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Lochinvar Knight KBN 399 Heat Exchanger Failure

Had the heat exchanger fail on a Lochinvar Knight KBN399. The heat exchanger started leaking on a cold start up after only three years of service.

Called Lochinvar and was informed that the heat exchanger is covered under warranty.

This was great news as this is one of my best customers.

We next called the supply house wher we purchase Lochinvar products and ordered the heat exchanger. They were very prompt in completing the order and assured me that I would see the part soon.

I next received a call from the supply house informing me that I needed to send a P.O. in the amount of 9000.00 to cover the heat exchanger. I asked why and was informed that while Lochinvar would gladly ship a new heat exchanger, they would need to inspect the failed heat exchanger to determine the cause of he failure. If determined that it was not a defect in manufacture, I would have to pay for the new heat excahnger.

What is the cost of a new boiler, I asked? $8500 was the reply.

I called Leslie Hix , head of the Knight Boiler VIP program since it's inception, and to date she has not the time to return my call. Pretty Arrogant.

I called and talked with the head of the southeast region and was asked to send pictures. After their review, they informed me that the failure was most likely due to refrigerant leaks from nearby chiller equipment and a warranty claim would most likely be denied.

I have never experienced or heard of this in the past. Has anyone ever experienced this?

I have attached pictures of the heat exchanger bottom for those interested in reviewing them.

Very disappointed in Lochinvar. Most of the people I talked to just said that Rules are Rules and there was nothing that could be done.

Take a chance on a heat exchanger that costs more than a new boiler? I don't think so/


  • GordyGordy Member Posts: 7,122

    Could have there been near by refrigerant leaks?
  • BurnertechBurnertech Member Posts: 6
    edited November 2013

    I deal with the giannoni heat exchangers a lot. Especially in armor sand knights, I service one property that has 50+ of them. I have never seen one fail like that. Could there be a refrigerant leak nearby? (Edit) at first I said no way on 9000 for the heat exchanger for a kbn399. Just checked the pricing that's about right.
  • Steve WhitbeckSteve Whitbeck Member Posts: 669

    Is this on propane?

    This leakage is caused by erosion due to highly corrosive condensate.

    I have seen this happen before.

    when these boilers run on propane they build up a mud coating on the bottom pan. If the boiler has exhaust gas reversion the condensate will be highly acidic.

    That boiler had the bottom eaten out.
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,579
    edited November 2013
    Big holes

    This loss of water problem must have been masked by the makeup water system, as those holes are big. How often is this boiler serviced?--NBC

    PS there must be some sort of corrosive atmosphere around the boiler, as the many holes are not likely the result of somebody falling asleep on the production line.

    The question is what caused it? Is the exhaust/intake close to an outside condensing unit (with a leak)?
  • Kenny GreeneKenny Greene Member Posts: 15
    Lochinvar Heat Exchanger Failure

    Thanks for all of the replies and information.

    I also have many of the Knight boilers installed in the Atlanta market, and all have performed well without any failures.

    The boiler is on natural gas.

    It is mounted outside in a cabinet that also houses a chiller system. There is a wall separating the components, but with the amount of refrigerant related failures, I am sure that the boiler was contaminated with R22 gas.

    Looks like this was a poor design right from the start.

    The entire piece of equipment has been a miserable failure.

    I will be writing about the entire experience, in the future.
  • Mark EathertonMark Eatherton Member Posts: 5,592
    Unfair to the manufacturer...

    This piece of equipment was obviously abused due to the freon leak. This is the reason they don't just assume its their fault and replace it sight unseen.

    Any time you are making thousands of widgets, you can expect a certain failure rate, and I am positive that Lochinvar (along with every other manufacturer) has documented failures. It's not a matter of if, but more a matter of when, and then it comes down to the response of all parties concerned, from the rep to the manufacturer.

    My experiences with Lochinvar go counter to yours in many ways. If they are wrong, they will go out of their way to get it resolved. Trust me, this is not the first time they've lost a heat exchanger due to a refrigerant leak. Read their installation manual. IT's spelled out in black and white.

    I'd recommend replacement of the whole unit, because once burned, the burnt refrigerant byproducts become aggressive towards the electrical components, AND human beings (Phosgene gas...).

    And how about that refrigerant leak... Think the EPA would like to know how many pounds have been released?

    I stand by Lochinvar.

    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.
  • SWEISWEI Member Posts: 7,356
    When you replace it

    consider the WHN399 instead.  Given its location and history, I would also repipe the intake to use outside air. 
  • hot rodhot rod Member Posts: 7,208
    frustrating, no doubt

    but I doubt Lochinvar is turning their back on you.

    What about the supplier that sold you the boiler? Will they step up and cover the replacement $$ until the warranty claim is resolved? Seems they made a % on the sale and are in the link between you and the manufacturer.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Chain of responsibility

    What about the designer of this installation? He also is part of the problem.--NBC
  • LeslieHixLeslieHix Member Posts: 1
    Follow Up

    We understand your concern and will be happy to discuss this issue with you again.  Please feel free to contact John Sinclair, National Service Manager or Mike Lahti, Vice President, Sales at 615-889-8900.
  • Kenny GreeneKenny Greene Member Posts: 15

    I wanted to take a couple of minutes to clear up any misconceptions with my post.

    I have not and will never ask a manufacturer of equipment to replace equipment or parts not covered under warranty.

     I did want to find out if anyone had experienced this type of failure in such a short period of time.

     I was disappointed with my perceived lack of response to my situation from Lochinvar and the fact that a heat exchanger would cost more than a new boiler.

    When I referenced poor design, I was not referring to Lochinvar, but to the manufacturer of the packaged Boiler/Chiller Unit. I have several of the Lochinvar Knight boilers installed in the Atlanta area and all are performing well. They are used for heating and providing domestic hot water with an indirect tank. All of the units are on a maintenance program.

    I was also disappointed that the Lochinvar unit had a circuit board, blower motor and exhaust temp sensor fail previous to the heat exchanger failure. Could this also have been caused by the refrigerant leaks?

    I have condensing boilers of two other manufacturers installed in Atlanta. I called to ask them the cost of a heat exchanger that needed to be replaced because of a non warranty issue. One manufacturer quoted 20% the cost of a new boiler while the second quoted 50% the cost of a new boiler.

    I will replace the boiler and relocate it to a clean environment. I will also have to replace the 15 ton chiller that has had multiple failures and many refrigerant leaks due to poor workmanship.

    I did talk to Lochinvar again after their post on this thread. They assured me that they had read all of my emails concerning this subject.

    Thank you for all of the comments, it is greatly appreciated. Have a great Thanksgiving holiday.

  • Mark EathertonMark Eatherton Member Posts: 5,592
    Thanks for the follow up Kenny

    and yes, exposure to refrigerants will cause electronic components to fail, as well as regurgitating flue gases back into the boiler vesitbule.

    I can't speak to the replacement cost of a new heat exchanger because I've never had to replace one, but regardless, if you "fix" it, you own it, and if I am going to "own" it, I want it to be as close to new as possible.

    Good luck, and good eating!

    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.
  • JohnNYJohnNY Member Posts: 1,854
    edited November 2013

    I'm sorry you had a problem, Ken. There are 1 or 2 every year in my experience that have us wondering "Why me!"....but we get through them.

    For what it's worth, I've got a Lochinvar product installed where the air intake is near some a/c equipment in a mechanical area between two buildings in Manhattan.

    Upon Dept of Buildings' inspection, we were directed to install a refrigerant sensor and interlock to protect the boilers. I'd never heard of this being a problem but like many things in this industry, you either learn the hard way or get lucky enough to learn by others.

    I very reluctantly bought one of these:

    and my inspector was satisfied.

    That, along with this thread, has been a learning experience for me.

    As for Lochinvar, so far I've been very happy with their products and services the last three years or so that I've been using them. My rep is Wallace-Eannace and they're top-notch as well. I'd be very surprised to hear either party weren't making every effort to live up to the terms of their stated warranties/support, but it's a busy season now for everyone and I'm sure you can appreciate they have their processes to go through before they can hand over costly materials at anyone's say-so. It sounds like you're getting to a resolution, and that's a good thing.
    For private consulting services, find John "JohnNY" Cataneo here at :
    "72°F, LLC"
    Or email John at
    Or at Gateway Plumbing & Heating
    John travels regularly to out-of-state clients for consulting work.
  • tim smithtim smith Member Posts: 2,226
    edited November 2013
    Re: KBN failure

    Go to WHN if you have the option.
  • Steve WhitbeckSteve Whitbeck Member Posts: 669
    heat exchanger

    The heat exchanger didn't fail - the drum it is contained in failed due to chemical erosion from Freon contamination. Any stainless steel heat exchanger will fail if exposed to the same contaminants.
  • Kenny GreeneKenny Greene Member Posts: 15

    You had a good inspector. Thank you for the follow up. Hopefully we have helped others avoid this issue. 
  • Kenny GreeneKenny Greene Member Posts: 15

    Not sure what you mean?
  • Kenny GreeneKenny Greene Member Posts: 15
    Heat exchanger

    Technically correct and thank you for the clarification. Since the heat exchanger and tank are only available as one part assembly, I refer to the failure as a heat exchanger failure,
  • Steve WhitbeckSteve Whitbeck Member Posts: 669

    The Lochinvar WHN is a Wall Hung Natural gas boiler.

    Just make sure to get the new fire tube design. Much better design.
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