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Troubleshooting and connection
diagrams for the 24 Volt control
systems may be located in the back
of this manual. All digital control
troubleshooting tips and connection
diagrams are located in WSHP-IOP-2
(ZN510) or WSHP-PRB002-EN
(ZN524).
Basic 24V Controls
Safety devices for equipment
containing the basic 24V control
option include a low pressure switch
or suction line temperature sensor to
prevent compressor operation during
low temperature activity. The switch
or sensor is set to activate at
refrigerant pressures of 20 psig (1/2
to 5 ton units) or 7 psig (6 to 25 ton
units) to fit most applications.
A high pressure switch prevents
compressor operation during high or
excessive discharge pressures
exceeding 395 psig.
The lockout relay communicates the
low or high pressure situation to the
compressor to prevent operation. For
units that contain a condensate
overflow switch option, a condensate
overflow situation will also be
communicated to the compressor
through the lockout relay if an
overflow condition exists. The relay
may be reset at the thermostat, or by
cycling power to the unit.
General alarm is accomplished
through the lockout relay and is used
in driving light emitting diodes
(LEDs). This feature will drive dry
contacts only, and cannot be used to
drive field installed control inputs.
Trane recommends 3 minute or
greater minimum off time for
compressor control.
Deluxe 24V Controls (option)
Units containing the Deluxe 24V
control design will incorporate a
microprocessor-based control board.
The Trane microprocessor board is
factory wired to a terminal strip to
provide all necessary terminals for
field connection. The deluxe board is
equipped with a random start relay,
anti-short cycle timer, brown out
6
General Information
protection, compressor disable,
condensate overflow, unit safety
control, diagnostics and a generic
relay (which may be available for
field use).
SeeTable 34
for diagnostic
information and
Figure 62
Figure 63
for thermostat connections.
Trane recommends 3 minute or
greater minimum off time for
compressor control.
Tracer ZN510 or ZN524
Controls (option)
The digital ZN510 and ZN524
controller is designed to support the
1/2 through 25 ton water-source heat
pumps in either a standalone, peer-
to-peer with a Tracer Loop Controller,
or as a full building automation
(open protocol) system. The 1/2
through 5 ton units that incorporate
direct digital controls will typically
come equipped with the ZN510
control board. The exception to this
would be if the equipment contained
hot gas reheat, waterside
economizer, or boilerless control with
electric heat. The ZN524 digital
control board is designed to interface
and run these mechanical options. All
units over 5 tons would ship with the
Tracer ZN524 control board.
For installation, operation and
diagnostics of the ZN510 and ZN524
WSHP-IOP-2 (ZN510) and/or WSHP-
PRB002-EN (ZN524).
Waterside Economizer
(option)
Instructions for mechanical
connection of the waterside
economizer to the water-source heat
pump may be found in the
dimensional section of this manual.
The waterside economizer is
designed to begin economizing
mode when water temperatures fall
below the field adjustable
temperature of 25, 35, 45, 55 or 65 F
(for the Deluxe control option), or
below the programmed set-point (for
the ZN524 control option).
When the temperature is less than
the setpoint, fluid will flow into the
economizing coil, while
simultaneously halting mechanical
operation of the compressor.
Mechanical cooling will continue on a
call for a second stage from the
thermostat or system control.
Boilerless Control/Electric
Heat (option)
Systems that do not contain a boiler
may contain a boilerless control with
electric heat. Trane offers both a
and
factory mounted electric heat option,
and a field mounted duct heater
option.
If the 1/2 through 5 ton GEH and GEV
unit incorporates the factory
mounted option, the unit will ship
from the factory with an internally
mounted nichrome open wire
heating element, designed to start-up
electric heat as the systems primary
heat in the event entering water
temperature falls below 55 F . Once
the entering water temperature rises
above 60 F , the boilerless controller
returns the unit to normal
compressor heating operation, and
locks out the electric heater.
If the unit contains a cooling only
heat pump design, the electric heat
contactor is wired directly to the
thermostat for primary heating, and
the compressor contactor for
cooling.
For units comprised of the field
installed duct heater option, the unit
will ship from the factory with
controls available to interface with
the field provided electric heat
selection.
Note: For geothermal applications,
the boilerless controller has
an adjustable setting of 25,
35, 45, 55 and 60 degrees.
Supplemental or Boilerless
Electric Heat (option)
The 6 through 25 ton models which
contain boilerless control electric
heat or supplemental electric heat
will contain the controls interface
ONLY for field provided electric heat
selection. The heater for this model
shall be external to the equipment by
the contractor for ease of installation.
All power connections for the electric
WSHP-SVX01E-EN
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