Thermostatic vs. Pressure Balancing

The Basics

• Pressure balancing and thermostatic shower and bath valves exist to prevent sudden changes in water pressure and temperature. For instance, if someone turns on a sink or flushes a toilet while you take a shower, the water pressure and temperature in the shower may change. Pressure balancing and thermostatic valves adjust the pressure and temperature of the water so it stays at or quickly returns to set levels. In addition to maintaining regular water pressure in a shower, these valves help prevent scalding when cold water pressure drops suddenly.

Pressure Balancing

• Pressure balancing valves sense changes in the ratio of cold to hot water and make adjustments to maintain this pressure ratio. For instance, assume you set the hot to cold water pressure at a ratio of 2:1. If someone runs cold water in a sink elsewhere in the house, it lessens the amount of cold water going to the shower. This raises the temperature of the water, changing the pressure ratio of hot to cold. If the pressure ratio suddenly rises to 3:1 as a result of this change, a pressure balancing valve adjusts the pressure to return it to the original ratio of 2:1.

Thermostatic

• A thermostatic valve adjusts for changes in water pressure and temperature by monitoring the temperature of the water. For instance, assume you set the water in your shower to a temperature of 80 degrees Fahrenheit. If someone runs the cold water somewhere else in the house, the temperature may rise to 100 degrees F because less cold water runs to your shower. A thermostatic valve senses this change and adjusts the amount of hot water in a stream to return the water to its initial temperature.

The Differences

• The obvious difference between pressure balancing and thermostatic valves lies in how they sense and adjust to water changes. Pressure balancing valves maintain constant pressure and temperature by sensing pressure changes. Thermostatic valves do this by sensing temperature changes. Furthermore, thermostatic valves allow you to set a specific temperature for every time you shower by having two controls, one to turn the water on and off, and one to set the temperature. Pressure balancing valves require you to set the temperature with each shower or bath.