Thermostatic mixing valves allow you to precisely preselect your water temperature beforehand, the mixing valve (TMV) is a valve that mix hot water with cold water to ensure constant, safe shower temperatures, thus preventing scalding due to any drop of cold water flow.In other words thermostatic mixing valve provides increased safety against scalding, and increased user comfort, or sudden temperature shocks as the hot-water temperature always remains constant.
Thermostatic valves provide a higher degree of temperature control and provide a wider blanket of true temperature protection. In general they also offer more control. Temperature and volume versus just temperature.
On the other hand 2 main difference between thermostatic shower valve and pressure-balance valve. In general pressure valve control a temp to +/-3 degrees, while thermostatic valves to about +/-1 degree. The second main difference is pressure-balance valve are single-control valves. maening you turn the single lever and essentially get 100% volume flow out of the shower head. so there is no true volume or flow control. Each time you turn the valve ON you're getting full flow, rotating the valve simply sets the temperature. On the other hand thermostatic mixing valves allows you to set the volume flow and to control temperature.
The scald setting on a thermostatic valve limits water temperature to a specific temperature.
Instant safety cut-off prevents scalding. The mixer valves have easy access from the front for maintenance this make components can easily be removed without the need for re-plumbing