Campbell Scientific CNR4 Net Radiometer - Manual (Page 57)

Appendix B. CNF4 Heater/Ventilator
'Compute net radiation
Rn = Rs_net + Rl_net
'CNF4 ventilator control - the ventilator will be turned on when flag(1) is set high
SW12 (1,flag(1))
'CNF4 heater control - the heater will be turned on when flag(2) is set high
SW12 (2,flag(2))
CallTable cnr4_data
CallTable cnr4_ts
NextScan
EndProg
B.5 CNF4 Heater/Ventilator Maintenance
B.5 g the Heater
NF4 consists of a heater and a ventilator. To check the heater
he resistance between the two heater wires (green and yellow).
ance value of the heating resistor inside should be around 15 Ω (cable
e should add about 0.026 Ω per each foot of cable). An infinite
e reading indicates the likelihood of a broken wire, or cable.
B.5
c
per e resistance value is measured, but the
vent ossible that the ventilator is stalled by an
obje ve the black cover at the bottom side of the
ventilator unit, by prying it open with a small flat-head screw driver or by
straight out. Inspect the fan inside for any object that might impede
s rotation. Upon completing the inspection, put the filter and the cover
place.
B.5 Filter for the Ventilator
eeds to be checked for every 6 to 12 months. Remove the black
bottom side of the ventilator by prying it open with a small flat-
screw driver or by pulling it straight out. Inspect the filter for dust and
icles that might impede the air flow into the ventilator. The filter can be
cleaned with warm clean water, or can be replaced with the new one. You can
purchase the replacement filters, pn 26010, from Campbell Scientific.
.1 Testin
The optional C
unit, measure t
The resist
resistanc
resistanc
.2 Testing the Ventilator
To heck the ventilator, first measure the impedance of the ventilator motor.
The value should be around 30
Ω (cable resistance should add about 0.026 Ω
ach foot of cable). If the correct
ilator still mal-functions, it is p
ct blocking the fan. Remo
pulling it
the fan’
back in
.3 Replacing the
The filter n
cover at the
head
part
B-11