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LWCO: Float vs Sensor

A friend of mine was replacing a boiler today.  It was a 2 year old Steam Burnham I helped him install.  He said the float got stuck and no one checked it, so it cooked. 

I always thought low water cut outs were things that helped you sleep at night, not keep you up.  Is one style better than the other?


  • LWCO

    Did he test it once a week?
  • Al Letellier_21
    Al Letellier_21 Member Posts: 402
    lwco, which is best

    As Rod said, was it blown down weekly. I believe in probe type as you dont' have to flush them down and I've seen so many failed boilers due to lack of maintenance of the lwco by both the owner and the service company. However, you should clean the probe annually when the boiler maintenance is done. It can foul as well and give a false signal.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    edited February 2010

    Either one must have proper service.

    The probe type can act up and keep the boiler on when it shouldn't be.

    I like the float type but seldom install them on new installs because of the cost.

    The advantage of the float type is the burner will stay on while it is adding water.(steam)

    If your boiler is on the small side and it is cold out the ten minutes that it is off every hour while it is adding water may be enough to not heat the house up to setpoint.
  • shoudabeenaplumba
    shoudabeenaplumba Member Posts: 74
    I'm sure he didn't check it

    How could a float keep a boiler on longer than is should?  I thought it was just a NC relay that broke power to the burner. 
  • Big Ed_4
    Big Ed_4 Member Posts: 2,696
    Steam Leaks

    Their must be a few leaks in the system as well .... When Loosing steam the system must make up with fresh water … Water after turning to steam would leave behind minerals or what is call solids ... This would gum up the workings of a mechanical low water cut off .. Steam leaks cost you money , burns more fuel and corrodes the system ..

    Steam is a hand on system , it needs maintenance and checked regularly ....
    I have enough experience to know , that I dont know it all
  • Big Ed_4
    Big Ed_4 Member Posts: 2,696

    Solids collect the macanical low water cut off and prevents the float from falling .. Should be flushed when burner running to make sure burner turns off ..

    Sometimes the switch would fail, could be improperly wired , or jumped out for the wrong reason ..
    I have enough experience to know , that I dont know it all
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    edited February 2010
    More than a few times

    I've repalced many a steamer and got the " deer in the headlights " look from the customer when were done .......... after explaining the float lwco needs to be flushed once a week . Alot of them come right out and admit they never did it before .

    Now we install mainly probe style . And 2 is better than one . Cheap insurance in my opinion .  
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