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Copyright © Acutherm 2009
5.
Return Therma-Fuser diffusers to operating
condition by pushing the balancing lever down until
it latches.
6.
Return the remainder of the system to operating
condition.
ADJUSTING MINIMUM FLOW
Turn dial until desired minimum flow on the scale
intersects with the lower metal piece. See Fig. 5.
ADJUSTING TEMPERATURE
SETPOINTS
The STR Therma-Fuser diffuser is factory set at
74°F/23°C. Because heat loads in various rooms diff er
and individual occupants prefer different temperatures,
it is recommended that the thermostat not be adjusted
until after a few days of operation.
Room temperature setpoints for heating and cooling
are separately adjusted by turning the heating and
cooling thumbwheels. Align the outside of each
thumbwheel with its respective temperature scale. See
Fig. 6. Each setpoint can be anywhere between 70°
and 78°F/21° and 25°C. Both are factory set at
74°F/23°C. (The model STR-C has only one
thumbwheel).
If the cooling thumbwheel is tight when the room is
cool, continue to turn the thumbwheel and pull the
changeover close rod outward to relieve the tightness.
See Fig. 6.
RECOMMENDED ADJUSTMENTS FOR VARIOUS
CONDITIONS
Room
Temp.
Disc
Position
Recommended
Action
Open
Adjust cooling for higher room
temperature set point. (Turn cooling
thumbwheel out.)
Too
Cold
Closed
Therma-Fuser diffuser is correct.
Check if cooling is still required, and if
not, turn cooling unit off.
Open
Therma-Fuser diffuser is correct.
Check for lack of air or for too warm
air temperature.
Cooling
Mode
STR-C
STR-HC
Too
Warm
Closed
Adjust cooling for lower room
temperature set point. (Turn cooling
thumbwheel in.)
Open
Therma-Fuser diffuser is correct.
Check for lack of air or too low air
temperature.
Too
Cold
Closed
Adjust heating for higher room
temperature set point. (Turn heating
thumbwheel out.)
Open
Adjust heating for lower room
temperature set point. (Turn heating
thumbwheel in.)
Heating
Mode
STR-HC
Too
Warm
Closed
Therma-Fuser diffuser is correct.
Check if heating is still required, and if
not, turn it off.
Too
Noisy
STR-C
STR-HC
Any
Any
Reduce static pressure.
Recommended static pres-
sure is .05 to .25 wg / 10 to 62 Pa at
the inlet of the diffuser. If lower noise
level does not result from lower static
pressure, check for and correct noise
generating restrictions in the duct up
stream such as large pressure drops
over dampers, heaters, etc.
MAINTENANCE
The moving parts of the STR 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
References:
•
System Design, STR brochure, Form 046.101.
•
Chapters 2.2, 3.1 and 3.2, pp 6, 7 and 8, Designing
Modular VAV Systems Form 5.2.
