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Posted by Tim D on October 19, 2004 at 17:45:58:
In Reply to: Re: water column and water level controller posted by Bob D. on October 19, 2004 at 05:32:39:
: This one got my attention REAL FAST, because I've got three (3) brand new Cleaver-Brooks 600 HP firetube units, also with MM-150s and MM-194s, and ALL THREE have MAJOR water column surging problems (3-4 inches in seconds). I've put a surge column on one unit, and installed CB's recommended "surge baffles" in another unit. They both helped a little, but just to mask the surging. No root cause has been identified. Very low loads and we still get occasional ALWCO manual-reset trips. At higher loads, they're only good for a few hours before tripping. There is no chemistry or oil problem, and there is no major load swings (building heating). Cleaver-Brooks has "washed their hands" of the whole thing, the mechanical design team is clueless, and the mechanical contractor is ready to jump off the roof! I think the 150 and 194 relative elevations should be spread more, but other than that I've got my hands tied. Does anyone think that maybe there is a common thread with all these problems? I'm open to anything right now.
I would suggest surface skimming boiler for an hour. Check initial surface skimming water quality for oil or milky oil/water. We had same problem with level surging after even minor plumbing work.
I plan to install (2) new MM150S on a two low pressure boilers later this year. These were recommended over the MM67lwco which are allowing feed pumps contacts to stick on periodically. The MM150S are rated for electric feed pumps and have a larger differential.
I will have to see if we have problems when we install.