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moneymgmt 01-05-2008 05:47 PM

shower valve doesn't "mix"
Ok, can't get my head around this one: I turn the shower on hot, it runs hot for about 3 seconds and then instantly cools off. We've tried changing the position of the handle to change the hot/cold mix but once it goes cool it won't get warmer. However, I run the bathroom or kitchen sink at full blast and the scalding hot runs endless; I wanted to make sure the problem wasn't the water heater. The shower valve is a piece of garbage, looks like it was put in rather shotty with a whole coil of solder. I just can't figure out why the heck it does this! Ideas?

jpplumber 01-05-2008 07:13 PM

Brand of faucet? Single handle pressure balanced cartridge? May be a pressure balanced cartridge that needs to be changed would be my guess.

redline 01-05-2008 09:02 PM

How old is the faucet?

How old is the water heater?

May have debris in the shower faucet on hot side.

troubleseeker 01-05-2008 09:54 PM

Try removing the cartridge and looking for any obvious beads of solder that could be jamming the balancing mechanism, which is just a plunger that floats back and forth reacting to water pressure differences on hot or cold side. If not, change the cartridge as suggested.

marks5894 01-05-2008 11:11 PM

are there individual shut off valves to the shower? If the sinks have their own shut off valve and this shower has it's own shut off for the hot and another for the cold then check to be sure the hot supply valve is wide open. If it is only open slightly and the cold supply valve is open fully, then you will get a short spurt of hot from build up and then mostly cold in the mixture resulting in cool water. Either the hot supply valve is not fully open or something else between the hot water tank and this shower is limiting the flow, and possibly something within the faucet itself as others have said. When the shower is off the limited hot water to the shower has time to build up, but when you open the shower faucet and release this initial built up pressure the obstruction takes over and dimishes the flow of hot water creating this uneven cold/hot water for an almost shut valve or some other inline problem..good luck..mark

moneymgmt 01-06-2008 01:21 AM

there isn't a shower shut-off valve separate from anything else, so no luck there. next up, "cartridge" has been said several times..... what do you mean by cartridge? The valve I have looks like a brass compass.... east and west are hot and cold, north is shower, south is tub. everything is brass/copper and soldered together. Nothing appears removable. It is a Moen faucet. Thanks all!!

jpplumber 01-06-2008 09:58 AM

Call Moen and see if they will send you the cartridge for free, it is guaranteed for life, it will come with instructions on how to replace the cartridge or they cost about $30 or $40 dollars. Sounds like a Moen posi-temp cartridge if it doesn't pull out to turn on but just rotates to the left for cold and then hot all the way to the left and a pull knob on the spout for the shower. If you get the cartridge and get "stuck"....just give a holler on here and I'm sure someone can walk you through it or give Moen a call. The cartridge can actually seize in the valve but it comes with a plastic insert to help rotate the cartridge before you pull it out.

moneymgmt 01-08-2008 03:25 PM

Good call about the cartridge, I called, should be here in a week, free of charge. Hopefully that's the issue because my lack of HOT showers is irking me.

jpplumber 01-08-2008 07:18 PM

I hope so too. Let me know.

moneymgmt 01-23-2008 09:45 AM

so a week was more like 2 weeks but I finally got the cartridge in the mail. Guess in all my endeavors as a DIY'er this was a first with a shower valve. Took the old one out (didn't realize how simple it was) and it was OBVIOUSLY the problem.....

My shower feed lines had been changed to copper before I bought the house but only the area behind the shower. So we changed the entire house to copper over the last year, never messing with the shower lines (we union'd into them). Apparently before I did that the build up in the galvanized pipes was braking off and getting caught on/in the cartridge. There were 4 pieces each about 1/8" caught in the flows. Now it all makes sense in my head why we were having the problem.....

Good call JP, thanks.

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