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What is a Pressure Balance Valve?

A pressure balance valve prevents water from being scalding in the shower.
Pressure balance valves are required in new home construction.
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  • Written By: John Sunshine
  • Edited By: Niki Foster
  • Last Modified Date: 23 September 2014
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A pressure balance valve is a sophisticated plumbing device that reacts to changes in the pressure of the delivery water. Typically, both hot and cold water sources are fed into the valve, and its job is to ensure that the volume of water that leaves it is a constant mix of these two sources, even if the delivery pressure of the two sources changes. This is very important to keep the temperature of a shower constant even when the supply is not.

Drastic changes in water temperature in the shower can be dangerous, and there have been cases of the water temperature changing from normal to scalding hot. Temperature extremes in the other direction have also caused problems, with people slipping and falling trying to avoid a suddenly very cold shower. These problems are exacerbated when very young or very old people are involved.

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Since a pressure balance valve can prevent scalding, they are now required in all new home construction. Homeowners can also replace a valve in an older home, but it will likely require the assistance of a certified plumber. In older homes, the new valve may not work very well if there is an inadequate flow of water due to clogged water pipes or poor water pressure related to the age of the plumbing system. A certified plumber can help in such situations, because he or she will be able to determine beforehand the extent of the problem and what will be required to provide a functional solution.

For the ultimate in shower comfort, homeowners can also consider installing a thermostatic valve. These cost more, but they provide much better temperature control. A big disadvantage of the pressure balance valve is that it can provide limited flow rate control. A thermostatic valve can provide a full range of flow rate control, while still providing water at a constant temperature.

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anon325103
Post 16

I installed a pressure balance faucet (or had it installed) in our bathroom, and now we have no water pressure. I did not know it would be bad in our 130 year old house, and apparently the plumber did not either. I do not want to take all the tile off to remove it. What can we do?

Also, can I install the face trim that came with the other shower on the older (nine years old) plumbing?

anon277807
Post 15

We had our bathrooms redone and the contractor installed pressure balance valves in the showers. Ever since, whenever the cold water is turned on elsewhere in the house (showers not being used), hot water flows out of the water heater tank, up the cold water intake and mixes with the cold! So our kitchen cold water isn't that cold, we're watering the lawn with almost lukewarm water and we're paying for heating the water. What's going on?

anon244848
Post 13

The temperature valve on the mixer shower bar keeps sticking at 30 percent and it's very hard to turn it down further when needed. Any suggestions?

anon172380
Post 12

I just replaced my shower body with a new Moen single lever Brabbury unit. After install I got no water at all. I replaced that unit as well with the same make and model. Now I not only get no water at all I have no or little hot water in the entire house. Any ideas?

anon162076
Post 11

The pressure balance valve must be calibrated. Tightening the screws does not help since these are integral stops for service. Meaning they are used to shut the water off at the source.

anon153304
Post 10

The pressure balance valve incorporates a cartridge that consists of movable spool or piston that changes the hot and cold volumes simultaneously when a pressure imbalance exists. This cartridge is made up of two pieces that are removable for servicing: the spool and the housing. It may be difficult to remove the cartridge, as it is usually frozen and full of mineral deposits.

Once removed, a replacement part can be installed. Alternatively, if you can spare the extra time, a good soak in CLR or solution of 100 percent vinegar will attempt to dissolve the deposits. By moving the spool with the aid of an awl or tiny screwdriver, you will get them apart for easier cleaning and polishing.

Now the internal spool should move with very little force from within its housing and can be reassembled in the valve. Test for leaks and alter the settings and you'll find the valve is operating correctly again.

anon52922
Post 9

Solutions: I have a Pegasus model F1222100CPBV pressure balance valve. It was not giving me enough flow and would shut off when I turned it too far to the right. The contractor installing it had shut off the cold water stop too much.

I unscrewed the knob, unscrewed the retaining screw, removed all of the trim, and shut then reopened the stops equally. I then put a plastic sheet over the hole (like a curtain) to prevent shower water from entering my wall and turned the thing on and adjusted the flow while taking a nice hot shower!

I have noticed that the plumber installed the cold and hot backward, so next, I will attempt to figure out how to remove the "cartridge" and reverse that.

In the meantime, I have removed the flow restrictor from the shower head and voila! more volume! --Art of Homestead

anon50004
Post 8

I have the hot water heater turned all the way up, and I get a lukewarm bath. I also can't warm the bath up by adding a little hot water because the water coming out of the tap isn't hot enough. You also can't cool down a bath you run too hot (for the kids) with cold water because cold water comes out only at a trickle. I hate my pressure balance valve.

anon45181
Post 7

Often when working on these valves, the valve is not seated completely thus causing this effect. If your assembly has multiple parts, do this: Turn both source valves off. Remove all parts and assemble them out of the housing. This is important! Remove all o rings, then ensure *all* parts are seated fully together. They sometimes will make a snapping sound. Then replace the O rings and reinsert the assembly. If the large O ring that provides a seal for the balance unit and the housing body is not properly seated, it could prevent the unit from seating fully and allow it to function properly.

anon37965
Post 6

5)Check the shower head. It may be clogged. Its easy to unscrew counterclockwise. If not sure put it on another shower and see how it works. Otherwise the valves have been closed up behind the handle and need to be fully opened (the last guy turned the valves the wrong direction- closed). I am a General Contractor not a plumber. These inexpensive valves are problematic. You may need to upgrade to a thermostatic valve which is easily double the cost but adjusts for flow as well as doing a better job on limiting temperature variations.

Jimmy1670
Post 5

Does anyone know how to get more pressure out of your pressure balancing valve? I have a pressure balanced valve and I get no pressure at all out of my shower, it is new construction so there aren't any leaks or flow problems this head is restricting my pressure and I want it to stop! Help Me.

anon22244
Post 4

I have the same problem except I have the Chanteaux series. I have tightened the right/cold screw only to have low pressure and whistling. Did you ever figure out your problem? Is there an adjustable rotational stop limit?

anon19062
Post 3

What type of role that a balancing valve play? Is it the same as the check valve? Does balancing valve allow flow of water in both directions? Any information you can provide is greatly appreciated. Thank you!

anon17398
Post 2

I am having the same problem. Does the pressure balance valve go bad? Does it go bad if not used? The one in question is in a spare bathroom where the shower rarely is used.

mbnoll
Post 1

my graff pressure balanced shower/tub mixer valve (pesaro series)doesn't allow the water temp to get hot enough. I've tried adjusting the left and right screws but this has not helped. True to form, when I tighten cold or hot all the way down, I only get a trickle. Any suggestions on how to get a hotter mix?

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