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Wiring

NycwrenchturnNycwrenchturn Posts: 19Member
How do you wire 67 McDonnell miller manual reset on steam boiler . 24 volts and primary lwco is prone type 400

Comments

  • NycwrenchturnNycwrenchturn Posts: 19Member
    Can I just bring power to terminal 1 and 2 and then terminal 4 breaks my Tstat?
  • Jamie HallJamie Hall Posts: 12,132Member
    It doesn't require power. The terminals are plain switches, and it is wired in series will all your other safeties.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Mike_SheppardMike_Sheppard Posts: 643Member
    It depends on how it’s wired with your boiler. And if it’s controlling a feeder or not.

    It would be best to consult the manual.
    Never stop learning.
  • NycwrenchturnNycwrenchturn Posts: 19Member
    Manual stinks it only shows reg 67 not manual reset . Primary is controlling feeder I just need it to turn burner off
  • NycwrenchturnNycwrenchturn Posts: 19Member
    So which terminals do I run the limits through ?
  • NycwrenchturnNycwrenchturn Posts: 19Member
    Terminal 3 is the manual reset button . Then there is terminal 1 2 and 4

    Do I just run a limit through 1 and 2 and call it a day
  • NycwrenchturnNycwrenchturn Posts: 19Member
    ?? Anybody ??
  • DanHolohanDanHolohan Posts: 14,875Member, Moderator, Administrator
    I don't think you can do manual reset with the 67.
    Retired and loving it.
  • JUGHNEJUGHNE Posts: 6,532Member
    The 2013 M&M catalog shows a 67-M part number 149700, 67w/manual reset.

    I don't think the wiring would be any different with manual reset unless you want to connect an alarm to notify of boiler hard lock out.....not a bad idea sometimes.
  • NycwrenchturnNycwrenchturn Posts: 19Member
    I have a 67 that’s manual reset . Normal terminal 3 isn’t there anymore it’s where reset button pushes in . Can I just run my Tstat for boiler through terminals 1 and 2 ?
  • Jamie HallJamie Hall Posts: 12,132Member
    There is no wiring diagram in the manual? Odd. Well, if not, the principle is this: 1 and 2 are the terminals for the float switch. Normally closed. You want to wire it in series with your pressuretrol(s) and the other LWCO you mentioned. Sometimes -- but not always -- the thermostat is in this loop. More commonly, the thermostat goes to T-T on the burner control, and the safeties (of which this is one) are on another loop -- but there are a variety of ways to hook things up.

    The important point is that this is a safety control, and must be in series with all the other safeties on the boiler -- however that is done on your setup.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ZmanZman Posts: 5,532Member
    It is a simple double pole, single throw switch.
    1-2 and 3-4 will make or break simultaneously.
    If you are trying to disable the t-stat, what you are proposing will work fine. Most boilers have a string of safeties wired in series. typically your safety switch would be tied into that.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • JUGHNEJUGHNE Posts: 6,532Member
    I was taught years ago that a switch is determined to be labeled as NO or NC when it is on the shelf or still in the box without any outside influence applied.
    So I would say you are looking for normally open contacts and when the float is up in the water the switch would be closed for "normal operation". Loss of water would put the switch in the dry mode, as if still in the box or on the shelf, and the contacts would open shutting down the burner.

    The main thing is that during water loss or blow down the LWCO will shut down the burner. And even if the water returns to normal the burner will NOT restart until you manually push the reset button. It should be tested with the burner running.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,556Member
    Yes you can have a manual reset #67. It just has a manual reset switch instead of the normal switch a #11 switch or a #11m I believe.

    With either switch you wire terminals 1 & 2 in series with you thermostat, operating controls and other safeties, those are the low water cutoff terminals

    MAKE SURE ALL YOUR SAFETY'S WORK AFTER MAKING WIRING CHANGES.

    Terminals 3 & 4 are use for operating a feeder or for an alarm. You can't use a feeder with a manual reset so that is why terminal 3 is missing
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