The control system has detected open contacts at the Blocked Exhaust air pressure switch – the water heater is not venting properly.
Check for restrictions, too many equivalent feet, or too many elbows in the vent pipe. Ensure Review venting installation section of the
Instruction Manual that came with the water heater – see Table 1 on page 7 in this manual. Ensure the vent/intake air piping has been installed within manufacturers requirements.
Check all wiring between the Blocked Exhaust air pressure switch and the CCB’s J6 Socket (page 36) pins 5 & 10. Perform close visual inspection of the pins inside the plug and socket – ensure plugs and sockets are mating properly and providing good contact. Repair/replace anything worn or damaged.
Review the air pressure switch information beginning on page 18. Perform the pressure switch test procedure for the Blocked Exhaust air pressure switch – see pages 21 through 23. Replace the Blocked Exhaust switch if defective.
Call the technical support phone number shown on the water heater labeling for further assistance if the problem has not been corrected after performing the procedures outlined here.