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directly to the outdoors, or into another part of the building. To maintain negative pressure, the air
exhaust must exceed the air supply by the greater of 10% or 100 CFM. To achieve this differential, the
air supply volume to the area may have to be reduced. Negative pressure levels should be continuously
monitored.
2.
Recirculation
-
used to reduce concentrations of airborne contaminants in a room or area by
continuously cleaning the air and exhausting it back into the same room or area.
3.
Positive Pressure
- used to help prevent airborne contaminants from entering a containment area, by
keeping that area under positive pressure compared to adjacent spaces, so any air leakage will be an
outflow of clean air, and not inflow of contaminated air. This pressure differential can be established by:
a. placing the unit inside the containment area, and using it to pull air into the area by attaching flex
duct between the inlet collar and a location outside of the containment area.
b. placing the unit outside of containment area, and using it to push HEPA-filtered air into the area
through flex duct attached between the outlet collar and a location inside the area.
To ensure that the proper pressure differential is maintained, the volume of HEPA-filtered air supplied to
the area must be the greater of 10% or 100 CFM higher than the volume of air exhausted from it by the
HVAC system. Positive pressure levels should be monitored continuously.
Important Note: Do not operate the unit unless the pre-filter(s) and HEPA filter are installed, and the
filter access door and panel are in place and closed.
DAISY CHAINING
“Daisy Chaining” refers to the operation of multiple units on one circuit, with only one of the units plugged into a
120V/15A electrical power supply receptacle. Each subsequent unit is plugged into one of the GFCI
receptacles on the prior unit, up to the maximum number allowed based on the amperage draw per unit. The
National Electrical Code limits the total amperage draw of devices operating on one circuit to 80% of full load,
which means that the total amperage draw on a 120V/15A circuit, including the unit plugged into the building
electrical power supply receptacle, must not exceed 12 amps.
A total of three PRED1200 units can be “Daisy Chained” on a 15 amp circuit, including the unit plugged into the
building electrical power supply receptacle.
TO START UNIT
1. Check to make sure that the Speed Control Switch is in the “OFF” position. Plug power cord into a 120 volt
AC, 60Hz, 15 amp supply circuit.
2. Turn Speed Control switch clockwise past the click at the “HIGH” setting to turn power “ON”.
3. Set Speed Control switch to desired setting.
Note: Refer to the chart in this instruction manual entitled “AIRFLOW RATINGS” that lists the airflows for the
PRED1200.
Note: In the event of a power failure while the unit is running, or loss of power due to any other cause,
this unit’s motorized impeller will re-start when power is restored, after a brief delay.
FILTER CHANGE INDICATORS
“Change Pre-filter” light “ON” indicates one or more of the following:
1. Loaded pre-filter(s). Refer to filter change procedures.
2. Restrictions on air intake. Refer to Troubleshooting Guide.
“Change HEPA” light “ON” indicates the following:
1. Loaded HEPA filter. Refer to filter change procedures.
2. Excessive restrictions on air exhaust. Refer to Troubleshooting Guide.
