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Cat III venting

347 Member Posts: 136
Hello All,
I have a cat III on demand water heater (Takagi T-K3) that was installed about 7 years ago. I need to have it inspected. I have the installation instructions and looking at the vent termination it has an asterisk for a inside/outside corner. It says refer to ANSI Z223.1 /NFPA 54 for clearances. I looked up NFPA 54 and found for cat III vents refer to the manufacture or inspector. Well my inspector does not know and the installation page does not have it listed.
I'm looking for clearance to combustibles (ceiling joists) which I'm assuming is 1" . This unit terminates next to a brick chimney on the outside of a house. The termination is in a out cove( between two chimneys) about 5' wide . I'm thinking it should come pass the chimney to be properly vented but I have nothing that states that and the inspector is looking for something in black and white.
Can someone point me in the right direction?
Thanks for you help.


  • newagedawn
    newagedawn Member Posts: 586
    its in the install manual, look it up on line, and from what you are saying, it sounds like its installed wrong
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
  • 347
    347 Member Posts: 136
    This is what I have. I'm looking at E &F and there is an asterisk.
    I belive it tell me to look it up the HFPA 54. I found nothing there about cat III termination.

  • 347
    347 Member Posts: 136
    My bad, I must be going blind. Just realized that the measurement is listed on the opposite page with the multiple exhaust terminations. I did not see it because I was not doing multiple vents.
    Sorry about that.
    EBEBRATT-Ed Member Posts: 13,800
    With most of the condensing and near condensing and power vent equipment the rule is to follow the manufacturers instructions. The gas code cannot keep up with all the "newer equipment" so most codes for that type of equipment say to refer to the mfg instructions.
  • Bob Harper
    Bob Harper Member Posts: 985
    Consider discharging away from masonry. It will eat it up.