Boiler locks out frequently during very cold weather but no specific error code is shown

Safety first: Do not use open flames to thaw frozen pipes or vents. Turn off power and gas if you suspect frozen components.

• Step 1 – Check outdoor sensor: Verify the outdoor sensor is not exposed to direct wind or mounted in an abnormally cold micro‑location. Relocate if necessary.
• Step 2 – Inspect condensate drain: Look for ice in the condensate line or trap. Thaw gently with warm towels or a hair dryer and insulate or heat‑trace the line to prevent refreezing.
• Step 3 – Verify vent terminations: Ensure intake and exhaust are not blocked by snow or ice. Clear a wide area around terminations.
• Step 4 – Antifreeze and gas supply: For systems in unconditioned spaces, consider adding approved hydronic antifreeze. Have a technician verify gas pressure under peak demand conditions.

Persistent cold‑weather lockouts should be evaluated by a heating professional to protect the boiler and piping from freeze damage.