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dhw ghost flow

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drosner
drosner Member Posts: 68
in THE MAIN WALL

My indirect stored domestic hot water is 160 degrees most of the winter when the boiler is running. Finally got around to putting pressure gauge on supply and return side. Return is about 4psi higher than the supply side when the primary loop and heat zones are running. As you can see in the picture the return tees at the boiler inlet after the primary loop pump.

easy right - just need something that allows water to flow from supply to return but not the other way around. I’m confused by all the different types of check valves - which kind do I need for this? spring, swing, weighted, etc…

IMG_0342.jpeg

Comments

  • 109A_5
    109A_5 Member Posts: 3,724

    Does the circulator have a check valve ? If not you may be able to add one there.

    image.png image.png image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    bjohnhy
  • drosner
    drosner Member Posts: 68
    https://forum.heatinghelp.com/discussion/comment/1885758#Comment_1885758

    yep it’s ifc pump - taco 0015

  • bjohnhy
    bjohnhy Member Posts: 188

    Did you confirm that your taco pump has the internal flo check (IFC) Installed? These IFCs are removable. If the model is IFC it doesn't mean the IFC is installed or working appropriately.

    To prevent the ghost reverse flow in that loop, I would buy a new taco IFC check valve, then isolate that circulator with the yellow and green valves, pull the circulator off, remove the old valve if there is one, and put in a new IFC (make sure the check valve is oriented the correct way), put back together and burp the air before fully tightening the bolts on the circulator.

  • Big Ed_4
    Big Ed_4 Member Posts: 3,421
    edited 12:29AM

    Check valve in the circulator could have gone bad , I fine them falling apart on some over heating calls ..

    There was an error rendering this rich post.

  • drosner
    drosner Member Posts: 68

    it’s a brand new pump but I guess the ifc inside it could not be working properly. does the IFC stop 100pct of the flow going backward? I don’t think it would take much flow to keep the dhw heated. Plus a 4-5psi pressure differential seems a lot to me so there is a good amount of pressure/flow going in reverse. Are these IFCs on these pumps made for this or just typical gravity type ghost flow?

    something tells me a heavy duty spring valve on the return side would be bulletproof?

  • 109A_5
    109A_5 Member Posts: 3,724
    edited 3:51AM

    If the pressure differential is in the backwards direction, why would you need a "heavy duty spring valve" type valve ? You want the DHW circulator to be able to open the check valve.

    I would think a gravity swing check is all you would need, assuming that is the actual fix.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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