Have you ever taken a shower that was perfectly adjusted for the right temperature, only to have someone somewhere else in the house turn on a tap or flush the toilet and completely mess up your perfect temperature shower? If you have, you may wish to head to your local plumbing supplier and inquire about a pressure balance valve. 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 a pressure balance valve, and its job is to ensure that the volume of water that leaves the pressure balance valve 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 your shower constant even when the supply is not.

Drastic changes in water temperature in the shower can be dangerous. There have been cases of the water temperature changing from normal to scalding hot and causing minor burns. 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.

Since a pressure balance valve can prevent scalding, they are now required in all new home construction. You can also replace an older style valve in an older home, but it will likely require the assistance of a certified plumber. In older homes, a pressure balance 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 is very useful 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, you can also consider installing a thermostatic valve. These cost more than double what a pressure balance valve costs, 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.