Greenheck Vari-Green Control - Constant Pressure Indoor (474766) - Manual (Page 3)

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It is best to mount the wall static pressure pickup
port using an electrical box. A simple hole in the
wallboard may be used, but in any case be sure
that the foam gasket on the back of the pickup seals
tightly against the wall
Duct Pressure Tap
Positioning the duct pressure tap to get the best
results depends on the layout of the system. For
stacked systems, locate the pressure tap 1/3 of the
way from the bottom of the duct.
Select a location on the duct that is a minimum
of 1.5 duct diameters upstream or downstream
from any dimensional change, elbow, damper or
other obstruction. The mounting location should
be towards the top of horizontal run duct to
prevent condensation from entering the tube. On
rectangular duct mount the pressure tap away
from the corners. Remove any exterior insulation;
insulation may be replaced after installation.
1. Drill a 3/8” hole in the duct where pressure tap is
to be installed.
2. Place the 6” tube into the hole and move the
mounting base up to the duct. Orientation does
not matter.
3. For round duct rotate the tap so the mounting
holes contact the duct
4. Using the supplied self drilling zip screws, attach
the duct pressure tap to the duct compressing
the gasket evenly.
5. Connect tubing from the barbed port to the
pressure controller.
6. When a total and static probe are used to
measure velocity pressure, mount the pressure
taps as shown in the diagram below. Be sure
to orient the total pressure tap in the direction
of airflow. Select a location in the ductwork that
is at least 5 duct diameters from any elbows,
dampers, transitions or diffusers.
Electrical Box
1. Using a 1/16” Allen wrench, separate the mounting
base and the cover by driving in the 1/16” Allen
screws until the cover comes free. Driving the
screws in prevents you from losing them.
2. Pull the pressure tubing through the wall and out
of the junction box, leaving about two inches free.
3. Secure the pressure tubing to the pressure fitting.
4. Secure the base to the box using the #6-32 x 3/4
inch mounting screw provided.
5. Attach cover by latching it to the top of the base,
rotating the cover down and snapping it into place.
6. Secure the cover by backing out the lock-down
screws using a 1/16” Allen wrench until they are
flush with the bottom of the cover.
Room Pressure Tap
Mount the static pressure pickup port in an area that
is representative of the zone near the center of the
zone. Do not mount in a closet or other enclosed
space that is in the zone being monitored. Avoid
mounting locations in areas that are prone to drafts.
Electrical Box Mount
Electrical Box
Mounting Plate
Cover