Price acutherm Therma-Fuser TL Series User manual

v001 –Issue Date: 10/26/22
© 2022 Acutherm. All rights reserved.
MANUAL – INSTALLATION, BALANCING + MAINTENANCE
Therma-Fuser™
TL Series

acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
THERMA-FUSER™ - Manual | acutherm.com
TABLE OF CONTENTS
Installation Instructions.................................................. 1
System Balancing......................................................... 3
Adjusting Temperature Setpoint (TL-C and TL-CW)....... 4
Maintenance, Controlling the System
& Minimum Flow ........................................................... 6
Trouble Shooting........................................................... 6
Ten Year Warranty......................................................... 8

1
acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
INSTALLATION INSTRUCTIONS
Damaged Freight Claim Procedure
When the diffusers are received, inspect for damage which may have occured during shipment. If damage is evident, it should be
noted on the carrier's freight bill. A written request for inspection by the carrier's agent should be made at once.
Storage
Cartons should always be stacked on end. Do not stack cartons flat on their sides. Excessive weight may cause damage to the
diffusers. Do not store for prolonged times at temperatures exceeding 130°F/56°C.
Identification
Units are factory shipped two per carton. The model designation is on the unit and on the carton. See Fig. 2
on page two.
Installation Precautions
When installing units, make sure construction debris does not enter units or duct system. Because models TL-C and TL-CW
control room temperature by sensing the room air induced up the center of the room, care should be taken not to disturb room
air induction and entrainment. For example, when located next to walls or dropped lights, air blown toward them results in the
reflection of primary air back at the Therma-Fuser diffuser and should be avoided.
Installation Instructions
1. Inspect the carton for damage before opening. Notify carrier if external damage exists. Submit all claims for shipping damage
to the carrier.
2. Move diffusers (in cartons) to installation area. Note unit identification.
3. Remove cardboard box and cardboard insert. Discard packaging material. Model TL-C and TL-CW have factory installed
balancing stops which hold the blade(s) open. See Fig. 5. Do not remove those stops until after balancing.
4. Install in ceiling grid. Install T-bar support wire close to each corner of unit. Make sure that only wire suspended T-bars are
used to support unit weight. The diffuser can be hung with hanging holes in the top of the diffuser. See Fig. 3. Do not block
the induction nozzle on the control panel end of the diffuser. Do not use screws or drill holes in the areas marked “No Holes or
Screws” on the control panel end of the diffuser.
FIG. 3 HOLES FOR HANGING
a. Do not install standard model TL-C and TL-CW linear Therma-Fuser units
end-to-end. A 2 in. / 51mm clear space is required beyond the induction
air outlet. For end-to-end installations, use continuous look (model TLC-XX)
linear Therma-Fuser units.
b. Where ceiling tiles lay directly on the longitudinal edges of the diffuser,
the longitudinal edges of the diffuser should be in the same place as the
T-bars. Loosen the screws holding the end angles, raise the end angles
and retighten the screws. The end angles will rest on the T-bars with the
longitudinal edges in the plane of the T-bar bottoms. See Fig. 4 on
page three.
5. Connect and secure the supply duct to the collar. Flexible duct should NOT be
formed in a centerline radius of less than 1½ times the duct diameter.)
6. Do NOT reset the temperature set point on the TL-C and TLCW models until the space is occupied. It is factory preset for
average conditions (74°F / 23°C).
7. Balance the system. See System Balancing.
8. After the air conditioning system is started and after the space is occupied, where necessary adjust the temperature set
point on ST-C and ST-HC models to suit the occupant. See Adjusting Temperature.
FORM 21.2 REV 1704
THERMA-FUSER
™
THERMALLY POWERED VAV DIFFUSER
IINNSSTTAALLLLAATTIIOONN,,BBAALLAANNCCIINNGG&&MMAAIINNTTEENNAANNCCEE
MODULAR VAV SYSTEMS
Models:  TL-C VAV cooling only
TL-CW VAV cooling and warm up (constant
  volume heating)
 TL-D Manually adjustable diffuser
 TL-RADReturn-ducted
 TL-RAP Return-ceiling plenum
  (See Fig. 1 on page two for dimensions)
TABLE OF CONTENTS
Installation Instructions . . . . . . . . . . . . . . . . . . 1
System Balancing . . . . . . . . . . . . . . . . . . . . . . . . 3
Adjusting Temperature Setpoint . . . . . . . . . . .  4
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
Controlling the System . . . . . . . . . . . . . . . . . . . 4
Minimum Flow . . . . . . . . . . . . . . . . . . . . . . . . . 5
Trouble Shooting . . . . . . . . . . . . . . . . . . . . . . . . 5
Ten Year Warranty. . . . . . . . . . . . . . . . . . . . . . .  5
DAMAGED FREIGHT CLAIM PROCEDURE
When the diffusers are received, inspect for damage which may
have occured during shipment. If damage is evident, it should be
noted on the carrier's freight bill. A written request for inspection
by the carrier's agent should be made at once.
STORAGE
Cartons should always be stacked on end. Do not stack cartons
flat on their sides. Excessive weight may cause damage to the
diffusers.
Do not store for prolonged times at temperatures exceeding
130°F/56°C.
IDENTIFICATION
Units are factory shipped two per carton. The model designation
is on the unit and on the carton. See Fig. 2 on page two.
INSTALLATION PRECAUTIONS
When installing units, make sure construction debris does not
enter units or duct system.
Because models TL-C and TL-CW control room temperature by
sensing the room air induced up the center of the room, care
should be taken not to disturb room air induction and entrain-
ment. For example, when located next to walls or dropped lights,
air blown toward them results in the reflection of primary air back
at the Therma-Fuser diffuser and should be avoided.
INSTALLATION INSTRUCTIONS
1. Inspect the carton for damage before opening. Notify carrier if
external damage exists. Submit all claims for shipping damage
to the carrier.
2. Move diffusers (in cartons) to installation area. Note unit iden-
tification.
3. Remove cardboard box and cardboard insert. Discard packag-
ing material. Model TL-C and TL-CW have factory installed
balancing stops which hold the blade(s) open. See Fig. 5. Do
not remove those stops until after balancing.
4. Install in ceiling grid. Install T-bar support wire close to each
corner of unit. Make sure that only wire suspended T-bars are
used to support unit weight. The diffuser can be hung with
hanging holes in the top of the diffuser. See Fig. 3. Do not
block the induction nozzle on the control panel end of the dif-
fuser. Do not use screws or drill holes in the areas marked “No
Holes or Screws” on the control panel end of the diffuser.
a. Do not install standard model TL-C and TL-CW linear
Therma-Fuser units end-to-end. A 2 in. / 51mm clear space
is required beyond the induction air outlet. For end-to-end
installations, use continuous look (model TLC-XX) linear
Therma-Fuser units.
b. Where ceiling tiles lay directly on the longitudinal edges of
the diffuser, the longitudinal edges of the diffuser should be
in the same place as the T-bars. Loosen the screws holding
the end angles, raise the end angles and retighten the
screws. The end angles will rest on the T-bars with the lon-
gitudinal edges in the plane of the T-bar bottoms. See Fig. 4
on page three.
5. Connect and secure the supply duct to the collar. Flexible duct
should NOT be formed in a centerline radius of less than 1½
times the duct diameter.
6. Do NOT reset the temperature set point on the TL-C and TL-
CW models until the space is occupied. It is factory preset for
average conditions (74°F / 23°C).
7. Balance the system. See System Balancing.
8. After the air conditioning system is started and after the space
is occupied, where necessary adjust the temperature setpoint
to suit the occupant. See Adjusting Temperature Setpoint.
Fig. 3. Holes for Hanging
Continued on NEXT Page
For hanging, use two
diagonal .110 in / 2.7mm
holes in the top of
the diffuser.

2acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
INSTALLATION INSTRUCTIONS
THERMA-FUSER™ - Manual | acutherm.com
Models TL-C, TL-CW, TL-D and TL-RAD
One and Two Slot
W2
Length
Designa-
tion
Actual
Length * Inlet A B W1 1 Slot 1 Way
2 Slot
1Way
2 Slot
2 Way
24 23 ¾ in.
603 mm
5 7 / 8in.
150 mm
15 1 / 16 in.
382 mm
8 11 / 16 in.
221 mm
4 in.
102 mm
2 9 / 16 in.
65 mm
3 ¾ in.
95 mm
4 in.
102 mm
36 35 ¾ in.
908 mm
5 7 / 8in.
150 mm
21 1 / 16 in.
535 mm
14 11 / 16 in.
373 mm
4 in.
102 mm
2 9 / 16 in.
65 mm
3 ¾ in.
95 mm
4 in.
102 mm
48 47 ¾ in.
1213 mm
7 7 / 8in.
200 mm
28 1 / 16 in.
713 mm
19 11 / 16 in.
500 mm
4 in.
102 mm
2 9 / 16 in.
65 mm
3 ¾ in.
95 mm
4 in.
102 mm
60 59 ¾ in.
1518 mm
7 7 / 8in.
200 mm
34 1 / 16 in.
865 mm
25 11 / 16 in.
653 mm
4 in.
102 mm
2 9 / 16 in.
65 mm
3 ¾ in.
95 mm
4 in.
102 mm
Four Slot
W2
Length
Designa-
tion
Actual
Length * Inlet A B W1 2 Slot 1Way
2 Slot
2 Way
24 23 ¾ in.
603 mm
7 7 / 8in.
200 mm
15 1 / 16 in.
382 mm
8 11 / 16 in.
221 mm
6 5 / 16 in.
160 mm
6 in.
153 mm
6 3 / 8in.
162 mm
36 35 ¾ in.
908 mm
7 7 / 8in.
200 mm
21 1 / 16 in.
535 mm
14 11 / 16 in.
373 mm
6 5 / 16 in.
160 mm
6 in.
153 mm
6 3 / 8in.
162 mm
48 47 ¾ in.
1213 mm
9 7 / 8in.
250 mm
28 1 / 16 in.
713 mm
19 11 / 16 in.
500 mm
6 5 / 16 in.
160 mm
6 in.
153 mm
6 3 / 8in.
162 mm
60 59 ¾ in.
1518 mm
11 7 / 8in.
300 mm
34 1 / 16 in.
865 mm
25 11 / 16 in.
653 mm
6 5 / 16 in.
160 mm
6 in.
153 mm
6 3 / 8in.
162 mm
* 595, 895, 1195 and 1495 mm lengths are available to fit metric ceilings.
† Oval shaped inlet
FIG. 1 DIMENSIONS
FIG. 2 MODEL DESIGNATION
FRONT INLET
ONE WAY BLOW DIFFUSERS BLOW TOWARD THE
SAME SIDE AS THE FRONT INLET
OPPOSITE INLET
ONE WAY BLOW DIFFUSERS BLOW AWAY FROM
THE SIDE WITH THE OPPOSITE INLET
MODEL TL-RAP
Fig. 2. Model Designation
Therma-Fuser—Linear
 TL = Lay in
 TLC = Continuous*
 TLW = Side wall*
Type-C = VAV cooling only
CW = VAV cooling plus
warm-up (fully opens
for constant volume
heating with supply air
temperature above
80°F/26.5°C)
D = Manually adjustable
diffuser
RAD = Ducted return air
RAP = Ceiling plenum
return air
Nominal Length—24, 36, 48 or
60 inches. 72 inches available
for type RAP only. 595, 895,
1195 and 1495 mm lengths are
available to fit metric ceilings.
Number of slots—1, 2 or 4
Blow direction—1 way or 2 way
Factory installed options
 I = Internal insulation
 O =Opposite inlet
 R =Rectangular inlet
 A1= Heater for remote 
   adjust 1 and 2 slots
 A2= Heater for remote 
   adjust 4 slot only.
*See separate dimensions and separate
instructions for models TLC-XX and
TLW-XX.
Page 2
Fig 1. Dimensions
MODEL TL-RAP
W2
W1
1
/ 2 "
13 mm TYP.
1¾"
45 mm
3¾"
95 mm
ACTUAL LENGTH 3/8"
10 mm TYP.
1
15
/ 16"
50 mm
TYP.
MODELS TL-C, TL-CW, TL-D and TL-RAD
OPPOSITE INLET—One way blow diffusers blow away from
the side with the opposite inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH 3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
Note: Dimensions  inches ± 1/16
 millimeters ± 1.6 mm
FRONT INLET—One way blow diffusers blow toward the
same side as the front inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH
3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
TL-CW-4822-I
ONE AND TWO SLOT
W2
 Length Actual Inlet A B W1 1 Slot 2 Slot 2 Slot
 Designation Length*    1 Way 1 Way 2 Way
24 233/4in. 57/8in. 151/16 in. 811/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  603 mm 150 mm 382 mm 221 mm 102 mm 65 mm 95 mm 102 mm
36 353/4in. 57/8in. 211/16 in. 1411/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  908 mm 150 mm 535 mm 373 mm 102 mm 65 mm 95 mm 102 mm
48 473/4in. 77/8in. 281/16 in. 1911/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1213 mm 200 mm 713 mm 500 mm 102 mm 65 mm 95 mm 102 mm
60 593/4in. 77/8in. 341/16 in. 2511/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1518 mm 200 mm 865 mm 653 mm 102 mm 65 mm 95 mm 102 mm
FOUR SLOT
W2
 Length Actual Inlet A B W1 4 Slot 4 Slot
 Designation Length*    1 Way 2 Way
24 233/4in. 77/8in. 151/16 in. 811/16 in. 65/16 in. 6 in. 63/8in.
  603 mm 200 mm 382 mm 221 mm 160 mm 153 mm 162 mm
36 353/4in. 77/8in. 211/16 in. 1411/16 in. 65/16 in. 6 in. 63/8in.
  908 mm 200 mm 535 mm 373 mm 160 mm 153 mm 162 mm
48 473/4in. 97/8in. 281/16 in. 1911/16 in. 65/16 in. 6 in. 63/8in.
  1213 mm 250 mm 713 mm 500 mm 160 mm 153 mm 162 mm
60 593/4in. 117/8in.† 341/16 in. 2511/16 in. 65/16 in. 6 in. 63/8in.
  1518 mm 300 mm† 865 mm 653 mm 160 mm 153 mm 162 mm
*595, 895, 1195 and 1495 mm lengths are available to fit metric ceilings.
† Oval shaped inlet
Fig. 2. Model Designation
Therma-Fuser—Linear
 TL = Lay in
 TLC = Continuous*
 TLW = Side wall*
Type-C = VAV cooling only
CW = VAV cooling plus
warm-up (fully opens
for constant volume
heating with supply air
temperature above
80°F/26.5°C)
D = Manually adjustable
diffuser
RAD = Ducted return air
RAP = Ceiling plenum
return air
Nominal Length—24, 36, 48 or
60 inches. 72 inches available
for type RAP only. 595, 895,
1195 and 1495 mm lengths are
available to fit metric ceilings.
Number of slots—1, 2 or 4
Blow direction—1 way or 2 way
Factory installed options
 I = Internal insulation
 O =Opposite inlet
 R =Rectangular inlet
 A1= Heater for remote 
   adjust 1 and 2 slots
 A2= Heater for remote 
   adjust 4 slot only.
*See separate dimensions and separate
instructions for models TLC-XX and
TLW-XX.
Page 2
Fig 1. Dimensions
MODEL TL-RAP
W2
W1
1
/ 2 "
13 mm TYP.
1¾"
45 mm
3¾"
95 mm
ACTUAL LENGTH 3/8"
10 mm TYP.
1
15
/ 16"
50 mm
TYP.
MODELS TL-C, TL-CW, TL-D and TL-RAD
OPPOSITE INLET—One way blow diffusers blow away from
the side with the opposite inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH 3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
Note: Dimensions  inches ± 1/16
 millimeters ± 1.6 mm
FRONT INLET—One way blow diffusers blow toward the
same side as the front inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH
3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
TL-CW-4822-I
ONE AND TWO SLOT
W2
 Length Actual Inlet A B W1 1 Slot 2 Slot 2 Slot
 Designation Length*    1 Way 1 Way 2 Way
24 233/4in. 57/8in. 151/16 in. 811/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  603 mm 150 mm 382 mm 221 mm 102 mm 65 mm 95 mm 102 mm
36 353/4in. 57/8in. 211/16 in. 1411/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  908 mm 150 mm 535 mm 373 mm 102 mm 65 mm 95 mm 102 mm
48 473/4in. 77/8in. 281/16 in. 1911/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1213 mm 200 mm 713 mm 500 mm 102 mm 65 mm 95 mm 102 mm
60 593/4in. 77/8in. 341/16 in. 2511/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1518 mm 200 mm 865 mm 653 mm 102 mm 65 mm 95 mm 102 mm
FOUR SLOT
W2
 Length Actual Inlet A B W1 4 Slot 4 Slot
 Designation Length*    1 Way 2 Way
24 233/4in. 77/8in. 151/16 in. 811/16 in. 65/16 in. 6 in. 63/8in.
  603 mm 200 mm 382 mm 221 mm 160 mm 153 mm 162 mm
36 353/4in. 77/8in. 211/16 in. 1411/16 in. 65/16 in. 6 in. 63/8in.
  908 mm 200 mm 535 mm 373 mm 160 mm 153 mm 162 mm
48 473/4in. 97/8in. 281/16 in. 1911/16 in. 65/16 in. 6 in. 63/8in.
  1213 mm 250 mm 713 mm 500 mm 160 mm 153 mm 162 mm
60 593/4in. 117/8in.† 341/16 in. 2511/16 in. 65/16 in. 6 in. 63/8in.
  1518 mm 300 mm† 865 mm 653 mm 160 mm 153 mm 162 mm
*595, 895, 1195 and 1495 mm lengths are available to fit metric ceilings.
† Oval shaped inlet
Fig. 2. Model Designation
Therma-Fuser—Linear
 TL = Lay in
 TLC = Continuous*
 TLW = Side wall*
Type-C = VAV cooling only
CW = VAV cooling plus
warm-up (fully opens
for constant volume
heating with supply air
temperature above
80°F/26.5°C)
D = Manually adjustable
diffuser
RAD = Ducted return air
RAP = Ceiling plenum
return air
Nominal Length—24, 36, 48 or
60 inches. 72 inches available
for type RAP only. 595, 895,
1195 and 1495 mm lengths are
available to fit metric ceilings.
Number of slots—1, 2 or 4
Blow direction—1 way or 2 way
Factory installed options
 I = Internal insulation
 O =Opposite inlet
 R =Rectangular inlet
 A1= Heater for remote 
   adjust 1 and 2 slots
 A2= Heater for remote 
   adjust 4 slot only.
*See separate dimensions and separate
instructions for models TLC-XX and
TLW-XX.
Page 2
Fig 1. Dimensions
MODEL TL-RAP
W2
W1
1
/ 2 "
13 mm TYP.
1¾"
45 mm
3¾"
95 mm
ACTUAL LENGTH 3/8"
10 mm TYP.
1
15
/ 16"
50 mm
TYP.
MODELS TL-C, TL-CW, TL-D and TL-RAD
OPPOSITE INLET—One way blow diffusers blow away from
the side with the opposite inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH 3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
Note: Dimensions  inches ± 1/16
 millimeters ± 1.6 mm
FRONT INLET—One way blow diffusers blow toward the
same side as the front inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH
3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
TL-CW-4822-I
ONE AND TWO SLOT
W2
 Length Actual Inlet A B W1 1 Slot 2 Slot 2 Slot
 Designation Length*    1 Way 1 Way 2 Way
24 233/4in. 57/8in. 151/16 in. 811/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  603 mm 150 mm 382 mm 221 mm 102 mm 65 mm 95 mm 102 mm
36 353/4in. 57/8in. 211/16 in. 1411/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  908 mm 150 mm 535 mm 373 mm 102 mm 65 mm 95 mm 102 mm
48 473/4in. 77/8in. 281/16 in. 1911/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1213 mm 200 mm 713 mm 500 mm 102 mm 65 mm 95 mm 102 mm
60 593/4in. 77/8in. 341/16 in. 2511/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1518 mm 200 mm 865 mm 653 mm 102 mm 65 mm 95 mm 102 mm
FOUR SLOT
W2
 Length Actual Inlet A B W1 4 Slot 4 Slot
 Designation Length*    1 Way 2 Way
24 233/4in. 77/8in. 151/16 in. 811/16 in. 65/16 in. 6 in. 63/8in.
  603 mm 200 mm 382 mm 221 mm 160 mm 153 mm 162 mm
36 353/4in. 77/8in. 211/16 in. 1411/16 in. 65/16 in. 6 in. 63/8in.
  908 mm 200 mm 535 mm 373 mm 160 mm 153 mm 162 mm
48 473/4in. 97/8in. 281/16 in. 1911/16 in. 65/16 in. 6 in. 63/8in.
  1213 mm 250 mm 713 mm 500 mm 160 mm 153 mm 162 mm
60 593/4in. 117/8in.† 341/16 in. 2511/16 in. 65/16 in. 6 in. 63/8in.
  1518 mm 300 mm† 865 mm 653 mm 160 mm 153 mm 162 mm
*595, 895, 1195 and 1495 mm lengths are available to fit metric ceilings.
† Oval shaped inlet
Fig. 2. Model Designation
Therma-Fuser—Linear
 TL = Lay in
 TLC = Continuous*
 TLW = Side wall*
Type-C = VAV cooling only
CW = VAV cooling plus
warm-up (fully opens
for constant volume
heating with supply air
temperature above
80°F/26.5°C)
D = Manually adjustable
diffuser
RAD = Ducted return air
RAP = Ceiling plenum
return air
Nominal Length—24, 36, 48 or
60 inches. 72 inches available
for type RAP only. 595, 895,
1195 and 1495 mm lengths are
available to fit metric ceilings.
Number of slots—1, 2 or 4
Blow direction—1 way or 2 way
Factory installed options

I =Internal insulation

O =Opposite inlet

R =Rectangular inlet

A1= Heater for remote 

  adjust 1 and 2 slots

A2= Heater for remote 

  adjust 4 slot only.
*
See separate dimensions and separate
instructions for models TLC-XX and
TLW-XX.
Page 2
Fig 1. Dimensions
MODEL TL-RAP
W2
W1
1
/ 2 "
13 mm TYP.
1¾"
45 mm
3¾"
95 mm
ACTUAL LENGTH 3/8"
10 mm TYP.
1
15
/ 16"
50 mm
TYP.
MODELS TL-C, TL-CW, TL-D and TL-RAD
OPPOSITE INLET—One way blow diffusers blow away from
the side with the opposite inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH 3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
Note: Dimensions  inches ±
1
/ 16
 millimeters ± 1.6 mm
FRONT INLET—One way blow diffusers blow toward the
same side as the front inlet.
1
15
/ 16"
50 mm
TYP.
W2
W1
2"
51mm
13½"
343 mm
½"
13 mm
TYP.
INLET
¼"
6 mm ½"
13mm
13"
330 mm
BA
ACTUAL LENGTH
3/8"
10 mm
TYP.
Keep 2"/50mm clearance
for induction discharge
T
L-CW-4822-I
ONE AND TWO SLOT
W2
 Length Actual Inlet A B W1 1 Slot 2 Slot 2 Slot
 Designation Length*    1 Way 1 Way 2 Way
24 233/4in. 57/8in. 151/16 in. 811/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  603 mm 150 mm 382 mm 221 mm 102 mm 65 mm 95 mm 102 mm
36 353/4in. 57/8in. 211/16 in. 1411/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  908 mm 150 mm 535 mm 373 mm 102 mm 65 mm 95 mm 102 mm
48 473/4in. 77/8in. 281/16 in. 1911/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1213 mm 200 mm 713 mm 500 mm 102 mm 65 mm 95 mm 102 mm
60 593/4in. 77/8in. 341/16 in. 2511/16 in. 4 in. 29/16 in. 33/4in. 4 in.
  1518 mm 200 mm 865 mm 653 mm 102 mm 65 mm 95 mm 102 mm
FOUR SLOT
W2
 Length Actual Inlet A B W1 4 Slot 4 Slot
 Designation Length*    1 Way 2 Way
24 233/4in. 77/8in. 151/16 in. 811/16 in. 65/16 in. 6 in. 63/8in.
  603 mm 200 mm 382 mm 221 mm 160 mm 153 mm 162 mm
36 353/4in. 77/8in. 211/16 in. 1411/16 in. 65/16 in. 6 in. 63/8in.
  908 mm 200 mm 535 mm 373 mm 160 mm 153 mm 162 mm
48 473/4in. 97/8in. 281/16 in. 1911/16 in. 65/16 in. 6 in. 63/8in.
  1213 mm 250 mm 713 mm 500 mm 160 mm 153 mm 162 mm
60 593/4in. 117/8in.† 341/16 in. 2511/16 in. 65/16 in. 6 in. 63/8in.
  1518 mm 300 mm† 865 mm 653 mm 160 mm 153 mm 162 mm
*595, 895, 1195 and 1495 mm lengths are available to fit metric ceilings.
† Oval shaped inlet

3
acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
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 Akfactors for the different linear
lengths are shown in Table 1. Multiply the velocity in fpm
times Akin ft2to get air flow in cfm.
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. Akfactors in ft.² for TL Therma-Fuser diffusers
fully open.
Type AkType AkType Ak
TL-2411
TL-3611
TL-4811
TL-6011
0.07
0.11
0.14
0.22
TL-2422
TL-3622
TL-4822
TL-6022
0.14
0.18
0.26
0.28
TL-2421
TL-3621
TL-4821
TL-6021
0.12
0.20
0.28
0.32
TL-2411
TL-3641
TL-4841
TL-6041
0.31
0.42
0.60
0.70
TL-2422
TL-3642
TL-4842
TL-6042
0.30
0.39
0.55
0.65
BALANCING (TL-D)
1. The damper blade opening is factory set. Readjust where
necessary by turning the adjusting screw. See Fig. 7.
2. Place a direct reading diffuser balancing hood over the
face of each TL-D diffuser
SYSTEM BALANCING
FIG. 4 END ANGLE RAISED SO THAT LONGITUDINAL EDGES ARE IN THE
PLANE OF THE T-BARS
Page 3
Continued on NEXT Page
 Type Ak Type Ak Type Ak
TL-2411 .07 TL-2422 .14 TL-2421 .12
 TL-3611 .11 TL-3622 .18 TL-3621 .20
TL-4811 .14 TL-4822 .26 TL-4821 .28
 TL-6011 .22 TL-6022 .28 TL-6021 .32
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 5. Balancing Stops
Fig 4. End angle raised so that longitudinal edges
are in the plane of the T-bars.
Table 1. Akfactors in ft.² for TL Therma-Fuser
diffusers fully open.
Screws
T-bar
End Angle Longitudinal edge in the same plane
as the bottom of the T-bar.
Diffuser
BALANCING (TL-D)
1. The damper blade opening is factory set. Readjust where nec-
essary by turning the adjusting screw. See Fig. 7.
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.
Balancing Stop
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-
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
be wedged between the foam side of the blade and the curved
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
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
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 Akfactors for the dif-
ferent linear lengths are shown in Table 1. Multiply the velocity
in fpm times Akin ft2to get air flow in cfm.
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.
Figure 6. Location of Velometer
Probe
Velometer
1250 to
2300 fpm
Measure in the outside slots
on the same side as the duct
connection 2 In. / 51mm from
either end of the blade.
FIG. 5 BALANCING STOPS
Page 3
Continued on NEXT Page
 Type Ak Type Ak Type Ak
TL-2411 .07 TL-2422 .14 TL-2421 .12
 TL-3611 .11 TL-3622 .18 TL-3621 .20
TL-4811 .14 TL-4822 .26 TL-4821 .28
 TL-6011 .22 TL-6022 .28 TL-6021 .32
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 5. Balancing Stops
Fig 4. End angle raised so that longitudinal edges
are in the plane of the T-bars.
Table 1. Akfactors in ft.² for TL Therma-Fuser
diffusers fully open.
Screws
T-bar
End Angle Longitudinal edge in the same plane
as the bottom of the T-bar.
Diffuser
BALANCING (TL-D)
1. The damper blade opening is factory set. Readjust where nec-
essary by turning the adjusting screw. See Fig. 7.
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.
Balancing Stop
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-
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
be wedged between the foam side of the blade and the curved
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
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
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 Akfactors for the dif-
ferent linear lengths are shown in Table 1. Multiply the velocity
in fpm times Akin ft2to get air flow in cfm.
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.
Figure 6. Location of Velometer
Probe
Velometer
1250 to
2300 fpm
Measure in the outside slots
on the same side as the duct
connection 2 In. / 51mm from
either end of the blade.
FIG. 6 LOCATION OF VELOMETER
Page 3
Continued on NEXT Page
 Type Ak Type Ak Type Ak
TL-2411 .07 TL-2422 .14 TL-2421 .12
 TL-3611 .11 TL-3622 .18 TL-3621 .20
TL-4811 .14 TL-4822 .26 TL-4821 .28
 TL-6011 .22 TL-6022 .28 TL-6021 .32
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 5. Balancing Stops
Fig 4. End angle raised so that longitudinal edges
are in the plane of the T-bars.
Table 1. Akfactors in ft.² for TL Therma-Fuser
diffusers fully open.
Screws
T-bar
End Angle Longitudinal edge in the same plane
as the bottom of the T-bar.
Diffuser
BALANCING (TL-D)
1. The damper blade opening is factory set. Readjust where nec-
essary by turning the adjusting screw. See Fig. 7.
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.
Balancing Stop
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-
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
be wedged between the foam side of the blade and the curved
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
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
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 Akfactors for the dif-
ferent linear lengths are shown in Table 1. Multiply the velocity
in fpm times Akin ft2to get air flow in cfm.
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.
Figure 6. Location of Velometer
Probe
Velometer
1250 to
2300 fpm
Measure in the outside slots
on the same side as the duct
connection 2 In. / 51mm from
either end of the blade.

4acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
THERMA-FUSER™ - Manual | acutherm.com
Adjusting Minimum Flow
The room temperature set point is adjusted by turning
the phillips screw with a phillips screwdriver to move the
thermostat slide up or down. Four slot units have two
thermostats, each controlling two slots, which are separately
adjusted. The temperature scale, located behind the
thermostat slide, can be viewed at the end of the diffuser
slot. Each graduation on the temperature scale is 1°F/.53°C
providing an easy way of determining the amount of
adjustment. Turning the phillips screw clockwise will move
the slide down over the temperature scale for a cooler set
point. Turning the phillips screw counterclockwise moves the
thermostat slide up to a warmer setpoint. About 1½ turns will
change the setpoint by 1°F/.53°C.
The diffuser is factory set to maintain approximately
74°F/23°C. It is not necessary to adjust the temperature set
point at time of installation. Instead, make any adjustments
after the system has been started and the space is occupied.
Then adjust only those Therma-Fuser difusers where
occupants are uncomfortable at the factory set point.
Readjust to the factory set point by turning the phillips screw
clockwise (cooler set point) until the thermostat slide hits the
stop. Then turn counter clockwise (warmer) for nine turns.
ADJUSTING TEMPERATURE SETPOINT (TL-C AND TL-CW)
FIG. 4 MEASURING VELOCITY
Recommended Adjustments For Various Conditions
Mode Room Temp. Blade Position Recommended Action
Cooling
TL-C
TL-CW
Too
Cold
Open Adjust for higher room temperature set point.
Closed Therma-Fuser diffuser is correct. Check if cooling is still required, and if not, turn cooling unit off.
Too
Warm
Open Therma-Fuser diffuser is correct. Check for lack of air or for too warm air temperature.
Closed Adjust for lower room temperature set point.
Too
Noisy Any Any Reduce static pressure. Recommended static pressure is .05 to .25 in. wg / 12 to 62 Pa at the inlet of the diffuser.
Recommended
Action
Adjust for higher room temperature set point.
Therma-Fuser diffuser is correct. Check if cooling is
still required, and if not, turn cooling unit off.
Therma-Fuser diffuser is correct. Check for lack of
air or for too warm air temperature.
Adjust for lower room temperature set point.
Reduce static pressure. Recommended static pres-
sure is .05 to .25 in. wg / 12 to 62 Pa at the inlet of
the diffuser.
Blade
Position
Open
Closed
Open
Closed
Any
Room
Temp.
Too
Cold

Too
Warm

Any
Mode
Cooling


TL-C
TL-CW
Too
Noisy
MAINTENANCE
The moving parts of the TL Therma-Fuser diffuser have no main-
tenance or lubrication requirements. We are often asked to rec-
ommend periodic maintenance procedures and a spare parts
stock. Recommended maintenance is to clean the outer surfaces
of the Therma-Fuser diffuser—nothing else. We do not recom-
mend stocking any spare parts. Our customers also confirm that
stocking is unnecessary.
CONTROLLING THE SYSTEM
(TL-C and TL-CW)
References:
• System Design, p 5, TL brochure, Form 21.1.
• Chapters 2.2, 3.1 and 3.2, pp 6, 7 and 8, Designing Modular
VAV Systems, Form 5.2.
• Air Handling and Fan Coil Units Subzoned with Therma-Fuser
VAV modules, Form 6.7.
• DX Equipment Zoned with Therma-Fuser VAV Modules, Form
6.5.
SUPPLY AIR TEMPERATURE
The source of cooling is controlled from supply air temperature.
As with all VAV systems, the goals are to achieve a constant
supply air temperature (may be reset to another constant supply
air temperature) and to limit the supply air temperature. Limits
for supply air temperature should be between 50°F/10°C and
68°F/20°C. These objectives are best achieved by modulating
chilled water valves, and other variable equipment from supply
air temperature. On/off equipment such as DX compressors are
cycled from supply air temperature. Use a discharge air sensor
for the supply air temperature signal.
For TL-CW models, mode change between heating, recirculation
and cooling is controlled from room temperature. Signals from
one or more room temperature sensors may be used for mode
change. When using more than one sensor, a “majority rules”
approach is recommended. Constant volume heating
temperature for TL-CW models should be as low as possible but
no lower than 80°F / 26.5° C.
STATIC PRESSURE
As with all VAV systems, the fan must run continuously during
occupied times. Goals of static pressure control are to provide
enough static pressure to obtain the required air volume
especially at the diffuser farthest from the fan, to avoid diffuser
noise by limiting static pressure at both full flow and turndown
and to provide pressure independence or consistent operation as
the system flow changes.
These objectives can be achieved with the usual methods of
automatic static pressure control: bypass dampers, discharge
dampers, zone dampers, and fan control (variable speed drives,
inlet dampers, etc.). Locate the static pressure sensor as far
down the duct as possible—at least 2/3 down the duct from the
first takeoff.
ADJUSTING TEMPERATURE
SETPOINT (TL-C and TL-CW)
The room temperature set point is adjusted by turning the phil-
lips screw with a phillips screwdriver to move the thermostat
slide up or down. Four slot units have two thermostats, each con-
trolling two slots, which are separately adjusted. The temperature
scale, located behind the thermostat slide, can be viewed at the
end of the diffuser slot. Each graduation on the temperature
scale is 1°F/.53°C providing an easy way of determining the
amount of adjustment. Turning the phillips screw clockwise will
move the slide down over the temperature scale for a cooler set
point. Turning the phillips screw counterclockwise moves the
thermostat slide up to a warmer setpoint. About 1½ turns will
change the setpoint by 1°F/.53°C.
The diffuser is factory set to maintain approximately 74°F/23°C.
It is not necessary to adjust the temperature set point at time of
installation. Instead, make any adjustments after the system has
been started and the space is occupied. Then adjust only those
Therma-Fuser difusers where occupants are uncomfortable at
the factory set point.
Readjust to the factory set point by turning the phillips screw
clockwise (cooler set point) until the thermostat slide hits the
stop. Then turn counter clockwise (warmer) for nine turns.
Page 4
Figure 7. Adjusting Temperature
C
O
O
L
E
R
W
A
R
M
E
R
Warmer
Cooler
W
C
78°F/25°C
74°F/23°C
70°F/21°C
Warmer
Cooler
Thermostat
Slide
Temperature
Scale
Read the temperature set point at the
bottom of the thermostat slide.
RECOMMENDED ADJUSTMENTS FOR
VARIOUS CONDITIONS

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acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
Maintenance
The moving parts of the TL Therma-Fuser diffuser have no maintenance or lubrication requirements. We are often asked to
recommend periodic maintenance procedures and a spare parts stock. Recommended maintenance is to clean the outer surfaces
of the Therma-Fuser diffuser—nothing else. We do not recommend stocking any spare parts. Our customers also confirm that
stocking is unnecessary.
Controlling the System (TL-C and TL-CW)
References:
• System Design, p 5, TL brochure, Form 21.1.
• Chapters 2.2, 3.1 and 3.2, pp 6, 7 and 8, Designing
Modular VAV Systems, Form 5.2.
• Air Handling and Fan Coil Units Subzoned with Therma-
Fuser VAV modules, Form 6.7.
• DX Equipment Zoned with Therma-Fuser VAV Modules,
Form 6.5.
Supply Air Temperature
The source of cooling is controlled from supply air temperature. As with all VAV systems, the goals are to achieve a constant
supply air temperature (may be reset to another constant supply air temperature) and to limit the supply air temperature. Limits for
supply air temperature should be between 50°F/10°C and 68°F/20°C. These objectives are best achieved by modulating chilled
water valves, and other variable equipment from supply air temperature. On/off equipment such as DX compressors are cycled
from supply air temperature. Use a discharge air sensor for the supply air temperature signal.
For TL-CW models, mode change between heating, recirculation and cooling is controlled from room temperature. Signals from
one or more room temperature sensors may be used for mode change. When using more than one sensor, a “majority rules”
approach is recommended. Constant volume heating temperature for TL-CW models should be as low as possible but no lower
than 80°F / 26.5° C.
Static Air Pressure
As with all VAV systems, the fan must run continuously during occupied times. Goals of static pressure control are to provide
enough static pressure to obtain the required air volume especially at the diffuser farthest from the fan, to avoid diffuser noise by
limiting static pressure at both full flow and turndown and to provide pressure independence or consistent operation as the system
flow changes.
These objectives can be achieved with the usual methods of automatic static pressure control: bypass dampers, discharge
dampers, zone dampers, and fan control (variable speed drives, inlet dampers, etc.). Locate the static pressure sensor as far down
the duct as possible—at least 2/3 down the duct from the first takeoff.
MINIMUM FLOW (TL-C and TL-CW)
Standard TL units have a 10% leakage. To obtain higher minimum flows, a shorter length of blade gasket (foam) for each blade
can be factory installed or it can be field removed per the table below. The blade gasket must be removed at the end opposite
from the induction slot.
Amount of Gasket to be Removed from each Blade
Length Designation
Minimum Flow as a % of Maximum Flow
20% 30%
24 5 in. / 128 mm 10 in. / 254 mm
36 8 in. / 204 mm 11 in. / 280 mm
48 11 in. / 280 mm 16 in. / 407 mm
60 14 in. / 356 mm 28 in. / 712 mm
MAINTENANCE, CONTROLLING THE SYSTEM & MINIMUM FLOW

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THERMA-FUSER™ - Manual | acutherm.com
TROUBLE SHOOTING
Trouble shooting Therma-Fuser diffusers requires looking at the system as a whole. Before examining the Therma-Fuser diffuser for
failure it is worth the time to be sure the system is functioning properly and that something has not been overlooked. Before calling
Acutherm, please complete the data log for all Therma- Fuser diffusers to be evaluated.
System Check
The system should be:
1. Delivering 50°- 68°F/10° - 20°C supply air when in the
cooling mode.
2. Delivering 80°-120°F/26.5° – 49°C supply air when in the
heating mode. (TL-CW only)
3. Maintaining static pressure at the inlet to each Therma-
Fuser diffuser between .05 and .25"wg/12 and 62 Pa.
4. Maintaining continuous fan operation during occupied
hours.
Therma-Fuser Diffuser Check List
Once the above checks have been completed, examine and record the following (conditions may vary over time;
severalmeasurements at different times may be required):
1. Room temperature 4 ft / 1.2 m above the floor directly
under the Therma-Fuser diffuser.
2. Supply air temperature at the inlet of the Therma-Fuser
diffuser.
3. Static pressure at the inlet of the Therma-Fuser diffuser.
4. Cooling setpoint(s). See Fig. 7. Read the cooling
setpoint(s) by counting the lines from the bottom of the
scale to the bottom of the slider.
5. Blade opening(s). Look into the diffuser slot and observe
the blade position. Is it fully closed, fully open or part way
between? Is the gasket installed on the full length of each
blade?
6. If possible, measure air flow with a flow hood or measure
air velocity as shown in Fig 6.
7. Are the ends of the diffusers at least 2 in. / 50 mm apart?
8. Is construction or other debris clogging the perforated
plate in the inlet?

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acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
TROUBLE SHOOTING
Trouble Shooting Data Log
Location
Type Diffuser
Date Time Room
Temp
S.A.
Temp
Duct
S.P.
Set
Point(s)
Blade
Opening
Air
Flow
Length No. Slots

acutherm.com | MECHANICAL THERMAL VAV DIFFUSERS - Manual
8acutherm.com | THERMA-FUSER™ - Manual
THERMA-FUSER™
THERMA-FUSER™ - Manual | acutherm.com
cutherm warrants that its Therma-Fuser diffusers, exclusive of any options and accessories (whether factory or field installed)
shall be free from defects in material or workmanship for a period of ten (10) years from the date of shipment and agrees to
repair or replace, at its option, any parts that fail during said ten (10) year period due to any such defects which would not have
occurred had reasonable care been taken, provided that such parts have been inspected by Acutherm and found defective and
provided the diffusers have been given normal and proper usage and all parts and controls remain unaltered. Acutherm makes
NO WARRANTY OF MERCHANTABILITY OF PRODUCTS OR OF THEIR FITNESS FOR ANY PURPOSE OR ANY OTHER
EXPRESS OR IMPLIED WARRANTY WHICH EXTENDS BEYOND THE LIMITED WARRANTY ABOVE. ACUTHERM’S
LIABILITY FOR ANY AND ALL LOSSES AND DAMAGES RESULTING FROM DEFECTS SHALL IN NO EVENT EXCEED
THE COST OF REPAIR OR REPLACEMENT OF PARTS FOUND DEFECTIVE UPON EXAMINATION BY ACUTHERM.
IN NO EVENT SHALL ACUTHERM BE LIABLE FOR INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
DAMAGES FOR INJURY TO PERSONS OR PROPERTY. Acutherm shall not be responsible for freight to or from its plant in
connection with the inspection, repair or replacement of parts under the terms of this limited warranty nor for cost or installation.
TEN YEAR WARRANTY

9
MECHANICAL THERMAL VAV DIFFUSERS
NOTES
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