Greenheck IG Installation, Operation And Maintenance Manual page 37

Check Operation - Recirculating
Units (optional)
Blower Start-Up, steps 1-5 should be performed
before the blower is run.
Recirculation Operation
The recirculation operation option is recommended
when the ventilation equipment provides the primary
source of heating for the space. Recirculation can
vary from 100% return air to 100% outside air. Control
strategies include 2-position and modulating dampers.
Before the unit is left in service, the recirculation
control system should be tested.
2-Position Damper
A 2-position spring return actuator is used to control
the return air amounts. The damper moves from open
to closed. If power is cut to the unit,
the outdoor air damper will fail to
close.
Turn the recirculating switch on
the remote control panel to each
position and confirm that the return
air damper adjusts accordingly. The
damper actuator may take a few
minutes to open or close.
Modulating
Potentiometer Control - a modulating spring return
actuator is used to control the return air amounts. The
return air damper modulates from fully open to fully
closed based on a signal from a remote potentiometer.
To test potentiometer operation,
turn the potentiometer to the two
extremes. Confirm that the return air
damper fully opens and fully closes.
When the potentiometer is at 0, the
return air damper will open. When the
potentiometer is at 100, the return
air damper will close. The damper
actuator may take a few minutes to
open or close.
®
NOTE
EXHAUST
BLOWER
(OPTIONAL)
SUPPL Y
MAIN V AL VES
HEA T
RECIRCULA TION
DIRTY FIL TERS
70
75
65 (OPTIONAL)
80
60
85
55
90
2-Position
Damper Control
BLOWERS
EXHAUST
(OPTIONAL)
SUPPLY
MAIN VALVES
HEAT
DIRTY FILTERS
70
75
65
80
60
85
55
90
Potentiometer
Control
Building Pressure Control - a
modulating spring return actuator
is used to control the return air
amounts. The return air damper
modulates from fully open to fully
closed based on a signal from a
remote pressure sensing device.
Turn both knobs to the upper most
pressure setting. You may have to
remove the outdoor pressure tap
tubing. The return air damper should
close.
Set both knobs at the lowest setting and the damper
should open. It may take one to two minutes for the
damper to reach the desired position.
Reset the correct pressure limits before starting the
unit.
This picture shows
a typical photohelic
setting. Typical settings
are 0.0 in. wg for the
lower and 0.10 in. wg
for the upper pressure
setting. The needle in
this photo indicates
a negative building
pressure. During correct
operation, the indicating
needle will remain
between or near the setting
needles.
External Signal - a modulating spring return actuator
is used to control the return air amounts. Return air
damper modulates from fully open to fully closed
based on an external 2-10 VDC or 4-20 mA signal (by
others).
The return air damper will close with a 10 VDC or
20 mA signal. The return air damper should open with
a 2 VDC or 4mA signal. The damper actuator may take
a few minutes to open or close.
(OPTIONAL)
BLOWER
EXHAUST
(OPTIONAL)
SUPPL Y
MAIN V AL VES
HEA T
DIRTY FIL TERS
75 70
65
80 (OPTIONAL)
60
85
55
90
PHOTOHELIC
Building
Pressure Control
Pressure Indicating Pressure Setting
Needle Needles
Pressure Setting Knobs
Photohelic Gauge
Model IG / IGX Make-Up Air
37