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A peek inside a dual coile indirect tank

Point taken, but we're not testing materials. We're testing indirect water heaters, and the heat exchangers in those water heaters have different surface areas and thicknesses, as well as different materials.


  • hot_rod
    hot_rod Member Posts: 22,105
    This cut a way tank

    was an excellent demo at my FarmFest booth this weekend. For the first time I was able to clearly show and explain the indirect concept to homeowners.

    This tank allowed me to demonstrate the solar coil/ wood boiler option. Wood boiler/ radiant, dual boiler, dual coil 1 heat source, and all the other possible options.

    This tank from Heat-Flo will also be available with a 1" FIP tap for an electric element option.

    Heat Flo talked about making these tanks available for dealers and contractor special events.

    This tank has a 316L, 1-1/8" smooth stainless coil. 20 feet coiled plus about 4 feet of riser tube

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Home Depot Employee
    Home Depot Employee Member Posts: 329

    The Triangle Tube Smart Tank is available as a cutaway and it is impressive!
  • Joe Billow_6
    Joe Billow_6 Member Posts: 69

    Hot Rod, Have you used these tanks.
  • Dread27
    Dread27 Member Posts: 5

    I have heard of people using this dual coil tank from that manufacture and the response was not very good. They were not impressed with it. I question the heat tranfer of stainless steel in a solar system.
  • Constantin
    Constantin Member Posts: 3,796
    Question of HX?

    I have no idea if the tank in question is any good, but your second statement re: stainless in solar not being a good heat exchanger choice intrigues me. What is your basis for this statement? What materials would you prefer, and why?

    I ask, simply because my solar heat transfer seems to be just fine despite using a stainless tank.
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
    Stainless tank is fine

    However; there are better materials for transfering heat (water to water) than stainless steel. Heat Transfer Products uses a cupronickel exchanger inside a stainless tank for example.

    In the solar game, scraping every last bit of temperature is what it's all about, so using a more conductive metal for the heat exchanger is more desirable.
  • Andrew Hagen_2
    Andrew Hagen_2 Member Posts: 236

    Cupronickel is a much better conductor than stainless steel. However, heat exchanger surface area and thickness are as important as the material. Also, last I looked, there is far less coil in a Superstor than there is in a Megastor or Verticell. I also question some of the ratings of indirect tanks. I was once told by technical service at a major manufacturer that their double wall tank had a better first hour rating because it had twice as much heat exchanger wall. I would love to see every indirect manufacturer publish literature similar to the Viessmann literature.
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
    Tounge in cheek here...

    >Cupronickel is a much better conductor than stainless steel. >However, heat exchanger surface area and thickness are as important >as the material.

    If you are comparing two heat exchangers that are not of the same wall thickness, or if the surface areas are different, then it's not really a fair test of the conductivity of the metal. :)
This discussion has been closed.