Straight Talk About "On-Demand Tankless Water Heaters by A.O. Smith

Discussion in 'Tankless Water Heater Forum' started by SewerRatz, Feb 10, 2009.

  1. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    The following is some questions and answers about tankless water heaters. I think this will be a great help to all that are considering a tankless unit. Click on the picture to see a larger image.
    [​IMG]
    Last edited: Feb 10, 2009
  2. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
  3. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
  4. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
  5. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    You had me saying "NO" at tankless :D
  6. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Just a note to those that think A.O. Smith doesn't want to sell you a tankless water heater. That is false, what they want you to do is make an informed choice when you are considering a tankless unit. They want people to realize here in the USA we take the amount of water we use at once for granted, and if you install a single unit in a high demand situation the water will not get hot enough to be satisfactory. Which is why they point out it could be costly to replace your tanked heater with a tankless unit.

    For some homes two units are needed to provide you enough hot water for those peak usage times. Below is a pic showing how two units are installed. Just a note if you are just washing your hands only one unit fires up, the only time the second unit will turn on is when you exceed the flow rate of the first unit to get the desired temperature.

    [​IMG]
  7. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Another note about the cost of installing tankless units is gas pipe sizing. Most Tank units only use 1/2" piping due to BTU ratings which the most common is 40,000 BTU's. Tankless units on low flow mode usually draws 25,000 BTU's and full flow mode can go as high as 199,000 BTU's, some units can go higher but they must follow boiler installation codes once they go over 200,000 BTU's. Well in most cases you will need to tap off the main gas supply coming into the home with a 3/4" line to the tankless unit, if you have to install multiple units as this next picture you will see they ran 1 1/4" pipe up to the units then reduced it down to the 3/4" to the units, This insures that when all three units fire up at their 199,000 BTU's they will get enough gas to run at that setting. So this is the other part of the expense that A.O. Smith is talking about.

    [​IMG]
  8. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    How loud are the tankless units? I don't think I ever found reliable decibel information.

    David
  9. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    They are no louder than a power vent water heater. I never went and measured the decibels. I will try to research this a bit and post it here when I get the answers.
  10. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    They are a little quieter than one of these...

    [​IMG]

    Seriously the powervent is a good comparison..
  11. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
  12. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Ah yes, my local plumbing supply hands that out to homeowners that come in asking about tankless heaters. I am going to make jpgs of them 4 pages and post them here in this thread too. I like to see this thread stay on the facts of tankless heaters instead of a battle ground like the other threads ended up becoming. Thank you Redwood for posting this PDF
  13. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
  14. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    I dunno to possibly save that .15 a week I might be tempted :rolleyes:
    I was hoping to see long term test to allow for scale buildup
  15. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas

    I'll let you know this August (1st year anniversary) when I do my first descale how hard it was and how bad :rolleyes: the system was hosed up....:eek:
  16. Ladiesman271

    Ladiesman271 Homeowner

    Messages:
    221


    I was going to point out how they stacked the deck in that test and have commited a few "code" violations, but those issues have been beaten to death in other threads.

    The NG and electric costs are also way out of date!


    Link to this "test" - read section called What about tank manufacturers?


    .
    Last edited: Feb 23, 2009
  17. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    That is from 2005 so yes 4 years out of date. But still some information explaining some of the issues.
  18. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    Hi Ladiesman271,

    What's the decibel level when measured at 1 meter? That's the usual distance for taking noise measurements.

    David
  19. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    My Rinai R75lsi is what I would say to be about 50-55db....with 50 db being Normal conversation and 70 db being a Vacuum cleaner.
  20. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    WHAT!! ??

    So you mean with better insulation in the tank models recently the gap is even closer!! :D

Share This Page