Steam/water heaters are typically classified as instantaneous,
semi-instantaneous and tank-type. Temperature control can be
defined as either feed-forward or feedback.
Feedback systems are error-driven and rely upon an outlet or
downstream thermostatic temperature-sensing device to detect a
temperature change requirement and then modulate the steam to
effect the heat exchange in an attempt to recover the heater
set-point. Feedback systems are reactive, and a significant concern
is their speed of response to system and application temperature
control requirements.
ARMSTRONG - Flo-rite temp , Instanteneous Water Heater