Packaged rooftop units
18
Checks in the centrifugal fans (optional)
• Soft starter (optional):
Soft starter of the supply and/or
return centrifugal fans (optionals)
which prolongs the set time mainly
aimed at installations with fabric
ducts.
Pulleys must stay on the same plane
Tensor
screw
Pulley
screws
Taper pin
- Before commissioning, check the blade rotation direction and that
the axis turns without strokes nor vibrations.
- Once running, check the operation conditions: pressures,
fl
ows and
consumptions.
- The overlapping of characteristic curves of the fan and the room is
very important, so that the
fl
ows and pressures provided to the duct
network are as required.
Note:
the access panel to the supply fan(s) is
fi
tted with quarter-turn
latches (models 90 to 180) or quarter-turn latches (models
200 to 360). These latches of stainless steel have triangular insert 8
mm. The closing mode is described in the chapter of “Maintenance”.
Important:
in models 90 to 180 with MC0x and MRC0x assemblies
there is no space to install the
fl
ow control pressostat with return fan.
In this case, the
fl
ow control is performed through a potentiometer
installed on the electric panel.
Checks in the EC plug-fans
- Before commissioning, check the blade rotation direction and that
the axis turns without strokes nor vibrations.
- Once running, check the operation conditions: pressures,
fl
ows and
consumptions.
- The coupling of characteristic curves of the fan and the room is
very important, so that the
fl
ows and pressures provided to the duct
network are as required.
- The variable-speed plug-fans, both supply and return, have a
fl
ow
control pressostat. This pressostat comes from the factory adjusted
to the indicated
fl
ow. However, the
fl
ow for different conditions can
be readjusted on site from the pGD1 terminal (please refer to the
CARRIERrtc control brochure).
Pulley and belt calibration
If the unit has centrifugal motorfans in supply and/or return from the
indoor circuit, they are coupled through pulleys and belts. In these fans,
the following must be taken into consideration:
- The pulleys must be on the same plane, so it is important to check
them with the help of a ruler or a laser aligner.
- In case they are not aligned, remove the pulley screws, and after
removing the taper pin, the set of pulley and taper can be slided over
the axis (this action can be performed both in the motor as well as
in the fan).
- After
fi
xing the pulleys on the same plane, the belt tension is made
by tightening the tensor screw.
- The belt tension must be checked after 24 hours of motor operation.
Attention:
Before performing these operations, it is necessary to verify
that the unit is disconnected from mains.
Note:
the access panel to the supply fan(s) is
fi
tted with quarter-turn
latches (models 90 to 180) or quarter-turn latches (models
200 to 360). These latches of stainless steel have triangular insert 8
mm. The closing mode is described in the chapter of “Maintenance”.
Summary of Contents for 50EH
Page 34: ...Packaged rooftop units 34 Notes...
Page 35: ......
