Route hazards before troubleshooting. Current gas or emergency-service guidance controls suspected fuel, CO, fire, or dangerous venting conditions. The page should not tell visitors to relight, reset, bypass, clean, or open equipment when a hazard or uncertainty is present.
Capture the exact heater. Request safe exterior label and control-display photos, fuel, model, serial, age if known, location, visible vent arrangement, error light or code, when the pilot fails, recent outages or work, warranty, and prior repairs.
Describe diagnosis without pre-selling a part. State how the technician follows current manufacturer information and checks the ignition, sensing, control, burner, air and vent path, fuel, safeties, water exposure, and installation factors within licensed scope.
Define quote boundaries. Separate the diagnostic fee, after-hours charge, exact part, labor, manufacturer warranty, shipping, access, venting or installation correction, permits where applicable, return visit, tax, and exclusions. Added work requires evidence and approval.
Compare repair and replacement fairly. Use confirmed failure, tank integrity, combustion or venting safety, part support, warranty, leak history, installation condition, repeated faults, and total scope. Do not use age, one failed lighting attempt, or a cheap component price as the whole decision.
Document safe handoff. Record the confirmed fault, exact work and part, leak checks, ignition sequence, flame and shutdown behavior, relevant combustion or venting checks within scope, hot-water response, settings, unresolved conditions, warranty, and return plan.