Could my new pressure balance valve be reducing my water pressure?

[JenJen]

I just finished my first shower remodel and had a friend of a friend install the new shower valve that came with my American Standard faucet. After months of work I was finally able to use the shower last weekend and was disappointed to find that the pressure is much lower than prior to the remodel. I do have an old house (1930), but my pressure is quite good.
I've ruled out the new shower head as the culprit for the low pressure by testing it in the other shower, where it works great. Besides, the pressure is low coming out of the tub filler as well as the shower head. I've also noticed that when I turn on the water, then pull up the diverter on the tub filler, the shower head turns on, but a bit of water continues to run from the tub filler. Is this an indication of low pressure, or just a crappy tub filler? This never happened with my old fixtures, which were much cheaper. I also disassembled the valve and inspected it carefully. I found a small piece of solder, but removing that didn't seem to improve the flow.

The only thing that has really changed is the pressure balance valve. Could this be causing the low pressure? If so, how do I fix it, I really want my old water pressure back. Is it even possible to buy a non pressure balance valve? I don't have the flushing toilet temperature fluctuation problem that this valve is useful for, so I really don't need it in the first place.


Thanks!
Jen

[jadnashua]

A pressure-balanced valve by itself doesn't affect the flow or pressure. It is sensitive to pressure changes, but if they are even on both sides, it does not affect the flow or water balance. If the rough-in valve has in-line shutoffs, are you sure they are both fully opened? On valves that use both the upper and lower outlet, the upper one designed for the shower has a smaller opening. This normally isn't an issue, as all new showerheads are restricted in flow. Did you for chance use pex to supply the valve verses copper? If you used the threaded inputs rather than soldering the pipes to the valve, it's possible there's some teflon tape blocking things, if you weren't careful.

[LLigetfa]

The principle that many pressure balance systems work on is to hold back some of the pressure and use that pressure to move the balance. In some parts of the world, water is a precious commodity and wasting it could probably get you 40 lashes or worse. I feel some of this conservancy is being foisted on us whether or not we have any need to conserve water.

On my pressure control valve body in my shower, I noticed that the tub filler outlet was a much larger bore than the shower outlet. Since I didn't need the tub filler, I connected the wall union to it, rather than to the shower outlet. Now, I must mention that it was advised by the manufacturer not to do that. The reason was not given but I suspect it is because it limits the pressure balance and could result in scalding under certain conditions.

Years ago when I lived in rentals, I would solve the toilet flush induced scalding issue simply by opening the fill valve on the toilet just a small amount so it would take longer to fill. When I designed and built my house, I ran the plumbing to minimize pressure balance issues at the shower.

Back to your problem... what is the house pressure and is there any way to increase the pressure?

[JenJen]

Thanks for the quick replies.

Jim, to answer your question, copper pipes were soldered to the valve. And I don't believe I have in-line shutoffs, but I'll have to double check that.

LLigetfa, I honestly don't know what the house pressure is, but I do know that my other shower has really good pressure. My friends have even commented on how great it is. The shower/tub combo that I just finished remodeling used to have that same great pressure, but now it's below average. I agree with you on the water conservation regs. I spend twice as much time in a shower with a super low flow shower head just trying to get the shampoo out of my hair.

I did some research and found that the flow rate for the American Standard valve I have is about 4 gmp at 45 psi, whereas a similar valve from Kohler (not the expensive high flow valve), is 6 gmp at 45 psi. Do you think this would make a difference?

[Phil Lloyd]

I wonder if you you have iron pipes feeding that bathroom.
If you do, it could be one or both are partially blocked (like arteries in an 80-year old man).
In a pressure balanced valve, if just one side is partially blocked, the balancing mechanism should reduce the pressure to compensate resulting in an overall drop in pressure.
The fact that the pressure seem lower than before makes me think of this.
Another thing that might cause low overall pressure is any debris such as rust and crud that breaks free in the lines (or even a ball of solder) and blocks an inlet port on the valve body.
With iron pipe I usually run the lines above the valve body and angle down into the bath tub or shower drain after fitting dielectrics. That allows for purging debris and also checking the flow at each line. If the valve was attached witout purging /checking it's hard to know if something might be lodged in the inlet ports of the valve body, but I would first check the cartridge.
Fill a sink of water so when you remove the cartridge you can swish it around and see if any crud comes out.
If it is clean, maybe you can have someone barely turn on the water as you watch the exposed valve body.
Have something like 5 gallon bucket handy to catch/deflect water and be aware that one port will be pure HOT WATER, wear safety goggles and make sure to instruct the helper to turn the water off after 5 seconds. You can always increase the time if the pressure is easy to handle. (Cell phones are handy for this kind of thing, but is can be hard to hear or handle a phone while catching water or turning it on)
You may be able to tell if water is coming out of one port more than the other, but if not, you can at least see if there is more debris still coming out.

On the side ...
Low pressure overall can make a tub spout diverter not seal well (although sometimes you find one that is defective and won't seal well regardless of pressure)
Dripping from the tub spout won't affect affect the shower head pressure noticably, as there is a restrictor in the head, but a steady stream can...depending on the volume of water lost and how much pressure is available to begin with.

[LLigetfa]

Do you have access to the backside to change it out to a different rough-in? Does your rough-in accept different valves?

[LLigetfa]

Phil makes some very good points. Did your rough-in come with a blank for pressure testing/flushing? My Delta did and also had a small screen to catch debris during flushing. The screen needed to be removed afterwards.

If you have the blank, it would be as if both the hot and cold were full open and you could measure how much flow there is without the pressure balance valve.

[JenJen]

Phil, I was wondering the same thing, if perhaps the hot water pressure was lower, therefore causing the cold water pressure to drop as well. If it was a clogged hot water pipe, how would I fix that?

LLigetfa, I think I have access to the back, through a closet. The valve was installed from the shower side before the tiling was done, but the hole in the tiles is almost large enough to change out the valve from the front side if necessary.

This is probably a dumb question, but is there anything in the valve that can be removed...like removing the water restrictor in the shower head?

Thanks guys. I'm going to go home now and seal my grout

[Phil Lloyd]

Phil, I was wondering the same thing, if perhaps the hot water pressure was lower, therefore causing the cold water pressure to drop as well. If it was a clogged hot water pipe, how would I fix that?
---8< ---

NOTE: If you can find out what model valve you have and get the installation instructions (available online too) it makes it easier to figure out by knowing if it comes with a pressure testing cap, etc.

As LLigetfa mentioned (and i forgot to) using a pressure testing cap or blank is an easy way to purge/check the flow from the tub spout without having to wonder about the effect of the cartridge, but your only way of knowing if one side has low pressure by this method is by temperature. If the water is lukewarm that may mean equal pressure (usually you have to set your temperature knob a bit to the hot side to get really warm water). If it is mostly cold or hot it might mean a restricted line.

With any method, you want to make sure you catch any water that may shoot out .. and also that may dribble .. very important if you remove the inline shutoffs, as the face of the port will be behind the surface of the wall, so any water will dribble behind the wall!
If removing the cartridge and /or using a pressure cap that should not be a problem, and you should not need to remove the trim plate with most valves.

As far as how to clear a blocked line .. first it's important to know if you have all copper lines or if you have galvanized iron pipe feeding that bathroom. Your other bathroom has good pressure ... maybe you have all copper now to BOTH and so it is unlikely you have any problem with debris in the line .. unless it's a solder ball. Sometimes when being liberal with the solder and flux, solder can be 'wicked' far into the joint and drip into the pipe or orifice and become a little ball. If so, that ball may flush out. ) It's good to try to catch any water to check for what sort of debris may come out, either in a bucket or in the tub- close the drain.

If you decide to remove the shutoffs to purge, it requires removing the trim plate, and it might be easier to remove the cartridge, but i is an option if your valve has shut-offs. BUT ... The water from the shutoff ports will be a direct stream, aimed at you, so be careful! The pressure will be high, and the hot water dangerous ... so turn the water on very gradually.
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As far as the GPM of the valve: 6 vs. 4 will only make a difference in what comes from the tub spout (so may fill the tub faster, depending on size of pipe to tub spout) and shower heads have restrictors to limit them to 2.5 GPM (restrictors can sometimes be removed- on Delta's website they describe how some people have done it ... but say they don't approve of it or some disclaimer like that )
If you were running multiple shower heads or body jets it would be important to have a higher GPM valve.