On demand /tankless water heaters?

Discussion in 'Michigan Homesteading and Home Improvement' started by d_rek, Oct 19, 2020.

  1. kroppe

    kroppe

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    What is the complete business case for a tankless unit?

    Purchase price delta vs tank, $:
    Operating cost (utilities) vs tanks, $/yr:
    Hot water supply performance GPM:
    Expected life span, years:
    Installation cost delta, $:
    Maintenance expense delta, $/yr:

    If this isn’t a slam dunk or no brainer, if it were me I would go with a tank style. The reason to go tankless needs to be patently obvious, which to me it isn’t.
     
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  2. Scadsobees

    Scadsobees

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    One thing to keep in mind is that the GPM isn't how much hot water you'll get at your desired temperature....it's how much you'll get for a specific degree rise.
    Mine is 9GPM, but I can tell you that I get more hot water GPM in the summer than in the winter, due to the input water temperature fluctuation. I don't get 9GPM ever, because I have the output temp cranked way up. But it's enough for 2 showers at a time.

    I'm not sure what electric tank heaters run, but if you have a 8.8GPM 36kW tankless you could be drawing up to 3/4 of the capacity of your two panels. To pick a random one.....
    upload_2020-10-19_13-12-41.png

    EDIT: Changed GPH to GPM, I'm not driving my water heater :)
     
    Last edited: Oct 19, 2020
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  3. M.Schmitz87

    M.Schmitz87 Premium Member

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    Those are absolutely valid and good points. For my customers there are more things to consider though:

    The convenience of never running out of hot water anymore.
    That's a big concern for some people. And they then have to decide how much this comfort is worth to them.

    Also warranties are usually better and longer on the better tankless units than on any tank.

    For me the biggest part is hygiene and health.
    Cut open a used water heater. It is horrendous and disgusting. I rather not have a 50 gal body of water where bacteria can grow.

    Safety is a big one too.
    My tankless heaters come with a flood save option. That's a sensor sitting underneath the unit shutting off the water supply as soon as a drip of water hits it. No more flooded basements.

    Another feature would be wifi capability letting you know what's going on with the system while you're away helping you saving money and or piece of mind.

    There's a lot to consider about besides the rational return of investment
     
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  4. Scadsobees

    Scadsobees

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    Just curious how often you've run into the need for the flood save option? I'm into the smart home stuff, and have been interested in the automated valve shutoffs and sensors... But I wonder if by the time the device is needed, if it even works anymore?
     
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  5. d_rek

    d_rek

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    Yeah... like I said I feel like we are draining our tank regularly these days. It's only going to get worse as the kids get older.

    Our electric water tank is already not cheap to run, and if the delta on cost isn't too wide i'd rather have the convenience of tankless versus waiting 20-30 minutes to get enough hot water for a shower.
     
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  6. M.Schmitz87

    M.Schmitz87 Premium Member

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    I started putting them in about 3 years ago. They are getting tested and exercised once a year with the water heater tune up. So far they've been good.
     
  7. jjlrrw

    jjlrrw

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    When you flush out a tankless do you pump the cleaner in the cold inlet and out the hot or in the hot and out the cold inlet?
     
  8. jjlrrw

    jjlrrw

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    Another thing to think about if you travel from home a lot that 50 gallons of water can get pretty nasty just sitting there.

    I first looked into the tankless heaters for a cabin we purchased, there was only room for like a 5 or 10 gallon tank heater and it was located under the sink, being we were not planning to heat the place when we were not there we went with a tankless, it mounted on the wall above the toilet and vented out the side wall, total cost including the venting was ~$175 a 100# LP tank would last a couple years sharing gas with a cooking stove, we would use the place about 80% of the weekends.
     
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  9. Team Camo

    Team Camo Premium Member

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    Gives you a pretty good idea on how to do it. I clean mine the same way. I have a propane on demand with a water softener {well water}. Usually about once a year with the vinegar method.
    https://www.waterheaterhub.com/how-to-flush-tankless-water-heater/
     
  10. M.Schmitz87

    M.Schmitz87 Premium Member

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    They should have a flow sensor in them and a check valve, depending on the unit. I would not flush against the dedicated direction of flow.
     
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  11. Team Camo

    Team Camo Premium Member

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    IMG_20201019_170213490.jpg
    Can't speak for the electric on demand. But I had a natural gas when I lived in the city. Young daughters and Wife loved it...showers were forever compared to the usual 15 minutes so all could get one. Had to chase them out more than a couple times..:lol:. Been living in Sanilac over 5 years now after my dads passing. My dad had a propane on demand installed when he had the house built. Less space for sure. And with flushing the unit once a year or so there is no build up at the bottom of the tank of a regular stand up unit.. We have a softener and well water here also..high iron content. Installed Feb 2007 and still running strong with no issues. If your electric service can handle what the unit demands you will not regret the purchase. Also be prepared for a larger vent opening. The one I installed in the city I believe required a 5 inch I cheated and bought an adapter...dam thing kept shutting down. So of course was more work cutting out the roof and doing it right. Will attach a pic of mine in a few...
     
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  12. Team Camo

    Team Camo Premium Member

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    And seeing that sticker reminds me it's over due...I'm certain I did it last year and didn't write it down...I think..;)
     
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  13. Scadsobees

    Scadsobees

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    Electric doesn't need a vent :)
    Nowadays gas heaters can vent through the wall pvc, would have saved you a lot of work.
     
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  14. Team Camo

    Team Camo Premium Member

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    Well crap in my haste to give some advice...I didn't even think of that. Saves some headache for D rek. :lol:
     
  15. CrankYanker

    CrankYanker

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    The cost of an electric unit will be pretty steep. Look into a hybrid electric heat pump. Lots of great rebates available.

    Sent from my SM-G973U using Michigan Sportsman mobile app