
94
Error occurrence conditions and check items
5.19. 21Error
Error
Description
If an error (open: 14
ı
or lower) in the cold water inlet thermistor is detected
continuously for 3 seconds, the system displays the 21E error message on the
remote controller. The boiler maintains the Safety-Shutdown status.
1. Check if the thermistor is open and if the connector is connected properly.
2. Check the defect of the thermistor.
3. Defective PCB.
21E
Cold water inlet
thermistor open
Check
items
Is the Return thermistor
normal?
Yes
No
Replace Return thermistor
Resistance between two blue wires of CN 13 is from
0.8
to
20
KO
at normal condition.
Check connector
Caution
: Before measuring resistance of the thermistor,
remove the connector form the PCB.
©
Navien
Ameri
c
a
I
n
c
.
20
1
0
CH
series
servi
c
e
Manua
l
Version
1
.0
Summary of Contents for CH-180
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