Thermostatic concealed shower valves Thermostatic valves allow you to set the temperature of your bath or shower and maintain the flow of water at that same temperature. Concealed Thermostatic showers have their valves fitted into the wall. This means that the wall must be excavated to accommodate the shower's valve. The controls will be neater and more compact and are a good choice for a smaller showering enclosure where every inch of space matters.