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Zone keeps heating when thermostat is off

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cerbysam
cerbysam Member Posts: 7
We have an 8 year old Lochinvar Knight Boiler. Gas. There are 7 zones. One zone on the second floor continues to heat the baseboard even when set on 46 degrees and turned off. We changed the thermostat and the Taco Power head on that zone but it continues to do it. The heating technician said there must be a wire rubbing in the wall and wanted to take out all the wiring to the second floor. I think the problem is at the zone valve. Is there any way to test it or fix it. Taking all the wiring out to the second floor would be a huge job and I don’t believe that is the problem. Thanks for any help you can give.

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  • mattmia2
    mattmia2 Member Posts: 9,941
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    Which model Taco zone valve is it?

    If you disconnect the wiring from the valve and it is still heating, it isn't the wiring.(unless it is a power close type valve).
  • JUGHNE
    JUGHNE Member Posts: 11,102
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    New problem or was always an issue?
  • Alan (California Radiant) Forbes
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    Have you checked voltage to the zone valve? If there's 24 volts, there's a problem with the wiring. If no voltage, there's a problem with the valve not closing all the way.
    I'm saying the same thing as @mattmia2.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • cerbysam
    cerbysam Member Posts: 7
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    This has been going on for about a year. The valve is Taco Power Head 555-050RP
  • JUGHNE
    JUGHNE Member Posts: 11,102
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    You mentioned a failed circulator that broke and passed some pieces. Your zone valve may have some junk that is not allowing it to firmly seat and close completely.
    Possibly opening and closing it several times might pass the kidney stone. There may be a time delay to open and close.

    If this does not work then possibly valve repair or replacement.

    Another possibly is "ghost flow" thru the return piping, but that would have been there from the start.
    rick in Alaska
  • Intplm.
    Intplm. Member Posts: 2,083
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    Would like to see a picture or two of your system if you can post them here. It would help.
    A possible flow-control valve could also be the culprit?
  • cerbysam
    cerbysam Member Posts: 7
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    Unfortunately I cannot get it to insert the photos.
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,344
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    @cerbysam, you can click on the document or photo icon in the tools panel above the message box to insert photos. You can also send me a message with the photos and I'll post them for you. Here are some more tips for using the forum: https://heatinghelp.com/forum-user-manual

    President
    HeatingHelp.com

  • cerbysam
    cerbysam Member Posts: 7
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    I did that but after I pick the image size there is no prompt to attach it to the message.
    Thanks for any help you can give me.
  • Intplm.
    Intplm. Member Posts: 2,083
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    Ok, So no pictures.
    @cybersam
    The reason you have heat in that area when that area or zone is not calling for heat, is probably because there is a valve serving that zone that is not working properly.
    This could be the zone valve? check valve? flow control valve?
    Any one of these, or a combination of these could be the reason. If the wiring is not at fault this is where I would look next.
  • Alan (California Radiant) Forbes
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    What is your city and state?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • cerbysam
    cerbysam Member Posts: 7
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    There are 3 wires going to the zone valve .a white and a red coming from the thermostat and a green wire. What is the green for? And what will happen if I disconnect it. If I disconnect all 3 wouldn’t that eliminate the thermostat being the problem
  • Zman
    Zman Member Posts: 7,605
    edited January 2020
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    cerbysam said:

    There are 3 wires going to the zone valve .a white and a red coming from the thermostat and a green wire. What is the green for? And what will happen if I disconnect it. If I disconnect all 3 wouldn’t that eliminate the thermostat being the problem

    Thats exactly what you should do, disconnect all 3. You either have a mechanical issue within the valve or a wiring issue. The first step should be to figure out which.

    The 3rd wire is a powered end switch which is is a little confusing.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • dopey27177
    dopey27177 Member Posts: 887
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    If I understand the problem correctly.

    If you have multiple zones hot water can flow backwards up the zone that is not calling for heat.

    Install a check valve at the lowest point of the affected zone before the returns come together and enter the boiler.

    This will stop any back feed that is occurring.

    Jake

    Pictures will be more helpful.
  • JUGHNE
    JUGHNE Member Posts: 11,102
    edited January 2020
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    Did the problem start after you had the broken circ pump replaced?
    IIRC, you mentioned pieces broke off of the pump?


    Note: I thought I read about the pump in one of your prev postings; Perhaps I read the wrong post.
  • cerbysam
    cerbysam Member Posts: 7
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    Yes
  • cerbysam
    cerbysam Member Posts: 7
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    Thank for the information on the back flo. Will check that.