still warm) but further and it would begin to become nearly scalding. The valve handle rotates from 6 o’clock (supposedly full cold water) counter clockwise to about 7 o’clock (full hot). In the past, the typical setting for a comfortable warm shower is somewhere in the range of 12 o’clock to 2 o’clock. I have checked the other (rarely used) shower and all three sinks in the house and they have absolutely no problem putting out rather cold water on demand. T would appear that the issue is likely with the shower water valve, I am just looking for help or maybe just a second opinion ……………………………………
 
#3 ·
It definitely sounds like the valve. House is 18 years old so it likely has reached or surpassed its' lifespan. Now you will have to get to it through an access panel and replace it. This is not usually a DIY type job. I have tried to replace them in the past on my own without much success. I just call the plumber. In less than an hour, he's done.
 
#4 ·
This was a very common issue in a building I once worked at. Scale would form inside the valve and prevent the free movement of the anti-scald mechanism. This gizmo required cold water pressure to open the hot side and theoretically prevented scalds. Every now and then we would find one that was connected wrong and it would behave like your valve. The fix with these was pretty simple. Once the face plate was removed the water cold be shut off at the valve via two recessed allen screws. Then all you had to do was pull out the core and clean it up in CLR, Lime away, or if you where in a big hurry, muratic acid. We would replace all the rubber while we were at it. When you shake the core you should hear the guts sliding freely inside.
 
#5 ·
I once resolved a similar problem, by backflushing the mixing valve. The details are foggy, but basically, you remove the shower head and screw on a 1/2 NPT or 3/4 NPT cap, like one of these: http://www.lowes.com/pd_20113-88808...+cap&pl=1&currentURL=?Ntt=iron+cap&facetInfo=

Make sure to put some teflon tape on the threads, before the cap goes on.

Next, open the shower mixing valve, to the position that would normally give equal amounts of hot and cold.

Then, go to your lavatory faucet and remove the aerator screen. Turn the lavatory faucet to full cold (since we want to backflush the shower's cold supply) and let it run for several minutes. Watch what comes out. If sediment is lodged in your shower mixing valve, it will be pushed out the lavatory faucet, into your sink.

Once the water runs clean, you can either shut everything back down and reinstall the showerhead, or see if you can work some more sediment out. For this bonus round, work the shower valve from full-hot to full-cold, back and forth several times, all the while, leaving the sink running on cold. Then, go back to half & half on the shower valve. Finally, go back to the sink and turn the cold quickly on and off, before letting it run for a few more minutes.

If this backflushing procedure does not help, then you'll likely need to service the mixing valve.
 
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