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Thread: Tankless Whole House Hot Waster System

  1. #1
    Join Date
    Jul 2016
    Location
    Lebanon, TN
    Posts
    1,374

    Tankless Whole House Hot Waster System

    Looks like one, of our two, hot water systems may have finally died.

    Both, I believe, are original for when the house was built 22 years ago and are electric units in my crawl space.

    So, I think I will take this opportunity to go with whole house instant hot water system.

    I now have natural gas, so I think that's the direction I'd like to go.

    Also, I think an external unit would be preferable for the annual servicing.

    So I'm looking for pro's and con's and recommendations from those of you who may have been down this path.

    Thanks.

  2. #2
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
    Posts
    6,405
    external mount may freeze. there is no pilot light to prevent freezing.
    Bill D

  3. #3
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
    Posts
    58,263
    I had two NG-fired tankless hot water systems in our old house and loved them. There was never a want for hot water and they required a minimum of space. We could have three showers plus the dishwasher going with no issues. (I do not have gas here at the new property...it's in the street, but the cost to bring it in is steep. Not for the install of the line, but for the requirement to convert so many things within 12 months to not have to pay over five grand for the install)

    In extremely temperate/tropical climates, external systems are fine. I would not consider outside in your geography at all.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #4
    Join Date
    Feb 2003
    Location
    McKinney, TX
    Posts
    1,863
    Don’t confuse instant with unlimited. Tankless will provide unlimited hot water but before the hot water gets to your faucet it still has to travel the length of the pipes.
    Steve Jenkins, McKinney, TX. 469 742-9694
    Always use the word "impossible" with extreme caution

  5. #5
    I represented Rinnai in my business for 29 yrs. you get enough of a winter in TN to make me say, avoid .the outside units. The ,freeze. Protection (elec) kicks in around 38*. Do they work, yes, but .a direct .vent interior .will be best for you. Steve is correct. You have to look at your homes lay-out fixture wise. I one unit sufficient? Hmm,in looking at what Iíve written so far I find that topping with my broken hand is an issue. Ipíll p\m you my .phone number.
    PI can cover more territory that .way.

  6. #6
    Quote Originally Posted by ChrisA Edwards View Post
    ... Also, I think an external unit would be preferable ...
    My neighbors have them outside in this area, with zero reported issues (AFAIK).

    The (name brand) gas-fired units I have looked at in the recent past all had 2 stage freeze protection: 1- ceramic heaters (elec) turn on when low temps are detected; 2- if the heat exchanger, or other such components, drop below freezing, then the gas heater itself also fires briefly/repeatedly (even with no flow) to hold temps above freezing.

    Obviously, if your electric or gas service is unreliable, you are open to serious water heater issues (among other things).

  7. #7
    Join Date
    May 2021
    Location
    Spartanburg South Carolina
    Posts
    111
    When I ran the numbers it just didn't add up for me. I have ample room in the basement for a $500.00 gas WH that I replaced myself. When I compared that to tankless they cost more.

  8. #8
    Join Date
    Sep 2009
    Location
    Medina Ohio
    Posts
    4,180
    Looked at one for my son and the savings was not there to change.

  9. #9
    I have two units at my house. Love them. Highly recommended.

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  10. #10
    Join Date
    May 2008
    Location
    Peshtigo,WI
    Posts
    1,030
    Didn't we have a thread here a few months ago about the tankless water heaters failing in Texas last winter during the power outages?

    I wouldn't put one outside at all.

    I think you'll have to take into account how you're going to power the tankless heater. Will you have to run new electrical or gas service to the unit? Either one could be costly and have a long payback.
    Confidence: The feeling you experience before you fully understand the situation

  11. #11
    Quote Originally Posted by Jerry Bruette View Post
    Didn't we have a thread here a few months ago about the tankless water heaters failing in Texas last winter during the power outages?..
    Yes, I was one of the victims (along with many in my neighborhood). For better or worse, the common method of installation around here is exterior mount. My immediate neighbors have a Rinnai and drained the unit prior to Freezemageddon. Their unit survived just fine. Ours got bricked because I didn't think ahead and do the same. This fall, I'm going to do some winterization steps:

    -Fabricate some sort of insulation blanket for the housing and some sort of insulative wrap for the service valves.
    -Install one of these: https://safeguardpowersolutions.com/...ritz-and-more/
    -Get a compressed air fitting for the hose barb, so I can fully blow any water out of the heat exchanger.
    -Pay f***** attention to the weather and not just "assume" the grid will hold.

    I imagine that the builders do surface mount because it's easier and cheaper than interior but will add that I know a guy whose Rinnai burst INSIDE the attic, because it was around 15 degrees for 3-5 days with no power. All this being said, I love our Rinnai and have no hesitations in recommending them.

    Erik
    Felder USA Territory Representative: Central & South Texas

  12. #12
    Join Date
    Mar 2019
    Location
    Central New Jersey
    Posts
    21
    We put in a Rinnai 2 years ago and we are very satisfied. It is not cheap, but we did it to reclaim about 9 soft of floor space in our tiny laundry room. We have the unit with the recirc pump and have it programmed so the water is warm we we get up in the morning and before we go to bed. It needs yearly maintenance where you pump 3 gallons of white vinegar trough the system and clean a filter, very easy if you have the isolation valves.

    Make sure you get a good installer, I asked that the heater be place as close to the ceiling as possible so that I could use the reclaimed floor space for a cabinet, etc.
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  13. #13
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
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    58,263
    Quote Originally Posted by Jerome Stanek View Post
    Looked at one for my son and the savings was not there to change.
    When I installed them in my previous home, it wasn't for "savings" specifically...it was primarily for constant, un-interrupted hot water. That said, the gas usage was pretty low, anecdotally speaking. We have a 50 gallon electric tank type here at the new property. So far, it's worked fine for just the two of us and since we do not currently have natural gas connected to the house, I don't even have the option of going to a tankless unit. If I had gas, I wouldn't immediately change out the relatively new existing system, but I'd consider it down the road at replacement time.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  14. #14
    Join Date
    Oct 2006
    Location
    Minneapolis, MN
    Posts
    4,719
    The natural gas for my water heater costs me about $3.50 per month. (Does not include the $9.00 service fee.) I would never see payback if I went to a tankless water heater. My water heater was installed in 2014 and is a power vent model.

  15. #15
    We never really got the tankless for power savings (gas). The "on-demand" part plus form factor were the attractions. We were doing a major remodel at the time, so it made sense. Our upstairs shower, which is farthest from the unit, takes maybe 30-45 seconds to receive hot water. Not a negative in my book. I wouldn't install on just to have it but as Jim mentions, it's worth considering if there are other reasons.

    Erik
    Felder USA Territory Representative: Central & South Texas

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