T-Series Climate Changer ® Air Handlers Sizes 3 through ... - Trane

Draw-Thru or Blow-Thru
Here are common air handler
arrangements, along with general
application considerations for each.
Horizontal Draw-Thru
(Figure A-7) Traditional arrangement
for air handlers.
Accepted system design practices are
generally the only “restrictions” on its
application. Note: When using a Model
Q fan or plug fan section, provide a
medium blank section between the
coil/filter and the fan for proper air
distribution.
Figure A-7 - Single Zone Draw-Thru Unit
Figure A-8 - Single Zone Blow-Thru Unit
Applications
AHU Arrangements
Single-Zone Blow-Thru
(Figure A-8) This arrangement places a
coil section downstream of a fan
section.
To promote proper air distribution
through each section and reduce the
risk of moisture carryover:
• For units with FC, BI, AF or plug-type
fan sections: Add a medium blank
section 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
sections: Add a blank section with a
drain pan (i.e., medium for unit sizes 03
to 10; medium-large for sizes 12 to 14;
large for sizes 17 to 100) or a moisture
eliminator immediately downstream of
the cooling-coil section.
• Blow-thru configurations with Q-fans
require factory approval.
16
Optimizing an Arrangement
for Acoustical Performance
Designers are often challenged to
select and arrange the air handler
components so that the inlet, discharge
and casing-radiated fan generated
sound power levels help create a quiet
space. To accomplish this, the designer
must choose the right fan and
determine whether additional unit
attenuation is necessary.
Choosing the Right Fan
Obviously, the quieter the noise source
(in this case, the fan), the less
attenuation is needed along sound
transmission paths. Selecting a quieter
fan often increases the initial cost of the
air handler, but can be a cost-effective
system solution because it:
• Reduces the need for path attenuation
(e.g., silencers) by diminishing the
sound level along all transmission
paths
• Reduces energy consumption (i.e., a
fan is normally quietest when running
at the most efficient point on its
operating curve), providing operating
cost savings to offset the initial cost.
Trane acoustical tests have shown that
a fan’s sound power (Lw) level depends
on three factors: its type/design, its
operating point on the fan curve and its
application requirements (e.g., critical
octave band frequency). Table A-1 and
Table A-2 compare the inlet and outlet
sound power levels of four different
fans. Together, these charts
demonstrate that fan inlet sound is not
equivalent to fan outlet sound. More
importantly, they underscore the need
to obtain accurate, ARI 260 tested
sound data from the manufacturer so
that appropriate source and/or path
attenuation methods can be applied.
The T-Series Climate Changer ® air
handler gives designers a choice of
many different fan types. “AHU
Components: Fan Section” later in this
section summarizes each fan’s
application considerations and
acoustical characteristics.