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Knight info...

Hvacman Member Posts: 159
My Knight locked out with an odd message: "Sensor 1 Open" I've seen this on one of my commercial installs when the spade connectors under the terminal box became loose but that is not the case on my own Knight. Anyone have ideas?


  • Yep...

    Under the cover, you will find the sensor has a nylon zip tie holding it firmly in the well. Cut that tie loose and move the wire so it comes out of the well straight and your problem should be resolved. THe factory is aware of this issue...

  • Hvacman
    Hvacman Member Posts: 159
    Hey, thanks...

    Is "sensor 1" the inlet, outlet, or high limit sensor? I'm running down to the basement now to free up those tie wraps... Is a new sensor indicated or will this cure the situation?

    edit -------->

    Heh! Answered my own questions... The high limit is in a threaded bung, inlet is in the back, outlet is sensor 1 because as soon as I cut the tie wrap I got the fault again! I will handle it gingerly till my distributor can get me a new one...

    Thanks again for the assist.
  • Tom Hopkins
    Tom Hopkins Member Posts: 552

    It is the supply sensor...Lochinvar sends an extra sensor with the boiler (Inside of the plastic bag in the front cover), it is to be used on the supply of the system.
    In a pinch and if Mark's idea does not work, you could use it as a temporary replacement. -Greg

  • Gerry May_2
    Gerry May_2 Member Posts: 7

    The Knight boiler uses the same sensors as Tekmar. At least they are similar in appearance. They are both 10K at 77 deg F. The problem with the supply/return sensor is that if you overtighten the zip tie, after a while, the sensor will be crushed. If you take that sensor off, you'll notice the deformation of the sensor. I have had two repairs where this has happened.(other installation contractors, of course. In addition, I was at a Tekmar training course in Vernon, British Columbia.....As part of the training, they warn of the overtightening of the zip tie......You know plumbers.... Anyways, when we install these systems, we usually cut in a "Tee" fitting in the system loop and install a well fitting. We then install the sensor within the well. We use a sensor heat transfer paste made by Honeywell...It's really good stuff. And...You really get a good reading of the actual water supply temperature rather than just a surface temperature of the pipe.....Way better

  • Hvacman
    Hvacman Member Posts: 159
    System sensor...

    Hi Gerry,

    Yep, I've got my system sensor in a well, this boiler also uses a supply, return, and high limit sensor mounted to the manifolds within the boiler jacket. The sensor in question has it's leads bent over at a sharp angle at the top of the well and the wires are secured with a tie wrap from the factory... The sensor doesn't deform as it is in a well but it looks like the leads can't take the sharp bend. I have a number of options for spares, the Honeywell p350/ s350 sensors also match... so far so good for now though. Thanks for the input.
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