Carrier 69NT40-561-300, Operation And Service Manual

Page: 101 / 174

5–3 T-365
Figure 5.2 Upper Fresh Air Make Up Flow Chart
5.3.2 Lower Fresh Air Makeup Vent
a. Full Open or Closed Positions
Maximum air flow is achieved by loosening the wing nuts and moving the cover to the maximum open
position (100% position). The closed position is 0% air flow position. The operator may also adjust the
opening to increase or decrease the air flow volume to meet the required air flow.
b. Reduced Flow for Lower Fresh Air Makeup
NOTICE
In order to prevent inaccurate display readings on units equipped with a Vent Position Sensor
(VPS), ensure that the rack and pinion drive of the VPS is not disrupted when adjusting the air
makeup vent.
NOTICE
Do not loosen the hex nut beyond its stop. Doing so may cause inaccurate display readings
and errors in DataCORDER reports.
Similar to the Upper Fresh Air Makeup vent, two slots and a stop are designed into the Lower Fresh Air
slide for air flow adjustments. The first slot allows for a 0 to 25% air flow; the second slot allows for a 25
to 100% air flow. To adjust the percentage of air flow, loosen the hex nut and rotate the disc until the
desired percentage of air flow matches with the arrow. Tighten the hex nut. To clear the gap between the
slots, loosen the hex nut until the disc clears the stop.
On some models the air slide is supplied with two adjustable air control discs. The fresh air makeup can
be adjusted for 15, 35, 50 or 75 cubic meters per hour (CMH). The air flow has been established at 60
Hz power and 2
− 1/2 inch T bar and with 15 mm (0.6 inch) H
2
O external static above free blow.
Loosen the hex nut, adjust each disc to the required air flow, then tighten hex nut.
NOTICE
The main air slide is in the fully closed position during reduced air flow operation when
equipped with air control discs.
0
50
100
150
200
250
0 10 20 30 40 50 60 70 80 90
100
TBAR
1 1/2”
TBAR
2 5/8”
TBAR 3”
AIR
FLOW
(CMH)
50HZ
PERCENT OPEN
0
50
100
150
200
250
300
0 10 20 30 40 50 60 70 80 90 100
TBAR
1 1/2”
TBAR
2 5/8”
TBAR 3”
AIR
FLOW
(CMH)
60HZ
PERCENT OPEN