Basic plumbing questions.

I have some very basic questions around plumbing that I figured someone here might be able to answer. I am planning to do some research online and at Home Depot after work.

I found a valve under the sink in one of the bathrooms. To be clear there are three valves under that sink - one for the cold water, one for the hot water, and this third one. I looked at the other bathroom and could not find a similar valve there.

I decided to turn it on last night and found out that water starts running immediately when I turn it on. I found out that the valve is connected to the water supply line and to a copper line that goes to the ceiling and through the roof (actually - it doesn’t stick outside the roof as I can’t see it from the outside). It stops just underneath the shingles very close to the a/c unit on the roof. The problem is that it is not connected to anything and when I open the valve under the sink, water starts pouring out of the copper tube on the ceiling.

I believe it has something to do with the A/C unit, but I could not figure it out yet. Any ideas?

I will also check at my home tonight to see if I have a third valve under the sink in one of the bathrooms. I may be able to learn something from the system I have at my home.

My other problem is that I don’t have water coming out of the shower and bathtub. I don’t believe the two problems are related, but they might be. Any suggestions/ideas for the reason why I don’t have water in the shower and bathtub?

I want to do some research before I decide to call a plumber. Thank you.

Coopcan - I believe you are absolutelly right. I am in Arizona. I asked my wife to check if we have a third valve under any of the sinks in the bathrooms and she could not find any. I know the previous owner of this house had just installed a new A/C before he left. I guess the guys who did the installation cut the water line and left the valve in place. I will do as you suggested - put a cap on the top and remove the handle on the valve. Thank you.

By the way - I fixed my original post to refer to valve, instead of register… :O)

In regards to the no water in the shower and bathtub - the house doesn’t have a crawlspace or basement. And I looked around and could not find other valves. What bugs me is the fact that both the shower in the master bath and the bathtub in the second bath are not working. This was the reason why I turned on the third valve under the sink… In the shower I can hear water when I turn the shower on. In the bathtub, I can’t hear anything… I will take the shower heads/handles out tonight to see if I can figure out what is the problem.

Thank you again for answering my questions. Welcome to the site. I hope you stick around - there are tons of good information here… :O)

So last night I worked on the shower and bathtub. I was able to find the problem with the shower in the master bath - the valve is broken. After some meddling I was able to get water coming from the shower head. I had to push and turn the valve. I will have to replace it. Easy enough.

Now in regards to the bathtub in the second bathroom - I took the valve apart and it looks brand new. It is the traditional one valve/mixer with 2 pipes coming in (one for hot and one for cold water) and 2 pipes going out (one going up for the shower head above and one going down to the bathtub spout). Everything looks fine from the outside but when I turn the valve I don’t even hear the noise of water coming in. Not sure what is the problem. At this point I don’t know if there is water in the two incoming pipes. Is there a way to tell without opening the connection? I tried tapping on the pipes but could not tell the difference.

Is there a way to disassemble the stem without removing the whole valve? If I could do that I would be able to figure out if there is water on those pipes…

I am going to home depot at lunch time to see if they have any ideas.

Thank you for any insight/help you may be able to provide on this problem.

Have a nice day! :O)

I’ve installed a bunch of those mixer valves in our apartments. I don’t know if yours is a Moen brand or not (that’s the one we used). The valve stem had a little part cut down on one side of it. I can’t remember now if the correct installation of that tab was to be on top or on bottom, but that could be your problem. When you take your handle or knob off your valve, you should see a couple plastic rings with ridges all around them. These pieces slide onto your valve stem and can be adjusted to change your hot/cold water mixture when the valve is fully open. So maybe try to shut the water off to the house first, then remove the plastic pieces, and flip over that valve stem 180 degrees to see if that works. If that’s not it, there may be some shut-off valves upstream in the supply lines you just haven’t found yet. Since it sounds like you’re on a slab, there’s not many options for shut-off valves besides right there at your shower.

Mine is a Price Pfister. I found the problem. I went to Home Depot and they showed me how to remove the cartridge. I was able to take it out and re-install it - it was stuck. Now it is working like a sharm…

Thank you for the tip. I was almost breaking the wall to check the pipes… :O)

I also bought the cap end to close the line going to the roof. I will do it this week… I don’t want tenants messing with the valve under the sink and causing a major water leak in the ceiling… :O)

So, all the plumbing systems inside the house are working. The only thing I need to do now re. plumbing is to replace the main shut-off valve outside the house (the valve doesn’t close). I am going to install a ball valve, instead of the regular one. This way the tenant shouldn’t have a problem shutting off the water to the house in case he finds a leak. :O)

Ball valves are great. Quick acting and don’t usually leak by like a globe valve. Better flow rate than globe valves too.