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Replacing LWCO & Sight Glass

nznz Member Posts: 89
Last heating season, when doing my weekly LWCO flush, the LWCO (McDonnell Miller 67) started having an issue where it wouldn't shut off the auto-feeder. If I whacked the side of the switch, it would stop.



I'm looking to replace it, but I don't know if I need the millivolt model or just the regular 67. I've attached a few pictures - can someone help me identify what model I need? There is a transformer on the wall.



Also, the drain valve from the sight glass fell apart when I tried to turn it - so I'm looking to replace the sight glass. Not sure where to start with this - I know you can buy kits - does anyone have any recommendations?



Thanks,



Nick

Comments

  • fixitguyfixitguy Member Posts: 79
    MM67

    I have been using these lwco's and the microswitches for years on millivolt systems. the top terminals are for the millivolt circuit and the bottom terminals are for the water feed, either 24v or 110v. Just make sure that there is no jumper from top to bottom.
  • Hap_HazzardHap_Hazzard Member Posts: 1,558
    If you need a replacement

    I have one of those that only has a couple of seasons on it. If you're near SE PA you can have it. It's too used to sell but too good to throw out.



    btw, my memory might be shot, but I thought one set of terminals was NC and the others were NO--that is, break on low water vs. make on low water (to signal an alarm), but you could flip them over to reverse them. Am I imagining this?



    If you have a transformer, you have a 24 volt control circuit. That's what I've got. Millivolt' aka powerpile, systems are a whole other beast. Be glad you don't have one.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • fixitguyfixitguy Member Posts: 79
    Beast indeed!

    Millivolt systems ROCK! Who will have heat when the power goes out?
  • Hap_HazzardHap_Hazzard Member Posts: 1,558
    I will!

    Can you say "standby generator"?



    I'll have heat AND lights. Hot coffee too. Life is good! :-)
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • nznz Member Posts: 89
    No Millivolt

    Ok, it sounds like if i was to order a replacement LWCO...I would order the standard 67 and not the 67 with the millivolt switch.



    So this one:



    http://www.pexsupply.com/Mcdonnell-Miller-149400-67-Float-Type-Low-Water-Cut-off-Steam



    Right?



    Just want to avoid doing an online-order return, such a pain.



    Thanks in advance.



    Hap_Hazzard - I'm in Detroit...so thank you very much for the offer, but I'm not really nearby you :)



    Nick
  • JStarJStar Member Posts: 2,668
    67

    My guess is that the millivolt model comes shipped without a jumper.
  • Hap_HazzardHap_Hazzard Member Posts: 1,558
    We almost forgot about the glass gauge.

    I just ordered one of these: http://www.pexsupply.com/Conbraco-20-104-00-1-2-Conbraco-Gauge-Glass-Set



    It does not look like the picture, but it's a well made set. It has a petcock (which I replaced with a ball valve) and check valves.



    Don't get one of the "imported" ones--I made that mistake last year. That's why I had to order this one.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • nznz Member Posts: 89
    Thank you

    Thanks for the recommendation!
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