McQuay IM-701 Installation Manual

Installation and Maintenance IM-701

DesignFlow

TM

Precision Outdoor Air Measurement System

Group:

Part Number:

Date:

Applied Systems

April 2001

IM701

© 2001 McQuay International

General

DesignFlow™ airflow measurement stations are located
inside the louvered outdoor air intake doors between the
intake louver and outside air dampers. Essentially, they con­sist of a vane that is repositioned by airflow, the amount of
rotation indicating the amount of airflow. They have been
precision calibrated at the factory and no further calibration
is required. However, a leveling adjustment is required. The
DesignFlow unit must be accurately leveled so that when
operating it will be orientated the same as when it was cali­brated.

The rotational position of the DesignFlow unit vane is trans­lated into CFM by the microprocessor in the MicroTech II
control system. The position of the vane is determined by
two things - the force of the airflow impacting the vane and
the gravitational effect on the vane. Gravity is the only factor
at the lower CFM end of the range. On a correctly leveled
unit, this gravitational effect will be the same as when the
unit was calibrated in the factory.

Both the right-hand and left-hand DesignFlow stations must
be accurately leveled. To accurately level a station, a precise
mechanical force is applied against the vane. That force
should cause the vane to move to a specific position if the
DesignFlow unit is correctly leveled. If the vane does not
move to the correct position with the force applied, the
DesignFlow unit is not properly leveled and gravity is caus­ing the difference.

The DesignFlow unit is mounted such that it pivots at the top.
A lock nut, a slotted hole, and a threaded adjuster allow posi­tioning the bottom of the assembly so it can be correctly lev­eled. When the lock nut is loosened, the threaded adjuster
allows precise, controlled movements.

3. Remove the covers from the access opening in the bottom
blade of the outdoor air intake louvers (See Figure 1). The
leveling procedure must be accomplished with the louvered
door in the closed position. These openings provide access
for leveling.

Figure 1

ACCESS
OPENING

COVER

4. The leveling procedure is performed with the fans off and
the outdoor air dampers closed. If there is a wind, the out­door air louvers should be covered with poly film, cardboard,
etc. to prevent adverse readings due to wind.

5. Tape the fulcrum Alignment Plate to the vane (See Figure

2). Locate the Alignment Plate so the bottom edge of its
notches are flush with the bottom edge of the vane, one side
of one notch is even with the bend near the outer edge of the
vane, and the plate is flat against the outer surface of the
vane.

Figure 2

DesignFlow Airflow Measurement
Station Startup:

Note: Before starting the station startup procedure, locate the
leveling components kit that can be found in the main unit con­trol box.

Note: Before starting the station startup procedures, varify
that power has been supplied to the unit’s MicroTech II con­trol system. The DesignFlow startup procedure cannot be
completed without use of the MicroTech II controls.

VANE

DUCT TAPE
THIS EDGE FLUSH
WITH BEND ON VANE

THESE EDGES FLUSH
WITH BOTTOM OF VANE

ALIGNMENT
PLATE

FULCRUM
DUCT TAPE

1. The swinging vanes on the measurement stations have
been locked in place for shipment. The stations are accessi­ble when the louvered outdoor air intake doors are opened.
Remove the two shipping screws from each vane. One screw
is located one inch from the top of the vane. The other is one
inch from the bottom of the vane. Both are about eight
inches in from the outer edge of the vane.

2. Examine the station for shipping damage. Manually rotate
the vane and verify that it does not rub against anything.
Close and latch the louvered intake door.

2 IM-701

6. Install the fulcrum that is used in the leveling procedure
(See Figure 2). The fulcrum will be held in place with duct
tape. Wipe the bottom of the louver door where the fulcrum
will be located so the tape will stick. Pre-apply the duct tape
to the top surface of the bottom flat of the fulcrum, having it
extend about one inch beyond the edges on three sides. Once
the fulcrum is positioned, these extensions can be pressed