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Radiant heating on floor joists

neohio Member Posts: 1
Looked at several old posts that mentioned this but they were from years ago and had some differing opinions, so not sure if anything has changed since then but.....

I have exposed joists in my basement and would like to retrofit a radiant heating system for my first floor. Problem is there are hundreds....maybe thousands....of nails poking through the subfloor. These things are from the 1920s so they are hefty.

Obviously I can't install the aluminim plates on the subfloor with the nails poking through (and I have yet to come to terms with the prospect of having to cut/grind them all down).....could the pex and plates instead be installed along the joists? I saw some posts from a while back basically arguing that while not ideal, the loss in efficiency would not be significant. Any updated insight would be appreciated.....


  • hot_rod
    hot_rod Member Posts: 19,899
    Look into the UltraFin product the used aluminum plates attached to suspended tube. They do require higher operating temperatures, but you avoid dealing with the nails. 
    A die grinder and cutoff wheel make short work of nails, if you are up for the challenge.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    neohiokcoppHomerJSmithrick in Alaska
  • ewang
    ewang Member Posts: 77
    Look into an oscillating tool with a metal cutting blade.

    Wear ear protection and goggles, but way less debris and fire-starting potential when compared to a cutoff wheel.
  • Dave H_2
    Dave H_2 Member Posts: 527
    First thing I would do is a heat loss and a radiant design as to whether or not you need the plates in the first place. Depending upon the heat loss and the calculated water temperature, you may be able to install a suspended pipe system rather than use plates. The difference in water temp design can be up to 40 degrees, a plated system would use a lower water temp.

    So if you can use a suspended system, you could route the tubing in the joist bay and not come in contact with the nails.

    Dave H
  • jhewings
    jhewings Member Posts: 139
    I find a hammer smack will break most of the nails at the bottom of the subfloor. Some only bend over so maybe hit them again in the opposite direction or use the claw of the hammer or a flat chisel or even pliers to finish the job. On second thought I am referring to screws.... Try a test with a hammer anyway. It might work.
  • hcpatel78
    hcpatel78 Member Posts: 150
    edited April 2021
    Hi...I feel your pain. But believe me hard work will payoff for the rest of the life with best comfort.
    I just finished my radiant after few months of hard work.
    Covid-19 Layoff was blessing to finished my project quicker. And I was busy with project without getting depressed without work/job. I had something to divert my energy and mind. I started my project in December 2019 and finished in Summer 2020 and I had my first best ever comfortable winter with radiant. As of today we have 20 degree F night temperature in Northern part of New Jersey and my house temperature is 70 F. Just found out that my Jasmine Plant is blooming flowers now instead in August in NJ. This is all because of radiant heat.

    I have 1000 sq.ft of the open joists basement . All hardwood installed with staples and cleat nails. I tried every single tool to cut it faster and quicker. You name it....pneumatic small cutting tool, Dremel, oscillating tool, hammer, cut off wheel, angle grinder.....nothing worked perfectly. One thing worked perfect and that was Channellock 357 nail cutter. Worked like magic but all manual cutting....lots of labor and pain......Because of Covid-19 I could not call friends and family, otherwise project would become more enjoyable.

    I had 22 joist, each 30 ft. long. I decided to do one joist a day And I was done cutting all nails and staples within one month. It was almost 25K to 30k nails and staples, half full of 5 gallon bucket of cut nails. Once you finish cutting nails your 80% work is done effort wise and labor wise.
    10% will be Uponor Joist track Plates and Hepex tubing and boiler piping another 10 % of work...

    Please see my topic here...


    If you need help....This is the best place to get technical advice and you will find America's Best Professional People here on this forum.
    Thank you,
    Hiren Patel
  • TAG
    TAG Member Posts: 751
    With the proper wheel -- they come off rather quickly.
    A cheap HF and some wheels --- eye glasses and ear protection ...gloves
  • hcpatel78
    hcpatel78 Member Posts: 150
    edited April 2021
    3M Face shield and safety glasses are must. Don't start project without that, otherwise you will regret it for rest of life if you shot nail in your eye.

    Thank you,
    Hiren Patel
  • kenjohnson
    kenjohnson Member Posts: 81
    It's a pain in the neck, but just grind off the nails or find some other way to cut them off. You will be able to have the lowest operating temperature that way and therefore lowest operating cost. This is my post from a couple of years ago. https://forum.heatinghelp.com/discussion/163346/would-like-some-feedback-on-my-radiant-design-plans#latest
  • Zman
    Zman Member Posts: 7,467
    hcpatel78 said:

    3M Face shield and safety glasses are must. Don't start project without that, otherwise you will regret it for rest of life if you shot nail in your eye.

    That and you will be paranoid every time you get a MRI
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,467
    There are plenty of options if you have room to add to the top of the floor. They work very well
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein