OK, this may be an easy one for some of you. But my Dad taught me there were only two things you needed to know about plumbing: "poop" runs downhill and payday is on Friday. Unfortunately, neither of those lessons help me out here...

I've got a built-in shower with two faucets to control hot and cold water supply. Been there for almost 30 years now, never touched since they were installed except to replace the handles. Just recently, I've got a problem where if you turn on the hot water valve, you don't get any water flow, not even a drip. The cold water valve works fine.

Now here's the catch. If you turn on the cold water, then turn on the hot water, then turn the cold back off...you get hot water. So you can get hot water through the hot water valve, but it will not flow until you flow the cold water first. If you turn the hot water off, then back on again, nothing. You have to get the cold water running first, then turn on the hot water.

WHY?

Nothing has been touched on the valves since they were put in. This only recently started happening. The only plumbing related activity that occurred around the same time this started was a water heater replacement.

Any ideas?

 

Yes, something is messed up!

Did that help?



I'm no plumber, but it seems like maybe the **** on the valve is partially stripped and won't grasp the stem enough to overcome the pressure in the line to open the valve. Open the cold water valve and it releases enough pressure in the system so that the stripped **** has enough grip to turn the stem. Shut it all off and system pressure returns so that the stripped **** is once again useless.

I know I'm a wiseguy, but I hope the second explanation is somewhat of a help. There are some plumbers here that will offer better explanations I'm sure.

chaikwa.

 

I didn't learn anything on roads or commodes in engineering college...

 

Check valve....thats my guess.

 

Mixer behind wall is screwed up. May just need reaming and a new washer......may need replacing.

 

If you were happy with it before, take it apart and learn how it works, might just need to get some lime out of there. If a part is worn, you'd be surprised at what parts you can still find available. New mixers restrict your heat more for new codes, so you might be happier with the original. If you're careful, some new ones may be tweakable, but I can't help you with which ones. I tweaked my kitchen faucet for better flow than stock.

 

That confirmed what I was thinking.


I guess I'll have to dig into the wall and see what is going on back there. Of course, there is no access to the plumbing, so it looks like it's time to create one.

Always ready to take something apart and see how it works. Just have to make sure I can get it back together with the tools I have on hand.

 

i would start by replacing the valve stems. as chaikwa said, they might be partially stripped. when you change out the valve stems, don't forget to replace the valve seat- if you don't already have one, you should buy a seat wrench to help with the job.

good luck, and don't have too much fun!

 

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Well only on DTR we will get a thread on water faucet bombing soon- and maybe a performance plumbing forum in the future

On a more serious note- Depending on the mineral content of the water in your region the valve may just have plugged up and now a piece of scale holds back the rubber seal ring- under pressure it stays on it's seat, and the opening of the cold water relieves enough pressure so that the rubber snaps up.

Good luck!

AlpineRAM

 

Well... now that your bring it up.... my particular model (seperate hot and cold handles), has a mostly plastic valve body, even for as expensive as it was. The notch that stops the valve from spinning all the way around, can be shaved away to allow the handle to turn open more. Stock, it only allowed the valve to feed about a third of the port at the mixer. You can't shave off too much, because they don't put alot of beef behind the other side of the stopper. Shaving off just enouph to see half or just a hair more, was a huge improvement though. Kinda like going to larger banjo bolts, next will be twins.

 

A performance plumbin' section would fit right in actually. We already have ported an' polished toilets here at DTR!

chaiwka.