Filter
Top Products
VIII. STEP 8 — INSTALL OUTDOOR-AIR HOOD
The same type of factory-installed hood is used on units with
25% air ventilation and units with an economizer.
NOTE: The hood top panel, upper and lower filter retainers,
hood drain pan, baffle (size 300), and filter support bracket
are secured opposite the condenser end of the unit. The screens,
hood side panels, remaining section of filter support bracket,
seal strip, and all other hardware are in a package located
inside the return-air filter access panel (Fig. 17).
1. Attach seal strip to upper filter retainer. See Fig. 18.
2. Assemble hood top panel and side panels, upper filter
retainer, and hood drain pan (Fig. 19).
3. Secure lower filter retainer and long section of filter sup-
port bracket to unit. See Fig. 19. Leave screws loose on
size 300 units.
4. Slide baffle (size 300) unit behind lower filter retainer
and tighten screws.
5. Loosen sheet metal screws for base unit top panel lo-
cated above outdoor-air inlet opening, and remove screws
for hood side panels located on the sides of the outdoor-
air inlet opening.
6. Match notches in hood top panel to unit top panel screws.
Insert hood flange between unit top panel flange and unit.
Tighten screws.
7. Hold hood side panel flanges flat against unit, and in-
stall screws removed in Step 5.
8. Insert outdoor-air inlet screens and spacer in channel
created by lower filter retainer and filter support bracket.
9. Attach remaining short section of filter support bracket.
A. Enthalpy Control Installation
NOTE: The accessory outdoor-air enthalpy sensor must be
installed BEFORE the economizer hoods are installed on the
unit or hoods will have to be removed.
1. Remove and discard the factory-installed jumper assem-
bly containing the 800-ohm resistor on the economizer
control module (between terminals S
R
and +). See Fig. 15.
2. Remove black wire assembly containing the 620-ohm re-
sistor from between economizer control module termi-
nal S
O
and the outdoor-air thermostat (OAT). Place this
wire assembly (containing the 620-ohm resistor) be-
tween economizer control module terminals S
R
and +,
replacing the jumper removed in Step 1. See Fig. 15.
3. Disconnect the blue wire from the OAT.
4. Remove OAT from the outside of the economizer (see
Fig. 14).
5. Mount the enthalpy sensor (Fig. 20) to the economizer
on the outside of the unit (in the same location from which
the OAT was removed) using the 2 screws provided. See
Fig. 14.
6. Reconnect the blue wire removed in Step 3 to the en-
thalpy sensor terminal +.
7. Cut the violet wire provided to desired length and ter-
minate with quick-connect terminal provided. Route the
violet wire from the enthalpy sensor terminal S, through
the snap bushing, and to the economizer control module
terminal S
O
. See Fig. 15.
8. Set changeover set point to the desired location.
See Fig. 21.
Fig. 17 — Outdoor-Air Hood Component Location
Fig. 18 — Seal Strip Location (Air Hood Cross-Sectional View)
HOOD TOP
PANEL
HOOD SIDE
PANELS (2)
BAFFLE
(300
ONLY)
LOWER
FILTER
RETAINER
FILTER SUPPORT
BRACKET
HOOD DRAIN PAN
UPPER FILTER RETAINER
BAFFLE (300 ONLY)
LOWER FILTER
RETAINER
FILTER SUPPORT
BRACKET
NOTE: The outdoor-air hood comes with a baffle which is used on
size 300 units only; discard baffle for 180-240 units.
Fig. 19 — Outdoor-Air Hood Details
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