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New radiant loop interferes with old one

dori
dori Member Posts: 16
in Radiant Heating
Original system is a 1950 radiant 1" pipes in ceiling. In the sketch below, this is the loop with the two parallel recirculators. The feed from the mixing valve is 1 1/2". The return is 2" . The zones from the main are fed with declining pipe diameters, with the last one 3/4". The returns of the main loop connect to the 2" return all along the way, with the furthest about 60' away from the boiler room.



The system was converted from an open air expansion tank to an air-out closed system as shown. The pressure is set at 15 psi. The single loop on the right is for cast iron radiators on second floor. There seem to be no issues with that loop.

The newer loops are a 3/8" pex radiant floor and a kick space heater, both in the kitchen and both very close to the boiler room.

When the radiant loop in the kitchen is active, the main loop is mostly cold -- especially the far branches.

Under suspicion is how the expansion tank is connected to the system although the interaction dates before the tank was added.

Thanks for any advice.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,852
    What, if anything, is powering flow through the kickspace and radiant floor? Am I missing something?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,477
    Your pumps are pumping toward the expansion tank which is not good.

    Don't take this the wrong way but if it was me I would repipe it differently. very difficult to troubleshoot the way it is
    ZmanSuperTechdori
  • Zman
    Zman Member Posts: 7,611
    Yes, a classic "pumping away" poster child....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    SuperTech
  • JohnNY
    JohnNY Member Posts: 3,291
    Jamie Hall said:

    What, if anything, is powering flow through the kickspace and radiant floor? Am I missing something?

    The sketch shows pumps on the returns from those zones. It's piped the old way.
    I'm guessing the pumps are fighting each other somehow but it's difficult to know without model numbers at least.
    If the expansion tank is in question just get the system up to temperature and shut the valve on it. Run everything and see what happens. Shutting the valve makes like it's not there.

    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
  • Jamie Hall
    Jamie Hall Member Posts: 24,852
    I must be blind (you don't have to agree..) but I still can't see what pump or pumps is driving circulation in the kitchen floor/kickspace loop...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,611
    They are smaller pump symbols on the return side.
    It looks like the OP @dori is "one and done" we are just talking to ourselves and I am good with that.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    STEVEusaPA
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,477
    @Jamie Hall
    all the way to the left the blue riser coming from the kikspace heater has a pump in it (I think)
  • Big Ed_4
    Big Ed_4 Member Posts: 3,019
    edited March 2019
    It's piped incorrect , when the kitchen calls for heat it opens a boiler bypass ..Mr Hall is correct , no Circulator or pressure drop for kitchen , assume only a zone valve is used on the kitchen . You would need to add a circulator and a check . The other zones would need a check as well .. .. Reverse return and pumping away are other issues

    There was an error rendering this rich post.

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Also if your return sensor is affecting any of the heating, it's not picking up the return temps from the 2 kitchen zones.
    You also seem to have a lot of air elimination, and a lot of y strainers.
    Zman said:

    They are smaller pump symbols on the return side.
    It looks like the OP @dori is "one and done" we are just talking to ourselves and I am good with that.

    Wouldn't be the first time, right?

    There was an error rendering this rich post.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,477
    Maybe I am the one who's blind. Sure looks like a pump to me on the kitchen loop.

    But we are all commenting and the OP hasn't returned
  • Jamie Hall
    Jamie Hall Member Posts: 24,852
    Oh yeah. Sorry. Now I see them -- two tiny pump symbols, one for the radiant and one for the kickspace heater. Getting old has its problems, folks. Ain't for sissies.

    And I don't even want to get into figuring out the relative flows and headlosses in the circuits...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,477
    @Jamie Hall Having issues myself. As far as flow and head loss I wouldn't have a clue. You read my mind
  • dori
    dori Member Posts: 16
    Sorry guys for having initiated the discussion and then disappeared. I was never notified of your postings by the Wall, and I assumed as a newbie that no one came to my rescue.

    I did move the expansion tank to the other side of the recirculators of the Main loop. It helped like magic for a week, but 2 weeks later the system is air locked. All my attempts to flush the air have failed to take hold. The heat is resumed for a day and next morning it is no-show or partia-show.

    The problem with the Kitchen loop (pex) was solved by adding a Spirovent on the supply side. Never had an issue thereafter.

    I just posted a new thread. If you wish to respond, please use that one.

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