MECHANICAL INSTALLATION (continued)
DUCTING
Duct work Specifications
•Plan on temporarily installing two air flow measuring devices. The system will have to be balanced (BALANCING THE SYSTEM SECTION), after all duct work has been installed.. The measuring devices are removed after the system has been balanced..
•A sound absorber at least 6 ft. long, consisting of 1” thick rigid fiberglass duct or insulated flexible duct is recommended for maximum absorption of air movement sounds between the unit and the living space return grille..
•All flexible ducts must meet UL safety standards for Class 1 air ducts and connectors.
•All ducting must be installed according to local HVAC codes and standards.
•Round 6” galvanized duct or equivalent is recommended for all duct runs that do not require insulation.
•All ducting located in an unheated space must be completely sealed and insulated.
•For optimum performance and quite operation, all duct runs should be kept as short, straight, and equal in length as possible.
•If the ERV will not be running continuously, a field supplied butterfly damper must be installed in the intake duct near the hood.
GrillE and Hood Specifications
•The living space return grille should not be less than 75 in2 of free area.. Grille surfaces less than this may produce excess air noise..
•Exterior intake and exhaust hoods must be weather resistant. The hoods must also incorporate a screen to prevent unwanted debris, animals, and insects from entering the duct work.. The screen should have a maximum of ¼” openings..
•Caulk both hoods to prevent water leakage.
•Intake and exhaust hoods should be above the expected snow line or a minimum of 18” above ground level, whichever is greater.
Duct work Connections – ForceD Air System
•All duct collars are clearly labeled and must be connected properly.
•Rigid duct work should be connected to the collars with sheet metal screws.
•Flexible duct work must be connected with clamps or bands.
•All duct connections should be sealed with duct tape or mastic to prevent leakage.
Figure 14 – Fully Ducted Energy Recovery Ventilator
NOTE: FRESH AIR INLET TO RETURN DUCT 10 FEET MINIMUM FROM HVAC BLOWER.
FRESH AIR TO HOUSE
STALE AIR TO OUTSIDE
STALE AIR FROM HOUSE
(CENTRALLY LOCATED SUCH AS HALLWAY)
AIR MOVEMENT
SOUND ABSORBER
STALE AIR FROM HOUSE
FRESH AIR FROM OUTSIDE 
BUTTERFLY DAMPER 
(IF ERV NOT RUNNING CONTINUOUSLY)
10 FT MINIMUM
NOTE: THE FRESH AIR INTAKE SHOULD BE INSTALLED
A MINIMUM OF 10 FEET FROM ANY EXHAUST VENT.
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