McQuay IM 672-7
17
Mechanical Installation
Mounting Actuators
The installing contractor is responsible for the mounting of all
field-installed actuators. No provisions are made for the
location of these actuators due to the number of options and
arrangements available and the variety of specific applications.
Typically, actuators are mounted inside the cabinet. Provide
proper support for the actuator to avoid excessive stress in the
cabinet, linkage, or damper shafts.
Fresh air and return air dampers can be linked together and
driven from the same actuator if the dampers are the same size.
If the dampers are different sizes, they must be driven by
separate actuators and controlled appropriately. Exhaust
dampers are always driven by a separate actuator.
A typical rotary electric actuator can handle up to 40 sq. ft. of
damper. For pneumatic actuators, allow 5 in-lb per square foot
of damper area.
Face Bypass Damper Torque Requirements
Face and bypass dampers may or may not be linked together.
When dampers are placed before a single bank of coils, they
always are linked together and require a single actuator. When
dampers bypass a stacked or staggered coil, the dampers are
not linked and require multiple actuators. Unit sizes 040 to 090
provided with external face and bypass require three actuators.
Other arrangements with stacked or staggered coils require
two actuators. A damper shaft extension is provided.
Normally, the shaft extension is located on the drive side of the
unit, but it can be moved to the other side.
Face and bypass dampers have a torque requirement of
10 in-lbs per square foot of damper face area.
Piping and Coils
When designing and installing piping:
•
Follow applicable piping design, sizing, and installation
information in ASHRAE handbooks.
•
Observe all local codes and industry standards.
•
Do not apply undue stress at the connection to coil headers;
always use a backup pipe wrench
.
•
Support pipework independently of the coils.
Water Cooling Coils
•
Water supply, water return, drain, and vent connections
extend through the end panel of the coil section. All
connections are labeled on the end panel.
•
Water supply and water return connections are typically
male NPT iron pipe.
•
When installing couplings, do not apply undue stress to the
connection extending through unit panel.
Use a backup
pipe wrench to avoid breaking the weld between coil
connection and header.
•
Follow recommendations of the control manufacturer
regarding types, sizing, and installation of controls.
Direct Expansion Coils
•
The coil distributor and suction connection extend through
the end panel of the coil section.
•
Check nozzle in distributor for proper tonnage.
•
When a field supplied thermostatic expansion valve is used,
it is located outside the unit and connected directly to the
distributor. Do not apply heat to the body of the expansion
valve.
•
The thermostatic expansion valve must be of the external
equalizer tube type. Connect the 1/4-inch diameter external
equalizer tube provided on the coil to connection on
expansion valve.
•
Use care when piping the system to see that all joints are
tight and all lines are dry and free of foreign material. For
CAUTION
Maximum damper rotation is 70°.
Maximum shaft torque is 205 inches/pound.
Greater rotation or torque can cause equipment damage.
ATTENTION
La rotation maximale des volets est de 70°.
Le couple (torque) maximum de l’arbre est de 205 po/lb.
Une plus grande rotation (ou torque) peut endommager
l’équipement.
