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hydronic tubes in a single story cabin new build

WOlenikWOlenik Member Posts: 4
This is my first attempt and I'd love some recommendations. Thank you for your help. Wendy - PS I'm not confident in my measurements either.


  • IronmanIronman Member Posts: 5,685
    Has a room X room manual J load calculation been done? That's the first step and the foundation for everything.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • GroundUpGroundUp Member Posts: 995
    No good. The blue and purple? (bottom) have far too much exterior exposure to balance decently. The perimeter should be split between at least 4 loops (one per wall, minimum).
  • EzzyTEzzyT Member Posts: 995
    As @Ironman has mentioned need a room by room Heatloss analysis done first. Do you want every room to be zoned separately?
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  • johnlemenjohnlemen Member Posts: 5
    keep the pex tubing one (1) foot away from the wax ring under the toilet, unless you want it to melt
  • JUGHNEJUGHNE Member Posts: 6,985
    It can be difficult to get enough heat into a bathroom with a shower/tub.
    Mine is on the NW outside corner with 2 outside walls.
    I added wall heating of about 70 sq feet for ours in addition to the limited floor heat.
    Did an inside corner of the vanity area for about 30 sq feet.
    The wall above the tub and the skirting of the tub for the balance. The floor only amounted to about 20 sq feet of ceramic tile installed on 1 1/4" of solid plywood. It alone would never have heated the room. It was just added a few years ago and only is a convenience to step on a warm floor.
    The walls are the real heaters.
    We keep this room at 74 and the bedroom is closed off and may be 60....we like open windows at night.
    Such exuberance and privilege....but we pay the bills.
    Grew up cold with ice on bedroom windows, getting dressed with the clothes I took to bed with me and only one dog in the family of seven.
  • GroundUpGroundUp Member Posts: 995
    johnlemen said:

    keep the pex tubing one (1) foot away from the wax ring under the toilet, unless you want it to melt

    It's not 1980 anymore. Slab temps will never get anywhere near hot enough to melt a wax ring
  • WOlenikWOlenik Member Posts: 4
    Thank you! While I don't have the skill to do a j load calculation or heatloss analysis, I do understand the concept of balancing exposure. I'll try again. Question though - if my boiler is in the left bottom corner, can I put in a line from there to the top left corner and run tubes starting from this line into each space? I've heard the term, "extended manifold". Would this be a good fit for such a thing?
  • WOlenikWOlenik Member Posts: 4
    I should also have said, this home hasn't been built yet.
  • IronmanIronman Member Posts: 5,685
    edited July 16
    Proper design is the key to having a radiant system that performs correctly. Without it, you won't be pleased with the way it turns out. The load calc is the first step in designing and to do that, the construction data of the house is needed. In other words, a detailed set of plans to work from. Some of your questions could be better answered then.

    A radiant floor is like a cast iron radiator: you wouldn't put the same size in each room, because each room has a different load. So, the tubing layout is different for each room based on its load. To attempt a tubing layout without a load calc is getting the cart before the horse.

    There are some pros on this site that a good at designing and offerer that service. Steven Minich and Rich McGraph are two that come to mind. I would suggest that you contact them or start another post titled: "Looking for a Radiant Designer".
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • ZmanZman Member Posts: 5,872
    Don't take this the wrong way but...
    The floor plan in general would benefit from some reworking. In a small house, you need to be super conscientious of wasted space and traffic flow and how spaces are defined. There may be a purpose that I am unaware of but you seem to be wasting tons of space and creating some very awkward little rooms.
    Susan Susanka does a great job of explaining how to design a smaller home.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ZmanZman Member Posts: 5,872
    As for the heating system, spending a few bucks having someone do a room by room heat loss and adjusting your tubing spacing to match that heat loss will make for a nice comfortable home.
    The folks Ironman suggested would do great job.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HomerJSmithHomerJSmith Member Posts: 929
    edited July 16
    So, you're using barrier 1/2" PEX and keeping it under 300'
    in gyp-crete or cement pour. Good.

    I would want to know the coldest winter day outdoor temp, whether you plan to use Glyco and what percentage, the envelope R-factor, etc. That is where the whole house heat loss comes in, real important. You can do that yourself with programs designed for it. You can probably download "WIRSBO COMPLETE DESIGN ASSISTANCE MANUAL" , now Uponor from their web site. Layout spacing is important in getting the BTU's into the living space. It is all covered in these design manuals.

    You have a mixture of serpentine and counter-flo patterns. I would probably do it somewhat differently depending on the environmental conditions.

    Heat energy travels in a straight line to what ever is coldest, up, down, or sideways. Slab insulation is important, where to put it.

    Are controlling the zones with thermal actuators with flow control manifolds? Ahhh! so much to know and so little time!

    Do more homework and get it right as it is a costly investment that may not be correctable, once done.
  • WOlenikWOlenik Member Posts: 4
    :) Yes, so much to learn. And can you believe I was trying to keep it simple? The average low winter temps are 31F. We have seen it go down to 2-10F but that is thankfully rare. My intention is a simple gable roof. There is an attached garage which would be on the lower left. I didn't include it in the image - now I'm realizing I should have done so. Yes, a slab, new construction. Yes, glycol. Yes, thermal actuators and yes flow control manifolds. Not sure about the glycol percentage or r-factor but I would defer to the experts.

    I'm still perplexed about how to get the heat loop in the upper right corner of the home when the boiler is in the bottom left corner of the home. I will look up the manual and I do have time to research and get it right before construction begins.

    Thank you so much to everyone who is able to make recommendations.
  • hot_rodhot_rod Member Posts: 13,526
    A manifold located in the center of the home, that utility closet would help with those remote zones. Decrease leader length and avoid over-heating where tube travels across zones.

    A designer or manufacturer supplied load calc and LoopCAD would be a good first step.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
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