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Unit Start-up
WARNING
No Step Surface!
Failure to follow instruction below could result in
death or serious injury.
Do not walk on the sheet metal drain pan. Walking on
the drain pan could cause the supporting metal to
collapse and result in the operator/technician falling.
Note: Bridging between the unit main supports may consist
of multiple 2 x 12 boards or sheet metal grating.
Arbitrarily adjusting the outside air dampers to open fully
when the return air dampers are closed or; failing to
maintain the return air pressure drop with the outside air
dampers when the return air dampers are closed, can
overload the supply fan motor and cause building
pressurization control problems due to improper CFM
being delivered to the space.
The outside air/return air damper linkage is connected to a
crank arm with a series of holes that allows the installer or
operator to modify the amount of outside air damper travel
in order to match the return static pressure.
Refer to
Table 51, p. 110
for the equivalent return air duct
losses that correspond to each of the holes illustrated in
Figure 98, p.
109.
To Adjust the Outside Air Damper Travel
1. Drill a 1/4" hole through the unit casing up stream of the
return air dampers. Use a location that will produce an
accurate reading with the least amount of turbulence –
several locations may be necessary, then average the
reading.
WARNING
Hazardous Voltage!
Failure to disconnect power before servicing could
result in death or serious injury.
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Verify that no power is
present with a voltmeter.
Important: HIGH VOLTAGE IS PRESENT AT
TERMINAL BLOCK OR UNIT
DISCONNECT SWITCH.
2. Close the disconnect switch or circuit protector switch
that provides the supply power to the unit terminal block
(2XD1 on 20-75T units / 1XD1 on 90-130T units) or the
unit mounted disconnect switch (2QB1 on 20-75T units
/ 1QB1 on 90-130T units).
3. Turn the 115 volt control circuit switch (1S1) to the "On"
position.
Turn the 115 volt control circuit switch (1S20) to the
"On" position. (90-130T units only)
4. Open the access door located in the unit control panel,
and press the Manual Override key to display the first
108
service screen. Refer to the latest edition of the
applicable programming manual for applications for the
SERVICE TEST screens and programming
instructions.
5. Use tables in
","
to program the following system
components for operation by scrolling through the
displays;
•
Supply Fan (On)
•
Variable Frequency Drive (100% Output, if
applicable)
•
RTM Occ/Unocc Output (Unoccupied)
•
Outside Air Dampers (Closed)
6. Once the configuration for the components is complete,
press the NEXT key until the LCD displays the "Start
test in __Sec." screen. Press the + key to designate the
delay before the test is to start. This service test will
begin after the TEST START key is pressed and the
delay designated in this step has elapsed. Press the
ENTER key to confirm this choice.
7. Press the TEST START key to start the test.
Remember that the delay designated in step 6 must
elapse before the fan will begin to operate.
8. With the outside air dampers fully closed and the
supply fan operating at 100% airflow requirements,
measure the return static pressure at the location
determined in step 1.
9. Press the STOP key in the unit control panel to stop the
fan operation.
WARNING
Live Electrical Components!
Failure to follow all electrical safety precautions when
exposed to live electrical components could result in
death or serious injury.
When it is necessary to work with live electrical
components, have a qualified licensed electrician or
other individual who has been properly trained in
handling live electrical components perform these
tasks.
WARNING
Rotating Components!
Failure to disconnect power before servicing could
result in rotating components cutting and slashing
technician which could result in death or serious
injury.
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized.
10. Open the field supplied main power disconnect switch
upstream of the rooftop unit. Lock the disconnect
switch in the "Open" position while working on the
dampers.
RT-SVX072D-EN
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