Selectra® systems from Maxitrol maintain precise, stable gas-fired temperatures. Selectra\'s unique electronic Modulator or Modulator-Regulator valves control gas flow with instantaneous response and continual adjustment. They are the superior alternative to mod motors and butterfly valves. Selectra® Series 44 systems are designed primarily for space heating, as components of direct fired equipment. A wall mounted Selectrastat® senses space temperature and has an integral selector with either a 55° to 90° F or 40° to 80° F range. A discharge air temperature sensor (and mixing tube) is a means of limiting the minimum and maximum discharge air temperature.