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