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FORM 100.50-EG5 (108)
9
JOHNSON CONTROLS
persons. Erecting a fence around the unit is common
practice.
• Roof curb – YORK offers optional roof curbs
designed specifi cally for the Eco
2
footprint. This
curb comes as an open condenser model and is
shipped disassembled and requires fi eld assem-
bly and installation. For bottom supply and return
openings, the curbs have matching connections to
ease installation. A pipe chase that matches the
rooftop unit pipe chase is also included in the curb
footprint for through-the-curb utility connections.
The curb should be located according to the loca-
tion recommendations above, and properly sealed
to prevent moisture and air leakage into and out of
the duct system. Flexible collars should be used
when connecting the duct work to prevent unit noise
transmission and vibration into the building.
Duct work should be supported independently of the unit.
DUCT CONSIDERATIONS
Unlike competitive units where air can leave the rooftop
unit stratifi ed across the width of the unit, the Eco
2
unit
suffi ciently mixes airfl ow to ensure consistent air tem-
perature from the unit. No special Tee considerations are
required and the unit may be oriented either way.
UNIT ORIENTATION
For applications with multiple rooftop units located in
close proximity on the roof, the orientation of the unit
may be important to reduce the potential for re-entrain-
ment of outside airfl ow. Regardless of the outside air and
exhaust air openings on a unit, all rooftop applications
can permit recirculation of exhaust air to the return, if
applied improperly.
HORIZONTAL APPLICATIONS
The spectrum of applications for roof top units in today’s
market is continuing to grow wider by the day. Flexibil-
ity in unit design and construction is a must in today’s
market in order to insure safe and sound applications of
HVAC equipment. The Eco
2
has been designed for spe-
cifi c application of horizontal supply and return airfl ow
taking the guess work out of unit application by building
a unit specifi c to these needs. If the application calls for
horizontal supply and return air, YORK can ship it from
the factory as a horizontal unit. This option elevates the
need for fi eld modifi cation of equipment, saving time
and money. The Eco
2
can support a left discharge on all
units except 1,125 MBH gas, and/or right discharge on
all cooling-only units. Return air can be brought through
the end or side return air inlet making the unit specifi c
to building needs.
ECONOMIZER
The economizer section is used for ventilation of the
conditioned space to maintain indoor air quality, and
also to reduce energy consumption by using outdoor
air cooling in lieu of mechanical cooling. If outdoor air is
appropriate for cooling, but not suffi cient for the cooling
demand, mechanical cooling will stage on as necessary
until the cooling load is met.
Dual (comparative or differential) enthalpy operation is
the most accurate and effi cient means of economizer
operation. The unit controller monitors the return and
outside air energy content, and selects the lower of the
two for operation.
LD08045
NOTE:
This diagram is provided as a visual reference of the Eco
2
discharge & return air openings & locations for all sizes. Please refer to the dimensional
data for exact size & location of panels and openings.
TABLE 1 – SUPPLY-AIR DUCT-CONNECTION CONFIGURATIONS
Unit Confi guration
Supply Air
Bottom Left Right
50-65 Tons
Cooling only
Cool/gas heat 375-750 MBH
N/A
Cool/gas heat 1,125 MBH
N/A N/A
TABLE 2 – RETURN-AIR DUCT-CONNECTION CONFIGURATIONS
Unit Confi guration
Return Air
Bottom Left Rear
50-65 Tons
No exhaust
Barometric relief damper
N/A
Powered exhaust fan
N/A