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radiant floor, stand off or flush mount clips?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by 88rxn/a, Mar 2, 2008.

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  1. 88rxn/a

    88rxn/a Member

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  2. 88rxn/a

    88rxn/a Member

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    and another Q, i read that the water needs to be at around 140 for radiant floor heat, would it be easier to run 3 way valves (1 FOR EACH ZONE OF COURSE) for the 3 zones, or use a tempering valve then to 3 different 2 zone valves?
  3. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    The type of clips depends upon the installation method. Under the floor? Poured in a slab? How thick is the slab, if that's the method?

    The fluid temperature is dependent upon the design of the system. It can be anything from 90 to 180, depending on how the system is designed. It may be the same for each zone, or it may be different.

    Joe
  4. 88rxn/a

    88rxn/a Member

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    im installing it by running with the joist in the basement for the first floor(living room and etc.).

    im guessing the heat calc. will give me more answers for the water temp.?
  5. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    "With the joist"? Do you mean the direction that the joists run, stapled to the underside of the floor, or do you mean stapled to the joists?

    Your heat calc will give you the heat loss for each zone. Then you find out if the radiant floor can work alone (ie, if the floor can actually heat the room, without being too hot). Then you figure out what water temp is needed to get the floor surface the right temperature, based on the insulation value of the construction (eg, carpet will require hotter water, in order to get the surface the correct temperature, compared to much cooler water to achieve the same thing with tile).

    Joe
  6. 88rxn/a

    88rxn/a Member

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    ill run the tubing the direction that the joist's run and stapled to the underside of the floor.

    and i got the heat calc. today so im playing around with it trying to familiarize myself with it.
  7. 88rxn/a

    88rxn/a Member

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    im still not sure which ones to get running the PEX this way??
    any thoughts?
  8. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Missed the first reply, somehow...

    You want the tubing in direct contact with the floor, no air gap.

    I'd strongly recommend aluminum transfer plates, though. Stapled tubing does not transfer heat as effectively, and will require hotter water temps to achieve the same performance, which means less efficiency.

    Joe
  9. 88rxn/a

    88rxn/a Member

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    OIC, i guess ill start researching for the cheapest place for the plates.

    again, thanks alot!
  10. Chris S

    Chris S New Member

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    If your system will work with it.... 3/8 tubing is much easier to work with than 1/2"-
    You'll need the calculations to check this though This shouldn't be an experiment.

    Best of Luck
  11. 88rxn/a

    88rxn/a Member

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    no experiment, just a guy thats never done this before.
    when i do the calculations for downstairs on the heat loss calc. i see if it works
  12. Jersey Bill

    Jersey Bill Member

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    The best that you can probably do is to run 1 loop in each joist space in contact with the floor above. this will give you a spacing of 8" assuming that the joists are 16" O.C.
    Use the heat plates around the tubes. The best price that I found is from houseneeds.com. In the last few designs that I have done , the max output is around 20 btu/sqft with a max design water temperature of about 140 deg. f
    The plates come for 1/2" pex only.
    The 3/8 pex is easier to work with, but the loops have to be shorter so the manifolds are bigger, and the pump has to be a little bigger to push the water. I use the 3/8" tube in slabs and run shorter lengths in parallel with tighter spacing that required. This provides redundancy in case a tube fails it can easily be turned off with only a minor hit on capacity. The thinner tube also works better in thin (1.5") slabs.

    The clip system shown in your link wont work with the plate installation. I get a tired arm just thinking about manually stapling tubing down (or up). I use a 1" crown stapler (pneumatic) to lay out the tubes, then on the 2nd pass install the plates over (under) the tubes and staple them to the subfloor w/ a 5/16" stapler. make sure that the staples are short enough so they dont go through the subfloor.

    Anything over the 20 btu/sqft has to be taken up with supplimental baseboard. use a 2-stage tstat.

    You want to try to use 1 temperature to avoid multiple mixing valves. the Radiant panel association recomends a reset loop with constant circulation. this is especially important with staple up under wood.

    ut oh- watch out for the topic police!
  13. EForest

    EForest Member

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    you probably already saw this on bluerigde but I'll post anyway.
    this is a much better deal than houseneeds.com for aluminum plates http://www.blueridgecompany.com/radiant/hydronic/316
    and an easier install.
    best of luck!
  14. 88rxn/a

    88rxn/a Member

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    actually, no i didnt!
    thanks a million.
    i havent been having the greatest luck fiding these things.
  15. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    I've also heard of folks making their own - get aluminum flashing and a dowel (same OD as the pex you will use), cut lengths of flashing and form over the dowel.

    Supposed to be cheaper, but that Blue Ridge price is pretty cheap, too...

    Joe
  16. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    You know, I think that's one of the simplest ways I've heard to do under-mount. I still like the extruded-aluminum "snap in" plates, but they are pretty expensive compared to the simple sheetmetal plates. Using staples and then forcing the plate over would certainly save hassle compared to sliding plates onto the tube and then mounting the plates.

    Joe
  17. Chris S

    Chris S New Member

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    Joe,
    Twenty years ago I bought some non barrier tubing from a company (from Vermont I think) who also sold us aluminum plates. I remember asking the man on the phone why I couldn't just use flashing and save a bunch of money. He expalined & he was right that flashing is not soft enough to make the nice bends etc. I still have a few of these flay plates & they are soft and maleable- nothing like aluminum coil.
    I don't know how I remember all of this since I can't remember what I had for breakfast yesterday- funny how the brain works.

    The end of the story is that a few years later I first heard about the dangers of non-barrier tubing. I called up my customer went to their house and removed all of the plastic, replacing it with roll copper - I had to because they loved the warm floor. Fortunately it was only a foyer and bathroom.

    The sit you provived the link to above is the most economical ( we try not to say the c word- it infers big box) I have ever seen- always learning thanks

    Speaking of learning Joe Brown was the name of a CFI who taught me how to properly stall a Cessna 152 was that you? :)

    Chris
  18. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    I guess it depends upon the grade of flashing being used - some folks have managed to make their own plates that way.

    Nope. There sure are a lot of us out there, though...

    Joe
  19. 88rxn/a

    88rxn/a Member

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    good idea on using the flashing. id just have to come up with a way of using the dowel to form the flashing to fit the PEX.
  20. heaterman

    heaterman Minister of Fire

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    Those aren't really plates...............more like heavy aluminum foil. A good plate will have a thickness of .080 to .100", slightly less than 1/8" if you're decimally challenged. :) You want to get something that's heavy enough to maintain it's shape and stay in good contact with the floor. Otherwise you might as well just staple up the tube directly to the floor and put some 3 1/2" Fglass under it. That doesn't work to badly for just floor warming.
  21. Jersey Bill

    Jersey Bill Member

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    I have done both. 7 years ago the heavy plates were a reasonable price, around $1/ft. When I priced them recently they were $5/ft. It wasnt realistic to dump that much money into it. On a job, we just stapled aluminum flashing under (over) the tubes and didn't pre-bend the plates. The plates had pretty good contact area, but not as good as the pre-formed plates. Its been running for 3 years now, with no complaints.
    On some recent jobs I used the pre formed (thin) plates because they look nicer and werent that expensive. The job that I have on my board now will require about 1000 2'x5" plates. That will cost about $1000. Not cheap, but I wont even suggest to my customer that we install the heavier ones for 4 or 5 times the price.
    Just a note, in both cases I de-burrred the edges that come in contact with the tubing. This is to prevent cutting into the tube with any slight movements.
    Another suggestion- make sure that you are not against the temperature limit in design. Then if the plates dont perform up to expectations you can bump up the water temperature.
  22. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Tube stapled directly has very little contact area, and a round tube has the least surface area of any extruded shape. Even if you installed the plate upside-down so there was no increase in contact as a result, it would be dramatically increasing the surface area of the tube, just like the fins on baseboard element do.

    Joe
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