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Lochinvar Boiler System Pump Always On.

Hammertime Member Posts: 6
Hi guys,

I've installed a Lochinvar WHN110 using a traditional primary loop design in the mechanical room..

- I was always getting a Delta T High Blockout so,

- I have set the DHW setting from NORMAL to ZONE, as suggested in the manual,

- but now the System (radiant floor) pump is turning on during DHW call for heat, thus sending floor cracking temperatures into the radiant loops.. does anyone know how can I stop this?


  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Describe traditional primary design....

    It makes a difference, because the boiler should have 3 pumps.

    1 for the boiler loop, 1 for space heat distribution loop and one for DHW.

    How many do you have?

    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.
  • icesailor
    icesailor Member Posts: 7,265
    In Other Words:

    In Other Words,

    Did you read and follow the manufacturers "suggested" near boiler piping?
  • NYplumber
    NYplumber Member Posts: 503
    Rev A

    Is your board a Rev A control board?

    I dealt with a similar issue on a whn boiler.
  • Hammertime
    Hammertime Member Posts: 6
    Yes 3 pumps.

    Hey Mark,

    Yes I have a boiler loop pump, and DHW loop pump, and a Radiant loop Pump.


    This is the one problem i've had installing this boiler on a system where the 'near boiler piping' is not as suggested. The whole system runs great but there must be a control in the boiler somewhere that will allow me to manage this issue. The Boiler allows for the DHW to be set to ZONE control if you are using near boiler piping that has a primary loop and two secondary loops one for DHW and one for Radiant.

    the problem remains that the manual does explain to set the DHW to ZONE in this case, but goes no further to explain how to set the Radiant pump so that it will run as a Zone as-well.

    maybe I should just choose a different boiler.
  • Hammertime
    Hammertime Member Posts: 6

    Yeah, Im not sure i know what kind of board its got, Im not directly in front of it right now. Lets say that it is a Rev A control board that im dealing with.

    did you find a fix? is it possible to describe it here?
  • NYplumber
    NYplumber Member Posts: 503

    Post photos of the near boiler piping.

    Also, what method was used to activate a call for heat with the radiant zone? Is it constant circulation via odr and wwsd, or a thermostat of some sort?
  • CMadatMe
    CMadatMe Member Posts: 3,086
    DHW & Radiant

    Are not secondary loops, they are heating circuts or zones unless your doing injection mixing into both these loops.

    I would think the reason for the DHW change to zone is so that the boiler knows to run the boiler pump on a DHW call and nothing more. If DHW was piped on the boiler side of the proper pri/sec piping, the DHW circ becomes both the domestic and boiler pump on a DHW call, shutting down the boiler pump.

    You sure your not getting the hot water because you can't move enough gpm across the hx fast enough?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Zman
    Zman Member Posts: 7,330
    post a picture

    If you post a picture or drawing of the near boiler piping you will get some solid answers. Without some details these are just guesses.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Hammertime
    Hammertime Member Posts: 6
    PC Program

    Hey guys,

    thank you for trying to help out. After speaking to the rep they new exactly what i needed to remedy the issue. They gave me a PC Program that will allow me to change a setting on the controls for the boiler that you cannot access otherwise..

    this setting allows me to change a setting called: "DHW not forces system pump on" from false to true.. allowing me to keep my current Near boiler piping the way I like it.

    I will get a picture of it sometime this week after going back to this job.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    I was going to suggest that...

    But not knowing for sure if you were a contractor or not, we have to be careful what we suggest.

    Lochinvar does have a homeowners software program that doesn't allow them to manipulate any of the critical parameters.

    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.
  • NYplumber
    NYplumber Member Posts: 503
    Rev A?

    Still interested which version board is in that boiler, because I was told that i wouldn't be able to use the software for that.

    The boiler "issue" I had was that when a call for dhw was initiated, the boiler pump turned off as to keep the boiler from pumping too hot water into the system, and yet the system pump stays on for the duration of the call, cooling the radiators off substantially. Piping is traditional pri/sec except I have a buffer tank piped in as the pri/sec connection.

    As for the rest of this system mentioned here, it works superb.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    cooling the radiators off substantially

    I am just a homeowner, but I have an indirect  and primary-secondary piping for heating the house. One boiler circulator, one system circulator for each of two zones, and one circulator for the indirect.'

    The controls on my boiler turn off the boiler circulator if there is a call for the indirect. The indirect is connected in the primary (boiler) loop. When the indirect is getting heat, the system circulator for one of the heating zones is cut off, but the other one continues to run if that zone is calling for heat (because it would be too complicate for the controls to turn it off: not impossible, but too complicated).

    This is not a problem for two reasons:

    1.) The indirect never calls for heat for more than 10 minutes at a time (it is allowed to; it just does not).

    2.) If the system circulator keeps running, it pumps the same hot water through the (baseboard, in this case), so it does not cool off any more than it otherwise would if the circulator were off. The hot water to the indirect does not leak up into the secondary loop because there is a real flow check valve in there.
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