Applicable Systems
Cleaver-Brooks Hawk 6000 Controller
Symptoms
Controller displays E1, indicating a low water level condition. The primary low-water cutoff switch has tripped, and the burner has been locked out to prevent damage to the boiler pressure vessel. This is a critical safety condition.
Possible Causes
- Feedwater pump failure or loss of water supply pressure
- Make-up water valve stuck closed or control malfunction
- Scale or sediment buildup in the low-water cutoff float chamber causing false readings
- Blowdown valve left open or leaking excessively
Troubleshooting Steps
- Step 1: Check the boiler water level gauge glass - verify actual water level matches controller reading
If water is visible in the gauge glass, the cutoff switch may be faulty - Step 2: Verify feedwater pump operation and discharge pressure
Repair or replace pump if not delivering water at rated pressure - Step 3: Check make-up water valve and automatic level controller operation
Cycle valve manually to verify free movement and close properly - Step 4: Blow down the low-water cutoff float chamber to remove sediment and scale
Perform blowdown procedure per manufacturer instructions
How to Reset
To reset E1: 1) Verify actual water level is above the minimum safe level shown on the gauge glass. 2) If water level is low, restore water supply and allow boiler to refill. 3) Reset the primary low-water cutoff switch by pressing the reset button. 4) The burner will restart after the safety circuit is satisfied.
Common Replacement Parts
- CB-820-101: Primary low-water cutoff switch, Cleaver-Brooks CB-700 (Test weekly by blowdown procedure)
- CB-820-105: Feedwater pump assembly, 3/4 HP (Verify impeller clearance during maintenance)
- CB-750-201: Make-up water solenoid valve, 3/4 inch NPT (Check screen for debris if valve is sluggish)
Frequently Asked Questions
- Q: How often should I test the low-water cutoff?
Test the primary low-water cutoff daily by blowing down the float chamber while the burner is firing. The burner should shut down within 3 seconds of the water level dropping below the cutoff point.
- Q: What happens if E1 is ignored?
Continuing to fire a boiler with low water will cause severe overheating of the pressure vessel, potentially leading to tube failure, vessel rupture, and catastrophic safety hazards. Never bypass the low-water cutoff.
Source: Cleaver-Brooks CB-700 Boiler Operation and Maintenance Manual, Form 750-250
Category: Boiler