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Water level

... say that the water that is leaving as steam isn't being replaced fast enough at the higher loads. It could be that the pump is worn out, running backwards (if it's 3 phase), or it's not kicking-in fast enough. The first thing that happens when relatively cold feedwater hits the boiler, is that it collapses some of the steam bubbles. This intially drops the water level in the boiler, just for a moment. If the boiler is already on the edge for a low water trip, that can be just enough to tip it over.


  • Rob Raynor
    Rob Raynor Member Posts: 3
    Smith 4500 water level

    I am working on a mystery of "steam" that has my keister kicked. It is a Smith 450 Mills 18 section steam boiler with Power Flame burner. When I get the burner to fire at 50% and higher on the firing rate, the water steadily drops right out of the gauge glass and trips the feed pump and then the low water cutoff, finally tripping the manual reste low water cutoff. This happens every cycle unless I keep the firing rate below 50%
    The boiler was cleaned with TSP and boiled out over the course of a full day. We skimmed all the way up into the supply drum, so the entire boiler and drum were flooded for the skim. The burner at high fire (when I can get it there for only 3 to 4 minutes before it begins to steam, at which point I lose the water level) is running at 450 degree gross stack temp at 12% CO2 and 6.5% O2 with 11 PPM CO. It doesnt appear to be overfired at all.
    The supply drum has a 4" equalizer line at the back of the boiler, tied into the end of the supply drum per factory specs. I tried to valve off the boiler feed tank to eliminate the idea of the water being pushed back into the tank. Problem still exists. My last idea is to valve off the main steam supply line gate valve and see if the water remains iin the boiler and if I can build a head of steam. (have been unable to reach 1/2 lb. so far.) The valve unfortunately is 35 feet in the air with no chain operator to open or close the valve.
    Does anyone have an idea where I may be losing the water line to. I hope I gave enough info on this question to spark some thoughts. Any response would be more than welcome. Thanks in advance for any help.
    Rob Raynor. (Connecticut Contractor)
  • Rob Raynor
    Rob Raynor Member Posts: 3
    Water level

    Thats a great idea for me to check on Tony. I appreciate it very much. Its a brand new boiler and boiler feed package but that does NOT mean it is feeding at the evaporation rate plus 50% I will lok deeeeeper thanks! *S*
  • Guy_6
    Guy_6 Member Posts: 450
    Mills 4500

    I will forward this thread to our engineering dept. I am still learning the ins and outs of the Mills products, but the history (and answers) are in Westfield MA. If you want to contact me directly, I will do whatever I can to help.

    Guy Woollard
    Mestek/Smith Boiler/ Mills
    [email protected]
  • Rob Raynor
    Rob Raynor Member Posts: 3
    Water Level

    Thats a wonderful offer Guy and I appreciate it tremendously. A little more info for the thoughts. The feed pumps are 20GPM @ 20psig which exceeds the boiler evaporation rate. I am beginning to suspect a dirty water condition even after 5lbs of TSP. The old boiler was dirty and the returns may be contributing to the general water conditions inside the boiler. Have worked on quite a few Mills and have not had this problem before. By NO means do I believe it to be related to Smith in any fashion. I KNOW in my heart its something I am missing on this site. Thanks again for the offer!
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