Cleaver-Brooks E2: Cleaver-Brooks CB-700-250 Error Code E2

Symptoms

Controller displays E2, indicating a flame failure alarm. The burner management system detected loss of flame signal during the main flame operation period. The burner has shut down and locked out after the retry sequence.

Possible Causes

Dirty or misaligned burner nozzle causing poor fuel atomization
Faulty flame scanner or flame rod not detecting flame properly
Fuel supply pressure dropped below minimum during burner operation
Combustion air damper misadjusted or blocked air intake

Troubleshooting Steps

Step 1: Inspect and clean the burner nozzle - verify correct size and spray pattern
Replace nozzle if worn or if spray pattern is irregular
Step 2: Clean the flame scanner lens or flame rod and verify signal strength
Scanner should produce at least 20V DC signal when viewing flame
Step 3: Check fuel supply pressure at the burner inlet during operation
Gas pressure should be within manufacturer specified range for firing rate
Step 4: Inspect combustion air intake and damper for obstructions
Verify damper opens fully and air filters are clean

How to Reset

To reset E2: 1) Allow the burner management system to complete its post-purge cycle. 2) Press the Reset button on the flame safeguard controller. 3) The burner will attempt a restart through the full purge and ignition sequence. 4) If flame is established and maintained, normal operation resumes.

Common Replacement Parts

CB-830-201: Burner nozzle, Cleaver-Brooks CB-700 (Verify gallon per hour rating and spray angle match specification)
CB-830-205: Flame scanner UV type, self-checking (Clean lens monthly with lint-free cloth and approved cleaner)
CB-830-210: Gas pressure regulator, 2 inch NPT (Verify outlet pressure stability under flow)

Frequently Asked Questions

Q: What causes flame failure on a Cleaver-Brooks boiler?
The most common causes are dirty burner nozzles, faulty flame scanners, and fuel pressure fluctuations. Regular cleaning and calibration of burner components prevents most flame failure events.
Q: How many times can I reset the flame safeguard before calling a technician?
The flame safeguard controller typically allows 1-3 reset attempts. If the burner does not establish and maintain flame after 2 reset attempts, stop resetting and contact a qualified boiler technician to diagnose the root cause.

Cleaver-Brooks CB-700-250 Error Code E2