83
110331-07 - 8/23
PHTM II
Combi Installation, Operating & Service Instructions
19
Troubleshooting
(continued)
Table 19-5: Active Fault Code and Corrective Actions (continued)
Detailed Fault Code found on "
b
" and "
c
" menus in brackets, e.g. [
1
.
0
].
Code/
Name
Possible Cause
Corrective Action
H21
E21
Fuel Gas
Fault
[
21
.
0
], [
21
.
2
] No gas,
insufficient gas supply
pressure.
• Verify no air in gas line.
• Check gas valve inlet pressure while boiler off and during operation.
[
21
.
0
], [
21
.
2
] Flame signal
unstable at specific firing
rate.
Manually modulate boiler from max load to min load in 10% increments.
Monitor flame signal. If flame signal fluctuates greater than 10 points
almost instantly, reduce gas pressure and perform test again.
Consult manufacturer if problem persists.
[
21
.
1
] Defective gas valve. • Check gas valve wiring, correct if necessary.
• Check gas valve inlet pressure during operation.
• If problem persists, replace gas valve.
• If problem persists, replace control.
[
21
.
3
] Gas valve wiring
problem.
H22
E22
No Flame
After
Ignition
Ignition cable not plugged
in.
Connect ignition cable.
Break in ignition cable.
Check ignition cable continuity.
Fuel Gas Selection,
parameter
A06
or gas
valve setting is incorrect.
Check Fuel Gas Selection, parameter
A06
, and gas valve setting (Figure
15-3). Both selections must be set to the same fuel type.
No gas, insufficient gas
supply pressure.
• Verify no air in gas line.
• Check gas valve inlet pressure while boiler off and during operation.
Lean ignition mixture.
After verifying no air in gas piping and gas supply pressure, gradually
increase (1% at a time) parameter
F07
until successful ignition.
Dirty or damaged ignitor/
flame
sensor.
Check ignitor/flame sensor gap and distance to burner. See Figure 18-2
and Table 18-3 for distance specifications. Replace ignitor/flame sensor
if necessary.
H23
E23
Flame
Out Of
Sequence
[
23
.
0
] Blocked
condensate trap.
Check trap and clean if necessary.
[
23
.
1
] Defective gas valve. Replace gas valve.
[
23
.
2
], [
23
.
3
] Defective
control.
Replace control.