Results 1 to 11 of 11
  1. #1
    Join Date
    Nov 2003
    Location
    Stamford CT
    Posts
    33
    Boiler in question is a 2.5 million btu weil mclain. One t/stat and no zones. From what I understand it's about three, maybe four years old.
    On a call for heat, The boiler fires and runs for about four minutes. It's shutting off on a pressure safety (3 psi).
    I'm assuming, that under normal operating conditions, It should be at 1.5 to 2 psi.
    Boiler water in sight glass is filthy brown. I have no history on the service of this boiler. It' safe to say, It's been a while.
    So, my questions are; Why are there three pressure controls? Are they redundant safety's? First one is set at .5 psi cut in with a 3psi cut out. Second one set at 2psi cut in with a 4.5psi cut out. Third one is manual reset at 5psi. Is there any way to adjust pressure on the boiler? How about temperature?
    My sight glass is a bit over half way. Is it safe to say that my water feed is not over feeding?
    Boiler has two low water cut off's. One is a combo feeder and the other is a manual reset. I blew them both down and got a lot of nasty brown water. Even some clumps towards the end. Refilled the boiler and still had same high pressure problem.
    Tomorrow, I plan on skimming the boiler and blowing down the low water cut off's until it comes ot clear. I'm hoping this solves the problem.
    Any input would be greatly appreciated.

  2. #2
    Join Date
    Nov 2003
    Location
    rhode island
    Posts
    39
    try eight way boiler treatment,,,3 trolls,,,,1st highlimit manual,,2nd operates high low fire 3rd operating pressure

  3. #3
    Join Date
    Nov 2003
    Location
    rhode island
    Posts
    39
    try eight way boiler treatment,,,3 trolls,,,,1st highlimit manual,,2nd operates high low fire 3rd operating pressure

  4. #4
    Join Date
    Dec 2002
    Posts
    603
    A high-limit safety control that will shut off fuel to the burner when the pressure in a steam boiler reaches a predetermined maximum not to exceed 15 psi gage on alow pressure steam boiler or when the temperature in a water boiler reaches a predetermined maximum not to exceed 250 F. The high-limit safety control mechanism shall be in addition to the operating control required and manual resetting of the high-limit control or of the fuel valve or of the emergency control system shall be required to place the boiler back in operation after it has been shut down due to the operation of the high-limit safety control. Most lo pressure I have worked on usually run about 8 to 12#
    It also sounds like you need a good wter treatment service and proper and consistant service.

    [Edited by shogun8 on 12-21-2005 at 10:29 PM]

  5. #5
    Join Date
    Jan 2005
    Location
    steeler nation
    Posts
    2,071
    sounds like you have low fire,high fire and a manual reset high limit. water treatment may help .

  6. #6
    Join Date
    Jan 2005
    Location
    steeler nation
    Posts
    2,071
    wow that was my one hundreth post 20 plus thousand more and i will catch diceman

  7. #7
    Join Date
    Nov 2003
    Location
    Stamford CT
    Posts
    33
    thanks guys

  8. #8
    Join Date
    Jul 2004
    Location
    NJ
    Posts
    108
    Being that it is a Weil McClain, Series 88 I imagine, it probably has the pressure switches in a tap in the front of the boiler. The way the pressure switches are mounted stinks. If you remove all the pressure switches and the gauge you will probably find they are all clogged up with brown crud. Take the whole mess off and clean it out. The switch set at .5-1 Psi is your Hi-Lo switch and it probably isn't functioning. The boiler then runs on Hi flame too long and short cycles. Don't use oil based cleaners in it or you'll be replacing those crappy seals between the sections in about a year. I hate those boilers.

    I usually take the whole steam trim off the front tap of the boiler and put real pigtails and propper steam trim off a high tapping. Either way you really need to convince the customer get the water treatment in line and fix any leaks or that boiler won't last long.

    Rob

  9. #9
    Join Date
    Nov 2003
    Location
    Stamford CT
    Posts
    33
    I skimmed the boiler for a couple hours today until it ran clean.
    It seems to be running pretty good. A cycle is about eighteen to twenty minutes now. The building is nice and toasty.
    TXV, there are no pigtails on the pressure conrtrols. I did'nt take them apart to check for crud, but I think you may be right.
    The skimming and blow down seemed to do the trick.
    I do a lot of service for this customer. This is the only steam that they have. I will keep a close eye on it.
    Thanks for the help guys, keep it coming.

  10. #10
    Join Date
    Nov 2003
    Location
    rhode island
    Posts
    39
    here a thought ASME coderequires 3\4inch piping to the pressurtrolls with a plugged discharge line,,,as a boiler service rep i can tell you .all steam boilers over 600mbh are required to have manual reset pressurtrll an 3-4 control manifold,,,ask any boiler inspector

  11. #11
    Join Date
    Jul 2001
    Location
    Buffalo N.Y.
    Posts
    1,571
    What you have in way of controls are.
    cut-in, cut-out and the third is your hi-limit with manual reset, after that your safety valve will pop.
    The hi-limit has to be a manual re-set.
    Only the hi-limit is a safety contol the others are operating comtrols.
    A pigtail may not be needed if the controls are piped in such a fashion as to have an inverted U configuration.
    This method keeps water in the lower piping and keeps live steam from contacting the controls.

    You can adjust pressure( temp and pressure are relative) by the two operating comtrols.
    You have to look at the system through-out to dictate operating parameters, just can't advise through a forum situation.
    One stat and no zoning for a big boiler is a headache, the boiler is sized for largest load anticipated during the winter months and will usually short cycle during other times.

    The condition of the overall system, boiler and related piping to and fro will need to be looked at, you could be bringing back dirty water.
    As to cleaning, this take some knowhow, damage by using too much boiler cleaner is a likely concern, a hi alkaline level can and will cause problems, but if used correctly and at the proper levels can be benificial overall.
    One concern is the condition of the piping, older systems have a tendacy to show leaks when cleaned aggressivly with alkaline products.




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