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Should be simple HSI location

I have a trailer CMF 80 gas furnace that will not sense flame. I used a new HSI (carbide) listed for a nordyne. Control (UT) locks out after 2 seconds every time. I’m following another half tech half neighbor who messed with it. I am wondering if I simply have the ignitor in the wrong spot. It is mounted under the burner. I have a new control I will try tomorrow but maybe there is just a bracket that should locate it above the flame??? Not under??? Seems logical. Any thoughts? Popular furnace I know someone has noticed its location


    HVACNUT Member Posts: 4,592
    Do not under any circumstance relocate the HSI from the factory location.

    Does the HSI glow?
    Does the burner ignite?
    Is the HSI also the flame sensor? If not, have you checked resistance on the FS?

    You might want to get a qualified tech there who can go over the whole furnace for you, do a combustion test, and make sure it's safe.
    delta TSteve Minnich
  • I am the tech. 😱. The problem is I don’t know if the previous people who messed with it maybe left out a bracket. So I don’t know if the ignitor is in a good place to sense flame. Yes it senses flame from the HSI. It ignites great every time. It’s hard to remove the leads after fire up ant test the amps before it locks out. I also don’t know what reading the control requires. Being a popular furnace I didn’t know if someone knew the proper location.
  • ratio
    ratio Member Posts: 3,174
    Shouldn't need to hot swap the flame sense wire, use one of these.

    Huh. It's marked discontinued & even ePay doesn't seem to have one. That's odd. Pretty sure I've seen one on (or something identical) on the shelf at the supply house. Guess I better snatch it up, I can't seem to find anything closer to one of these than the Fieldpiece µA head.

  • Oooooh, fancy. It ended up being a bad control anyway. I have a tendency to overthink things
  • GBart
    GBart Member Posts: 746
    edited December 2018
    HSI is not a good flame sensor, most use a flame rod, impossible to test, and as the silicon carbide ages it forms a barrier that cuts the signal.