Johnson Controls T-901 User Manual

2 T-901/T-903/T-905 Instruction Bulletin
movement. The amount of movement depends on
the location of the sensitivity slider which causes the
control port lid to move. Thus, the lid moves with
respect to the control port, located directly beneath
the lid. This varies the amount of air leaving the
control port and results in varying control port
pressure. This varying pressure is used to operate a
relay of large capacity located in the thermostat.
Operation of Readjusting Mechanism
Set point depends on the position of the control
mechanism assembly with respect to the control port.
The assembly is so pivoted that turning the set point
dial positions the assembly to establish set point.
The readjusting bellows contacts the free end of the
readjusting mechanism assembly. As master
pressure changes, the bellows moves, repositioning
the control mechanism. Movement of the control

Johnson Controls T-901 Specifications

General

Brand	Johnson Controls
Model	T-901
Category	Thermostat
Language	English