5
acutherm.com | BACNET™ MOTORIZED VAV DIFFUSER - Manual
BACNET™ MOTORIZED VAV DIFFUSER
TROUBLE SHOOTING
Conditions Outside the EF-B Cont'
11. Measure the damper blade opening from the edge of the
housing perpendicular to the housing (see Fig. 2 Blade
Opening).
12. Use the information from the steps above to determine if
the damper blades are correct for the conditions.
a. Determine mode. The EF-B unit should be in cooling if
the supply air temperature is below the set point. It is
in heating if the supply air temperature is above both
the room temperature and the set point.
b. For room temperatures more than 2ºF/1.2ºC from
set point, damper blades should be moving to the
position as shown in the Fig. 3 Troubleshooting.
NOTE:
i. Room temperature more than ±2ºF/1.2ºC from
set point has been selected as a general rule
of thumb for trouble shooting to avoid more
complicated control algorithms within that band.
Control is intended to be tighter but will depend
on system conditions.
ii. If any of the set points are changed to achieve
full open or full closed conditions, wait 5 to 10
minutes to make sure the room and system have
stabilized.
iii. For room temperatures less than 2ºF/1.2ºC from
set point, the damper blades may be somewhere
between open and closed.
13. If the damper blades are not according to the table,
check if there are maximum or minimum flow settings
or any other overrides limiting opening or closing? See
step 10.c. above. Record any maximum or minimum flow
settings or other overrides and return to that setting after
troubleshooting. For troubleshooting, reset maximum flow
to 1000 and minimum flow to 0. Wait 5 to 10 minutes –
see step 12.b.,note ii.
14. If there are no limiting flow stops or overrides complete
EF-B Electrical below before contacting Acutherm.
FIG. 2 BLADE OPENING
FIG. 3 TROUBLESHOOTING
Cooling Heating
Room Temp
vs
Set Point
+2ºF / 1.2ºC -2ºF / 1.2ºC +2ºF / 1.2ºC -2ºF / 1.2ºC
Damper Blade
Position Open Closed Closed Open
FORM 901.205 REV 1403
(Supersedes nothing)
Page 3 of 6
System
The system should be:
1. Delivering 50º-68ºF/ 10º-20ºC supply air when in
the cooling mode.
2. Delivering 80º-120ºF/ 26.5º-49ºC supply air when
in the heating mode.
3. Maintaining a constant supply air temperature.
4. Maintaining static pressure at the inlet to each
Therma-Fuser diffuser between .05 and .25”wg /
12 and 62Pa.
5. Maintaining continuous fan operation during
occupied hours.
Once the above checks have been completed examine
and record the following:
Conditions Outside the EF-B
6. Room temperature 4ft/1200mm above the floor
directly under the Therma-Fuser diffuser.
7. Supply air temperature at the Therma-Fuser
diffuser. (Temperature may vary over time. Several
measurements at different times may be required.)
8. Static pressure at the inlet of the Therma-Fuser
diffuser.
EF-B Properties
9. Check that 24+3/-1VAC is supplied to the diffuser
across the terminals labeled 24VAC (POWER IN)
(see Fig. 5 Wiring Diagram).
10.Determine the current set point.
a. Use a computer on the network with BACnet
network management software to select the
specific EF-B unit.
b. Discover the diffuser Objects and locate
analog_input_3 (oEffectStpt). The value of this
Object is the current set point for the EF-B unit.
c. Check that other Objects are not overriding the
current set point or limiting flow. The following
are Objects that can override normal operation
and the default setting for each.
i. binary_value_0 (iVancancy Mode) = 0
ii. analog_value_0 (cMaxFlow) = 1000
iii. analog_value_1 (cMinFlow) = 0
iv. analog_value_2 (cMinStbyFlow) = 0
v. analog_values_4-9 (set points)
vi. analog_value_10 (cStPtLimit) = 2
vii. analog_value_11 (cStPtReset) = 0
viii. analog_value_12 (cMaxHeatsp) = 100
ix. analog_value_13 (cHCMode) = 0
x. analog_value_15 (cVacSpOfst) = 2
xi. analog_value_21 (iOccMode) = 0
xii. analog_value_22 (iHCMode) = 0
xiii. analog_value_23 (iTempSetpt) = 3276
xiv. analog_value_24 (iFlowSetpt) = 3276
xv. analog_value_25 (iOverride) = 0
xvi. analog_value_26 (iRmTemp) = 327
xvii. analog_value_27 (iSATemp) = 327
xviii. analog_value_28 (iFlowRate) = 3276
xix. analog_value_29 (iCO2Level) = 0
If they are other than as shown above,
temporarily remove the override to make the
Objects normal before further checking.
11.Measure the damper blade opening from the edge
of the housing perpendicular to the housing (see
Fig. 2 Blade Opening).
12.Use the information from the steps above to
determine if the damper blades are correct for the
conditions.
a. Determine mode. The EF-B unit should be in
cooling if the supply air temperature is below
the set point. It is in heating if the supply air
temperature is above both the room
temperature and the set point.
b. For room temperatures more than 2ºF/1.2ºC
from set point, damper blades should be
moving to the position as shown in the Fig. 3
Troubleshooting.
Notes:
i. Room temperature more than ±2ºF/1.2ºC
from set point has been selected as a general
rule of thumb for trouble shooting to avoid
more complicated control algorithms within
that band. Control is intended to be tighter
but will depend on system conditions.
ii. If any of the set points are changed to
achieve full open or full closed conditions,
wait 5 to 10 minutes to make sure the room
and system have stabilized.
