Picture of the mixing valve
is what many toilet mixing valves look like, it has a hot water
inlet, a cold water inlet and a mixed outlet that goes to the
The amount of hot and cold water mixed water line can be adjusted by
the two valves on either side of the mixed water line.
This type of mixing valve can fail, this is why it needs to be
installed in an assessable location, when put into wall or other
places, it makes it impossible to find and replace.