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Radiant under grand piano?

My clients are concerned about putting radiant loops underneath the Steinway.  Should I avoid putting loops in the proposed area of the piano or shoud this be a non issue in a stable low temperature concrete slab house?


  • Jed_2
    Jed_2 Member Posts: 781

    Grand Pianos need, as I understand, 40-45% RH at all times. Radiant Heat, HWBB, FHA, whatever; watch the RH. I did a music room, one time, in a residence, with an air handling unit, humidifier, evap coil, and humistat. She was a concert pianist and university professor. Things had to be right.

    Radiant, alone, without environmental monitors, might flatten your notes.

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    what Jed sed...

    RH is more important than worrying about the effects (none) of radiant heat on their notso baby grand,

    If at all possible, the piano should be in its' own room so that maintaining the optimum RH is not trying to humidify larger areas that don't need or want it.

    The better pianos I have seen actually have an internal moisture sensor with a flashing red light if humidity is low.

    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.
  • Gene Davis_3
    Gene Davis_3 Member Posts: 51
    A good instrument needs the right humidity

    It cost a lot of money to get a good repair job on my Martin guitar, the top of which developed a crack, and I blame it on myself, having left it in its case sitting atop a radiant-heated floor.

    I just did a web search on "piano humidifiers" and found a whole pageful of useful links.  There are products out there just for this situation.
  • Paulypfunk
    Paulypfunk Member Posts: 18
    radiant neutral?

    So is the heat issue neutral as far as the piano is concerned? If wood absorption is all about relative humidity should I be concerned about the client's request to avoid putting radiant loops underneath the area where the piano is supposed to go? Won't that make the area of the piano more likely to have temperature flux?
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Consider asking Steinway and Sons about this.

    They do, after all, make the things, and have over 150 years' experience.

    Their web site has the following information, but if you want more, you might give them a call.


    +1 718-721-2600
  • Gordy
    Gordy Member Posts: 9,546
    good read JD

     It seems that the whole key is a tight range in the area of humidity, and temp to keep the piano in tune. Eratic changes in either variable will effect the pianos tuning.

    No direct sun light for the finishes sake.

    Keep away from outside walls, heating/ air conditioning vents/humidification vents.

    I doubt that a grand piano being elevated on legs would be adversly effected. Maybe a seperate small loop in the area to keep a lower temp.

    Basically you don't want to create an enviroment where the wood is constantly swelling or shrinking. Which effects its tuning.

     On second thought in light of what I said above,I would give them what they want. Because heaven forbid something happen you know what they will blame. Like the wood floor guys.l
  • Jamie Hall
    Jamie Hall Member Posts: 22,918

    Before I replied on this one, I talked with our piano techicians and curators -- and they all had basically the same thought (for once in their lives): the key is relative humidity (that 45 to 65 bit) and slow slow slow change for either temperature or relative humidity.

    Based on that, it would be my feeling that radiant under the floor -- particularly with the thermal mass of the concrete -- would not be a problem.  Provided the temperature in that room is held as constant as possible.  No Setback!!!  (They were adamant on that one).

    This makes sense to me, as our three Steinways are in superficially very different conditions -- one is in the main room, kept at constant (65) temperature and as close to constant humidity as I can manage; one is in a studio which varies from about 50 to about 70 over the year, but very slowly, and one is in a summer studio, which varies from about 25 to 70 over the year.  All three have pretty constant humidity, and none of them have cracked.  The two in the studios are not tuned in the winter time, but need only minor corrections in the spring to bring them up.  The one in the main room is tuned monthly, so that's hard to judge by.

    I would add that the one in the main room (an 1898 concert grand) was rather badly damaged by high humidity at one point (a long story) and cost a small fortune to rebuild the action and restring...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Kendall
    Kendall Member Posts: 3
    Extra care

    Just moved my baby grand into the new house.  All tile floors, radiant heat.  Found very, very old piano tuner.  He requested foam mats under piano to go with the curtains and the fitted humidifier.  Oversize front door mats were light and cheap and pretty and two covered the floor.  Although the time lag is much less than we expected to raise the comfort level in the house, that means that the radiant effect is quicker than we anticipated.  Nice when we feel chilly, but it seemed smart to insulate the piano from it.  Large open area in house doesn't hold humidity well so with the really cold spell we were filling the humidifier weekly.  So far piano seems happy.  Mats are better than skipping a loop because what if they move the piano or get rid of the piano or move and the new folks don't have a piano.  We'd rather not have created an open area for cold tiles.
  • D107
    D107 Member Posts: 1,849
    Piano Humidifier/Dehumidifier in One

    My piano tuner years ago installed a the 'damp chaser' system in my upright. i think that's the model that this site promotes: http://www.pianolifesaver.com/english/home.php.

    With a hygrometer to measure the humidity, it adds moisture when dry and adds heat when too moist, keeping the level just where it needs to be. My piano is very close to a hw baseboard in a basement that gets humid in the summer (i do have a room dehumidifier.) I get tuned once a year, and this unit keeps the 1913 instrument pretty well tuned year round, with no noticeable changes during season shifts. Once a year the humidifier pads get changed, and during the winter i add a few quarts of water--with a few drops of corrosion inhibiting chemical--3-4 times.
  • Rich_L
    Rich_L Member Posts: 81
    edited January 2010
    What am I missing?

    I realize we're talking a big difference in cost here but, if held to the right temperatures, it won't hurt my wood floor, why would the heat under a piano, held to the right temps, hurt the wooden piano?

    Do a proper heat loss for the room, figure your spacing and insulation to allow for low water temps (always a good idea for radiant anyway) and rest comfortably! Your customer will too. :)
  • Kendall
    Kendall Member Posts: 3
    Wood floor question

    We spent years studying whether to put wood floors over radiant water for slab on grade construction.  Everything we found indicated that it was a toss of the dice to use wood so we went with tile - and are thrilled.  But it was hard to give up on the beautiful woods we had already chosen.  The final piece we got here in a detailed review that summarized it was theoretically possible, but in reality the odds were more in favor of the wood cupping than not.  Has there been some new info in the last few years since we made our decision?  Always wanting to learn and be ready for the next project.
  • Gordy
    Gordy Member Posts: 9,546
    Wood floors

     There never was any real elusive mystery about RFH and wood floors.  Maybe a few bad RFH installs that had excessive floor temps above 85* that did do strange things to wood floors 

     With those poorly controlled RFH installs under wood flooring the wood flooring guys found something to hang their hat on that will damage their product, and void the warranty.

     Its really quite simple with any type of wood application. Humidity the lack of it, or in excess once a product is installed will make the wood deviate from its original dimensions.

     Ways to prevent this in a wood floor is the width of your flooring strips, being the more narrow the better off you are with cupping, and shrinkage.  How the flooring is milled quarter sawn, and plain sawn. Quarter sawn lumber has less shrinkage, and is not as likely to warp.  Plainsawn is more productive, and has less waste.

     Humidity control plays a bigger role more then anything as to what will happen to your floor.  If the material is not acclimated to the environment its installed in then strange things will happen after your floor is installed, and starts drying out. Problem is that most new homes have a higher RH because other building materials are drying out also. This higher RH will not dissipate for a year or so.

     A good flooring installer will spread out the wood so all boards will dry evenly, and have a moisture meter for testing boards to see their moisture content. That is acclimating the wood to the environment.

     Something to ponder is the fact that on a sunny day if the sun is shining in the window on the floor will yield higher temps then what a well designed RFH system will ever warm it. Wonder if that voids the warranty on your flooring.

This discussion has been closed.