Cad Cell (Eye) Durability

Discussion in 'Boiler Forum' started by jhcole, Mar 12, 2014.

  1. jhcole

    jhcole Mechanical Engineer

    Messages:
    3
    Location:
    New York
    I have a client who's boiler shut down due to the cad cell not "seeing" the flame. The boiler was recently serviced 10-months ago: (1) is it common to check the cad cell as part of the annual boiler maintenance? and (2) is the failure of a cad cell relatively slow -- such that a check 10-months ago might have caught the problem and prevented the no-heat condition?

    Thank you

    jhc
  2. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    It depends on why the cad cell is not seeing the flame. If the cad cell isn't seeing flame, it locks the primary on safety so the question is whether the cad cell itself is bad or there is another issue.
  3. jhcole

    jhcole Mechanical Engineer

    Messages:
    3
    Location:
    New York
    The boiler service man replaced the relay, but the boiler did not start. The new relay was able to send him a trouble code that represented the resistance of the cad cell which was over 2000 ohms. He replaced the cad cell with a new one and the boiler started. He said the cad cell was bad. I don't know if it was dirty or if it stopped working.

    I'm trying to sort out if the cad cell going bad would-have or should-have showed up during the last boiler service. I'm also trying to find out if checking the cad cell is part of the normal annual boiler service.

    Thanks for the help

    jhc
    Last edited: Mar 13, 2014
  4. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    Checking the cad cell kind of depends on the company/tech that did the work. Most companies provide a complete check list of the things they check and the tests they run. We test the cad cell and maybe he did too. I really can't say how long it takes one to fail when it does fail. Usually we get a no heat call, run the diagnostics and determine cause. The cell may very well have failed the day the heat went out. The only way to know for sure is of there is a new style primary control that logs burner cycles like the Beckett Genysis control. In that case the service tech can scroll down thorugh the cycles, including cad cell resistance and see exactly what happened and when. Nobody would just replace a dirty cell. You wipe them off and put em back in.
  5. jhcole

    jhcole Mechanical Engineer

    Messages:
    3
    Location:
    New York
    Thank you for your help. I appreciate it. jhc

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