The clue is in the name. Thermo = temperature and static = unmoving. A thermostatic valve will keep your shower from going above a certain temperature (usually a factory setting, though some models allow you to select the desired maximum temperature yourself.) By automatically reacting to any change in the flow of hot or cold water, such a shower valve can instantly adjust the mixture of water flowing from the shower to ensure a constant flow that never exceeds a safe temperature.
How do Thermostatic Valves Work?
The clever mechanism of these valves is simple but effective. It has separate inlet ports for hot and cold water, both of which flow through a thermostat element. This element contracts or expands as changes in water temperature and pressure occur, which in turn moves a sliding valve which controls the shower output. If the cold water supply starts to weaken or fail (if the toilet downstairs flushes, or someone turns on the taps) then this valve will throttle the hot water supply to match, keeping the shower at a constant safe temperature. If the cold water totally stops, the valve will shut down the shower outlet completely to protect you from a scalding.
Why Thermostatic Valves are Better Than Manual Valves?
The main benefit of thermostatic valves is safety. Under some circumstances, a too-hot shower can cause serious injury to anyone. This becomes especially worrisome in a home with small children or elderly family members who are at higher risk of burns. With a properly fitted thermostatic valve, you have peace of mind knowing that your shower will never spray water above a safe temperature. The temperature control of these valves also works the other way, so no more icy cold shocks if the hot water runs out suddenly! This all means that you can relax completely and enjoy your shower worry-free.
There are also real ecological and financial benefits to installing a thermostatic valve. By controlling the flow of hot water, it uses much less energy. It also makes it easy for you to implement water-saving measures, if you like. For example, you can shut off the shower while you shampoo without stressing about finding just the right temperature all over again. As soon as you turn the water back on, your shower will deliver perfectly heated water instantly.