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Weil McLain U-control limits

Think of it like this, the manual reset limits are usually "Critical" trips which can harm or potentially cause damage. Auto resets are or can be the same, but if you are talking about circuit boards, the boards can also trip the system operation cutting off the firing of the unit or sometimes shut down everything. All manufacturers are different and incorporate what they want the problem trips to represent.

Mike T. I hope that made some sense....


  • Supply House Rick
    Supply House Rick Member Posts: 1,404
    Weil McLain U-control limits

    What actually happens when a limit to a Weil-McLain Ultra Series 3 boiler is triggered? There are manual reset and automatic reset options, I know. But what happens when either is activated? Does everything get shut off, or is just the firing to the boiler stopped? I.e., are the circulators allowed to keep running?
  • Supply House Rick
    Supply House Rick Member Posts: 1,404

    It made some sense, but I already knew that.

    What I want to know is what happens when a reset limit is triggered (either manual reset or automatic reset)? Does it shut down the entire system, or does it just turn off the fire?

    I put an aquastat on the supply to the radiant heat in slab zone of my house in case the boiler puts out water too hot for it. (I have not connected it to the U-control board yet.) I also have a hotter zone with Slant/Fin heaters, and a yet hotter zone for the DWH.

    What I would like to happen is for it to turn off the fire if that aquastat opens the circuit and to leave the circulators running (so that the water will cool down faster). If, instead, it turns off everything, it will be quite a while for things to cool down.

    The manual does not say what is turned off and what is left running when one of these limits is activated. See page 58 of the Ultra Gas-Fired Water boiler -- Boiler manual if you want to know what limits I am asking about.

    For the Manual Reset limits, it says it shuts the boiler down, but is silent about the circulators. For the Automatic Reset limits, it says nothing at all. I infer that it is the same as the Manual Reset limits, but since I do not know what they are, I do not know the answer to my question.

    I suppose I could set the limit on the aquastat down to 90F or something and set the thermostat up to 80F to get it to heat on a cold June night (not all that cold, but it sometimes gets under the Warm Weather Shut Down so I could actually make the system try to heat.

    It just seems to me that someone should already know the answer to this.
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