These Robatherm Hot Water Urns feature a unique mode selector switch that allows either variable or pre-set temperature control, providing ultimate flexibility and ease of use. With the mode set to variable, the temperature can be controlled across a wide range via the graduated knob. Variable mode will suit those users who require warm or boiling water for their special application. Switching the mode selector to pre-set will fix the temperature at 95 oC, the optimal temperature for most applications involving tea and coffee. Using pre-set mode offers a fast and easy setup, achieving consistent temperatures every time. Adjustment of the knob in pre-set mode has no effect on the temperature setting of the urn - it remains constant at nominal 95 oC. This prevents continuous boiling and excessive consumption of energy.