U-5 IOM
15
Operation
Startup using Mammoth DDC controls
Consult the factory for specific instructions for your
unit.
Startup with factory-mounted
Johnson Metasys controls
1. Turn power on.
2. The green light on the Johnson Metasys UNT
DDC controller should blink.
3. The outside air damper will open.
4. When the damper has opened 60-75%, the fan
will start.
5. Unit will operate according to the mixed air
temperature. If the mixed air temperature is
above the set point of the controller, the unit will
cool. If the outdoor air temperature is below the
set point of the controller, the unit will heat. Only
the fan will run if the mixed air is in the dead
band of the set points.
6. Plug the ZT (Zone Terminal) into the UNT
controller using the supplied phone cord. The
inputs listed on the left side of the ZT can be
monitored. The binary outputs are listed on the
right side of the ZT. A hash mark indicates a call
for that particular output to operate. Zone
Terminal controller is available as Mammoth part
number 73399930.
7. The adjustable set points are:
Occupied Cooling,
Occupied Heating, Unoccupied Cooling
and
Unoccupied Heating
. To adjust the set point,
open the access cover on the bottom of the ZT
and push the button to the left of the four LEDs
(Monitor, Adjust, Time Schedule and Password)
until the adjust LED is lit. Adjust the set point up
or down within the program limitations using the
up and down arrows. Your set point will appear
next to the Actual Clg Set and Actual Htg Set.
8. While the unit is operating in the cooling mode
with both compressors, adjust the water flow to
obtain a 12 F temperature rise in the leaving
water temperature as compared to the entering
water temperature.
Note:
Set point adjustment in #7 above may be
required to get both compressors on.
9. Check for clean filters. Replace if necessary.
10. The unit is ready for continuous operation.
Note:
Minimum dry bulb temperature drop between
supply and return airstreams should be about 16 F. a
water temperature rise of 12-25 Fcould be
anticipated at relatively low water flow rates.
Startup using thermostat
A special thermostat (supplied by others) will be
required for humidity control.
After installing the unit, connecting ductwork water,
condensate lines and the wiring as described in the
preceding instructions, the unit is ready for startup.
Check all wire connections in the unit and to the
external control devices
Make certain that the thermostat system switch is in
the “OFF” position and the fan switch is in the
“AUTO” position. Also, the electric box cover and
access panels should be mounted in place. Then turn
on the power to the unit.
Turn the thermostat fan switch to the “ON” position.
The unit blower should operate.
Note:
Unit may not start for 2-5 minutes due to usage
of random start relays and/or anti-short cycle relays.
1. Check the airflow and make sure no supply grilles
or duct dampers are closed to restrict airflow.
2. Set the thermostat temperature setting low and
turn the system switch to the heating mode.
3. Increase the temperature setting low and turn the
system switch to the heating mode.
4. After operating the unit for approximately ten
minutes, check the air temperature rise between
supply and return airstreams. The minimum
temperature rise should be about 18 F.
5. Using a surface pyrometer or other device, check
the temperature of the entering and leaving water
temperatures at the unit. The recommended water
temperature drop between entering and leaving
water may range from 5 to 9 F at 45 F entering
water temperature (ENT) and from 8 to 15 F at
70 F EWT.
If any of the above conditions do not exist, one or
more of the following problems exist: low airflow, low
water flow or unit not performing properly (contact
service department for assistance.
Next set the thermostat system switch to cooling
mode and reduce temperature setting gradually until
unit starts. After operating the unit for a few minutes,
check if unit is functioning properly and providing
satisfactory cooling.
Note:
Minimum dry bulb drop between supply and
return airstreams should be about 16 F. A water
temperature rise of 12 to 25 Fcould be anticipated at
relatively low water flow rates.
