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THERMA-FUSER™
SYSTEM BALANCING
VAV systems are balanced for design air volume at maximum air flow and systems using Therma-Fuser VAV diffusers are no
exception. When all the Therma-Fuser diffusers are set for maximum air flow by fully opening them, the system is really a constant
air volume system and is balanced as a constant volume system. Balancing dampers are best located at the takeoff before the
runout to the Therma-Fuser diffuser.
1.
Prepare the system for balancing. (Make necessary
checks for diversity, fan capacities, fan rotation, miminum
outside air requirements, duct leaks and static pressure
controller design settings. Set outside air control damper
for minimum air and return air control damper for
maximum air.)
2.
Make sure Therma-Fuser diffusers are open. TL-C and TL-
CW models are shipped with balancing stops in position
to hold the blade(s) wide open. The stops are a wedge
which should be wedged between the foam side of the
blade and the curved aluminum piece (pushing the blade
so that its back is in contact with the vertical aluminum
piece). See Fig. 5. For multiple blade units, all blades must
be wedged open for proper balancing.
3.
Start fans, adjust system for 100% air flow and make
system checks. (Measure static pressure across filters and
coils and at sensor for static pressure controller. Measure
supply, return and branch duct air flow.)
4.
Measure air flow from each Therma-Fuser diffuser and
adjust damper at the duct takeoff to obtain design air
volume. Air volume measurement may be made with a
direct reading balancing hood or air velocity meter. If a
velocity meter is used, the velocity is measured in the
outside slot on the same side as the duct connection 2
in. / 51mm from either end of the blade at the opening
between the outside blades and the curved aluminum
piece. See Fig. 6. The A k factors for the different linear
lengths are shown in Table 1. Multiply the velocity in fpm
times A k in ft
to get air flow in cfm.
2
5.
Return Therma-Fuser diffusers to operating condition.
Remove balancing stops by grabbing the looped end and
pulling straight down from the face.
6.
Return the remainder of the system to operating condition.
Table 1.
A k factors in ft.² for TL Therma-Fuser diffusers
fully open.
Type
Type
A k
TL-2411
0.07
TL-2422
TL-3611
0.11
TL-3622
TL-4811
0.14
TL-4822
TL-6011
0.22
TL-6022
TL-2411
0.31
TL-2422
TL-3641
0.42
TL-3642
TL-4841
0.60
TL-4842
TL-6041
0.70
TL-6042
Fig 4. End angle raised so that longitudinal edges
are in the plane of the T-bars.
Fig 4. End angle raised so that longitudinal edges
are in the plane of the T-bars.
Diffuser
T-bar
T-bar
Screws
Screws
End Angle
End Angle
Longitudinal edge in the same plane
as the bottom of the T-bar.
SYSTEM BALANCING (TL-C and TL-CW)
SYSTEM BALANCING (TL-C and TL-CW)
VAV systems are balanced for design air volume at maximum air
flow and systems using Therma-Fuser VAV diffusers are no
exception. When all the Therma-Fuser diffusers are set for maxi-
VAV systems are balanced for design air volume at maximum air
mum air flow by fully opening them, the system is really a con-
flow and systems using Therma-Fuser VAV diffusers are no
stant air volume system and is balanced as a constant volume
system. Balancing dampers are best located at the takeoff before
exception. When all the Therma-Fuser diffusers are set for maxi-
the runout to the Therma-Fuser diffuser.
mum air flow by fully opening them, the system is really a con-
1. Prepare the system for balancing. (Make necessary checks for
stant air volume system and is balanced as a constant volume
diversity, fan capacities, fan rotation, miminum outside air
system. Balancing dampers are best located at the takeoff before
requirements, duct leaks and static pressure controller design
the runout to the Therma-Fuser diffuser.
settings. Set outside air control damper for minimum air and
return air control damper for maximum air.)
1. Prepare the system for balancing. (Make necessary checks for
2. Make sure Therma-Fuser diffusers are open. TL-C and TL-CW
diversity, fan capacities, fan rotation, miminum outside air
models are shipped with balancing stops in position to hold
requirements, duct leaks and static pressure controller design
the blade(s) wide open. The stops are a wedge which should
settings. Set outside air control damper for minimum air and
be wedged between the foam side of the blade and the curved
return air control damper for maximum air.)
aluminum piece (pushing the blade so that its back is in con-
tact with the vertical aluminum piece). See Fig. 5. For multiple
2. Make sure Therma-Fuser diffusers are open. TL-C and TL-CW
blade units, all blades must be wedged open for proper bal-
models are shipped with balancing stops in position to hold
ancing.
the blade(s) wide open. The stops are a wedge which should
3. Start fans, adjust system for 100% air flow and make system
be wedged between the foam side of the blade and the curved
checks. (Measure static pressure across filters and coils and at
aluminum piece (pushing the blade so that its back is in con-
sensor for static pressure controller. Measure supply, return
tact with the vertical aluminum piece). See Fig. 5. For multiple
and branch duct air flow.)
blade units, all blades must be wedged open for proper bal-
4. Measure air flow from each Therma-Fuser diffuser and adjust
ancing.
damper at the duct takeoff to obtain design air volume. Air
volume measurement may be made with a direct reading bal-
3. Start fans, adjust system for 100% air flow and make system
ancing hood or air velocity meter. If a velocity meter is used,
checks. (Measure static pressure across filters and coils and at
the velocity is measured in the outside slot on the same side
as the duct connection 2 in. / 51mm from either end of the
sensor for static pressure controller. Measure supply, return
blade at the opening between the outside blades and the
and branch duct air flow.)
curved aluminum piece. See Fig. 6. The A k factors for the dif-
ferent linear lengths are shown in Table 1. Multiply the velocity
4. Measure air flow from each Therma-Fuser diffuser and adjust
in fpm times A k in ft
damper at the duct takeoff to obtain design air volume. Air
5. Return Therma-Fuser diffusers to operating condition. Remove
volume measurement may be made with a direct reading bal-
balancing stops by grabbing the looped end and pulling
ancing hood or air velocity meter. If a velocity meter is used,
straight down from the face.
the velocity is measured in the outside slot on the same side
6. Return the remainder of the system to operating condition.
as the duct connection 2 in. / 51mm from either end of the
blade at the opening between the outside blades and the
Table 1. A k factors in ft.² for TL Therma-Fuser
curved aluminum piece. See Fig. 6. The A k factors for the dif-
diffusers fully open.
ferent linear lengths are shown in Table 1. Multiply the velocity
Type
A k
A k
in fpm times A k in ft
to get air flow in cfm.
2
Type
A k
TL-2411
.07
5. Return Therma-Fuser diffusers to operating condition. Remove
0.14
TL-2421
0.12
TL-3611
.11
balancing stops by grabbing the looped end and pulling
TL-4811
.14
0.18
TL-3621
0.20
straight down from the face.
TL-6011
.22
0.26
TL-4821
0.28
TL-2441
.31
6. Return the remainder of the system to operating condition.
0.28
TL-6021
TL-3641
.42
0.32
TL-4841
.60
Table 1. A k factors in ft.² for TL Therma-Fuser
TL-6041
.70
0.30
diffusers fully open.
0.39
0.55
Type
A k
Type
A k
0.65
TL-2411
.07
TL-2422
.14
TL-3611
.11
TL-3622
.18
TL-4811
.14
TL-4822
.26
TL-6011
.22
TL-6022
.28
TL-2441
.31
TL-2442
.30
TL-3641
.42
TL-3642
.39
TL-4841
.60
TL-4842
.55
TL-6041
.70
TL-6042
.65
FIG. 4 END ANGLE RAISED SO THAT LONGITUDINAL EDGES ARE IN THE
PLANE OF THE T-BARS
Fig 5. Balancing Stops
FIG. 5 BALANCING STOPS
Diffuser
Longitudinal edge in the same plane
as the bottom of the T-bar.
FIG. 6 LOCATION OF VELOMETER
Figure 6. Location of Velometer
to get air flow in cfm.
2
BALANCING (TL-D)
BALANCING (TL-D)
1. The damper blade opening is factory set. Readjust where nec-
1.
The damper blade opening is factory set. Readjust where
essary by turning the adjusting screw. See Fig. 7.
2. Place a direct reading diffuser balancing hood over the face of
necessary by turning the adjusting screw. See Fig. 7.
each TL-D diffuser and adjust damper at duct takeoff to obtain
Type
A k
Type
A k
design air volume.
TL-2422
.14
TL-2421
.12
2.
Place a direct reading diffuser balancing hood over the
TL-3622
.18
TL-3621
.20
TL-4822
.26
TL-4821
.28
TL-6022
.28
TL-6021
.32
face of each TL-D diffuser
TL-2442
.30
TL-3642
.39
TL-4842
.55
TL-6042
.65
Type
A k
TL-2421
.12
TL-3621
.20
TL-4821
.28
TL-6021
.32
acutherm.com | THERMA-FUSER™ - Manual
Fig 4. End angle raised so that longitudinal edges
are in the plane of the T-bars.
Diffuser
T-bar
Screws
End Angle
Longitudinal edge in the same plane
as the bottom of the T-bar.
SYSTEM BALANCING (TL-C and TL-CW)
VAV systems are balanced for design air volume at maximum air
Fig 5. Balancing Stops
flow and systems using Therma-Fuser VAV diffusers are no
exception. When all the Therma-Fuser diffusers are set for maxi-
mum air flow by fully opening them, the system is really a con-
stant air volume system and is balanced as a constant volume
system. Balancing dampers are best located at the takeoff before
the runout to the Therma-Fuser diffuser.
1. Prepare the system for balancing. (Make necessary checks for
diversity, fan capacities, fan rotation, miminum outside air
requirements, duct leaks and static pressure controller design
settings. Set outside air control damper for minimum air and
return air control damper for maximum air.)
2. Make sure Therma-Fuser diffusers are open. TL-C and TL-CW
models are shipped with balancing stops in position to hold
the blade(s) wide open. The stops are a wedge which should
Balancing Stop
be wedged between the foam side of the blade and the curved
Balancing Stop
aluminum piece (pushing the blade so that its back is in con-
tact with the vertical aluminum piece). See Fig. 5. For multiple
blade units, all blades must be wedged open for proper bal-
ancing.
3. Start fans, adjust system for 100% air flow and make system
checks. (Measure static pressure across filters and coils and at
Figure 6. Location of Velometer
sensor for static pressure controller. Measure supply, return
and branch duct air flow.)
4. Measure air flow from each Therma-Fuser diffuser and adjust
damper at the duct takeoff to obtain design air volume. Air
volume measurement may be made with a direct reading bal-
ancing hood or air velocity meter. If a velocity meter is used,
the velocity is measured in the outside slot on the same side
Measure in the outside slots
as the duct connection 2 in. / 51mm from either end of the
on the same side as the duct
blade at the opening between the outside blades and the
connection 2 In. / 51mm from
curved aluminum piece. See Fig. 6. The A k factors for the dif-
either end of the blade.
ferent linear lengths are shown in Table 1. Multiply the velocity
Measure in the outside slots
in fpm times A k in ft
to get air flow in cfm.
2
on the same side as the duct
5. Return Therma-Fuser diffusers to operating condition. Remove
connection 2 In. / 51mm from
balancing stops by grabbing the looped end and pulling
Probe
either end of the blade.
straight down from the face.
6. Return the remainder of the system to operating condition.
Table 1. A k factors in ft.² for TL Therma-Fuser
diffusers fully open.
Probe
Type
A k
Type
A k
Velometer
1250 to
TL-2411
.07
TL-2422
.14
TL-2421
2300 fpm
TL-3611
.11
TL-3622
.18
TL-3621
TL-4811
.14
TL-4822
.26
TL-4821
TL-6011
.22
TL-6022
.28
TL-6021
TL-2441
.31
TL-2442
.30
BALANCING (TL-D)
TL-3641
.42
TL-3642
.39
TL-4841
Velometer
.60
TL-4842
.55
1. The damper blade opening is factory set. Readjust where nec-
TL-6041
.70
TL-6042
.65
1250 to
essary by turning the adjusting screw. See Fig. 7.
2300 fpm
2. Place a direct reading diffuser balancing hood over the face of
each TL-D diffuser and adjust damper at duct takeoff to obtain
design air volume.
Continued on NEXT Page
Continued on NEXT Page
Fig 5. Balancing Stops
Page 3
Page 3
Figure 6. Location of Ve
Velometer
1250 to
2300 fpm
BALANCING (TL-D)
1. The damper blade opening
essary by turning the adjus
2. Place a direct reading diffu
each TL-D diffuser and adj
design air volume.
Type
A k
.12
.20
.28
.32
3
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