Electric Shower

[bigquestion]

An electric shower works by heating the cold water by a filament. My question is:

Is the temperature altered by a changing the rate of flow or by changing the heat output of the filament?

Cheers

[buildersmate]

Both.
When the temperature knob is turned, it adjusts the flow rate such that either more water flows past the element (cooler shower), or the opposite.
However most of these showers also have a second knob, often with 4 positions at quarter turns, including one 'cold' position. This knob adjusts the power going to the element.