Combined Synopsis/Solicitation: Supply of Flex duct
The pressure drop shown in the table is for perfectly straight flex duct
, which has a roughness factor of about 2.
2) Upstream of the rigid duct is flex duct
that connects each of the branches to an inlet terminal.
Branch-to-diffuser distance is the total length of the flex duct
from the branch in the post VAV rigid duct to the diffuser.
The unit is easy to install with 4-inch round flex duct
and has a high performance rating of 70 CFM air movement for bathrooms up to 65 square feet.
The supply and return ductwork should not be flex duct
(Photo 8), as it is extremely difficult to seal--go with rigid duct (Photo 9).
This project consists of, but is not limited to, providing a negative air vacuum system for cleaning procedures, providing appropriate cleaning tools, cleaning all supply, return and exhaust ducts, cleaning all heating/cooling coils, cleaning Air Handling Units, installing access doors, replacing all flex duct
in kind, and cleaning bathroom exhaust ducts and fans.
ASHRAE 2007) If a horizontal duct is attached directly to a ceiling diffuser, either by bending flex duct
or a rigid elbow, the room discharge flow velocity can be more than four times higher from one side to the other (Landsberger 2008).
INLET DISCHARGE APPLICATION LOCATION LOCATION 1 Return Air Return Air Lined 5 ft Boot Plenum Plenum (Figure 3) 2 Return Air Return Air Flex Duct
Both Sides Plenum Plenum 3 Return Air Return Air Single Elbow Plenum Plenum (No Turning Vanes) 4 Return Air Return Air Double Elbow Both Plenum Plenum Sides (No Turning Vanes) 5 Ceiling Return Air Flex Duct
to Grille Plenum Perforated Face Grille 6 Ceiling Ceiling Flex Duct
to Grille Grille Perforated Face Grilles 7 Return Air Ceiling Toilet Makeup.
Type of all rigid rigid all flex duct
elbow, flex duct
Later, after having installed insulated flex duct
(which has no exposed insulation), the sound was reduced to 38 NC, but it ended up costing three times the original AAV terminal unit purchase price.
Round metal data from the 2005 ASHRAE Handbook--Fundamentals (ASHRAE 2005), measured round metal duct data and flex duct
data for 12" (305 mm), 14" (356 mm) and 16" (406 mm) flex ducts
are shown in Figure 2.