Johnson Controls DSV60B-300B, Installation Instructions Manual

Page: 20 / 48

FORM 145.29-IOM2 (814)
20
JOHNSON CONTROLS
BLOWER SPEED ADJUSTMENT
The blower speed can be adjusted to increase or decrease the unit CFM for non-VFD units. The RPM of the
supply air and condenser air blowers will depend on the required CFM, and the static resistances of both the
supply/discharge and the return/intake duct systems.
An air balance should be done after installation to verify air flow and static. Adjustments to drive may be required.
Only operate unit in the regions defined by the fan tables. Units can be ordered with oversized motors and/or
drive kits for high static requirements.
Units with oversized motors or oversized drive kits are designed to operate in the shaded
region of the fan table otherwise motor amp draw will exceed overload setting resulting in
overload trips and possible damage to unit. Refer to fan tables for recommended operating
range of standard and oversized motors and drive kits.
The RPM for the blowers can be determined from the blower performance tables. Adjustment of blower speed is
accomplished as follows:
1) Loosen belt tension by moving motor towards the blower shaft via the adjustable mounting.
2) Loosen the setscrew in the adjustable motor pulley flange. Remove external key on pulleys 4 in. diameter and
larger.
3) Blower speed will increase when moveable flange is adjusted towards the fixed flange (closed). Blower speed
will decrease when the moveable flange is adjusted away from the fixed flange (opened). Pulleys are
adjustable only in half-turn increments. Do not open pulley more than five full turns for "4L" and "A" belts, or
six full turns for "B" belts.
4) Once the pulley has been opened/closed the appropriate number of turns, replace the external key and
tighten the adjustment setscrew. Proper torque is 110-130 in.-lbs.
5) Install drive belt and adjust motor mount to tension belt (see page 20: MAINTENANCE/SERVICE for further
information).