Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Cad Cell Relay-Symptoms of failure

What are the symptoms of a failing cad cell relay ? Are there symptoms ? How do you test it when you have intermittent lock outs ?


  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    Try posting that question at

    [url=http://www.oiltechtalk.com]www.oiltechtalk.com or [url=http://www.firedragonent.com]www.firedragonent.com I am sure you will get some excellent responses.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,237
    edited January 2010
    OHM readings

    You test the cad cell using a ohm meter . Disconnecting it from the control and taking a reading while the burner is running , jumping out the FF terminals to keep the burner from locking out .. Under 1000ohm is good ,1000-1400 is a hit or miss ...1400+ its shutting down ... I like to see 500 0r less . It may not be the eye , it could be a bad fire , obstructions or a bad cad cell holder .. Burner would lock out with a short from TT and FF too .. carbon ,water or a frayed wire ..
    I have enough experience to know , that I dont know it all
This discussion has been closed.