Unit Start Up
RT-SVX36K-EN 125
Economizer Damper Adjustment
Exhaust Air Dampers
Verify that the exhaust dampers (if equipped) close tightly
when the unit is off. Adjust the damper linkage as
necessary to ensure proper closure. An access panel is
provided under each damper assembly.
Outside Air & Return Air Damper Operation
The outside air and return air damper linkage is accessible
from the filter section of the unit.The damper linkage
connecting the outside air dampers to the return air
dampers is preset from the factory in the number 1
position. Refer to Table 57 for the appropriate linkage
position for the unit and operating airflow (CFM).
Note: Bridging between the unit's main supports may
consist of multiple 2 by 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 57, p. 127 for the equivalent return air duct losses
that correspond to each of the holes illustrated in
Figure 81, p. 117.
To Adjust the Outside Air DamperTravel:
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, and
average the reading.
Table 56. Return fan performance—60, 70, 75 tons AC; 73, 80, 89 tons EC (36.5” fan)
CFM Negative Static Pressure
Std. 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
Air RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP
12000 459 1.07 502 1.59 541 2.13 578 2.71 613 3.31 647 3.91 681 4.54 713 5.20
13000 490 1.27 530 1.83 567 2.40 603 3.01 636 3.65 668 4.29 700 4.94 731 5.64
14000 520 1.49 560 2.09 595 2.70 628 3.34 660 3.99 691 4.69 721 5.38 751 6.10
15000 552 1.73 590 2.38 623 3.03 655 3.70 686 4.39 715 5.11 744 5.85 771 6.59
16000 583 2.00 619 2.70 652 3.39 682 4.09 712 4.82 740 5.57 767 6.34 794 7.14
17000 615 2.30 650 3.05 681 3.78 710 4.52 739 5.28 766 6.06 792 6.85 818 7.67
18000 646 2.64 680 3.43 711 4.20 739 4.98 766 5.78 792 6.60 817 7.41 842 8.27
19000 678 3.01 711 3.85 741 4.67 768 5.48 794 6.31 819 7.16 844 8.03 867 8.89
20000 711 3.42 742 4.30 771 5.17 797 6.02 823 6.90 847 7.77 871 8.66 894 9.59
21000 743 3.87 773 4.78 801 5.70 827 6.60 852 7.51 875 8.41 898 9.36 920 10.30
22000 775 4.36 805 5.31 832 6.28 857 7.22 881 8.17 904 9.11 926 10.09 947 11.06
23000 808 4.89 836 5.88 863 6.90 887 7.89 911 8.88 933 9.87 954 10.86 975 11.88
24000 840 5.46 868 6.49 894 7.56 918 8.60 941 9.63 962 10.67 983 11.71 1004 12.75
25000 873 6.08 900 7.15 925 8.26 948 9.35 970 10.42 992 11.49 1012 12.59 1032 13.67
26000 906 6.75 931 7.86 956 9.00 979 10.16 1001 11.28 1021 12.37 1041 13.49 1061 14.63
27000 939 7.47 963 8.62 987 9.79 1010 11.01 1031 12.18 1052 13.33 1071 14.47 1090 15.65
Notes:
1. Max fan RPM 1151 for 36.5" Class I Fan
2. Max motor available 20 HP for 36.5" fan size
3. Max motor available 20 HP for 60, 70 & 75T/ 73, 80 & 89T
4. Max CFM is 27000 for 60, 70 & 75T/ 73, 80 & 89T
5. Min CFM is 12000 for 60, 70 & 75T/ 73, 80 & 89T
6. Return fan belt drive RPM selections will be available to cover 500-1100 RPM range +/- 50 RPM
7. Performance data includes cabinet and rain hood effect. Damper pressure drop will have to be added to return duct static per table Table 49, p. 120
WARNING
No Step Surface!
Do not walk on the sheet metal drain pan. Walking on
the drain pan could cause the supporting metal to
collapse, resulting in the operator/technician to fall.
Failure to follow this recommendation could result in
death or serious injury.
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