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"Resting Water Level"

Have a WM EG-75 boiler... installed in Oct 2009.  The old boiler (75+ yrs) was removed.  I'm studying things carefully & trying to understand it's operation.  It heats fine, but the Low Water Cut-Off (LWCO) kicks in often, as the water level drops during operation.  I understand the principles of what's taking place here.. the water turns into steam, leaves the boiler and takes a while to return.  The LWCO is there to protect the system from getting too low and "dry-firing".

However, the "resting" water level, as I measure it in the guage glass is about 1" below what Weil-Mclain's book says it should be.  So, it this something to be concerned about?  By resting, I mean when this thing is cool and hasn't been running for an hour or more.

Is something out of adjustment??


  • nicholas bonham-carter
    low water level

    fill up the boiler to the correct level, and use a clothes pin clipped to the sight-glass rods to mark the level. disable any auto-fill, and see how long it takes for the water line to come back, after the burner has stopped.

    there are a number of ways in which water can be hiding in the system. the water can rise up in the returns due to over pressure, and bad venting, or there may be a horizontal pipe slightly above the waterline, which can hold a lot of water when the return pipe level rises with boiler pressure. there is also a lag between steam-up and condensate return, but the slowest returns would always point to a return/pressure/venting problem.--nbc
  • jim s_2
    jim s_2 Member Posts: 113

    Is it probe type or float?

    Reason being is some electronic probe types stop the heating cycle intermittently in order for return water to make it back to the boiler.
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