Application Considerations
Single-Zone Blow-Thru
(Figure A-11) To promote proper air distribution through each module and reduce the risk of moisture carryover:
For units with FC, BI, AF or plug-type fan modules:
- Add a medium blank module or diffuser between the fan and coil, or a diffuser
between the fan and final filter. For units with FC, BI
or AF-type fan modules:
- Add a blank module with a drain pan (i.e., medium for unit sizes 03-10; medium-large for sizes 12-14; large for sizes
17-100) or a moisture eliminator immediately
downstream of the cooling-coil module. For units with Q-fan modules:
- Use two turning modules to create a 180-degree turn between the fan and the coil or final filter. For units with final
filter modules:
- Do not place a final filter downstream
of the blow-thru cooling coil. (Placing the cooling coil upstream of the fan module is permitted since heat from the fan
motor will evaporate any saturated air leaving the
cooling coil.)
Multizone Blow-Thru
(Figure A-12) This arrangement places a multizone coil module immediately downstream of a fan module. A separate
thermostat serves each zone; see Unit Data on pages 34
to 57 for the number of zones available. When designing an air handler in this configuration:
- Use zone dampers to blend the air from the unit’s "hot" and "cold" decks and
produce the desired temperature for each zone.
- Use baffles to equalize the pressure drops over both decks; see Table P-11 on page 79. For units with Q-fan modules:
- Use two turning modules to create a 180-degree turn between the fan and the multizone coil module.
Stacked, "Coupled" . . . or Both
Stacked Units
The added IAQ functions performed by today’s air
handler typically result in a larger unit. That can
pose a problem for applications with limited equipment
floor space. A stacked arrangement places ("stacks") the air handler’s modules on top of each other. This strategy
can significantly reduce the length of the unit and
provide better acoustical performance, yet has very
little effect on unit static pressure drops, see Figure A-13 for some sample
configurations. Here are several factors to consider
when evaluating a stacked arrangement:
- Weight may constrain the size and number of modules that can be stacked.
- Check for possible ductwork and damper interference.
- Make sure that "upper-deck" modules are no larger than those below to prevent
overhang.
- Use intermediate channel spacers if the width of the upper deck is smaller than the bottom deck.
"Coupled" Units
"IAQ-readiness" may also make it necessary to join modules of dissimilar sizes. Insulated transition panels and adapter
plates are available to connect dissimilar modules.
Consult your local Trane sales engineer for application
assistance, or refer to Designing an "IAQ-Ready" Air Handler System (Trane publication number SYS-AM-14). |
