Webasto Blue Cool Premium Installation And Operating Instructions Manual - page 19
2004 SERIES - CHILLER SYSTEMS - OPERATION AND INSTALLATION MANUAL - PAGE : 18
2004 SERIES - CHILLER SYSTEMS - OPERATION AND INSTALLATION MANUAL - PAGE : 18
EDITION DATED 21ST AUGUST 2006
8F - AIR DUCTING - VENTILA-
TION
1) MINIMUM AIR-GRILLE SEC-
TIONS
In order to obtain an acceptable noise level at
max. blower speed certain requirements as
regards grille and ducts sections should be
observed.
Also the size of the transition boxe behind
the supply air-grille is important.
See table here-under to choose correct grille
sections according to BTU rating.
2) DUCT TYPE
Flexible air-ducts should be of high quality
with sufficiently strong steel spiral re-
inforcement to avoid accidental crushing.
Spiral type ducts should be extended to their
maximum possible length to obtain max.
interior smoothness.
For very long duct sections preference should
be given to rigid ducts (in PVC for example)
which offer a far greater smoothness than
flexible spiral type ducting and therefore will
greatly reduce internal friction.
For very short lengths non-insulated ducts
may possibly be used. Over greater lengths it
is advisable to use insulted type ducts to
avoid condensation on the outside of the air-
ducts.
AIR/HANDLER-WBCC SUPPLY AIR GRILLE RETURN AIR GRILLE DUCT DIAM. DUCT DIAM.
MODEL MODEL/ SECTION cm² MODEL/SECTION cm² <1.8 M DUCT LEN. >1.8 M DUCT LEN.
4000/4500 BTU
6000 BTU
9000 BTU
12000 BTU
16000 BTU or
16000 BTU
24000 BTU
32000 BTU
1 x 8x4”
150 cm²
1 x 10x4”
190 cm²
1 x 12x4”
235 cm²
1 x 10x5”
250 cm²
1 x 12x6”
390 cm²
2 x 10x4”
380 cm²
2 x 10x5”
500 cm²
2 x 12x5”
650 cm²
1 x 12x5”
325 cm²
1 x 11x8”
490 cm²
1 x 11x8”
490 cm²
1 x 14x7”
550 cm² or
1 x 14x10”
800 cm2
1 x 14x12” 1000 cm²
2 x 14x10” 1600 cm²
80 mm
100 mm
100 mm
125 mm
125 mm
125 mm
2 x 125 mm
2 x 125 mm
100 mm
125 mm
125 mm
150 mm
150 mm
150 mm
2 x 150 mm
2 x 150 mm
3) BLOWER OUTLETS
90° turns with flexible ducts directly from
blower outlets should be avoided at all costs
as they introduce severe restrictions in the
air-flow.
All WEBASTO blowers (except on 24000
BTU models) can be rotated through 45°
steps so as to obtain a straight-line outlet
from the blower. This facility should be used
whenever possible.
See also drawing to the right.
4) TRANSITION BOXES
Transition boxes behind supply air-grilles
essentially serve the following purpose :
Serve as an expansion volume for the air-
flow to be reduced in velocity and therefore
reduce air noise when crossing the outlet
louvres.
It follows therefore that the depth of the tran-
sition box is an important factor to allow dis-
persion of the air-flow
The table to the right gives the necessary
information as to the minimum dimensions
advisable for such transition boxes.
5) RETURN GRILLE OFFSET
It is best to avoid placing a return air grille
directly opposite the finned coil surface of an
air-handler. This will inevitably allow propa-
gation of direct blower-motor noise through
the grille.
Always try to offset the grille so as to chi-
cane the return air to the coil inlet.
This will lower direct noise propagation in a
significant manner.
AIR FLOW
AIR FLOW
BLOWER ROTATED TO
MINIMZE FRICTON LOSSES
H
H
DUCT DIAM. MINIMUM VALUE OF “H”
80 mm 100 mm
100 mm 120 mm
125 mm 140 mm
150 mm 165 mm
8.11 - TRANSITION BOX INFORMATION
Deflection curve for longitudinal
entry transition boxes
NB : For duct lengths over 1.80 ml, it may be possible to use the nominal duct diameter (for example 100 mm - 6000 BTU
model), if instead of spiral type flexible ducts, rigid perfectly smooth interior ducts are used.
8.10 - ROTATABLE BLOWER OUTLETS