Startup
RT-SVX34F-EN 75
Manual Fresh Air Damper
Units ordered with the 25% manual fresh air option have
two slidable dampers. By adjusting one or both, the
desired amount of fresh air entering the system can be
obtained.
To adjust the fresh air damper;
1. Turn the “System” selection switch to the “Off”
position and the “Fan” selection switch (if Applicable)
to the “Auto” position.
2. Close the disconnect switch or circuit protector switch
that provides the supply power to the unit's power
terminal block or the unit factory mounted disconnect
switch.
HIGH VOLTAGE IS PRESENT AT TERMINAL BLOCK
HTB1 OR UNIT DISCONNECT SWITCH.
3. Remove the mist eliminator retainer bracket and the
mist eliminators from the fresh air hood.
4. Remove the five (5) screws in the top and bottom of
each fresh air damper located inside the hood area.
5. Using the Service Test guide in Tab le 31, p. 56 -
Tabl e 36, p. 58, momentarily jump across the test
terminals one time for constant volume applications,
or three consecutive times for a variable air volume
application, to start the Minimum Ventilation Test.
6. With the supply fan “On” and rotating in the proper
direction, measure the return duct static pressure.
7. U s i n g Tabl e 57, p. 76, enter the desired amount of fresh
air and the return air static pressure reading to obtain
the proper damper opening dimension.
Table 55. 40 - 50 Ton downflow economizer (O/A)
damper static pressure setup
System
Design
Return Air Duct Static +
Return Air Damper Static
(Inches of Water)
CFM 0.200.400.600.801.001.201.40
Drive Rod Position
12000 A A C D E E E
12500 A A C D D E E
13000 A A B C D E E
13500 A A B C D D E
14000 A A B C C D E
14500 A A B B C D D
15000 A A A B C D D
15500 A A A B C D D
16000 A A A B C C D
16500 A A A B B C D
17000 A A A B B C C
17500 A A A A B C C
18000 A A A A B C C
18500 A A A A B B C
19000 A A A A B B C
19500 A A A A B B B
20000 A A A A A B B
Table 56. 40 - 50 Ton horizontal economizer (O/A)
damper static pressure setup
System
Design
Return Air Duct Static +
Return Air Damper Static
(Inches of Water)
CFM 0.20 0.40 0.60 0.80 1.00 1.20 1.40
Drive Rod Position
12000 A B E F G G G
12500 A B D E F G G
13000 A A D E F G G
13500 A A D E F G G
14000 A A C E F F G
14500 A A C D E F F
15000 A A B D E F F
15500 A A B D E E F
16000 A A A C D E F
16500 A A A C D E F
17000 AAABDEE
17500 AAABDEE
18000 AAABCDE
18500 AAAACDE
19000 AAAABDE
19500 AAAABCE
20000 AAAABCD
Figure 55. Economizer (O/A) damper assembly
WARNING
Live Electrical Components!
During installation, testing, servicing and
troubleshooting of this product, it may be 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. Failure to follow all electrical safety
precautions when exposed to live electrical
components could result in death or serious injury.
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