Radiant floor could be a liability in the long run?

Discussion in 'Radiant Heating and Cooling' started by TJamesW, Dec 25, 2012.

  1. TJamesW

    TJamesW Member

    Reading a couple of threads and other forums / articles, seems that many consider radiant floor to be a tricky combo with Geo. My wife would like warm floors, which will all be hardwood.

    - Does this require a Gypcrete pour? I need a nail base for the hardwood, so this really starts adding a lot of height / mass above the floor tubing. Seems reaction time would be slow.

    - AC would seem to best use forced air.

    - Basement will have open stairway down, and be 1/2 finished. No radiant heat down there, I suppose, so ducts needed down there, I imagine.

    I would think forced air would be the easier solution, but before I abandon the wife's thought of radiant, I thought I would ask.

  2. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Have your wife call me. We do geo/radiant all the time. I much prefer moving heat with water as it takes up less space.

    The more tubing installed in a radiant panel the lower the temperature required for comfort.

    Put tubing in the basement concreate and you have a high mass heat sink. If you decide to do an over pour with gypcrete you have a low mass fast acting floor and it only adds 1 1/2" and very little weight.

    You could do a staple up floor with plates and insulation and use care when installing the hard wood. We did a job in Avon Ohio and installed a dry floor over the sub-floor and used sleepers between the tubes for nailing down the final flooring.

    There is a new control available that automatically monitors dew point so one can remove the sensible heat from a space without condensation and the latent heat goes away with a duct work forced air system.

    A radiant system increases delivery efficientcy by about 30%.

  3. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Contractors that know radiant are a small percentage of HVAC contractors. Contractors that know radiant geo are less than 1 in 100.
    You really want to vette your contractor carefully.
  4. TJamesW

    TJamesW Member

    Joe, that's what I'm afraid of.
    Last edited: Dec 26, 2012
  5. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    This stuff is not rocket scince or cardiovascular stuff. It is just work. I do not need practice tying pex to rebar at my age. I hate zip ties.

    What I do know is how to make a system work well the first time.

    I am in the one percent.

    May I help you with your dream?

  6. TJamesW

    TJamesW Member

    How does radiant floor tubing cool a house if there's no forced air?
  7. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    By cooling the slab, monitoring humidity (dew poInt) , and switching to dehumidification wh
    en required.
  8. TJamesW

    TJamesW Member

    Thanks Chris, and if this if the first floor above the basement, one would definitely need a gypcrete pour, then nail base of two sheets of ply, then the hardwood.

    I'm seeing a lot of insulating lumber between me and the temp I want. I'm talking myself right outta radiant
  9. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    You see insulation a wet head sees thermal mass.
  10. TJamesW

    TJamesW Member

    I see insulation, yes. Three layers of less-than-conductive material between a foot and the source of the cold. At the very least, this would be a slower system to react I have to imagine. And while my wife may like a warm floor in the winter, she will not want cold floors in the summer.

    I'll admit I'm no expert, but it certainly seems like a very inefficient way to cool a building. Plus with the gypcrete pour required, this must be among the most expensive options possible.

    I think I'm going to pass on radiant. Back to looking at forced air.
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    My grandpa told me, "A fool convinced against his will, is of the same opinion still.", some one else may have thought that up, but that is who I learned it from.

    I am so sorry for your wife, that you are giving up on radiant. I do not know if the Radiant Panel Association has their web site and BB back on line yet, but if it is there is a wealth of information there.

    Joe Harden told you the key to how this works. You see insulation, and I, as a "wet head" see thermal mass. I bought, and have someplace on a flash drive, the value of various floor materials. What has to happen in a radiant panel is since heat goes to cold, the insulation needs to be more on the non-conditioned space side of the panel so the the heat goes to the conditioned space. Radiant cooling works the same way.

    I have noticed you missed the dry sleeper floor option I mentioned a few threads ago. It is entirely DIY possible and does not employ gypcrete which is considered a "wet" floor. Six years ago thermal enhanst gyp cost me $1.60 a square foot.

    Sorry for your loss.

  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    radiant is the best way to heat your home, and it is the most economical in combination with geo since you can reduce your supply temperature in well designed systems to run extremely efficient, way below the advertised COP. No way I would ever buy or build a house without radiant heat. But it is your call for your home. Good luck.
  13. TJamesW

    TJamesW Member

    Thank you for this.

    Between the sleepers there's essentially a small air cavity with the tubes? No conducting element like gypcrete? Is the hose in contact with the finished floor? Avoiding the cost of gypcrete is welcomed, but it would seem to drop efficiency, as that gypcrete is a good conductor.

    Even if efficient, you'd still have cold floors in the summer trying to cool the place. Am I missing something with this aspect?
    Last edited: Dec 29, 2012
  14. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Better performing top of the floor systems have embedded pipes in aluminum for conduction. Check at the Raupanel system from Rehau, it is one of the best performing systems out there. Alternatively, you could go with a cheaper version (Radiant Floor Heating - Over-floor Packages | Eagle Mountain | RadiantMax). Gypcrete adds thermal mass to a radiant system, making it less responsive. Yes, the floors would be cold in A/C mode, with the threat of condensation hanging over your head, thus still the need for dehumidification. I would always recommend ductwork for A/C.
  15. TJamesW

    TJamesW Member

    Thank you Doc. So if the AC was best delivered with ducting, does it make sense to have radiant for only heating? That would seem to be simply an extravagance given the tubing cost.

    EDIT: The Eagle Mountain system looks interesting. I assume something like that was what Marc was referring to. The subflooring sections in between the tubing would be less than gypcrete.
    Last edited: Dec 29, 2012
  16. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It depends on how you look at it. You call it an extravagance, I call it added comfort and performance I don't want to miss.
    Lets put it that way: I don't know anyone who has lived with a well performing radiant system and in their next house switches back to forced air. Once you had it, you can't live without it. It is a bit like PC or Apple computers. I know many people who switched from PC to Apple and are thrilled. I don't think I know a single person who switched from Apple to PC. Apple is much pricier, but well worth it, IMHO.
    Last edited: Dec 29, 2012
  17. TJamesW

    TJamesW Member

    I see. Good analogy... Thank you for the insight.

    So you would spec a radiant floor for heat and forced air for cooling. I can see the efficiency of radiant heat, but with the potential issues and cold floor it seems you'd need to force cold air. Sorry if I'm not following.
  18. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Radiant heat, forced air cooling, either with a hybrid heatpump or water-water with hydronic air handlers for cooling. I would advise against radiant cooling.
  19. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Radiant cooling does not make the floor or panel cold. The radiant system removes sensible heat. The duct work is there for removal of latent heat. A smart communicating control system runs the equipment monitoring both temperature and dew point. An example would be the Tekmar 406 control. We are installing one next month.

  20. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Once you have the ductwork there for the latent heat, why don't you use it to remove the sensible heat and bypass the complexity of humidity control with radiant cooling?

    Did not have much luck with the 406, it did not do the things Tekmar said it would do. I was trying to use it in the control setup in this system (Temperature and Energy logging by: Web Energy Logger), ended up with a bunch of relays, manual switchover and Tekmark 152s. Let us know how it goes.

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