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Tankless Hot Water

Boston
Boston Member Posts: 71
in THE MAIN WALL
This could be a dumb question - why do all you guys install these massivew indirect tanks - why not use something like an everhot indirect - it seems to be wasteful to buffer so much hot water when in reality it is used in large quantities for very short perods of time.

Seems like it would be much better to have a smaller tank at hotter temps mixed down to make dhw.

I have not seen indirects used in residential applications in the last 20 years, they used to be common and worked well.

Am I missing something? I am starting to think much more about efficiency at 3>00/gallon.


Along the same lines, why don't we see multiple smaller boilers installed - in a sense modulating by using multiple boilers. Do you guys think of this wen you go out and design systems?

I have never seem two small boiler replace large, older systems. Seem slike the cost of boiler and installation is going to be a lot less than cost of ongoing operation.

Comments

  • Supply House Rick
    Supply House Rick Member Posts: 1,399
    A thought on Tankless

    Say you have a large whirlpool with a 20 GPM filler, you have a let's say a Bosch 635ES that will give you 6 GPM, see my point? Going to be cold by the times it's filled.

    We sell tankless water heaters to people living alone, couples, weekend retreats, condos, works well with a shower etc. These are great for some applications, not all. It's all based on demand in GPM's...

    Rick
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Indirects or aquaboosters

    are arguably the most efficient form of hot-water storage since they don't have flues going thru them to create larger standby losses. Plus, if you have a really small house with a low heat loss, and for whatever reason can't use a mod/con, an indirect gives the boiler something to do.

    Multiple-boiler setups will get more and more attractive as fuel prices rise. We're working on a job that may go this way.

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  • Scott Gregg
    Scott Gregg Member Posts: 187
    I don't think so...

    Rick,

    Suppose that house is one of the standard new homes of which hundreds of thousands are built each year. These homes use PEX or CPVC water lines and 3/4" hot water mains. You can't get more than about 8GPM through them anyway! It doesn't matter if you have a 30GPM tub filler if the piping will only pass 8GPM after normal system losses. (Been there, seen and measured it.) It's going to take 8-10 minutes to fill the tub anyway, but at least with the tankless you’re not out of hot water once your done!

    If you have a tankless that will do 6GPM (in the winter) and add another 2GPM (Because everyone still sets the hot water at 120*+ and you have to mix in some cold) you are going to fill the same tub, just as fast in most homes.

    No, not all homes. If it is a luxury house piped for higher flows a Twin Noritz N-069M will do from about 10GPM to about 15GPM. (600-900 gallons per hour) and the unit is still almost aways off and full mod. There are bigger models for bigger needs.

    If you are going to spend tens of thousands of $$ for a high performance bath, you might as well be able to use it without adding a new mechanical room to house large tanks.

    (Plus the Bosch is a poor comparison for tankless. Look at Noritz and Rinnai.)

    Scott
    www.profitableplumbing.com
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