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Water Heater: Tankless, Tank in Tank, or Coil HX

hot_rod Member Posts: 21,848
depends on YOUR needs. I feel an indirect would be your best choice for a good supply of hot water. I have a Phase 3 in my own home, and we have hard, iron, well water. I feel the tank in tank design handles this water condition best.

This same tank is also sold under the Weil McLain badge if that helps.

Tanks, like most hydronic stuff, is a lot like buying or recommending a truck. Different strokes for different foks :)

The dealer, and installer are a bigger piece of the puzzle. Should a problem arise, it's nice to know the players will stand behind the product and installation.

I think you would be hard pressed to get a consensus on "the best tank". Good thing, I suppose or it would get boring around here :)

hot rod

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Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream


  • Susan_2
    Susan_2 Member Posts: 8
    Which Water Heater?-Tankless, Indirect Tank in Tank, or Coil HX?

    I am a homeowner trying to determine which type of water heater to have installed. I am already sold on indirect vs direct, but not sure about indirect vs. tankless or what kind of indirect (coil vs. tank in tank). I have town water, not well water, gas fired boiler and hot water baseboards, but hope to be installing radiant heat in kitchen floor.

    Triangle Tube Phase III indicates that indirect "tank-in-tank" provides a more even distribution of heat vs. a coil hx, and that a coil hx is more susceptible to liming (tank in tank has a self-cleaning design) and reduced efficiency, as well as to cold spots leading to bacterial growth. Is there any truth to this and is liming and bacteria growth really a big problem w/ indirect water heater having a coil hx?

    I am also wondering how INDIRECT and TANKLESS Water Heaters compare. Efficiency, Comfort, Cost, etc.
  • Paul Pollets
    Paul Pollets Member Posts: 3,656

    Take a look at the Viessmann indirects (VitoCell 300) They set the standards for both production technique and longevity. It's the only tank on the market with a real lifetime warranty.


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  • Susan_2
    Susan_2 Member Posts: 8

    Went to Viessman's website - sharp looking instruments!! They make no mention of lime deposits but talk about a "no sacrificial anode". What's this?
  • Susan_2
    Susan_2 Member Posts: 8
    Care to comment?

    Does anyone else care to comment on this issue?

    Your expertise is greatly appreciated.
  • Susan_2
    Susan_2 Member Posts: 8
    a lot depends on my needs?

    What should I be considering? There are 2 of us now, maybe more in due time:) (but not too many more), no jacuzzi/whirlpool - just regular people - showers, dishwasher, washing machine.

    I want a 40-50 gal tank, efficient, dependable, worth the money(!!!).

    You are happy with Phase III, but yesterday I found some previous threads on THE WALL that say Phase III is the cheaper of the Indirects. I don't want the most expensive, but ... I do want good equipment....

    Our contractor is recommending Viessman. I'm reading that this is the top of the line, any idea what makes this and/or Buderus better than others, and better than one another?

    As far as buying a truck goes....i'll take the sports car! Different strokes:)
  • Gregg Jackson
    Gregg Jackson Member Posts: 55


    Any indirect water heater will have an output chart based on the size of the boiler it is connected to. The boiler size (btuh) is the "horsepower" that determines how much water you can produce from any given tank. Once you know the output of your boiler - you can then determine the output of the tank based on transfer rate. Again, this all can be found from the charts from the manufacturer. I agree that the Viessman stainless tanks are the best. There is a alot of fancy marketing that goes into most products these days but I truly believe that the Viessman tanks are a proven leader. They do carry a premium price but as Paul said - it is the only heater with a true lifetime warranty. It will be the last tank you buy...period. Unless you move :)

This discussion has been closed.