System Balancing; Adjusting Miminum Flow - Price Acutherm THERMA-FUSER SYSTEMS Installation & Operation Manual

To remove the appearance panel:
1. Open appearance panel as described above.
2. Rotate the appearance panel away from the latch clip
bracket to force the hinge hooks open on the panel.
3. Slightly lift the panel to remove from the hinges.
To reattach the appearance panel:
1. Hang the appearance panel on the hinges.
2. Press the hinge hooks against the panel to close
around the hinge brackets.
3. Close panel as described above.
SYSTEM BALANCING (TK-HC, TK-C)
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. Open Therma-Fuser diffusers.
a. Open appearance panel.
b. Using a flat blade screwdriver or coin, turn the
damper opening cam clockwise until the damper
blades are fully open and the blade tips touch
each other. See
c. Close appearance panel.
Fig 2. Turn damper opening cam to open for balancing
Damper Opening Cam
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. Place a direct reading diffuser balancing hood over the
face of each Therma-Fuser diffuser and adjust damper
at duct takeoff to obtain maximum design air volume.
If a velocity meter is used, measure discharge velocity
at the housing (See
times A of .12 f to get air flow in cfm.
t
2
k
Page 2 of 6
Fig. 2.
3). Multiply the velocity in fpm
Fig.
5. Return Therma-Fuser diffusers to operating condition.
a. Open appearance panel.
b. Turn damper opening cam to allow damper blades to close.
c. Close appearance panel.
Fig 3. Measuring Discharge Velocity Figure 3 @200%
Appearance
Panel
BALANCING (TK-D)
1. The damper blade opening is factory set at 3/4
inch/19mm (See 4). Readjust where necessary by
Fig.
turning the damper opening cam (See
2. Place a direct reading diffuser balancing hood over the
face of each TK-D diffuser and adjust damper at duct
takeoff to obtain design air volume. If a velocity meter
is used, measure discharge velocity at the housing (See
3). Multiply the velocity in fpm times A
Fig.
get air flow in cfm.
Fig 4. Measuring damper blade opening
Foam
Blade
ADJUSTING MINIMUM FLOW (TK-HC, TK-C)
Minimum flow is adjusted by turning the damper opening
cam until the damper blades are open the correct amount.
Determine the correct blade opening for the required percent
minimum flow from the graph in
opening as shown in
Fig. 3
Fig 5. Percent Minimum Flow vs. Blade Opening
PERCENT of AIR FLOW CAPACITY vs. BLADE OPENING
100
80
60
40
20
0
0 .10 .20 .30
(0) (2.5) (5.1) (7.6)
BLADE OPENING — INCHES
Diffusion
Damper
Housing
Probe
Gauge
1250 to
2300 fpm
Fig. 2).
of .12 f
k
Housing
Small Steel Rule
5. Measure the blade
Fig.
and adjust the damper opening cam.
.40 .50 .60 .70
(10.2) (12.7) (15.2) (17.8)
(MM)
Figure 7 @ 200%
to
t
2
.80
(20.3)