Discharge Modification - Carrier 39LA-25 Installation, Start-Up And Service Instructions Manual

Table 17 — Field Wiring for Incoming Conductors
Sized for 125% of Heater Load
LOAD AMPS*
WIRE SIZE
(AWG or kcmil)
Copper
12 16
10 24
8 40
6 52
4 68
3 80
2 92
1 104
LEGEND
AWG — American Wire Gage
kcmil — Thousand Circular Mils
* Values are based on Table 310-16 of the NEC (National Electrical
Code) for 75°C insulated copper wire. Not more than 3 conductors in
a raceway.
NOTES:
1. Be sure to consider length of wiring run and possible voltage drops
when sizing wires.
2. Field power wiring — Heaters are furnished with a terminal block
sized for incoming copper conductors with 75°C insulation rated to
carry at least 125% of the heater load. However, conductors can
be sized to carry 100% of the heater load if the heater is rated at
50 kW or more, and the heater is controlled by a cycling device
such as a multi-stage thermostat, step controller, or SCR (silicon
control rectifier) power controller. Terminal blocks and knockouts
are sized to handle either 100% or 125% conductors.

Discharge Modification

If field modification of discharge position is required, 39L fans
can be converted (by a skilled mechanic) to any standard hand and
LOAD AMPS*
WIRE SIZE
(AWG or kcmil)
Copper
1/0 120
2/0 140
3/0 160
4/0 184
250 204
300 228
350 248
400 268
500 304
Fig. 49 — Fan Discharge Positions, Sizes 03-18
discharge without any additional parts. (NOTE: This does not ap-
ply to a model change conversion.) All mounting holes are
prepunched.
To convert a 39L fan, note the following:
1. Sizes 03-18 — See Fig. 49. It is not necessary to remove the
bearing support channels from the fan housing.
2. Sizes 21 and 25 — See Fig. 50. The "A" frame support must
be removed. To change from upblast to horizontal discharge
or from horizontal to upblast discharge, the bearings must be
relocated to keep the wheel centered in the housing. To
change from upblast front (UBF) to upblast rear (UBR) or
from top horizontal front (THF) to top horizontal rear (THR)
or vice versa, turn the entire fan housing 180 degrees about its
base.
3. The fan shaft may be driven out and reinstalled to place the
drive pulley on the opposite end.
4. The fan scroll is prepunched for horizontal or vertical dis-
charge to match the support angles at the base of the unit.
5. The motor and motor base may be rotated to place the motor
at the front or rear of the unit. Proper location is that which
results in the longest drive center line distance. The motor
conduit box location may need to be reversed.
6. When hand of fan is changed, it may be necessary to turn the
discharge panel inside-out to fit correctly with the fan dis-
charge. In this case, remove the existing insulation and install
new duct-liner type insulation on the opposite side of the dis-
charge panel.
7. Rebalancing of the unit is recommended.
48
LEGEND
THF — Top Horizontal Front
THR — Top Horizontal Rear
UBF — Upblast Front
UBR — Upblast Rear