g
comfort. The built in thermostat
senses average room air
temperature from a sample of air
induced into the unit. It controls
air flow to precisely match the
comfort requirements of the
room or portion of the room
served. Occupants breathe easier
knowing that their personal
temperature choice is concealed
and will not be changed by
someone else.
ONLY THERMA-FUSER
VAV OFFERS THESE
BENEFITS
I
Superior air distribution
longer throws, no dumping,
more entrainment, even
temperature distribution, higher
ADPI* and better ventilation
effectiveness.
I
Lowest cost per zone of
control.
I
Lowest energy VAV terminal
green VAV.
I
Low to no maintenance10
year warranty.
I
Easily adapts to office
changes.
*
ADPI (Air Diffusion Performance Index)
is defined in the ASHRAE Fundamentals
Handbook.
FORM 21.1 REV 0502 THE LINEAR

THERMA-FUSER THERMALLY POWERED VAV DIFFUSER
TL-C
VAV cooling only
TL-CW
VAV cooling with constant volume
warm-up
TL-D
Manually adjustable blades
TL-RAD Return air, ducted
TL-RAP Return air, plenum COOLER
WARMER
Page 2
the damper blades for constant volume
heating.
ADJUSTING
TEMPERATURE
SETPOINT
(TL-C and TL-CW)
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, graduated in degrees, located behind
the
thermostat slide can be viewed at the end of
the diffuser slot. Turning the phillips screw
clockwise will move the slide down over the
temperature scale for a cooler set point. Each
graduation on the temperature scale is
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 diffusers where occupants are
uncomfortable at the factory set point.
Readjust to the factory set point by turning
and expands. This pushes the damper blades
open. When the room cools, the wax
contracts and the spring pulls the damper
blades closed.
ROOM AIR SENSING
As with all diffusers, air circulates around the
room in a circular motion. Secondary air rises
under the diffuser, passes beneath the diffuser
and entrains with the primary air at the
outside edge of the diffuser. This secondary
air best represents average room
temperature.
To monitor average room temperature, a
continuous sample of secondary air is drawn
up into the induction chamber and over the
thermostat by the action of a venturi fed by
supply air. This venturi is located at the top of
the induction chamber.
CHANGEOVER
(TL-CW only)
Changeover between the cooling and heating
modes is determined by supply air
temperature. A second thermostat/actuator
(two in
the four slot models) located near the inlet,
senses supply air temperature. Supply air
temperature above 80�F/26.5�C fully opens
HOW IT WORKS
Model TL-C and TL-CW Therma-Fuser
diffusers are linear ceiling diffusers with built
in temperature controls and VAV damper. The
damper blades open and close, metering air
flow into the room in response to room
temperature. The damper is mechanically
positioned by a thermal element, which is
both room thermostat and actuator.
The room thermostat/actuator is a large brass
cylinder containing a petroleum based wax.
The wax melts and expands when heated,
pushing against a fixed piston which moves
the thermostat outward. A heavy spring pulls
the thermostat inward when the wax cools
and contracts. Four slot models have two
thermostat/actuators.
COOLING MODE
In the cooling mode, the damper blades open
on a rise in room temperature. As the room
warms, the wax in the room thermostat melts
2 Slot 2 Way
VAV Diffuser
1 Slot 1 Way
VAV Diffuser
2 Slot 1 Way
VAV Diffuser
4 Slot 1 Way
VAV Diffuser
4 Slot 2 Way
VAV Diffuser
Warmer
Cooler
W
C
78�F/25�C
74�F/23�C
70�F/21�C
Warmer
Cooler Damper
Blades
Supply Air
Room
Air
Induction
Chamber
Supply Air
Venturi
Power Spring
Cartridge
Blade Axle
Blade Arms
Room Temp
Sensing
Thermostat/Acuator
Thermostat
Slide
Temperature
Scale
Warm-up Thermostat/Acuator
(TL-CW-only)
Room
Temp
Sensing
Thermostat/
Acuator THERMA-FUSER
LINEAR DIFFUSERSAll the Acutherm Advantages
that bring individual comfort and personalized temperature control back to office
buildings.
INDIVIDUAL TEMPERATURE CONTROL
Each Therma-Fuser diffuser is a VAV zone. The thermostat, actuator and damper are built
into the diffuser. The temperature set point is adjusted between 70�F/21�C and 78�F/26�C. It
easily zones open offices. Thermostat adjustment is easily accessed but concealed and out
of casual reach for tampering by others.
SUPERIOR AIR DISTRIBUTION
Unlike the fixed opening diffusers used with VAV boxes, Therma-Fuser diffusers vary the
discharge opening as they vary air volume. The result is a constant discharge velocity with
comfort benefits of higher throws, no dumping, better room air movement and uniform
temperature distributionespecially when turned down.
BETTER SENSES AVERAGE ROOM TEMPERATURE
Unlike wall thermostats, Therma-Fuser thermostats are never in the wrong location. They
maintain average temperature within 1��F/0.9�C of set point by sensing secondary space
air at all times. Secondary air is the return air of the spacethe best place to sense the
average room temperature. Positive induction of secondary air over the thermostat at all
supply air flows from full open to full closed assures good sensing.
LOWEST COST PER ZONE OF CONTROL
A single trade can install Therma-Fuser VAV because it is self contained. When
comparing total installed costincluding laborsystems with Therma-Fuser VAV are
clearly the lowest cost of any VAV alternative because Therma-Fuser diffusers do not
require wiring and are more easily installed.
LOWEST ENERGY VAV TERMINAL
Therma-Fuser diffusers have the lowest pressure drop of any VAV terminal which allows
low pressure systems and low energy fan motors. Fan energy is further reduced by a
variable speed drive when the system turns down. It saves refrigeration energy because no
portion of the building is overcooled. No energy is required to operate the Therma-Fuser
controls.
LOW TO NO MAINTENANCE
Customers using Therma-Fuser diffusers for longer than 20 years testify that no
maintenance at all has been required. What VAV box or control offers similar results? Or
the Acutherm 10 year warranty? The construction is simplevery few moving parts. The
dependable Therma-Fuser diffuser has no costly electronics or pneumatics and nothing to
lubricate.
EASILY ADAPTS TO OFFICE LAYOUT CHANGES
No Therma-Fuser zone is split when office walls are put up or moved, a common problem
with VAV boxes. The self-contained diffuser is easily moved without recalibration.
Page 3
Continued on NEXT Page
ing Acutherm.
4) Other Therma-Fuser diffusers are avail-
able in 2'x2'/600mm and 1'x1'/300mm
square sizes.
5) Interoperable VAV diffusers for DDC net-
works are available.
GUIDE SPECIFICATION
(Suitable for Part 2 of CSI Specification section
15840) Material in italics applies only to model
TL-CW. Delete the italics for model TL-C.
2.2 Thermally Powered VAV Diffusers
A. Thermally powered VAV diffusers shall be
a complete VAV terminal and thermostat
self-contained in a linear diffuser. They
shall be thermally powered with room
thermostat/actuator and changeover
thermostat/actuator.
External wiring or
pneumatics shall not be allowed.
B. The room thermostat/actuator shall open
damper blades(s) on a rise in room
temperature and modulate air flow to
control the space within 1��F/0.9�C of
temperature setting. The temperature
setting shall be adjustable between
70�F/21�C and 78�F/26�C. The initial set
point shall be factory set at 74�F/23�C.
C. The diffuser and blades shall be
constructed of extruded aluminum with all
visible portions painted T-Bar off white
low-gloss enamel. The diffuser shall be
complete with plenum constructed of 24
gauge galvanized steel.
D. The diffuser shall have an induction
chamber and supply air venturi at one
end for inducing room air past the room
sensing thermostat/actuator. The venturi
shall be at least 4 inches/100 mm wide
for effective induction.
The VAV diffusers shall have positive
induction of secondary room air over the
room thermostat at all flows from fully
closed to fully open.
E. Manufacturer's ratings for flow and sound
shall be verified by an independent testing
laboratory certified for ARI 890 and ADC
testing.
F. The TL-CW unit shall be equipped with a
changeover thermostat/actuator to fully
open the diffuser for warm-up at supply
air temperatures of 80�F/26.5�C or more.
G. Power compression spring cartridges shall
be attached directly to the
thermostat/actuators to contain the forces
produced without distorting other parts of
the diffuser and assure accuracy of
control.
H. OptionalThe diffuser shall be lined with
�" 2 pound density black bonded blanket
of glass fibres with smooth fire resistant
airstream surfaces adhered with ASTM C
916 adhesive. The insulation and
shipment and installation.
Insulation (optional) is �" 2 pound density
bonded blanket of glass fibers with smooth
fire resistant airstream surfaces adhered with
ASTM C 916 adhesive. Insulation and
adhesive meet NFPA 90A and 90B