Surging, carryover and skimming

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Posted by jtown on October 01, 2001 at 12:29:22:

In Reply to: Water Line Problems in Steam Boiler posted by Evan Williams on October 01, 2001 at 11:34:04:

SURGING up and down of the water line is usually due to impurities(including cutting oil/or coatings for storage in new blr) floating on the water causing the surface to bubble like your washing machine in simple terms. The gage glass goes up and down due to these big bubbles forming and breaking. You will also get CARRYOVER, these bubbles carried up into your steam mains. This lowers your waterline and then your auto-feeder opens and adds water. Then when the condensate comes back down it floods the boiler. These symptoms can be caused by overfiring and/or poor near boiler piping, Carryover from the lack of vertical rise, undersized risers and headers to separate water from the steam or lack of an equalizer to allow the water to drop back from the header. Gas boilers rarely get the firing rate changed - you can check it by timing the meter and getting the Btu/hr while only it is burning gas. Since yours was working, your case sounds like the afore mentioned. SKIMMING the surface should be done. Some boilers have a big pipe plug (center of DHW coil plate?) at the waterline. Or remove the gage glass, safety etc and gently boil the water while letting it run out the hole (through an added pipe nipple into bucket) Skimming can take quite a while so take provisions. The bigger the hole the better the stuff will go over to it. Dump the boiler a couple of times first. That will leave some on the walls. Manually operate the water level and burner.

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