(3) Introduce step changes in controller setpoint,
and adjust the derivative mode constant setting until stable
control is achieved.
d) Step 4. After the controller manual tuning
procedure is complete, set the controller at the predetermined
setpoint in the design drawings.
Procedures for Single Zone Control System (Sample)
a) System Inspection. Observe the HVAC system in its
shutdown condition. Check to see that power (and main air) is
(are) available for the HVAC system control devices. Check to
see that the outside air damper, relief air damper, heating coil
valve, and cooling coil valve are closed, and that the return air
damper is open. Check to see that the preheat coil valve is
being controlled by the mixed air low limit controller.
in the shutdown condition. Take readings with a digital
thermometer at each temperature sensing element location. Read
each controller display, and log the thermometer and controller
display readings. Check the calibration accuracy of the sensing
element to controller readouts for outside air, return air, mixed
air, and supply air temperatures.
c) Actuator Range Adjustments. Apply a signal to each
actuator, by placing the controller manual-automatic switch in
the manual position. Verify visually the proper operation of the
actuators for dampers and valves. Vary the signal from 4 ma (or
3 psig) to 20 ma (or 15 psig), and verify that the actuators
travel from zero stroke to full stroke within the signal range.
Observe that sequenced and parallel operated actuators move from
zero stroke to full stroke in the proper direction, and move the
connected device in the proper direction from one extreme
position to the other. Example: Normally closed actuators are
closed at 4 ma (or 3 psig) and are open at 20 ma (or 15 psig).
Log the signal levels that move the controlled device to its
Control System Startup
(1) With the fan ready to start, apply the
optimized start mode command, and observe that the designated
supply fan starts. Observe that the outside air and relief air
dampers are closed, the return air damper is open, and the
heating coil valve and preheat coil valve (cooling coil valve)
are in the warm up (cool down) position. Change the command to
occupied mode and observe that the outside air damper, return air