Low hot water pressure ONLY in shower??

[mlight]

So I have two bathrooms and a kitchen sink in the ground floor of a brownstone, all fed by a single cold and hot line from the basement. The water pressure and temperature going to the toilets, kitchen and bathroom faucets is fine; all these function normally.

The two showers are a different story. They both run pretty cold, and the temperature cannot be controlled--it flows out at basically the same temperature no matter which way the lever is pointing (both are on Gerber single-lever faucets, which send water to the shower head and tub faucet). I removed the Gerber levers and cartridges and checked that the screws on the pipe bringing hot and cold water to the cartridge were fully open; they were. I turned on the cold water valve downstairs with the lever unit off; water spewed out easily. Turned on the hot water valve; water came dribbling out.

Do I have a clog somewhere in the line? Seems odd that both showers should have the same problem...but both showers also have the same plumbing...do I need to replace the pressure balance valve? And is the pressure balance valve the brass intersection that brings water to the cartridge, or is that something else??

Thanks in advance for anyone's advice!!! New homeowner, and wish I'd spent time learning how to plumb...

 

[phishfood]

The pressure balance piston is most likely contained underneath the hex head to the right of the main cartridge in your picture.

However, it does seem odd that both of the valves are experiencing the same issue at the same time. I tend to think that you have a supply problem, instead of a problem with the valves. That said, it wouldn't hurt to remove both valve's pressure balancing pistons to see if they have debris in them.

 

[SlowDrip]

Hrm, I'm not familiar with gerber faucets at all, but it is possible that they have an adjustable temperature limiter built in (likely behind the part of the unit not shown in your photo). These limiters usually consist of two plastic pieces with meshed teeth, the outer piece can be removed and rotated to the left for hotter water.

Of course, this only applies if you have had this problem since the units were installed.

 

[mlight]

Thanks for responding, and for your suggestions!

I removed the hex nut and tried running the hot water with the hex nut off. Although the hot water feed was all the way open, it still came out of the pressure balance piston as a dribble. I'm attaching a pic of the pressure balance piston; it looks pretty clean to me. But maybe there's something blocking it that I can't see. How do I remove it to clean it? I don't see any additional mounting screws and I wasn't able to get it out with needlenose pliers. Any suggestions?

I think it probably will end up being the hot water supply line to the shower (only the shower; the bathroom tap hot water has no pressure problems). Is there a way I can test/fix this line myself? What will a professional plumber do to locate the problem?

 

[SlowDrip]

Huh, not that this is a ton of help but I just went to the Gerber site and the first thing I saw was this link which briefly explains a temperature limiting device and limited hot water flow issues. Of course, it doesn't give you a lot of directions. It does mention that the limiting device is at the base of your cartridge stem, as expected.

 

[havasu]

I just have a hard time looking past the "Made in China" sticker in the first pic!

 

[phishfood]

Is there a way I can test/fix this line myself? What will a professional plumber do to locate the problem?

Well, my specialty is in new construction, with a little bit of remodel thrown in, so for your situation I don't think that I qualify as a real professional.

But what I would do from the point you are at is to shut the water supply off and drain it down. Then I would remove the little shut off valve from the hot side of the tub valve, take out the insides and reinstall the outer section back on the valve. This will funnel water out into the shower instead of back inside the wall for the next step. Have someone turn the water on for a very brief time, and watch to see what kind of pressure and volume you get there.This will let you know if it is a supply problem or a problem in the valve itself.

And if you flood your house out, I will delete this post and deny having ever posted it.

 

[mlight]

Thanks for your advice so far, all!

I'm just learning terminology regarding the pressure balance mechanism for my installation.

It looks as the the pressure balance insert should have TWO pieces: a collar which screws into the brass fixture and an little piston piece which fits inside that collar and rotates freely. Is that correct?

Because my pressure balance insert is MISSING the inside piece! Only the collar is installed; no inner rotating insert is present. Was this installed correctly?? (I'm attaching the picture again; what you see is exactly what I see when I remove the hex nut from the fitting.)

 

[phishfood]

Yes, a pressure balance piston should have two parts to it. Exactly how that is installed in a Gerber valve, I don't know, as I have no experience with them.

 

[mlight]

Can anyone out there explain how this Gerber pressure balancing system works? It seems like there needs to be at least one moving part somewhere to adjust the pressure...the pressure balance spool that you see in the picture does not move; is there another piece that moves and adjusts somewhere inside the brass fixture that I can't see? Gerber customer service has proven useless.

 

[SlowDrip]

I have never even heard of Gerber faucets until now. Maybe you just can't get them up here. The innards don't look like anything I have ever seen either, so I can't make a semi-educated guess.

The best I can do for you is this:
http://gerberonline.com/fileLib/GS-303 305_IPL.pdf