Installation Guidelines
Please note: DBF4XL fans
are not
explosion proof.
Do not use the fans if a
potentially explosive situation may exist. DO NOT USE with heated air in
excess 140˚F (60˚C).
Do not install in an exhaust ductwork where the equivalent duct length is <
25 feet (7.62 meters). The DBF4XL is suitable to overcome an equivalent
duct length of 130 feet (40 meters) of 4 inch diameter galvanized steel duct,
and to maintain a air velocity of 1200fpm (6.10 m/s).
Calculating Duct Run
To calculate the length of your planned duct run, measure from the dryer
to external venting point in roof or wall. For each bend or elbow add 5-7
feet to your total duct run calculations. The DBF4XL can be used on runs
up to 130 feet.
Fan and Switch Mounting
The recommended location of the booster fan is a minimum of 15 linear
(not equivalent) feet of duct from the dryer outlet. If the fan is mounted
closer than the recommended 15 feet, it may develop enough pressure to
lift wet lint into the fan impeller resulting in excessive lint loading in the fan.
The best location for the fan to be mounted is as close as possible to the
termination of the duct work. Exception: If a secondary lint filter is installed
between the dryer and the booster fan, the booster fan may be mounted
within the minimum distance otherwise recommended (See illustration on
right). A mounting bracket (included) attached to a rafter or joist should be
used to stabilize the fan. Although not recommended, a vertical rigid duct
may support the fan if the duct is securely stabilized. (Consult local codes
prior to supporting the fan in the duct alone.) It is recommended that duct
work be attached to the inlet and outlet of the fan by means of
FC
vibration
isolation clamps (optional) to permit periodic inspection of the blower. Refer
to maintenance instructions for inspection recommendations. All duct con-
nections should be properly sealed to prevent leakage and loss of fan per-
formance. Flex duct connections between the dryer duct connection and
exhaust duct should be stretched as smooth as possible.
Pressure Sensor Switch Operation
The DBF4XL contains a positive pressure sensing switch which recognizes
dryer operation and activates the booster fan from an independent electrical
circuit. This eliminates connections through the dryer circuit which may void
the manufacturers’ warranty as well as manual systems which require the
attention of the operator or costly current/temperature sensing systems.
Power to the booster fan is connected in series through a normally open ter-
minal on the switch. A pressure tap is connected to a nipple on the side of the
switch. When the dryer begins operation, positive pressure in the duct caus-
es the switch diaphragm to expand closing the circuit to the booster fan. An
integral delay-on-break timer in the switch will cycle the fan on for intervals of
10 minutes. Cycle will reinitiate after a few seconds as long as the dryer is
operating. This will continue until the dryer has stopped and the timer delay
period has lapsed. Drying cycles, the booster fan, the delay timer and the pres-
sure switch are not adversely affected by the starting/stopping intervals.
DBF4XL
FC Mounting
Clamps (optional)
Alternate Location
Secondary Lint Trap
Installation Instructions for
Model DBF4XL Dryer Exhaust Booster
READ & SAVE THESE INSTRUCTIONS!
Includes:
1 DBF4XL Dryer Exhaust Booster
1 Fan Mounting Bracket and Hardware
1 Wall Label (Mount on wall near dryer.)
1 Tubing & Grommet
