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110328-02 - 6/22
ALTA
Installation, Operating & Service Instructions
18
Troubleshooting
(continued)
Code
Name
Possible Cause
Corrective Action
H18
E18
Invalid
Application
Parameters
[
18
.
0
] Application
parameters are not valid.
Normal condition following a parameter download, set Factory
Defaults, parameter
A10
. (Table 15-11, Menu
A
, Quick Menu)
[
18
.
1
] Parameter Model
Mismatch.
Repeat reset to factory default using parameter
A10
. If problem
persists, replace control.
[
18
.
2
] CH Setpoint and
Modulation source both
selected.
(Feature not available with local user display). Only CH
Setpoint or Modulation source may be selected. Select only
a single feature. Check Central Heat Modulation Rate Source
and Central Heat Setpoint Source.
[
18
.
3
] Invalid header
sensor configuration.
(Feature not available with local user display). Header
selection must be set to "Header" when selecting CH
modulation sensor selection to "Header".
[
18
.
4
] Invalid Stepped
modulation parameters
(Start Offset Recycle
Limit)<5°F (3
˚
C).
(Feature not available with local user display). Check Stepped
Modulation Start Offset is 5°F (3°C) greater than Stepped
Modulation Recycle offset. Check Flow and Flue temperature
Stepped Modulation Start Offset is 5°F (3°C) greater than Flow
and Flue temperature Stepped Modulation Recycle Offset.
[
18
.
5
] Invalid Setpoint
interpolation parameters.
(Feature not available with local user display). Check CH
20 mA Water Temperature is greater than CH 4 mA Water
Temperature.
[
18
.
6
] Invalid Recirc
(Comfort) Mode
configuration.
(Feature not available with local user display). Auxiliary
thermostat input selection not set to "Recirculation Enable".
[
18
.
7
] Factory defaults not
turned on.
Ensure BCC is installed and select
A10
factory Default "On"
(Table 15-11).
[
18
.
8
] Pump mismatch.
Boiler pump set to 0 or boiler pump output set to 3 and Aux.
pump ouput is not set to 3.
E19
Gas Valve Or
Blower Fault
Air fuel ratio is persistently
outside acceptable limit.
Check wiring to gas valve and blower. If wiring is OK, replace
blower and retry. If blower OK, replace gas valve and retry.
H20
E20
Ignitor/Flame
Sensor or
Burner Fault
Ignitor/flame sensor wiring
issue.
Check the ignitor/flame sensor wiring and earth contacts at
burner.
Dirty or damaged ignitor/
flame sensor.
Check and correct ignitor/flame sensor gap and distance to
burner. Replace if necessary.
Dirty/ damaged burner.
Check burner. Replace burner if necessary.
H21
E21
Gas Valve
Fault
No gas, insufficient gas
supply pressure.
Verify no air in gas line. Check gas supply pressure.
Check gas valve inlet pressure during operation.
Defective gas valve.
Check gas valve inlet pressure during operation and check
wiring to gas valve.
If problem persists, replace gas valve.
If problem persists, replace control.
[
E21
.
3
] Gas valve wiring
problem.
Table 18-5: Active Fault Code and Corrective Actions (continued)
Detailed Fault Code found on "
b
" and "
c
" menus in brackets, e.g. [
1
.
0
].
