Enviro VB09-36, Installation Operation & Maintenance, Page: 23 / 40

FORM ET145.18-IOM1 (115)
ENVIRO-TEC 23
8. TOP MOUNTED FRESH AIR SUPPLY OPENING
A. Top Mounted Fresh Air
The optional fresh air intake provides a 4” round duct
connection on top of the unit (see Figure 12, for right and left
hand version). The fresh air is discharged upstream of the DX
coil through the discharge collector box.
Do not allow incoming air to bypass the DX coil,
otherwise damage to unit may occur.
Unit can be selected with the fresh air opening located on top
left or right hand side for ease of installation.
It is recommended that applications requiring 10% or more
outdoor air utilize a pressurized fresh air system. Unit cabinet
static pressure at the return air opening is not designed to draw
10% or more in passive fresh air systems.
It is recommended that fresh air with a high humidity ratio is pre-
treated before entering unit assembly using energy recovery
ventilators or make-up air units. Fresh air duct inside unit is
insulated to protect unit from condensation in the event of high
humidity air however excessively moist fresh air over prolonged
periods can potentially result in condensate inside unit or closet.
Recommend fresh air is pre-treated before entering
unit assembly by energy recovery ventilators (ERV)
or make-up air units to avoid condensate developing
inside ducts and equipment.
Unit comes with 4-1/4” return air sleeve. Front supply openings
will come with 4-1/4” supply plaster flange.
B. Top Mounted Fresh Air with Motorized Damper
Same features as in the top mounted fresh air intake option and
including a motorized damper assembly inside the discharge
collector box similar to depiction in Figure 12. Damper assembly
can be easily removed, for servicing see steps below. Motorized
damper assembly opens during FAN ON operation. See
Appendix for electrical schematic. For other control options
please contact the factory.
During transportation, handling or installation of the
cabinet, excessive handling can cause an inner black
plastic cover to come loose and jam the actuator
preventing the damper from opening.
During start-up check that the damper is opening when unit fan
is running. It can take 20 seconds to fully open. If damper opens
unit is operating as intended.
If it fails to open the cause is likely a loose cover preventing
actuator from rotating. To remove actuator and service the
damper refer to instructions below:
STEP 1. Looking up underneath top of the return air
flange you will notice the damper assembly. Remove
seven fasteners holding the damper plate. Drop the plate
down, disconnect the quick-connect terminals from the
harness.
STEP 2. a) Remove red cover from actuator body, b) if
black cover has become loose, position it in place, and c)
slide back onto actuator.
STEP 3. Secure red cover back over actuator assembly.
Ensure the plastic tabs are secured to the metal body
bracket. Connect quick-connect terminals and insert
damper assembly into discharge collector box. Fasten
using screws.
2A
2B
2C
1