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Uponor manifold balancing

Hoping for a little advice on balancing a manifold. We bought a new house in Minnesota and it has infloor radiant heat throughout, three zones.

The master bedroom is quite a bit colder than the rest of the second floor. So I opened up the access panel and this is what I found. The loop all the way on the right just goes from the supply directly to the return manifold and its flow is around 1.3 gpm while the rest of the loops are closer to 0.6.

The previous homeowners do not know who installed the system and the builder is no longer in business. Any advice is appreciated. Thanks!


  • ZmanZman Posts: 4,753Member
    Would need to know more about the system to advise. Basically, when you turn the black knob, the flow gauge on the other manifold moves. It sound like they are using the right as a bypass. Depending on the setup, that may or may not be a good idea.
    Posting pictures on the boiler and piping would help.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • GroundUpGroundUp Posts: 472Member
    Is the bedroom in a corner or somewhere with a lot of exposure to an exterior wall? Maybe a lot of glass? Furthest room from the boiler room perhaps? Seeing as there are no actuators on the manifold, it would appear as though they just had an extra port and thought it'd help the flow rate to connect them together. Usually unnecessary. There are a lot of variables here that may contribute to a chilly room, and unfortunately I don't think there is a whole lot you can do about it by balancing the manifold without adding actuators and running the bedroom on its own thermostat. Flow rate of .6 (if accurate) is pretty much tops for a 300ft loop of 1/2" so the only way to heat that loop more than others is more run time. Where are you located in MN? If you're close by I could maybe take a peek at it for you, otherwise some pictures of the rest of the setup posted here would be great too
  • nibsnibs Posts: 209Member
    Can I hitchhike here please?
    Balancing my new radiant floor, and am feeling the return pipes, am trying to get them to feel equally warm (bedroom loop cooler) once the house is close to set point, is this a reasonable way to balance?
  • djvtraveldjvtravel Posts: 4Member
    edited November 2018
    Will try to take some more pictures of the other manifolds tomorrow.

    In the basement and garage there are only three loops each and no bypass. I couldn’t find the 1st floor manifolds. Guessing they’re behind the drywall.

    GroundUp - you are spot on. The master bathroom and bedroom are basically the south end of the house. The boiler is in the basement on the north end and the manifolds are directly above on the first and second floors. If you’re ever in SW Minneapolis let me know!

    I’ll try to get pictures tomorrow.
  • GroundUpGroundUp Posts: 472Member
    Don't really need to see the other manifolds, but the boiler room and piping would be handy. I'm in SW Minneapolis all the time but unfortunately I have a no-compete agreement with my employer so I can't do residential work in the metro. I live 2 hours North of the metro and am based up here.

  • djvtraveldjvtravel Posts: 4Member
    Here are a few more pictures of the whole system, basement and garage zones. I couldn’t find the 1st floor.

    I balanced the entire second floor including the bypass so that they are all about 0.6 and it made a big difference for the master bedroom and bath. Still colder but improved.

    Is there any reason to keep the bypass open? I don’t really understand how the temperature drop calculations work. Is the bypass needed for the boiler controller so that the return temp isn’t too low?
  • GroundUpGroundUp Posts: 472Member
    edited November 2018
    Without actuators, I'm thinking you'll need to lower the flow to the other loops in order to gain more heat in the bedroom. Basically the bedroom loop gets more heat than the rest while they run together. Equal flow rates does not necessarily mean a balanced system if the loops aren't all the same length, and "balanced" is a term thrown around somewhat loosely. In theory, all loops of the same length with equal flow rates would be balanced. Then again, if the tubing layout is such that the installer didn't place it so that the delta T through each loop is also the same, you're out of balance despite the equal lengths and flow rates. For example, one of my local "professionals" up here will always work from the outside in. Meaning the first loop may have a full 300 feet of exterior wall exposure with a 50 degree delta, while the last loop is all 300 feet in the center with a 20 degree delta. So flow balanced, yes. But temp balanced, not so much. In your scenario it may come down to adjusting flow rate down some in the rest of the house so that the bedroom loop has more transfer than the rest in order to balance the temperature of the house
  • Tim PotterTim Potter Posts: 235Member
    I have a manifold with a similar extra loop at the end, but was designed with an extra port for future expansion, its meant to be closed. I also use the VT2218 set to 5* dt. works like a charm. make sure that bypass is closed down all the way, & let the system balance for a couple of days & see if it helps your bedroom temps.


    Winter Park, CO & Lenexa, KS
  • hot_rodhot_rod Posts: 11,228Member
    looks like a primary secondary piping, the valve between the two tees needs to be left full open. It could be the piping supplying all the zone valves is undersized. Is it two 1" and two 3/4 zones piped to a 1" header.

    Here is an example, although this schematic shows zone pumps, it could be a single pump with zone valves as you have.

    Balancing may get you there, but it could also be a lack of adequate flow with restricted piping, especially when you get to design days.

    Any idea of the load on the 4 zones? Either BTU/ hr or gpm?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Tim PotterTim Potter Posts: 235Member
    looks like your return temp sensor for your vt2218 is placed in the wrong spot.
    move the lower sensor down to right under the return pipe into the boiler but above the last zone return connection.

    its there to measure the dt of the house side of the system.


    Winter Park, CO & Lenexa, KS
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