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McDonald Miller PS-801-RX2-24v low water cutoff not shutting the feeder off

drainsurgeon Member Posts: 5
Main cause of this low water cutoff failing to shut off the new feeder and what are the problems causing this, also I searched online for this model replacement and didn’t find one to buy


  • Jamie Hall
    Jamie Hall Member Posts: 16,306
    This may be an obsolete, discontinued unit. I could be wrong on that... (the PSE variant is the current one).

    The most likely problem is lacking maintenance, however. Ideally the probe would be cleaned at least once in a while.

    Could also be as simple as the LWCO and the new water feeder just not wired up properly to talk to each other...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 14,694
    Either that, or the valve in the feeder is sticking open.

    Check to see if there is still 24V at the "feed" terminal on the feeder when the LWCO switches back to its normal mode, allowing the burner to run. If so, the LWCO is bad. If not, the feeder is bad. In the latter case, the Hydrolevel VXT-24 is the feeder to get.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service