The Bermad Model IR-430 Pressure Relief/Sustaining Valve is a hydraulically operated, diaphragm actuated control valve that can fulfill either of two separate functions. When installed in-line, it sustains minimum preset upstream (back) pressure regardless of fluctuating flow or varying downstream pressure; when installed as a relief or circulation valve, it relieves line pressure in excess of preset.

Many TMVs use a wax thermostat for regulation. They also shut off rapidly in the event of a hot or cold supply failure to prevent scalding or thermal shock.

A thermostatic mixing valve (TMV) is a valve that blends hot water with cold water to ensure constant, safe shower and bath outlet temperatures to prevent scalding.

Although other temperature regulating valves exist, thermostatic mixing valves are the preferred type in health care facilities, as they limit maximum outlet temperature, regardless of pressure or flow.

It is increasingly common practice around the world to regulate the storage water temperature to above 60 °C (140 °F), and to circulate or distribute water at a temperature less than 50 °C (122 °F). Water above these temperatures can cause scald injuries. Many countries, states, or municipalities now require that the temperature of all bath water in newly built and extensively refurbished domestic properties be controlled to a maximum of 48 °C (118 °F). Installing thermostatic mixing valves can ensure that water is delivered at the required temperature, thereby reducing the risk of scalding accidents; it also reduces hot water consumption from a supply that is maintained at a higher temperature.[2]

These are single Outlet Thermostatic Mixing Valves, often called "thermostatic faucets", "thermostat taps" or "thermostat valves".

There are three main categories for water temperature controlling devices: Heat Source, Group Control, and Point-of-Use.

The storage of water at high temperature removes one possible breeding ground for Legionella; the use of a thermostat, rather than a static mixing valve, provides increased safety against scalding, and increased user comfort, because the hot-water temperature remains constant.[1]