The Johnson Controls T-3311-2 Thermostat; PSI SUPPLY/REVERSE ACTING 15PSIG SUPPLY
The T-3311 has a liquid filled bulb temperature sensing element and external setpoint adjustment for space control based on return air temperature. The T-3311 is non-relay type controller requiring dual supply air pressures of 15 and 20 psig (105 and 140 kPa). The controller has two built-in restrictors in the switch stack assembly, eliminating the need for an external restrictor.
Changeover from heating to cooling is accomplished by switching the supply air pressure. Both setpoints on the controller may be calibrated individually for identical setpoints or for two different setpoints; turning the dial changes both setpoints by the same amount. The thermostat mechanism is protected by a snap-on cover.
A dial marked “Cool-Warm” and a pointer are located on the cover of the T-3311.
The pointer has tabs that permit restricting the temperature adjustment range to as little as + 2.5°F (+ 1.4°C). It is factory set for a nominal adjustment of + 7.5°F (+ 4°C).
Linear expansion and contraction of the liquid in the element permits uniform dial graduations and provides a high degree of accuracy over the entire range of operation