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    Question about floors over radiant heat (15 Posts)

  • oaktown oaktown @ 7:38 PM
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    Question about floors over radiant heat

    Hi,
    Does anyone have experience with engineered Brazilian Cherry wood floors over radiant heat?  Is it reliable?  Have you experienced checking or cracking?
    How critical is it to limit the max. outgoing temperature from the furnace driving the radiant heating system?  This is for an application in Oakland, CA.

    Thanks
  • M Lane M Lane @ 8:19 PM
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    Vail, Beaver Creek, Aspen

    All have numerous estates with really exotic hardwood floors, mostly engineered, and I've never seen a problem unless there was a leak or it froze up.
    Much less of a load in Oakland I would assume.
  • Derheatmeister Derheatmeister @ 8:50 PM
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    80 F

    In general the manufactures limit the >>>>Surface Temperature
    This post was edited by an admin on February 3, 2014 8:52 PM.
  • Derheatmeister Derheatmeister @ 9:17 PM
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    80 F

    In general the manufactures limit the >>>>Surface Temperature
  • Derheatmeister Derheatmeister @ 9:38 PM
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    80 F

    In general the manufactures limit the >>>>Surface Temperature
    This post was edited by an admin on February 3, 2014 9:40 PM.
  • Derheatmeister Derheatmeister @ 7:32 PM
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    Hello Dan...Warrum Nicht (Why Not)

    In general the manufactures limit the >>>>Surface Temperature
    This post was edited by an admin on February 4, 2014 7:37 PM.
  • Mark Eatherton Mark Eatherton @ 10:10 PM
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    The keys to stable wood flooring.

    Your choice of hardwood is one of the densest woods available, and considered one of the most stable wood available. The only thing better would be 1/4 sawn wood.

    The key to stable hardwoods over any type of radiant floor is to make certain that the wood is preferably kiln dried to begin with, and maintained that way right up to the time of field aclimation. The wood should not be acilimated until all other moisture producing processes (spackling, painting, steam carpet cleaning etc) are done, ad the dwellings relative humidity has normalized.

    Once this has been achieved, it is safe to place the hardwood flooring over the heated floor. Whenever the flooring is cut (assuming it was factory sealed and finished) it is important to dab a sealant on the fresh cut wood to avoid a point of moisture ingression.

    THe manufacturers of hardwood flooring systems have "adopted" a figure of 85 degrees F maximum allowable surface temperature. This is in their efforts to avoid the wood doing strange things like cupping, warping, cracking, crazing and checking, along with panelization , which is essentially a bunch of shrinkage showing up on one side of the floor. This magic threshold number originally came from the old RPA, and was initially mistakenly misinterpreted as the maximum allowable fluid temperature. Nice floors, but uncomfortable homes was the result.

    It would appear, based on Der Heatmeisters input, that the hardwood manufacturers have taken the maximum recommended floor surface temperature from the RPA (85 degrees F max.) and backed it off 5 degrees in hopes of avoiding "issues". While that is much better than the original water temperatures misquote, it may not be adequate in many cases to deliver comfort at design conditions. We shouldn't allow our floor finishes to dictate the thermal output capacity of our comfort systems… If they can't handle the heat, they should stay out of the kitchen :-)

    If in fact, 80 degrees F is the maximum allowable wood surface temperature, then it should be against the law to place any hardwood in any area where it will be near an East, South or West facing window. I have personally witnessed floor surface temperatures nearing the 140 degree F mark, and there wasn't a radiant floor heating system any where near the home! All done by the power of the sun.

    Once the wood is down, and all things related to the indoor environment are stable, then it is safe to start slowly raising the woods temperature. It is very important to maintain the relative humidity in the area of 50%. THis may require the installation of a humidification or dehumidification system within the envelope to maintain wood stability.

    If not, you can expect seasonal changes in the dimensions of your hardwood floor.

    I watched these changes in my own home, and I didn't (at the time) have any radiant heat in my home. Same thing I see in my wooden closet doors, drawers and other hydroscopic wood products.

    A good hydronic heatIng contractor will know how to adjust the maximum water temperatures to avoid cooking the floor and causing the checking and crazing you are referring to. I'd also recommend that the supply water temperatures change as a function of the outdoor air temperature (Outside Air Reset control) to lessen the thermal expansion of the floor.

    Another critical factor is to make certain that the joist bays below the radiant/hardwood floor are insulated. Contrary to popular General Contractor beliefs, radiant heat does NOT rise, and insulation below the floor is a must, otherwise you can expect problems.

    Once everyone understands the criticality of all of these issues, and they are maintained, the floors should work fantastically, and be relatively free of any issues.

    I have over 250,000 square foot of radiant floors, of which 75% are hardwood floors, and have only seen it be an issue when the rules are not followed (missing sub floor insulation in this case).

    It's really not that hard or expensive to do it right, the first time around.

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    This post was edited by an admin on February 3, 2014 10:17 PM.
  • Rich Rich @ 10:20 PM
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    RH

    is more the problem than surface temp . Everybody wants to blame the radiant floors .  Since we are talking specifically about Brazilian Cherry though the max temp should not exceed 29.44*c (85) but have no fear , if the relative humidity in the structure is not controlled and stable your floor will still suffer some issues but there is always that pesky radiant floor heat to blame . Doubt very much you'll ever need a surface temp in excess of 78* in Oakland though .
    You didn't get what you didn't pay for and it will never be what you thought it would
  • Rich Rich @ 10:25 PM
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    Really

    You posted that while I was typing ? Damn you Mark Eatherton ! LOL
    You didn't get what you didn't pay for and it will never be what you thought it would
  • Mark Eatherton Mark Eatherton @ 10:35 PM
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    Great and well trained minds...

    Think alike. :-)

    Controlling rH is the second biggest dictator of human comfort, second only to the Mean Radiant Temperature…

    Commonly overlooked by the hydronic heating contractor, even the good ones.

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • N/A @ 11:29 PM

    glad to

    Glad to see that I'm not the only one triple postings as its this website is causing it.!!
  • M Lane M Lane @ 6:42 AM
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    Sure wish

    I found this site 10 years ago. Thanks guys.
  • solsean solsean @ 7:42 PM
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    Dermeister what

    have you got to say about this?  Why is the admin blocking your comments?
  • Derheatmeister Derheatmeister @ 7:51 PM
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    Cannot say...Being Blocked

    I do not understand why the admin is blocking me???
    This post was edited by an admin on February 4, 2014 7:53 PM.
  • Mark Eatherton Mark Eatherton @ 9:14 PM
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    Doesn't look like you're being blocked to me Richard.

    Have you caught another virus in your PC? :-)

    You should come visit me in Heeney this weekend. Extra hot green chili…

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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