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BACNET™ MOTORIZED VAV DIFFUSER
TROUBLE SHOOTING
Trouble shooting Therma-Fuser diffusers requires looking at the system as a whole. Before examining the Therma-Fuser diffuser for
failure it is worth the time to be sure the system is functioning properly and that something has not been overlooked. Before calling
Acutherm, please complete the data log for all Therma- Fuser diffusers to be evaluated.
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.
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.)
Conditions Outside the EF-B
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
If they are other than as shown above, temporarily remove the override to make the Objects normal before further checking.
4
BACNET™ MOTORIZED VAV DIFFUSER - Manual | acutherm.com
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.
8.
Static pressure at the inlet of the Therma-Fuser diffuser.
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
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