What Is a Thermostatic Tap, and Why Would You Want One in a Shower?

Read article : What Is a Thermostatic Tap, and Why Would You Want One in a Shower?

In the US, the government requires some sort of temperature regulation on new shower valves to prevent sudden, drastic temperature swings (the same is probably true in Europe, as well). The simplest way to do that is through pressure-balancing. In this arrangement, the valve has a mechanism that monitors the relative pressure between the hot and cold lines and works to maintain that pressure balance. If the cold pressure dips (because someone flushed a toilet or opened another tap) then the valve will respond by reducing the hot pressure proportionately, thereby maintaining the set temperature within a degree or two.

A thermostatic shower valve is a more advanced form of temperature control that not only compensates for pressure changes, but also for water temperature changes. It actually measures the temperature of the outgoing water, comparing it to the set point you've selected, and will actively adjust the incoming hot/cold mix to reach and maintain your desired temperature. So if you have a tank-style water heater and you start running out of hot water, a thermostatic valve will automatically increase the hot water and decrease the cold as needed to maintain your set temperature.

Thermostatic valves are usually a bit more expensive than an equivalent pressure balanced valve, but they offer more convenience and functionality.