Maxitrol's Selectra systems 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. They are designed primarily for space heating, as components of direct fired equipment. <br><br> A wall mounted Selectrastat senses space temperature and has an integral selector with either a 55&#;176 to 90&#;176 F or 40&#;176 to 80&#;176 F range. A discharge air temperature sensor (and mixing tube) is a means of limiting the minimum and maximum discharge air temperature.