Weil-McLain Boiler Equipment & Error Codes

Platform & Control Notes

Evergreen models display plain-English text messages (e.g. 'IGNITION FAULT'). Ultra models show E-codes (E02, E18) for hard lockouts and 'b' codes for soft lockouts. GV90+ uses LED flash patterns, not codes — call us to interpret those.

Model Families & Platforms

• Evergreen & Evergreen Pro (Text-display condensing)
• Ultra Series (E-code / b-code condensing)
• GV90+ (High-efficiency cast-iron with LED flash codes)

Diagnostic Characteristics & Common Service Topics

Weil-McLain boilers utilize specific display codes and safety lockouts to protect the heat exchanger, combustion system, and hydronic loop. Everyday issues like pressure loss, flame sensing errors, or circulator faults trigger specific responses depending on the controller generation.

Sample Fault Code Summaries from Vault Records

Code	Meaning	Action Required
IGNITION FAULT	Evergreen: 5 ignition attempts with no flame detected.	Gas/ignition fault — don't service internally. It auto-resets after ~1 hour, but a no-light boiler in cold weather warrants a pro to check gas, igniter, and venting.
FLAME FAULT	Evergreen: flame detected when there should be none.	Requires manual reset. Combustion test and gas-valve check are pro tasks — call a technician; a leaking gas valve is a safety issue.
GAS VALVE FAULT	Evergreen: control detected a problem with the gas-valve output circuit.	Auto-retries; if it locks out it needs manual reset. Gas valve work is pro-only — call a licensed technician.
BLOWER FAULT	Evergreen: blower can't reach required speed, or won't return to 0 RPM when off.	Auto-retries after ~1 hour. Blower/electrical diagnosis is a pro task.
LOW WTR CUTOFF OPEN	Evergreen: internal low-water cutoff contacts opened — possible low water.	Check system pressure; if low, find/repair the cause of water loss. Probe cleaning/replacement should go to a pro.
HIGH TEMP LIMIT	Evergreen: boiler temperature sensor reached the high-temperature limit.	Verify isolation valves are open and circulators run. Requires manual reset. Repeated overheating lockouts need a pro.
FLUE TEMP TOO HIGH	Evergreen: flue temperature exceeded 210°F (warning) or 220°F (lockout).	Above 220°F requires manual reset. Heat-exchanger and vent inspection are pro tasks — call a technician.
TEMPERATURE SENSOR FAULT	Evergreen: a temperature sensor is shorted, open, or two sensors disagree by >10°F.	Auto-resets when the condition clears. Sensor diagnosis/replacement is a pro task.

Related Symptom & Diagnostic Guides

Sources & Documentation

• error-codes.json — https://www.weil-mclain.com/wp-content/uploads/Evergreen-Pro-Sizes-110-155-Boiler-Manual-1222-Web-Version.pdf