Optional Component Overview Economizer; Frost Control; Variable Frequency Drive; Co 2 Sensor - Greenheck ECV Series Installation, Operation And Maintenance Manual

Optional Component Overview
Economizer
The energy core operation can be altered to take
advantage of economizer operation (free cooling). Two
control options are available:
1. Bypass damper
2. Exhaust only operation
Bypass damper: An integral bypass damper will cycle
into a bypass condition allowing cool air to flow past the
energy recovery core rather than flow through it. When
outdoor air conditions are not suitable for economizer
operation, the damper will remain closed. Economizer
mode is initiated by temperature or enthalpy and
dependent on the sensor. To eliminate unnecessary
control sequences and the concern of overloading fans.
Energizing the bypass damper is accomplished one of
two ways:
1. The outdoor air temperature is <40ºF or >65ºF.
2. The outdoor air temperature is <40ºF or >65ºF DB
or >55˚F dew point.
Exhaust only operation: This option allows for the
exhaust fan to run continuously while the supply fan is
off.

Frost Control

Extremely cold outdoor air temperatures can cause
moisture condensation and frosting on the energy
recovery core. Timed exhaust and a electric preheater
are optional frost control features that will prevent/
control core frosting.
Timed exhaust frost control includes a timer as well as
an adjustable thermostat (preset at 35°F) that is factory
installed in the exhaust airstream. When timed exhaust
frost control is initiated, the timer will turn the supply
blower off. Timed exhaust uses a default timer setting
that will shut down the supply fan for 5 minutes every
30 minutes to allow for the exhaust air to defrost the
energy core.
Electric preheat comes standard as single-stage
on/off control. Preheaters are single point wired at
the factory. An adjustable thermostat (preset at 35°F)
is mounted in the exhaust airstream to monitor the
discharge air temperature and enable the preheater if
required. If the temperature falls below the set point,
the electric preheater will turn on. Access to the electric
preheat is through the outdoor air filter access door.
Reference Optional Start Up Components, Frost
Control Test Procedure for troubleshooting.
12 Energy Core Ventilator
Variable Frequency Drives (VFD)
VFDs are used to control the speed of the fan as either
multi-speed or modulating control. Multi-speed VFDs
reference a contact which can be made by a switch or
a sensor with a satisfied set point. Modulating control
references a 2-10 VDC signal to the VFD which will vary
the fan speed from a minimum 50% to full 100% rpm.
An optional CO sensor is available to provide both a
2
set point contact or a modulating 2-10 VDC signal.
CO Sensor
2
The factory-provided sensors can be set to reference a
set point for on/off operation.
On model ECV, this accessory is often used in Demand
Control Ventilation (DCV) applications. The factory
provided sensor can be set to reference a set point for
multi-speed operation on the ECV-20 and ECV-30. The
CO sensor can also be used to output a 2-10 VDC
2
signal to modulate the fan speed on the ECV-10-VG,
ECV-20 and ECV-30.
The CO sensor is either shipped loose to mount in
2
the room space, ductwork, or is factory-mounted in
the return air intake. Follow instructions supplied with
sensor for installation and wiring details.
Dirty Filter Sensor
Dirty filter sensors monitor pressure drop across the
outdoor air filters, exhaust air filters, or both. If the
pressure drop across the filters exceeds the set point,
the sensor will close a set of contacts in the unit control
center. Field-wiring of a light (or other alarm) to these
contacts will notify maintenance personnel when filters
need to be replaced. The switch has not been set at the
factory due to external system losses that will affect the
switch. This switch will need minor field adjustments
after the unit has been installed with all ductwork
complete. The dirty filter switch is mounted in the unit
control center.
®