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Low Boiler Water Level

New Weil McLain LGB5 steam boiler with a new McDonnel Miller 150SMD LWCO and boiler feed pump controller.  I took great care to install the 150 at precisely the height spec'ed in the Weil McLain installation guide.  The pump controller consistently maintains the boiler water level 1 1/4"  below the spec'ed waterline when the boiler is not firing. ( Yes, I've triple checked my math and the instructions.)

2 Questions:

Assuming I can read a tape measure and do basic math, is there something that could this other than inaccurate instructions or a faulty, factory setting on the 150?

Since this new boiler has a relatively small water capacity, is it advisable to pipe the 150  1 1/4" higher to increase the amount of water in the boiler?


  • DavidK_2
    DavidK_2 Member Posts: 131
    I'm no expert,

    but the low water feed is a safety device. It should be set to feed water before the level gets dangerously low. You do not want to  set the low water feed to feed water at the operating level - otherwise when the boiler was steaming, it might start feeding water and you'd end up with an over filled boiler.

    The low water feed is a safety device. It is not a replacement for a human making sure the water level is right. At least, that is the way I see it.
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