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Knight boiler ?

Blackoakbob Member Posts: 252
I just started up a knb210 and the dhwpump does not start at the boiler starts up. the dhw pump runs when the boiler pump runs but not on a call for dhw. This causes the safety to lift and dump, and the unit goes out on Overshoot. I actually check with a meter as the dhw call goes on and the boiler starts to purge and lite but at no time does the dhw pump get voltage on the terminal strip. It will however run with the boiler pump on a heat call. Any ideas? At the moment I have the dhw pump running all the time and the heat call turned off because of another source of heat, as this does give me hot water. The only thing I have done is set the dhw temp to 140. Thanks in advance, best regards, Happy Veterans Day!


  • Larry (from OSHA)
    Larry (from OSHA) Member Posts: 717
    Have you

    made sure that the wiring is correct? It sounds from your description that the DHW pump is wired where the system pump should be. Does the system pump run with a call for heat and do both the system and boiler pump run with a call for heat? (only those 2?) I have a knight 80 myself.

    Did you by any chance change the settings for the amount of time that the DHW pump runs after a call? If it is set to 0 seconds, it won't run at all. (At least that is what mine does.

    What exactly did you do to set the DHW temp to 140?

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    What NOT to do with Knight settings...

    and I must say, I found out the HARD way.

    New install, going through the settings in the 5309 screens, came to the space heating (I section?) time delay settings, thought to myself "Self, this is a zone valve system, you don't want ANY time delay on that space heating setting..."

    Customer called me the next day to tell me he had NO dhw, and that the boiler was rocking n rolling and going off on high limit (internal autoreset). So, what did I do? I tried to call my good friend Greg Gibbs, who was teaching a Tn4 class all day long. In frustration, I wen tout an dpurchased a new mother board. Installed it and had the exact smae condition. Finally crushed my pride and I called the Lochinvar Service Line, and after a short wait, was connected to a technician, who said, "First things first. Did you set the Space Heat Pump time delay to ZERO?" To which I replied affirmatively. He said, that's where your problem is... Set it to 10 (seconds) and everything will be fine.

    He was dead nuts on with his diagnosis. I felt about 6" tall and $600.00 lighter.

    Lessons learned, don't jump to expensive conclusions, don't depend solely upon the shoulders of the local reps, and don't be afraid to call Lochinvar's 1-800 number.

    When Gregory PEX did call me back, to his credit, he knew exactly what I had done as well.

    So, if you DID change the time delay for the space heating pump to zero, go back and change it to a minimum number and your problems will go away.

    I know, it doesn't make ANY sense, but it is what it is... Engineering will be making a slight modification on the operating instructions, trust me on that.

    I should have gotten the technicians name who helped me, but in my field haste, forgot to write it down. I did call his boss and let him know how impressed I was with his service...

    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.
  • Greg Gibbs
    Greg Gibbs Member Posts: 75

    I will take the mother board back, no problem.
    Another cause for this could be the wiring on the
    the "underside" of the 120v pump terminals...
    From time to time, a wire will come out of it's connector.
    If this happens, you will not see 120V on the terminal(S)
    Lochinvar has taken steps to prevent this from happening,
    by adding a drop of solder to each spade.
    This helps hold the connection tight during shipping.
    The first batch of Knights had a few "lose wires"...
    however it is pretty rare now...but worth a quick peek.
    Maybe your electrician, or someone found a wire(s) that
    were loose, and plugged them back into the incorrect terminals.

    Blackoakbob, how did you pipe the boiler, are you bringing
    the DHW supply off the "boiler loop" as the I&O shows?

    -Gregory Pex
  • [Deleted User]
    Thanks Greg, but....

    I think I will hang on to this one "just in case". Ya never know when you might need one on a Sunday...

  • hot_rod
    hot_rod Member Posts: 22,141
    Check the wiring UNDER the terminal strip.

    I have seen a few with the wires on the wrong terminals below. if they are not crossed on top, I'd bet they are crossed below.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • tim smith
    tim smith Member Posts: 2,752
    Re: pride & tech support

    I have tried to get our techs to use tech support for efficient service. You 1st go through the basics of operation, check all connections, checked for build up, checked readings on pressure, temps, switches for normal operation etc. But with so much of the new high tech equipment there are minor issues that crop up quite often to tech support but we rarely see these, so when you call tech support and give symptom, you alot of times get a response like Mark got, did you check...., voilla, fixed in half the time you would have been screwing around trying to find this simple but not common to all equip. problem. Just .02 worth, Tim
  • Blackoakbob
    Blackoakbob Member Posts: 252

    Thanks for the tips, I did look under the board, although just to see if there was a wire there. It is odd that the dhw pump runs when the boiler pump runs but not when the dhw calls and also during the heat call, if I close the dhw stat the boiler pump will drop out and the dhw pump will stay running. The only parameter that I changed was the dhw temp, partly to try to stop the boiler from jumping up and down because the dhw pump wasn't running and the boiler had run up to 91% and partly because the boiler is large for the dhw and system load and was sized for the unexpected addition of snowmelt. I did pipe it like the book says, as a separate load under or before the boiler pump and it is working until I get back there. I'm off to Orlando on Tuesday morning,with youngest daughter and grandson, in search of Barney. Therefore I don't want to mess with it 'til I return. Thanks again, I can always count on some great replys from some of the most knowledgeable people in the business. best regards,
    blackoakbob Veterans Day all I can say is " Your welcome, it was a time ago and another unpopular war."
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