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radiant floor retrofit

dnf | Posted in Energy, Heating & Insulation on November 21, 2007 08:31am

Hi:

Here is my crazy idea:

Have 1″ plywood sub floor. Add 3/4″ plywood, rout out grooves for the pex to run in. Install aluminum sheets in the groove (bent somehow or two pieces) for heat distribution. Hardwood over top. Kind of like a poor man’s version of Warmboard.

Any ideas on this, and more specifically, how can I get the aluminum sheets bent to fit the channels (or trenches) that I am routing out? I don’t have a brake. Is there a product out there or should I just talk to an aluminum siding guy?

cheers

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  1. calvin | Nov 21, 2007 08:40pm | #1

    rip strips of osb for the straights.

    make a curve template for your turns on a separate pc.  Put as many turns on that pc as you can.  Place the turns pc. along the opposite walls, run the straights between.

    A great place for Information, Comraderie, and a sucker punch.

    Remodeling Contractor just outside the Glass City.

    http://www.quittintime.com/

     

  2. MikeHennessy | Nov 21, 2007 09:08pm | #2

    See what Calvin said. I've never used Warmboard, but I have used Wirsbo's QuikTrak. This comes in straights and curves. The curves come in 4-to-the-piece. You butt the straights up against them.

    On the straights, the "slot" is just a space between two wooden strips. The wood is held together by a sheet of aluminum stapled to the backs of the strips. On the rounds, the "slot" is routed to about 1/32" from the bottom of the wood. The aluminum strip is not fastened to the wood, but is just layed on the floor below the strip.

    If I were going to try what you have suggested, I'd probably buy the curves and lay up the straights one at a time to meet them as I was running the tubing. I'd use flashing flat on the floor to distribute the heat. Lay one strip, butt the tubing up against it and around a corner, then butt a second strip up against the tube. Repeat. Accuracy would be critical to get everything to line up right.

    Wirsbo also sells caulk with hi metalic content to bond the tube to the aluminum for better heat transfer.

    All that said, for my money, this would be a royal pain and not worth the savings (if any) over using either Warmboard or QuikTrak.

    Mike Hennessy
    Pittsburgh, PA

    1. dnf | Nov 21, 2007 09:20pm | #3

      $9 a foot for Warmboard. Haven't priced out the stuff you mentioned. Plus I don't need an additional 1 1/8" added to my floors. 3/4" is bad enough.Also wasn't going to get too fancy. Just put in aluminum in the straights. I am ripping out the old flooring (80% carpet and 20% tile) anyways.Will look at the QuickTrak. Being in BC is a problem as we don't always get stuff that you guys get.Didn't think of just putting the pex in the spaces. Would save a lot of routing. I owe somebody a few beers.cheers

      1. MikeHennessy | Nov 22, 2007 09:48pm | #7

        I don't remember off the top of my head how much QuikTrak costs, but it sure ain't 9 bucks!

        Here's a shot of a recent install so you can see how it lays out.

        Mike HennessyPittsburgh, PA

  3. pebble | Nov 21, 2007 09:23pm | #4

    I made a press/stamp for the grooves in the aluminum flashing I used for heat plates. If using 1/2" PEX, go to the section of the hardware store where they have the metal dowels and get about a 3' length of 5/8" metal dowel. Using a couple pipe strappings attach it to a narrow piece of plywood slightly longer than the dowel. That will be the part that forms the groove when you beat it with a small sledge hammer. Then you need to put two 2x4's about 3/4" apart on a piece of plywood too. That will be what you place the flashing on so that the metal dowel goes into that space as you beat it. Here, I am gonna take a pic of my rig. And here are some of my bathtub alcove sandwich job. I used a 3/4" router bit to route the grooves, using a 2x4 for the straights and a curved template for the loops, like calvin said to. I saved a lot of money doing it this way, the roll of flashing was about $16 and the metal dowel about $6. The tubing was then held in place with temporary cleats until the silicone caulk dried to secure in the grooves. Using PEX-Al-PEX simplified the job as it holds it's shape when bent. Pin the plates into the groove with a brad nailer.

    View Image

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    Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK

    1. dnf | Nov 21, 2007 09:33pm | #5

      Thanks for that. Pics are great!Nice to see that I am not the only crazy one.

      1. pebble | Nov 21, 2007 09:39pm | #6

        You're welcome! I am in the process of tiling it then am going to do the kitchen and living floor using the same method. Sure, it is more labor intensive but seems to be well worth it. At the end of the day I have that much more money in my pocket!Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK

  4. frenchy | Nov 22, 2007 10:58pm | #8

    dnf

     What I did was to buy aluminum flashing in rolls and then buy a bead roller..($129.99 from  http://www.woodward-fab.com  )  

      I run the aluminum flashing thru the bead roller which provides a nice bead for the Pex to lie in.

      Nailing up the aluminum flashing was extremely easy since my subfloor is 2 inch thick I just used  1 1/4 roofing nails in my roofing nailer  to quickly pop the aluminum flashing up in place.  From a roll of flashing to the pex up in place takes only a minute or so.. I mean it's really, really, fast! Yes you are working from below but it goes up in place so quickly that the whoe house is a easy job..

      You could do the same with just a 1/4 inch thick sheet of plywood  on top of your one inch thick plywood subfloor.

      You could do it on top of your subflooring if you were going to put tile in place. simply put the pex down hold it in place with the aluminimum flashing and then do a dry mortor mix on top If you use 1 inch thick pipe as your guide bars you'd still have plenty of mortor thickness.

    1. dnf | Nov 22, 2007 11:47pm | #9

      Hey Frenchy:So I assuming that this bead roller allows you to run the sheet of aluminum through it (I looked at the site but it only shows the pic) and the little die does the trough for you? I am looking to fit 1/2" pex.I have 1500 square feet to do so it would be worth the price to put me in production mode.Still think I need to go 3/4 ply (or osb) thickness due to 5/8 o.d. on the pex.

      1. frenchy | Nov 23, 2007 04:02am | #10

        dnf

           It's not a perfect fit but it does wrap around the 1/2 pex 85% of the way so it picks up plenty of heat.

         If you want a perfect fit take one of the set of dies to a machine shop and have them make you up one slightly larger (just remember to allow a little extra because if you don't the bead roller turns into a shear  )  .. I didn't bother but I did have some made to put louvers in sheet metal so I can have some louvers to cool my hot rod...It cost me $45.00

         You can't believe all the stuff you can make with a bead roller.. I digress..

           Anyway what you do is take the coil of aluminum and feed it in one side and it comes out the other side with the bead. Just take a round shanked screw driver and slightly roll the start and finish so it won't scratch the pex as it expandsand contracts thru the heat cycle.. It literaly takes but a second or two to do. 

         

        1. debtfree | Jan 14, 2008 04:34am | #11

          What kind of metal did the machine shop use to make your louver dies, and did they have to be heat treated? I'm doing a retrofit like dnf, above the subfloor and plan on putting down 3/4" ply strips leaving a gap for the heat spreader and pex-al-pex and was assuming that the spreader plates would need an approx. depth of 11/16" to be flush with the ply strips. Also was wondering if you tried to make any end curves for returns. I seen a video by one of the manufacturers of a bead roller where they were using a smaller size ( maybe 1/4" or 3/8" ) and curves seemed pretty easy; but, with 5/8" bead and possible 11/16" depth thought if might be kind of tuff to do. Thanks for any thoughts.

          1. frenchy | Jan 14, 2008 01:49pm | #12

            debtfree,

             I don't know, I brought the dies there and told them what they were to be used for.

             I've done some stuff on a curve using the bead roller but that is definately a skill.   My first few pieces tended to be all kinky, not that they couldn't be used in this application since they would be hidden but it took more than a few tries to be able to follow the curve while rolling and wind up with a smooth, kink free, curve.

              To have a curve start and end where it's wanted without kinksisn't something that you do with the first sheet you grab..

               In my case since the plates go under the floor I didn't worry about the curve at the end.

  5. GRCourter | Jan 14, 2008 08:17pm | #13

    Did the exact same thing in Virginia.  Old (150 years+) and the floor had asbestos floor tile, building dept said cover the tile or have it removed (and this is $).  Ripped the plywood and used the plates that would be used on a retro under floor, the type that is soft and plyable.  Works fine.

    1. debtfree | Jan 15, 2008 05:01am | #14

      Do you have a manufacturer's name for the plyable plates or an online marketer? Still checking out my options.

      1. GRCourter | Jan 15, 2008 05:14am | #15

        I got them from Energy Reduction in Pittsburgh, Pa.  They have since changed to the heavier plate but I can check with Mark tomorrow and see if he can point me in the right direction.  I know that they are still available because I just saw them installed in another job.  Check back tomorrow.

      2. GRCourter | Jan 19, 2008 12:30am | #16

        Hey.  I found single groove plates 16" long $4-$4.25 each.  Let me know where you are. 

        1. debtfree | Jan 19, 2008 01:17am | #18

          Hope you didn't buy any at that price. I found them for $0.76 for 16" long and I plan on making my own for $200 a thousand foot cheaper than I can buy at $0.76 for 16" length or $0.57 a foot. I can buy the coil stock for $0.37 a foot and make my own in 4', 6' or 8'  lengths (or any custom length I need) for an easier installation; instead of dealing with multiple 16" pieces in a single straight run.

          1. GRCourter | Jan 19, 2008 01:25am | #20

            Go for it!

          2. GRCourter | Jan 19, 2008 04:58pm | #23

            Ok, help me.  Were are you getting them for $.76 each?  This is the best buy that I have found.

          3. debtfree | Jan 19, 2008 10:47pm | #24

            This is the link to the site that has them for $0.76 http://www.radiantec.com/pricing/individual-prices.php

  6. fingers | Jan 19, 2008 01:06am | #17

    Interesting thread so far.  I've thought of doing the same thing on the straight runs and maybe on the curves give the routed grooves and surrounding area of plywood a quick spray of adhesive and just use one or two layers of the heaviest aluminum foil you can find to help conduct the heat.

    Is there a reason it wouldn't work?  It would seem to be easy to form the foil into the groove with a lubricated finger.  Would the thin foil not have enough mass to transfer the heat efficiently?  Any thermodynamics experts out there?

     

    1. debtfree | Jan 19, 2008 01:24am | #19

      The guy that created this web site http://www.builditsolar.com is where I have been learning a quite a bit, and he did some experiments and it seems that something as light as aluminum foil is to light to be of much benefit. He used aluminum soffit at 0.018 thickness and I think I fould coil stock at 0.017 that I plan to use.

      1. eleft | Jan 19, 2008 02:39am | #21

        W/M .42 each

        Edited 1/18/2008 6:43 pm ET by eleft

        1. debtfree | Jan 19, 2008 03:23am | #22

          Now you left me in the dust and have my curosity peaked. What is "W/M .42 each"?

           

          1. eleft | Jan 20, 2008 01:54am | #25

            Weil Mclain panels

  7. jem777 | Mar 05, 2010 08:28am | #26

    You are doing it just right. I like your ideas though.

    scottsdale tile

  8. GaryGary | Mar 05, 2010 09:34pm | #27

    Hi,

    Here are some links on making alum fins for solar collectors -- they are basically the same as the heat spreader plates for radiant floors:

    http://www.builditsolar.com/Projects/WaterHeating/Fins/Fins.htm

    This is what I did for my radiant floor:

    http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/House.htm

    Note that while the press with the long handles looks "impressive", the simple sledge hammer jig and technique is almost as fast.

    Gary

  9. NRTRob | Mar 08, 2010 09:42am | #28

    be careful guys.

    tubing contact is very important.  the vast majority of lightweights out there have very poor contact, and that makes the plates much less helpful.  I haven't yet seen a home-made plate with good contact.

    Most cheap plates are likewise fairly sloppy.

    you want an "omega" groove that fits snugly.  and PAP does help as it can torque the lighter plates less as well.

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