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Knight boiler problems



  • Leisole2Leisole2 Posts: 23Member

    I did them off my phone and they flip for some bloody reason.
  • IronmanIronman Posts: 5,012Member
    edited November 2013

    As others have pointed out, please realize that a proper cleaning involves removing all the debris between the sections. As Steve mentioned, a feeler gauge or an old credit card work well. You've got to get out everything in the crevices.

    It should also be confirmed that there is proper flow through the water side of the heat ex. and there's no scaling.

    If your issue(s) aren't corrected, you're headed for a heat exchanger failure soon.

    Please post a pic or two of the burner.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Leisole2Leisole2 Posts: 23Member

    I will post a few pics tonight with hopefully a fairly detailed look throughout the system. I need to take the front plate off and find my snake cam.
  • ZmanZman Posts: 4,868Member
    Be sure...

    Be sure to inspect the venturi and all the parts on the intake side of the boiler. Cross contamination can destroy all sorts of things.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • solradmansolradman Posts: 47Member
    check the burner

    Check the burner cylinder holes to see if they are clogged.  The cylinder has dozens of small holes around it.  They are pinhole size and may need cleaning also.  I've seen as much as half of them clogged and this will affect the air flow.
  • MikeJMikeJ Posts: 103Member
    blower wheel

    A little recap, you have clean the heat exchanger, checked the vent pipes, redid the outside vents. and

    Still having problems.

    What does the blower wheel look like on the inducer motor? If you did or do have discharge air being suck in, the blower wheel will not look good. Do you have a picture of the impeller? you may not realize how bad it looks till you get the new one and compare.
  • Steve WhitbeckSteve Whitbeck Posts: 669Member

    The new blower will come with the wheel - it is a complete unit.
  • Leisole2Leisole2 Posts: 23Member
    Pics of blower, burner, HX

    I've posted some extra pics of the blower, burner, HX and exhaust as requested
  • IronmanIronman Posts: 5,012Member

    From what I'm able to see, it sure looks like that burner is plugged in several places. That would causes the blower to over-speed in order to compensate.

    I think you need a new burner.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Leisole2Leisole2 Posts: 23Member
    edited November 2013
    Could I take the burner out and test it

    Could I disassemble the air arm, remove the burner unit, unhook the ignition and test it, or am I asking for trouble?

    The parts and labor have now added up nearly to the cost of the boiler!
  • IronmanIronman Posts: 5,012Member

    You need to replace the burner if it's as plugged as it appears in the photo.You may find that you don't need the blower after doing that. Then you could return the blower you ordered if it's not been installed.

    I may have missed it due to the length of this thread, but where's your tech? Does he really understand how to service this, or any other mod/con? If we can see these problems through the pics you've posted and from the info you've given, why hasn't he when he's been on site?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • GordyGordy Posts: 9,264Member
    Great thread

    On why yo,u need to maintain a mod/con properly!
  • Leisole2Leisole2 Posts: 23Member
    I'm not sure he is a part of this site.

    I never asked. I'll ask him when comes back.
  • IronmanIronman Posts: 5,012Member

    As in your job site, your house, etc. Not this website. Though, that would do him a world of good to come hear on a long term basis.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • IronmanIronman Posts: 5,012Member

    To that, Gordy.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Kenny Greene_2Kenny Greene_2 Posts: 15Member
    Fan Hi Speed lockout

    I had the same problem with a KBN399. Called tech support and they advised me that it could be the board or the blower. No way to diagnose unless you bought their special tool.

    I work on boilers and commercial water heaters from all manufacturers and this is the only one that requires a special tool to diagnose a blower circuit.

    Not sure what is going on at Lochinvar, but they certainly are not the company that they used to be.

    While the tool was not expensive, I could not wait as the boiler is the source for domestic hot water year round.

    Installed a new board and blower. Problem solved temporarily. Upon start up, the heat exchanger leaks when cold.

    I will address this in another post.

    Will never purchase or recommend Lochinvar.
  • Leisole2Leisole2 Posts: 23Member
    Current Status

    The new fan has been installed and the system is working. I was not here for it, but the new pro checked out the burner and said it was fine and the cleaning I did was pretty thorough, but he says the burner and HX may not last nearly as long as it should due to the junk in the HX and on the burner. I watched it through several cycles and it seems to be performing fairly close to our previous nominal state.
  • smklinsmklin Posts: 67Member
    low fan lock out

    Had a problem on a 399 .Called tech support they told me to replace the fan. So i played with it a little bit it seamed like the fan was partly ceased . Took it apart and replaced a bearing in the fan housing. I picked up for like a buck .Put it back together . Have not had a problem sense . I own the boiler.  .

  • Mark EathertonMark Eatherton Posts: 5,844Member
    When you serviced this combustion chamber,,,

    Did you run a credit card in between the gaps of the heat exchanger? Or did you just vacuum out as much of the crap as you could? Did you use CLR or something to clean it as well? Did you power flush/vacuum out the condensate disposal system?

    There is a LOT more to doing a full and proper service to these things than meets the eye. If it were properly maintained on a yearly basis, you wouldn't have to resort to such drastic tactics (credit cards, flushing etc) but when they go that long, the problem goes much deeper than you can see with your eyes.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Leisole2Leisole2 Posts: 23Member

    I used a silicon knife and followed all of the gaps twice; once after the second vacuuming and one after the flush. I used only water under hand pump pressurization for the flush. I also rechecked the whole system using an inspection cam i have, inlcuding the condensate line. Lastly, I vacuumed one more time with a nylon ended slot brush.

    I hope I was fairly thorough, but I am more cognizant now of the potential problems.

  • bld999bld999 Posts: 43Member

    As Mark pointed out, using CLR or similar helps cut the hardened crud. A spraybottle of Lime-away is about $6 from a drugstore and is enough to clean 2-3 small boilers.

    What type of camera did you use?
  • Leisole2Leisole2 Posts: 23Member

    Sorry I didn't get back to you. I had to go out of town for a few weeks. I have a 16' waterproof USB camera I use for plumbing issues. I will go back and clean it again on a warm day with CLR.

    The boiler is nominal as of now, but the reroute of the vents did not go well. We had high winds last week, and I came home to a downed tree limb that knocked off the new vent.

    We will be repairing that this week.
This discussion has been closed.


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