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VAV
– Module NMV-D2M
Legend
Sequence
a)
Test start ‘Check system supply pressure’
-
System test: setpoint V’mid
- Volumetric flow zero [m
3
/h] / [l/s]
- Damper 100% open
b) - Test-Sequence discontinued
N-P1.3 VAV- / CAV-Box
.........................................................................................
no system supply pressure
Suggstion for a remedy
a) Check fan and pressure control, including the
protective devices
b) Check the function of the upstream dampers
(control and fire dampers)
c) Check damper direction of rotation
d) Rectify fault and repeat test
Suitable Test-Sequences
-
BasicTest Max-Min 5m.txt
Note:
The Test-Sequence is discontinued because of the lack of system
supply pressu
re. Fault alarm: ‘Inadequate supply air pressure’
Possible faults
- Fan pressure control defective or inoperative
- Protective device triggered (fuse, thermal trip)
- Upstream fire damper closed
- Damper rotation incorrectly set
a
b
Sequence
a)
Step 1: V’max
b)
Setpoint [V’max]
- Volumetric flow does not reach setpoint
- Damper 100% open
c)
Step 2: V’min
- Volumetric flow at setpoint
- Damper in control range
Suggestion for a remedy
1) Increase supply pressure (increase pressure
control setpoint), if this is impossible temporarily
isolate several air units on the same section at the
same time
2) Repeat test
3) Check fan and pressure control and set correctly.
Suitable Test-Sequences
-
BasicTest Max-Min 5m.txt
-
Test 4 Max-Mid-Min 9m.txt
Note:
If the system does not attain the required supply pressure
– during the
test start
– the Test-Sequence is discontinued and the fault alarm ‘In-
adequate supply air pressure’ is given.
During the installation and commissioning phases of plants they are
often set up for manual operation, i.e. maximum volumetric flow.
Result: Insufficient system supply air pressure.
Possible faults
- Fan or pressure control defective
- Pressure control setpoint incorrectly set
- Plant not set up or set up incorrectly
- All VAV- / CAV air boxes being operated at max.
volumetric flow (commissioning)
a
b
c
S
A
A
D
A
N-P1.4 VAV- / CAV-Box
......................................................................
insufficient system supply pressure
S
A
A
D
A
NMV-D2M
– Diagnosis
Legend
