York DH 300 - Manual (Page 6)

262260-YTG-E-1008
6 Johnson Controls Unitary Products
available for single enthalpy and differential enthalpy
configurations, respectively).
The rainhood is painted to match the basic unit and must
be field-assembled before installing.
• POWER EXHAUST - Our economizer options are avail-
able with power exhaust. Whenever the outdoor air intake
dampers are opened for free cooling, the exhaust fan will
be energized to prevent the conditioned space from being
over-pressurized during economizer operation. BAS-
ready economizer actuators have an adjustable auxiliary
end-switch to provide a range of damper positions available
to energize power exhaust. For units with optional VAV,
power exhaust is energized by means of a binary output
signal from the unit's VAV control board.
The exhaust fan, motor and controls are installed and
wired at the factory. The rain hood must be assembled
and installed in the field.
The power exhaust option can only be used on bot-
tom duct configurations.
• MOTORIZED OUTDOOR AIR INTAKE DAMPER -
Includes a slide-in / plug-in damper assembly with a 2-
position, spring return motor actuator which opens to a
pre-set position whenever the supply air blower is oper-
ating and will drive fully closed when the blower unit
shuts down.
The rain hood is painted to match the basic unit and
must be field assembled before installing.
• BAROMETRIC RELIEF DAMPER - This damper option
can be used to relieve internal building air pressure on
units with an economizer without power exhaust. This
accessory includes a rain hood, a bird screen and a fully
assembled damper. With bottom duct connections, the
damper should be mounted over the opening in the
return air panel. With horizontal ductwork, the accessory
should be mounted on the return air duct.
• PHENOLIC COATED EVAPORATOR AND CON-
DENSER COILS - Special coating process that utilizes
Technicoat 10-1" processes. Coating is applied by total
immersion of the complete coil for maximum protection.
• ELECTRIC HEATERS wired for single point power sup-
ply. These nickel chromium heater elements are pro-
vided with limit and automatic reset capability to prevent
operation at excessive temperatures.
• VARIABLE AIR VOLUME (VAV) - A factory-installed
variable frequency drive (VFD), mounted in the Blower
Access compartment, is used to control the speed of the
indoor blower motor in order to maintain a constant static
pressure in the supply duct. A pressure transducer and
VAV control board are mounted inside the control box.
The drive comes completely wired and pre-programmed
from the factory.
An optional, factory-installed manual bypass switch
available with factory-installed VFD can be found in the
Blower Motor Access compartment. The switch can be
used to either route power to the VFD for modulating
control of the blower motor, to bypass the drive and oper-
ate the motor at full speed, or to power the drive (and not
the motor) for diagnostic purposes.
Due to space limitations, VAV is not available with any of
the factory-installed BAS options described below, but is
available with ‘BAS-ready’ models. Terminal blocks are
provided in the control box for field wiring of the cus-
tomer-installed BAS.
A ‘VFD-ready’ option provides the provisions for a cus-
tomer-installed drive. The unit comes with a mounting
bracket installed in the Blower Access compartment
which may accommodate other vendor’s drives depend-
ing on their size. In order to utilize the unit’s mounting
bracket, the maximum recommended drive dimensions
are as follows:
For 5-hp motor applications ........................10” H x 6” W x 7” D
For 7.5 thru 15-hp motor applications .........13” H x 8” W x 8” D
If the drive will not fit in the allotted space, then it will
have to be mounted elsewhere; either within the building
on a perpendicular wall which is not subjected to exces-
sive temperature, vibration, humidity, dust, corrosive
gas, explosive gas, etc., or within an appropriate enclo-
sure rated for outside installation to safeguard against
moisture, dust and excessive heat.
A terminal block located in the control box is provided for
field connection of the VFD controls.
• HOT GAS BYPASS - To allow for low cooling load oper-
ation, a direct-acting pressure-modulating bypass control
valve installed on the system #1 discharge line is used to
divert high temperature, high pressure refrigerant around
the TXV in order to maintain a desired minimum evapo-
rator pressure. HGBP is standard on all units with VAV
and optional with CV units.
• FILTER OPTIONS - Standard units are shipped with 2”
throw-away filters installed. 2” pleated and 4” pleated fil-
ters are offered as a factory installed option.
• CONVENIENCE OUTLET - This 110 volt outlet can be
“powered” by the unit with a stepdown transformer or
you may order the unit with a “non-powered” conve-
nience outlet that can be wired in the field.
• DISCONNECT SWITCH - A HACR breaker sized to the
unit max fuse size is provided. Factory installed option
only.
• BAS - Building Automation System Controls (avail-
able on two-system cooling product only).
Simplicity® INTELLI-Comfort™ CONTROL - The York®
Simplicity® INTELLI-Comfort™ control is factory
installed. It includes a supply air sensor, a return air sen-
sor, and an outside air sensor. There are provisions for a
field installed dirty filter indicator switch, an air-proving