VAV – Module NMV-D2M
N-D Miscellaneous
N-D1 Function checks of the NMV-D2M
Detailed information on function checks for the NMV-D2M will be found in
4. NMV-D2M Product Information. Some extracts are described on the
two following pages, the Level 2 and 3 function checks.
N-D1.1 ‘Level 2’ function check
Possible cause:
c) inadequate supply pressure
1)
d) pressure sensor / pick-up device
hoses damaged, loose or dirty
c) check fan operation, correct
control parameters
d) measure active pressure
with Pascal meter, examine
pick-up devicee and hoses
Level 2 -
Function check
Reference value input w
Isolate signal from DDC,
room controller or CAV
step control
(terminal # 3)
Preconditions:
-
24 V power supply
- damper function
- Supply pressure
checked and OK
Test
Operating volumetric-
flow: V'min
Reaction:
terminal 3 open
Damper closed
Damper open
check
Possible cause:
a) V'min setting: 0%
b) V'min setting gives active
pressure below 2 Pa
(Creep flow suppression active)
try V'min setting higher, e.g. 50%
check
Next Step:
- test V'max function
Test
Operating volumetric
flow: V
'max
Reaction:
Link terminal 2+3
Damper open
Actual flow =
Reference flow
Actual flow =
Reference flow
1) inadequate supply pressure
N
ote: It happens quite often during a system
commissioning that all VAV units are being set
to V'max through the DDC control -> Result:
shortage of air
If this is the case, increase the supply pressure.
If this is impossible, temporarily:
- reduce the V'max setting
- isolate one or more VAV units on the same
section
Actual flow =
Reference flow
Check fan and correct settings
Re-establish the original status:
- reset the V'max setting
- de-isolate the VAV units
Check function
DDC / Room-controller
or Step control
2. Level
Function check
- set V'min and V'max to
Orginal values
- connect reference signal
to Terminal 3
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