Applicable Systems
Cleaver-Brooks Hawk 6000 Controller
Symptoms
The Cleaver-Brooks Hawk 6000 controller displays a Gas Pressure High alarm. The gas pressure in the burner gas train has exceeded the high gas pressure switch setpoint, triggering an immediate safety shutdown.
Possible Causes
- Utility gas supply pressure surge above normal operating range
- Gas pressure regulator failed open, allowing full supply pressure to reach the burner
- High gas pressure switch setpoint set too low or switch drifted
- Manual gas valve upstream partially closed then suddenly opened
- Gas filter or strainer removed, allowing debris to hold the regulator open
Troubleshooting Steps
- Step 1: Check the gas supply pressure at the main gas valve inlet with a manometer
Gas pressure is within the normal range (typically 7-14 in. WC for natural gas) - Step 2: Inspect and test the gas pressure regulator for proper operation
Regulator maintains the set outlet pressure under varying inlet pressures - Step 3: Verify the high gas pressure switch setpoint matches the burner specification
Switch setpoint is at the value specified in the burner manual (typically 5-7 in. WC above operating) - Step 4: Check for any manual valves that may have been recently opened or adjusted
All manual gas valves are in the correct open position - Step 5: If the regulator has failed, replace it with the correct model
New regulator maintains stable outlet pressure under varying inlet conditions
How to Reset
To reset: 1) Fix the gas pressure regulator or supply issue. 2) Verify the gas pressure is within range. 3) Press the RESET button on the Hawk 6000. 4) The controller will restart the ignition sequence. Caution: Never bypass the high gas pressure switch. Excessive gas pressure can cause over-firing, flame rollout, and explosion.
Common Replacement Parts
- 750-282: Cleaver-Brooks high gas pressure switch (Set to the pressure specified in the burner IOM manual)
Frequently Asked Questions
- Q: What does the high gas pressure switch do?
The high gas pressure switch monitors the gas pressure in the burner gas train. If the pressure exceeds the setpoint, it opens the safety circuit, causing the Hawk 6000 to immediately close the main gas valve and shut down the burner.
- Q: What gas pressure should I expect at the burner?
For natural gas, the typical operating pressure at the burner gas train is 7-14 inches water column (in. WC). The high gas pressure switch is typically set 5-7 in. WC above the operating pressure. Check the specific burner manual for exact values.
Source: Cleaver-Brooks Hawk 6000 Manual #750-359, Appendix F: Alarm List
Category: Boiler