Dunkirk Q95M-200 Modulating Condensing Boiler - Manual (Page 17)

17
SOFT LOCKOUT (Display flashes “9” and then “b” in first position; last two digits on steady (code))
Code Reason For Soft Lockout Corrective Actions (pressing RESET should restart boiler immediately):
08
0.14” Pressure switch contacts
open
1
Check pressure switch for proper operation. Replace pressure switch if moisture has
entered switch. Check venting for blockage. Clear if present.
18
High Limit Operation: Burner
off until outlet water temperature
drops below 180 °F
1
Happen when heat demand is lower than lowest firing rate of boiler, such as
operation of single, small zone. Check system for:
• Verify boiler and system are full of water.
• Verify system does not have trapped air.
• Inspect and verify system piping and components.
• Verify piping agrees with boiler manual recommendations.
2
Use contact thermometer to check outlet water temp. Compare to temperature
shown with display in “INFO” mode (“1” in first digit). Replace return temperature
sensor if results are not close. Replace control module if sensor replacement doesn’t
solve problem.
19
High Limit Operation: Burner
off until return water temp. drops
below 190 °F
1
Check system for:
• Verify boiler and system are full of water.
• Verify system does not have trapped air.
• Inspect and verify system piping and components.
• Verify water flow is not reversed or pipes crossed.
2
Use contact thermometer to check return water temp. Compare to temperature
shown with display in “INFO” mode (“2” in first digit). Replace return temperature
sensor if results are not close. Replace control module if sensor replacement doesn’t
solve problem.
24
High Limit Operation: Return
temp. is higher than supply temp.
1
• Verify boiler and system are full of water.
• Verify system does not have trapped air.
• Inspect and verify system piping and components.
• Verify water flow is not reversed or pipes crossed.
2
Use contact thermometer to check return water temp. Compare to temperature
shown with display in “INFO” mode (“2” in first digit). Replace return temp. sensor
if results are not close. Replace control module if sensor replacement doesn’t solve
problem.
25
High limit operation: Outlet
water temp. increased too quickly.
Non-adjustable default setting
9.8°F/sec
1
Indicates flow rate too low. Check system for:
• Verify boiler and system are full of water.
• Make sure system does not have trapped air.
• Inspect and verify system piping and components.
• Verify piping agrees with boiler manual recommendations.
2
Verify operation of boiler circulator:
• Check voltage at circulator junction box to ensure 120 vac when boiler
operates. If no voltage, check wiring and wiring connections.
• High voltage terminal strip terminals 5 and 6 should show 120 vac for space
heating; terminals 3 and 4 should show 120 vac for DHW. Replace circulator if
powered but not operating.
• Replace line voltage wire harness if necessary. Replace control module if wire
replacement doesn’t resolve.
26
Aquastat contacts open
or
LWCO contacts open
or
3.5” Switch open
1
Verify proper setting of control.
Water temp too high, wait for temperature to drop below 180 degrees.
2
Check water level in boiler, fill if low.
Press LWCO reset switch on display panel
If problem still exists, check LWCO probe and board according to manufacturer’s
instructions. Replace if necessary.
3
Check pressure switch for proper operation. Replace if moisture has entered switch.
Check venting for blockage. Clear if present.
9 - TROUBLESHOOTING