Mixet Values are no longer made and must be removed from your unit.

It cannot reiterate more that the Mixet shower valves (the whole valve) allows hot and cold water to mix across the lines even if the valve is turned off. This deterioration (they are at least 40 years old) affect all the units in the building so the boiler are fighting an uphill battle to provide hot water. It is the homeowners responsibility to maintain their unit and that means replacing these valves with a pressure balance valves. If you have an original shower valve or valves in your unit, you are welcome to ask the HOA or their agent to inspect them. Remember, this defective valves affects all your neighbors.

This is breakdown of the valve. Note what the outside looks like different in three different installations.

Mixet Shower Valve

Pressure balance shower system
With a pressure balance valve, you have one lever that is your on/off function and controls only the temperature of the water, not the volume of the water. When the valve is on, it is all the way on (2.0 gallons per minute in California). You cannot decrease the volume of water coming out, but you can always use an adjustable shower head to change the pressure. A pressure-balance valve is basically a standard single-handle mixing valve with one important addition: a pressure-sensitive piston, spool or diaphragm. When the hot water pressure increases relative to the cold pressure, it moves in one direction to limit hot water flow while at the same time increasing the flow of cold water. When the cold water pressure increases, it moves in the opposite direction to limit the flow of cold water and increase the flow of hot water. The ultimate result, in either case, is that the water temperature stays the same.

Common Pressure Balance Shower Valve