9
IOM, BS/BT Models
Enertech Global
Duct Work
All new ductwork shall be designed as outlined in
the Sheet Metal and Air Conditioning Contractors
National Association (SMACNA) or Air Conditioning
Contractors of America (ACCA) or American Society
of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE) handbooks.
All supply/return plenums should be isolated
from the unit by a flexible connector (canvas) or
equivalent to prevent transfer of vibration noise
to the ductwork. The flex connector should be
designed so as not to restrict airflow. Turning
vanes should be used on any transition with airflow
over 500 CFM.
All metal ductwork should be
insulated on the inside to prevent heat loss/
gain, condensation and to absorb air noise
. If
the unit is being installed with existing ductwork, the
ductwork must be designed to handle the air volume
required by the unit being installed. When running a
cooling or heating load on a building; size ductwork
accordingly to the building design load and heat
pump CFM.
Industry Standard
When sizing ductwork use 400 CFM per Ton.
As a general rule, maximum recommended face
velocity for a supply outlet used in a residential
application is 750 FPM. Maximum recommended
return grille velocity is 600 FPM. Systems with
higher velocities are likely to have noise problems.
In buildings where ceilings are 8 feet or more, at
least 50 percent of the return air should be taken
back to the heat pump from the ceiling or high
sidewall location and not more than 50 percent from
the floor or low sidewall location.
Unit Placement
When installing a geothermal heating and cooling
unit, there are several items the installer should
consider before placing the equipment.
1. Service Access and Installation Space
Is there enough space for service access? A
general rule of thumb is at least 2 to 2-1/2 feet in
the front and air coil sides depending on return
ductwork size.
2. Unit Air Pad
All geothermal heating and cooling equipment
should be placed on either, a formed plastic air
pad, or a high density, closed cell polyethylene
pad. Down flow units should be placed on a non-
combustible base. This helps eliminate vibration
noise that could be transmitted through the floor.
The use of corner pads alone is not
recommended.
3. R
EVIEW
The installer has verified that all applicable
wiring, ductwork, piping, and accessories are
correct and on the job site.
4. Unit Orientation
Configure left or right side return and discharge
air pattern prior to air handler unit installation.
⚠
NOTICE
⚠
WHEN MATCHING AN ST048 OR ST060
WITH AN MPD060B, REFER TO THE
CFM CHART IN THE ENGINEERING
SECTION FOR THE PROPER
AIRFLOW JUMPER SETTINGS.
Section 3: Installation Considerations
Table 1: Maximum Air Velocities
Location
Supply
Return
Main Ducts
900 FPM
600 FPM
Branch Ducts
700 FPM
600 FPM
Grills, Registers, Diffusers
750 FPM
600 FPM