Installation manual

Page 74 IM-487
Note: The supply and return fan drives are usually selected
for operation in the drive's midspeed range. The
return fan drives are usually shipped with fixed pitch
sheaves that will provide the selected fan speed; how-
ever, the supply fan drives are usually shipped with
variable pitch sheaves that are adjusted to provide the
minimum fan speed. Adjust both drives for proper
airflow during air balancing. For more information,
refer to “Air Balancing” on page 75.
Economizer Start-up
1. Check whether the outdoor air is suitable for free cooling
by displaying the keypad menu Temperature \ OA Damper
\ OA Ambient = "Low" indicates low outdoor air enthalpy;
"High" indicates high outdoor air enthalpy.Refer to
“Enthalpy Control” on page 60 to verify that the enthalpy
changeover control is working properly. You may want to
take temperature and humidity measurements.
2. Verify that the condensing unit is properly disabled to pre-
vent compressor operation during the procedure.
3. At the keypad, set the cooling setpoint low enough so that
the controller will call for cooling. The value in Tempera-
ture \ Zone Cooling \ Occ Clg Spt = will need to be
adjusted below the temperature shown in Temperature \
Zone Cooling \ Control Temp =. In addition, on DAC
units, the value in Temperature \ Discharge Cooling \ DAT
Clg Spt = will need to be adjusted below the temperature
shown in Temperature \ Discharge Cooling \ Disch Air =.
4. Place the unit into cooling mode through the keypad menu
System Summary \ System \ Ctrl Mode = Cool Only.
5. Observe the outdoor air dampers:
a.If the outdoor enthalpy is low, the control algorithm
should start to modulate the dampers open to maintain
the discharge air setpoint.
b.If the outdoor enthalpy is high, the dampers should
maintain their minimum position. Look at menu Tem-
perature \ OA Damper \ MinOA Pos =. Change this
entry to another value. Verify that the dampers move to
the new minimum position setpoint.
6. If the unit is equipped with the electromechanical
enthalpy changeover control (Honeywell H205) and the
outdoor air condition is borderline, attempt to change its
input to the MicroTech II controller by turning the switch
adjustment to "A" or "D". Check enthalpy status in key-
pad menu Temperature \ OA Damper \ OA Ambient =. If
this reading is "Low", go to step 5a. If it is "High", go to
step 5b.
Note: It may not be possible to check the economizer oper-
ation in both low and high enthalpy states on the
same day. If this is the case, repeat this procedure on
another day when the opposite outdoor air enthalpy
conditions exist.
Heating System Start-up
General
1. At the keypad, set the heating setpoints high enough so
that the controller will call for heating. . The value in
Temperature \ Zone Heating \ Occ Htg Spt = will need to
be adjusted above the temperature shown in Temperature \
Zone Heating \ Control Temp =. In addition, on DAC
units, the value in Temperature \ Discharge Heating \ DAT
Htg Spt = will need to be adjusted above the temperature
shown in Temperature \ Discharge Heating \ Disch Air =.
2. Place the unit into heating mode through the keypad menu
System Summary \ System \ Ctrl Mode = Heat Only.
3. Verify that the high ambient heat lockout temperature set-
point, Temperature \ Zone Heating \ OATHtg Lock = is
set above the current outside air temperature (shown in
System Summary \ Temperatures \ OA Temp = ).
Gas Furnace
Refer to the "Start-up and Operating Procedures" section of
the Forced Draft Gas Fired Furnace Installation Manual,
Bulletin No. IM 684 or 685. Perform the start-up procedures
given in it.
Electric Heat
Turn the electric heat switch HS1 to "On". The electric heat-
ers should energize. If the unit has multistage electric heat,
the MicroTech II Auxiliary Control board EHB1 should ener-
gize the heaters in successive stages. The rate of staging is
set in keypad menu Setup/Service \ Heating Setup \ Stage
Time =. The default value of "5 min" can be adjusted from 2
to 60 minutes.
Steam Heat
The steam valve actuator should open the valve. The steam
valve is open when the valve stem is up. If the unit loses
power, the spring in the actuator should drive the valve wide
open. Check this by opening system switch S1.
Hot Water Heat
The hot water valve actuator should open the valve to the
coil. The three-way hot water valve is open to the coil when
the valve stem is down. If the unit loses power, the spring in
the actuator should drive the valve wide open to the coil.
Check this by opening system switch S1.
Cooling System Start-up
1. Place the unit into the System Summary \ System \ Ctrl
Mode = Cool Only mode through keypad menu 11 {"Con-
trol Mode").
2. At the keypad, set the cooling setpoint low enough so that
the controller will call for cooling. The value in Tempera-
WAR
CAUTION
NING
Adjust dampers properly. Improper adjustment may
damage the dampers.
When an economizer is ordered without an actuator, the
linkage requires a 3.14" linear stroke to fully open it. Do
not allow dampers to be driven beyond their normal full
closed or full open position.