Responded to service call for IBC boiler CK199 reporting high vent limit error code and no hot water. Inspected venting system which showed proper condition, slope and clear termination. Diagnostic testing included running hot water for extended period while monitoring stack temperature, which remained below 127°F. Verified proper operation of exhaust temperature sensor, condensate drainage system, and central heating functionality. No current operational issues detected; likely caused by heavy hot water demand. Instructed customer on proper boiler reset procedure.
