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radient heat

RandallRandall Posts: 3Member
I am thinking of putting in a Radientec radient heat system in my home in northern NH. Right now I have a Rinnai tankless hot water system (propane)for my hot water. I am wondering can I hook up the Rinnai with a flat plate heat exchanger to heat my floors? I will have a 50-50 mix of antifreeze in the floor. Would a gas hot water heater that Radientec recommends be better? Would a boiler br better? Is there a better system than Radientec?
I plan on doing all of the installation myself. Any help or other suggestions would be appreciated.


  • Mitch_4Mitch_4 Posts: 955Member

    search rantiantec here put in no date and peruse the 162 results.

    Be ready...the concensus is generally opposed to them as there is no basis for their design (heat loss? we don't need a stinkin heatloss!!)

    basically they run on a you got floor we got school.
  • RudnaeRudnae Posts: 47Member
    That depends...

    As far as I know, you can only use the commercial unit to provide dual purpose heat and domestic hot water. If its not the commercial unit you will void your warranty. As far as equipment selection, as many wallies will tell you, start with a heat loss and go from there. Honestly the last thing I want to see anyone use to heat their house is a hot water heater. Maybe you could find a pro using the appropriate section on this website, and those fella's could give you some advice. You're heading in the right direction but you need to beware the low bidder. Good Luck!

  • hrhr Posts: 6,106Member
    What size project?

    how many zones, what temperature requirements, heat loads per room?

    These are some of the questions that you need to answer before you size and select equipment.

    There are some nice dual units available. Bradford White and Lochinvar offer several sizes of basic tank water heaters with a radiant coil inside.

    HTP offers condensing high efficiency tank heaters with coil for radiant inside.

    Plenty of options for dedicated boilers.

    hot rod

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  • ALH_4ALH_4 Posts: 1,790Member

    From what I have seen of jobs designed and sold by Radiantec, the quality of the products and methods is quite low. What method of radiant floor installation are you planning to use? As Hot Rod said, the size of the project is an important factor in determining what heat source is appropriate. Have you done a heat loss calculation? If not, there is a "Heat Loss Calcs" link at the top of this page. An accurate room-by-room heat loss is imperative as the first step of planning a heating system. Are you planning to use outdoor reset?
  • RandallRandall Posts: 3Member

    I have not yet done a heat loss study but I will soon. I will have 4 zones (one is a small bathroom) I only need a heater for the floor since I alraedy have the Rinnai for my hot water.
  • ALH_4ALH_4 Posts: 1,790Member
    Closed Loop Heating Box

    These guys specialize in this sort of system. Be absolutely sure your system is closed loop and does not circulate your domestic water through the floor.
  • reading material & drawing

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  • RandallRandall Posts: 3Member
    more info

    In addition, I am looking to heat about 700sq ft on the ground floor, 200sq ft on the second floor now and we will put in a garage that will be 480 sq ft slab with another 480sq ft of living space above it.
  • hrhr Posts: 6,106Member
    The loads and how much

    you want to spend to cover them are really the only two questions you need to answer.

    It could be done with a basic water heater on the low cost end, or a modulating condensing boiler with solar interface, or a ground source heat puymp on the high end. And there are dozens of options in the middle.

    I'm not a huge fan of forcing an instantanous DHW heater into thinking it's a radiant boiler and DHW generator via a heat exchanger. But it is possible and there is even a product on the market to accomplish that, The Heating Box..

    It's possible to build your own HX interface but you need to know and understand GPM, head, pressure drop, pump curves, delta T and a bunch of other hydronic lingo and how it all applies.

    It sounds like you are looking at two temperatures or more for slabs and framed floor applications on the upper level??

    It might be money well spent to have a hydronics pro design and size the system, then you can shop for equipment options.

    Or throw a dart at the wall :)

    hot rod

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