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Best Finish for Concrete with Radiant

newinnj
newinnj Member Posts: 36
Any thoughts on concrete floor finishes for a sub basement with radiant heating pex tubing? Thanks for the assistance.

Comments

  • Zman
    Zman Member Posts: 7,561
    Just concrete, stamped or smooth, will give you the best heat transfer. There are some great finishes out there.
    You can do just about any material and it will work just fine. If you put down carpet, get the high density pad designed for radiant.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    newinnjSTEVEusaPA
  • hot_rod
    hot_rod Member Posts: 22,024
    How nice of a finish are you after. Stamped and colored concrete can look amazing, but there is always the risk of some cracking, even the tiny "road map" cracks.

    Tile or any hard surface is another great match and ideal for low SWT operating conditions.

    Thin, engineered or laminate wood work well also and can be easily changed as they wear or age.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nibs
    nibs Member Posts: 511
    We are going with ceramic tile, good heat transfer and low maintenance.
  • nibs
    nibs Member Posts: 511
    Should have mentioned that it adds to the thermal mass, bonus.
  • newinnj
    newinnj Member Posts: 36
    I was thinking of metallic epoxy to get a dimensional look to the floor. I am thinking that should not interfere at all with the radiant.
  • Canucker
    Canucker Member Posts: 722
    Metallic paint is used to cut down the radiant output of radiators. I would imagine it will do the same to your floor
    You can have it good, fast or cheap. Pick two
  • hot_rod
    hot_rod Member Posts: 22,024
    newinnj said:

    I was thinking of metallic epoxy to get a dimensional look to the floor. I am thinking that should not interfere at all with the radiant.


    You should have plenty of surface area with radiant slabs to cover most residential loads, it's a massive radiator, really. I doubt a thin paint coat of any type would put the slab out of output range required.
    The load calc would spell out what is required from the slab in BTU/ sq. ft/ hr. In some cases increasing SWT is required when floor coverings, throw rugs etc limit output.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Zman
  • How thick is the slab? Any underslab insulation?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • newinnj
    newinnj Member Posts: 36
    I don't have any information on how thick the slab is and if there is any underslab insulation.

    When the contractors come in I will get more information and I will post. There seems to be two types of metallic epoxy. One is using metallic powder and the second using pigments. Stay tuned.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,979
    edited May 2019
    Are you installing the tubing? Doesn't sound like it.

    If you aren't, you should be talking to the guy that is. Although there's nothing wrong with checking here as well. It's good to call in with all your sources.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • JUGHNE
    JUGHNE Member Posts: 11,042
    In our basement we painted the floor.
    First warmed the floor with the tubing, brush wash with mild acid mixture. Rinse well, the heated floor helps the drying.
    Then a base color of floor paint was rolled on.
    After that each room received a variety of color/applications etc.
    If that didn't look good you just try a different Faux pattern until happy. Then apply a clear sealer...no painting changes after this.

    Most important thing is cleaning the raw concrete with the acid.
    Then the sealer at the end.

    This lasted over 20 years with teenage boys doing the typical roughhouse things they do.
  • Concrete is porous. Will the acid affect the tubing?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • hot_rod
    hot_rod Member Posts: 22,024
    I have had a number of jobs where they acid etched a finish on the radiant slab. They blend various elements with the acid to get some wild colors. Adding copper graduals get a green color for example.

    I imagine the acid Ph buffers up quickly when it touches the concrete. Possibly safer than some glycols when the Ph plunges inside the tube.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    CanuckerAlan (California Radiant) ForbesZman
  • JUGHNE
    JUGHNE Member Posts: 11,042
    We scrubbed with brushes, rinsed with clear water and shop vac
    dry repeat maybe 2 more times. This is to clean the concrete to have the paint adhere. When you can rub your hand on the floor and come up with no dust then is considered clean.

    Floor painted in 1995 no problem with tubing.
    BTW which is O2 barrier PB from Infloor.
  • nibs
    nibs Member Posts: 511
    A bit of topic drift here, as we look up tiling on our radiant concrete floor, we are reading that to minimize edge curl and shrinkage cracking of the slab, we should not start up the radiant for three months.
    They say that heating the slab drives off the moisture too quickly and leads to curl and cracking.
    Thoughts???
  • hot_rod
    hot_rod Member Posts: 22,024
    there are so many variables to how a slab cures, weather, temperature, wind humidity, the blend, thickness consistency, did they add water at the job site, the way it was finished, etc.

    It's always a good idea to use a cleavage membrane when tiling over a slab.

    https://www.tcnatile.com/faqs/69-cleavage-membrane.html
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    vibert_c
  • newinnj
    newinnj Member Posts: 36
    hi all, the slab and pex tubing is 15 years old. Finally getting around to put a finish on top. I only the owned the property for 8 years so some of the history of the install I am not aware of the details.
  • newinnj
    newinnj Member Posts: 36
    Just a quick note the metallic epoxy the metallic part is metallic pigments. The pigment is made from mica. I am going forward with most likely a big box off the shelf product. The commercial grade and commercial install is too expensive per square foot. Dan wrote the definitive history on the metallic paint on rads on this website. Canucker concern is an intresting point. Any info on epoxy can be found on All Garages website. I believe there is mica amount is already in paints. The question is will the amount of mica being used in metallic epoxy will it cut down on the heat. I will give it a whirl and see what happens
  • newinnj
    newinnj Member Posts: 36
    Hi All, The basement floor is finished. I went through 8 boxes of the epoxy. Each box had small container the size of a face lotion container that had the metallic flakes. The plastic jar lid was probably heavier than the flakes. I called the company and they get this call all the time since a lot people have radiant floors in their garages. There is no issue they said. This specific material works best under 80 F and low humidity. It seems during application of the paint, not running the radiant will be better for it. If you have questions about the floor please email me since that will be considered off topic. Now I have a question to the forum. I have three zones and one to the basement. That is one pex line going to the space under the stairs. There the pex line goes to a manifold and is split into four lines. The four lines returns back and they go to another manifold and back to one pex line back to the main return. The lines that go to the floor do not look like pex. I have included pics and wanted everyone's opinion on the setup. I don't know what I have and is it setup properly. Thanks for the help.
  • nibs
    nibs Member Posts: 511
    Don't think there is any problem with the Onix tubing, but is it clamped directly to copper pipe?
    Also the soldering looks worse than mine, and at 76 yrs of age, my hand just is not steady enough to do neat solder joints.
  • newinnj
    newinnj Member Posts: 36
    hi nibs,

    It sure looks like its clamped directly to the cooper. I think my tech term was incorrect. One pex tube that goes to the copper split. I don't know what to call that. I called it a manifold. The pic does not show it well but there are two copper splits on top of each other. Just tell me what to look for and I can take a look again. In short yes it looks like it is a direct clamp.
  • hot_rod
    hot_rod Member Posts: 22,024
    those are probably brass street adapters that are soldered inside the copper fitting, that was the most common Onix adapter

    without labels it’s hard to know which loop is which
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    kcopp
  • newinnj
    newinnj Member Posts: 36
    Hi everyone I posted another topic and was surprised that this old one got read this much. It seems less about the post and more about the topic of concrete. My sub basement project is finished with the metallic epoxy. It looks fantastic. Except one thing. I was just realy lucky on the installation. The fella who did it also did my garage earlier with a different epoxy. He has the knack and also an artistic touch so the floor came out good but even he needed to come back to a couple of times to get it in a good shape. The metallic epoxy looks very dramatic but would not recommend it in a high traffic area. It has a mirror and hight polish look which is prone to micro scratches. Also i dont' think it handles hard objects drops very well due to more visible scratches. The sub basement is right next to the boiler room. It is a small area so the door of the boiler room is kept open and actually heats up the area without even running the radiant to the floor, Go figure. I have now decided to set the boiler to high mass (concrete) and I run it now in spring and going to run it up to fall time. Anytime it runs below 72 for the room the radiant will take over. Once colder weather comes in the boiler will be set to low mass and the other floors will call for heat and the room will get indirectly heated. Anything that remotely sounds like I know what I am doing is due to the wisdom from this forum.
  • Bill_Gleisle716
    Bill_Gleisle716 Member Posts: 1
    Hello, I’ve been scrubbing the concrete on radiant heated floor with enzyme deodorizer in a house I just bought to get rid of cat and dog urine smell. If the smell doesn’t completely go away I was going to paint it with Kiltz. Will that affect the hear transfer out of the cement? 
  • Jamie Hall
    Jamie Hall Member Posts: 23,170
    No. The Kilz won't affect the heat transfer at all. Be aware that there are about two dozen different primers under the brand; not all of them are suited for concrete or masonry, nor for areas which get wet. Talk to your paint supplier (NOT a big box sales person) for the best for your application.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    kcopp