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APEX Installation, Operating, & Service Instructions APEX Installation, Operating, & Service Instructions
D. Hard Lockout
From the Help menu, select the blinking Hard Lockout icon to determine the cause of the hard lockout. See
Figure 12-4. The boiler will automatically restart once the condition that caused the lockout is corrected.
Figure 12-4: Example Hard Lockout
The Hard Lockout screen will display the lockout number, name, condition that caused the lockout, possible
causes, and a basic description of corrective actions that may be taken to fix the problem. An in-depth guide to
possible hard lockouts is provided in Table 12-5.
Lockout
Number
Condition Possible Cause
3
Burner Interlock
Open (ILK OFF)
ILK safety limit input not energized
Lockout input (ILK) is not ON. Refer to Limit String Status screen for
list of limits.
• Man Reset Ext. Limit device open or jumper not installed
• High or low gas pressure switch open or jumper not installed
• Thermal link open
• Burner door thermostat open
• Loose or defective limit string wiring
4
Outlet/Supply
High Limit
Supply temperature exceeded
fixed high limit, 210°F (98.9°C).
• Heating load much less than boiler minimum firing rate.
• Defective system pump or no flow in primary loop.
• Defective boiler pump, no flow or insufficient flow in boiler loop.
• Control system miswired so that the boiler operation is permitted
when no zones are calling.
6
Stack High Limit
Flue temperature exceeded
204°F (95.6°C).
• Heat exchanger needs to be cleaned
• Boiler over-fired
• Air-fuel mixture out of adjustment
12
Flame detected
out of sequence
A flame signal was present when
there should be no flame.
- Defective gas valve - make sure inlet pressure is below maximum
on rating plate before replacing valve.
14
Delta T Inlet/
Outlet High
Temperature rise between supply
and return is too high.
Inadequate boiler water flow.
• Boiler pump not operating
• Boiler pump undersized
• Valve closed
Table 12-5: Hard Lockout Codes
12 Troubleshooting (continued)
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