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New House -- Need to balance zones

BorisMD Member Posts: 2
Hi all -- First timer here. We built a house last year (I did the wiring) and half way through, the plumber, a long time friend, who installed the in-floor tubing in our slab on grade structure, succumbed to a very fast and aggressive cancer. The HVAC guy took over and finished the job. The boiler is Bosch, has a Grundfos circulator pump, and an 8 loop KaMo manifold. The house is high efficiency envelope (foot thick walls, triple pane windows, passive solar).

So far, we've done well with this system with the exception of two things.

First, the living room is two story and surrounded by windows. We get more of a cool draft coming from the windows (they are all airtight as verified by blower door testing) -- just cooler air from the windows not being as thermal as walls.

The second issue is the master bedroom and bathroom. Due to solar orientation, the bedroom can get pretty warm on a sunny day. Basically we don't want or need any heat in that room. On the other hand, it's nice to have the tile floor of the bathroom have some heat in the mornings.

With the plumbers demise, I don't have labels on any of the loops. What I do have are photos I took during construction. The photos that look to provide the best information show what appears to be two loops that serve the MBR/bath. I can also see where the loops for the living room terminate.

What I'd like to do is figure out how to balance the valves so that the living room gets more heat, the master bedroom less, and the master bath some. The rest of the zones could be somewhere in the middle. When I fiddled with the valves, I noted that they were all wide open. The pump was not running at the time so I could not see what the flow for each loop was at. As noted, I think I can tell which loops correspond to which valves and see where the loops circulate water in the house.

Thanks for any advice!




  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    You could verify loops by closing all of them and open one at a time to see what heats up.
    To balance, start with the loops for the living room open all the way and the others set to 0.5 GPM and see where that gets you. I bet you will end up with the bed room mostly closed and the rest at 0.5 GPM.
  • HomerJSmith
    HomerJSmith Member Posts: 2,393
    You should have flow indicators on that manifold. Adjust the shorter loops first and then go to the longer loops. Adjust the indicators to 1 gal/min and re adjust as necessary.
    JUGHNE Member Posts: 11,021
    I have multiple loops in several zones and can see them with the FLIR gun I have. Very handy tool for many things. Small color screen that allow you to see the actual tubes themselves in the floor or wall. Was $350 a few years ago.
  • Jamie Hall
    Jamie Hall Member Posts: 22,918
    So long as you are patient and follow any of the suggestions above you'll get there.

    However, it takes time for a radiant floor to adjust to a change in flow -- so I'd never make more than one change at a time, and allow a day to go by in between changes. As I say, patience...

    And don't even think about trying to get setbacks into the mix.

    It can be very hard to get consistently good balance in a house with a lot of solar gain and no way to transfer heat from the gaining spaces to the cooler/cold spaces.

    On the windows. Unless your plumber friend (sorry about that) installed closer spaced loops under the windows, to get more heat there, there really isn't much you can do about the cool downdraught off the windows. If it really is bothersome, you could look into thermal drapes -- but I've always thought those were more trouble than they were worth.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • BorisMD
    BorisMD Member Posts: 2
    Thanks all. I'll keep plugging away. Here's a photo of the lines. The top left (far away) is the bedroom. The LR is to the left and out of the frame.

  • Zman
    Zman Member Posts: 7,542
    Slowing the flow rate will help balance to some degree. It will not change the supply temp but will reduce the return temp.

    Your degree of success will depend on how the tubing runs. In some cases, you may want to switch the tubing ends on the manifolds to manage the hot and cold spots that low flows can cause.

    An infrared camera is essential for what you are attempting. Start with a cold slab and watch patiently.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein