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Rob_22-2Rob_22-2 Member Posts: 10
I'd like to add an LWCO to a Weil-McLain CGS-6 NG boiler.  I'd prefer a probe, but I am unsure if I need 120VAC or the 24V version and exactly how it should be wired on the control board.

Also, is this a 'universal harness' control board?



  • Good move,,,

    Did you have any particular "make" in mind?

    I usually use the Taco probe-type, you can go line voltage(120), or 24v LTR0243U-1 with the UTC harness should just plug right-in.
  • Rob_22-2Rob_22-2 Member Posts: 10


    Thanks for responding. Actually I'm looking at the McDonnell / Miller, 'Guard Dog' (RB-24 series (E-S)). It is to be installed in the 3/4" portion of the supply line tee. My difficulty is in determining its' position on the CGs control board. Weil McClain specs don't specifically indicate any arrangement and I'm not exactly sure if the 'universal harness' will work on this control board. A look at their wiring schematic was not exactly helpful.

    The other consideration I've come across is Weil McClain may deem that a LWCO is not mandatory for the boiler, but theory says put one in.

  • CMadatMeCMadatMe Member Posts: 3,066
    Just Wire

    The low water cutoff to shut down power to the boiler. Could easily just wire it to shut down the boiler at the junction box. So use a RB-122.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Rob_22-2Rob_22-2 Member Posts: 10
    Taco Part #

    After debating everything one last time I decided that Dave's method was the easiest. It should be noted that the LTR0243U-1 comes with a five foot harness for the United Technologies control boards. I found a great retailer on the web and came in at a very good price point (much lower than all other vendors who sold at about $125).

    The method seems the easiest because the harness splits between the additional limits pwr (factory harness) and control board.

    I'm installing this and a FasNseal SS venting system next week. I'll post one more time on this topic to let you know if this does the trick. The harness should make the run to the tee installed in the bypass but I'm not sure if there is a knockout that allows for the shortest route. 

    We passed the gas line pressure test last month with the County inspectors and we will be turning gas on in September.

    One last hurdle; Weil McLain had a recall on the CGs series about 2 years ago. The serial number is on the unit and I had not written it down prior to  installation. I will soon find out if this boiler was on that list. Weil McLain does have a fix if it is.

    Thanks to everyone and especially to Dave who lead me to the most expedious solution.

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