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Joist track insulation

fricard
fricard Member Posts: 18
Uponor says Insulation has to be tight up against the plates. My insulation contractor says that there should be a small air space of about 1 inch. He said that by doing this the floor will heat more evenly. He did say that I probably would never notice it but that he has checked it with infrared imaging to confirm it. I’m not sure what to do because my insulation contractor really seems to be knowledgeable about everything to do with insulation and heating and he says he has a lot of experience dealing with radiant. The Uponor rep said to fill the whole bay with insulation which is 14 inches. The insulation contractor said that is a waste of material and money and that he would recommend no more than R30. Also he said by doing the entire bay it will cause the insulation to not last as long because it will be compacted too much. I have no idea what to do now.

Comments

  • kcopp
    kcopp Member Posts: 3,819
    edited March 3
    Uponor is correct.
    The whole idea of the plates is to conduct heating to the floor. The 1" space would be more of a Convective approach.
    Your contractor may be thinking about a staple up installation where plates are NOT used. In that case a 1-2" space is commonly used.
    R-30 should be good.... I would use Rockwool if you have an option.
    STEVEusaPAgeno907Alan (California Radiant) ForbesRich_49
  • fricard
    fricard Member Posts: 18
    Sorry. R30 is basement ceiling. 1st floor ceiling he said R19. What is the problem I would have if he did the 1” airspace?
  • kcopp
    kcopp Member Posts: 3,819
    Slower response time.
    ethicalpaulRich_49
  • TAG
    TAG Member Posts: 489
    You want all the heat to go up -- with a stable up the idea is the gap allows the heat from the PEX to disperse -- with the insulation tight to the pex the only tranfer woudl be the tiny part where the pex touches the floor.

  • fricard
    fricard Member Posts: 18
    Even with aluminum plates?
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,304
    Put the insulation against the tubing and plates, like @kcopp said.
    No air space, no foil or paper faced insulation.
    Summarized by the popular saying “no space, no face”.
    Tell your insulator that’s how it’s supposed to be, and that’s how the professionals and the manufacture recommend, and that’s how you want it done.
    steve
    ethicalpaul
  • TAG
    TAG Member Posts: 489
    With plates installed -- the insulation goes tight against the sub-floor and the plates.

    The plates are there to disperse the heat to the subfloor -- you don't want any heat loss to an air space. You want all the heat to go to the plates and transferred to the subfloor.
    ethicalpaul
  • hcpatel78
    hcpatel78 Member Posts: 140
    edited March 4
    *Joist track extruded Plates-Transfer heat with conduction......
    *The staple up (tube hangs in air )- Transfer heat with convection.....

    For conduction heat transfer principle .....do not keep air gap.....as it will waste energy in that air pocket...basically less efficient and longer response time.

    For Convection heat transfer principle...…keep air gap as system needs space to transfer heat from hanging tube to the floor----in that case keep space....


    Hope you understand Heat Transfer principles...





    Thank you,
    Hiren
    Thank you,
    Hiren Patel
  • ewang
    ewang Member Posts: 74
    I put R13 up tight against the pex/plates and it works great. Note my basement is finished/insulated, so I don't care if some heat comes down into the space below.
  • fricard
    fricard Member Posts: 18
    I looked up Viega and they say to use foil with an air space. Uponor says no foil and no airspace. Weird. 
  • TAG
    TAG Member Posts: 489
    Viega recommends the air gap with staple up .... this is correct as best that can be achieved. They include that information on page 14 of my manual .... it's hard to say if they link the plates as being a "staple up". It seems they do. They also explain you have to assure there are no openings in the bay for any air currents to interfere with the intended static nature of this area -- or the gap will not work as anticipated. The reality is that even pushing the insulation up tight at the bay ends and any holes ..... there will be gaps. The people who make the heavy plates have you fully insulate w/o the need for space or foil.

    We don't live in an ideal world. When I did my first project over 30 years ago with plates the recommendation was typical R13 w foil (very common product). This required lots of insulation manipulation and a million of those small metal sticks to hold the insulation up. I'm sure it quickly waved and the gap above large. I'm sure the foil had some positives. When you fire up a plate system when it's all open there is great radiation downward. At some point the idea to just fill the cavity became the norm .... I always fully insulate my building interiors for sound anyway so this was the norm for me. Have placed my hand in and around the insulation and it seems to be very effective in keeping the heat where you want it to go ....up.

    It would take someone doing various tests to see the real world differences -- if any .... between the various ways and what is the actual ability to get the intended install. The plate manufacturer did studies of the plate thickness (they make two) and the thicker plates have higher outputs at a given temp. So getting that heat to the subfloor seems to be most important. With a gap this will be reduced. The vast majority of the plates sold are the thinner ones. There are also ones that are thiner still --- the type that cover the Pex. These may be wider -- but, don't work as well.

  • hot_rod
    hot_rod Member Posts: 15,022
    TAG said:

    Viega recommends the air gap with staple up .... this is correct as best that can be achieved. They include that information on page 14 of my manual .... it's hard to say if they link the plates as being a "staple up". It seems they do. They also explain you have to assure there are no openings in the bay for any air currents to interfere with the intended static nature of this area -- or the gap will not work as anticipated. The reality is that even pushing the insulation up tight at the bay ends and any holes ..... there will be gaps. The people who make the heavy plates have you fully insulate w/o the need for space or foil.

    We don't live in an ideal world. When I did my first project over 30 years ago with plates the recommendation was typical R13 w foil (very common product). This required lots of insulation manipulation and a million of those small metal sticks to hold the insulation up. I'm sure it quickly waved and the gap above large. I'm sure the foil had some positives. When you fire up a plate system when it's all open there is great radiation downward. At some point the idea to just fill the cavity became the norm .... I always fully insulate my building interiors for sound anyway so this was the norm for me. Have placed my hand in and around the insulation and it seems to be very effective in keeping the heat where you want it to go ....up.

    It would take someone doing various tests to see the real world differences -- if any .... between the various ways and what is the actual ability to get the intended install. The plate manufacturer did studies of the plate thickness (they make two) and the thicker plates have higher outputs at a given temp. So getting that heat to the subfloor seems to be most important. With a gap this will be reduced. The vast majority of the plates sold are the thinner ones. There are also ones that are thiner still --- the type that cover the Pex. These may be wider -- but, don't work as well.

    The terminology has gotten a bit muddled over the years.

    To me, staple up refers to the Heatway, Watts Onix type installation where you actually staple the tube to the floor, wall or whatever you are heating.
    The insulation method they proposed with staple up included a gap and foil backed insulation. In reality the foil backed insulation, if you can even find it, would dust over quickly and provide little if any reflective value. May as well push un-faced batts against the tube :)

    l have actually spray foamed a few of the transfer plate jobs, but beware that foam will find the tiniest crack and expand into it, including any gaps between the floor and plate!

    I like the spray foam as it seals the rim joist area better than any batts, that can be a huge infiltration loss area. Tough to find a leaking tube in a spray foamed radiant job however:)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    ethicalpaul
  • TAG
    TAG Member Posts: 489
    Hot Rod -- My understanding has always been just pipe = staple up. Your knowledge is much deeper than mine. Think I remember Heatway -- was that the twin tube rubber stuff. Wanted to try a thin layer of foam on the plates on my last project ..... was foaming the project. The foam guy was less than excited about doing it -- high ceilings. Stuck with conventional for all the floors.
  • Rich_49
    Rich_49 Member Posts: 2,608
    TAG said:

    You want all the heat to go up -- with a stable up the idea is the gap allows the heat from the PEX to disperse -- with the insulation tight to the pex the only tranfer woudl be the tiny part where the pex touches the floor.

    NO AIRSPACE with plates . R19 will be fine where you stated .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • hot_rod
    hot_rod Member Posts: 15,022
    TAG said:

    Hot Rod -- My understanding has always been just pipe = staple up. Your knowledge is much deeper than mine. Think I remember Heatway -- was that the twin tube rubber stuff. Wanted to try a thin layer of foam on the plates on my last project ..... was foaming the project. The foam guy was less than excited about doing it -- high ceilings. Stuck with conventional for all the floors.

    I think Wirsbo, now Upon started the suspended tube method as an answer to the direct staple up. Bare pex tube suspended an inch or so below the floor. Actually called joist bay heating. Limited output as it was mainly convection. Some tried to staple bare pex tight to the floor but it would squirm around too much, make noise and wear hints at the staples.

    Shortly after suspended tube UltraFin came along with louvered aluminum plates to add onto suspended tube, originally riveted on, then a clip on style. It increased the convection, same a fins on copper tube baseboard.

    Then of course all sorts of transfer plates, steel , aluminum, dual track, etc.

    The better the conduction transfer from tube to floor, the lower the required SWT and the highest BTU/ft. output.

    Perhaps the king of transfer would be the fairly heavy gauge Warmboard product, a solid aluminum sheet in contact with the flooring product. Although copper tube in ThermoFin, 8" on center comes real close for output.

    Notice where I routed across the WarmBoard and how the heat transfer stops there.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Rich_49ewangCanuckerkenjohnson
  • TAG
    TAG Member Posts: 489
    Hot Rod -- spent a lot of time on my first project 30+ years ago. It was a retrofit of a big old brick house from the 40's that is now my office. There was a guy near Chester PA back then that helped me a lot -- ordered all my Buderus stuff from him when the time came. The extruded plates were expensive back then .... or maybe I had less money !! Anyway -- used the Wirsbo 4' extruded plates in the areas needing higher output. The other areas got the 4' lengths that cover the PEX. There was no question the extruded pulled more heat from the Pex. This was noticeable from under the floor when it was first fired up w/o insulation. Wirsbo did not have you use anything in the grove of the cover plates as it seems they do now. Remember there were various sizes and widths of that type as well. Was either lucky that my loads matched the different outputs or there was not much difference in the end. Found the extruded easier to install -- so they were my go to after. The guy in Chester told me to stay away from staple up. On first start up the cover type can make some minor noise .... no more that what typical Pex does wrapped in foam insulation. The house was a great test case.

    You posted some of your test shots before -- the Warmboard one is very interesting. It shows how important that tight fit of AL is to the working of the product. Without the AL in the grove it drops off and you naturally get that hot spot. Was tempted to use some heavy AL foil in mine when you posted.
  • hot_rod
    hot_rod Member Posts: 15,022
    I believe Dale and Bob at the former Radiant Engineering in Bozeman, now Radiant Design and Supply, produced the first extruded aluminum plates, the ThermoFin. Others copied them. The first version was a heavy gauge, a thinner & narrower version came later. It's all about the cost of the aluminum when you compare extruded to flashing thickness transfer plates.
    Certainly the thicker gauge transfer to the edges a bit better, but what the ThermoFin excels at is the grip of the tube, they paid a lot of attention to that detail, the extrusion shape, thickness at the web, and temper of the aluminum.
    I think Radiant Design and Supply produces the extruded plates for many other radiant companies, they have the product and manufacturing nailed.
    They had an extruder near me and I went and got some 8 or 10 footers right off the press for an exposed radiant ceiling job once.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • TAG
    TAG Member Posts: 489
    Hot rod -- spoke to Dale when I was ordering my recent plates. The 8' are nice except for the shipping cost .. no predrilled. They do sell to other large sellers ...

    I had a nice conversation with him after others here had recommended going with the 3/8 Pex. He recommended going in the 160' range vs 200' for the tubing runs. Bought the Viega 3/8 from him -- Viega sells a 1200' roll. I was doing almost 1k sf room ... so I was not going to risk messing it up.

    Used 11 loops ...
  • ewang
    ewang Member Posts: 74
    I used a mix of Uponor joist track and this guy's plates off eBay.

    The ebay versions are less expensive, better quality and wider than Uponor.
    https://www.ebay.com/itm/20-47-EXTRUDED-Aluminum-Heat-Transfer-Plates-for-1-2-Pex-Tubing/224279744378
  • TAG
    TAG Member Posts: 489
    ewang: Not sure who makes the Uponor. The Thermofin is 4" wide .065 ...e-bay is not as wide but a tad thicker Al. The standard is 3 1/2 wide .. with a little thiner AL. I can't comment on the AL type or it's importance to the task.
  • fricard
    fricard Member Posts: 18
    They put R19 and they use the rods to hold it up tight against the plates. Do those rods stay in place?  The bays are 14” deep. I could put r30 under the r19 and it will hold everything in place. This will compress the insulation a little which he said is bad for the insulation and will cause it to fail also that it’s a waste of material and money. I’m just concerned that if those rods loosen up over time the r19 will fall down. 
  • hot_rod
    hot_rod Member Posts: 15,022
    Maybe just another layer of R-19 under what you have. That should easily fit in a 14" deep joist bay.
    Yes, the rods are a common way to hold the batts up in place.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream