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School me on Tankless water heaters

Discussion in 'Off-Topic' started by arlow, Mar 13, 2018.

  1. wilco_99

    wilco_99

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    If you already have oil just get a Oil fired H/W heater (Carlin w/Bock tank). Have your oil Co size and install it.
     

  2. sbi

    sbi NES Member

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    OK, I keep hearing this and I don't get it. What cold water does it push through the pipe? There is cold water in the pipe between the heater and your faucet, correct? Are you referring to that chunk of water? If so, it's the same as a traditional tank - there is cold water in the pipe between the tank and the faucet.
    Please explain.

    OP - you didn't mention this but do you have natural gas in the house? A friend of mine was looking into this change a few years back, they don't have natural gas in the street and converting to propane would require bringing in a huge tank, piping to the house and propane itself is much more expensive than natural, it wasn't worth it. He would never pay off this kind of upgrade.
    80 gallons is a huge tank. How many people are in the house? I would just get a newer, modern 50 gallons.
     
  3. ToddDubya

    ToddDubya NES Member

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    Quick research is telling me that:

    Electric is more efficient than gas but costs more so the fuel costs are about the same.
    Electric reliability and maintainability is also better
    Electric doesn't need to vent exhaust.
    Electric units are less expensive to buy.

    Do the efficient gas units have to be vented out the side of your house (vs up a chimney) like the new furnaces?

    I'll have to do some more research. I even have a 220V drop from an old water heater that I could put back in service.

    Electric vs Gas On Demand Water Heaters
     
  4. snax

    snax NES Member

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    I have 2400 sf with a ton of can lights, all Led. Separate fridge/freezer in kitch, and another in the basement. two furnaces (gas) with a/c... I have solar panels that I don't own, the solar company does, but I get a way lower rate and a credit from national grid when they are producing, and my electric bill will barely break 200 at peak A/C use in the summer. My house is also super insulated tho.
    Add in the gas for HW, Dryer, Stove, and i'm still not at 400 total utilities. Do you pay for cable too?
    You should get a meter and check the draw on that water heater. 80 gallons is huge, mine is 40 and is sufficient for a family of 6.
    A friend of mine has tankless and likes it, in his kitchen sink he's got a small undersink electric on demand so he gets instant hot water in the kitchen sink instead of waiting... that could be an option.
    If you do some homework you could probably find yourself an extra 200/month.
     
  5. W.E.C

    W.E.C NES Member

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    It takes up to a minute of water flow to receive the heated water , as there is no storage , so it flows cold till it gets to the heated water . A little more time than a tanked system.
     
  6. massgun

    massgun

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    This was about a year ago, so I don't really remember the numbers, but I think it was going to be about $2400.00 for the Rinnai gas fired one. My water heater is in the garage in a spot pretty much useless for anything else. As far as an energy rebate, I'm not sure if there was one available to me. Despite my screen name, I am no longer in Mass, but in the South, was the rebate a fed thing or something through Mass Save?

    Anyhow, it probably still would have cost a lot more than a standard gas water heater, and you still have to figure yearly maintenance ( I am on a private well ), and it still wouldn't get to the faucets any quicker, so I decided against it.
     
  7. xcrracer6

    xcrracer6 NES Member

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    How many people live in the house? you could get a 50 gallon hybrid water heater. they are electric with a heat pump they are really efficient and are eligible for a mass save rebate
     
  8. Kevin_NH

    Kevin_NH NES Member

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    Small Point-of-use (POU) electric tankless is a great solution for instant hot water at a distant bathroom, but tankless electric does not scale up well.

    Speaking of scale, both electric and gas fired tankless units will collect scale from hard water. Needs to be cleaned about once a year, an easy DIY project, only takes about an hour.

    Yes. For me that was a positive, as I was replacing an electric tank-type heater.

    Electric is efficient, but electricity is very expensive here, so making hot water with gas is still much less expensive than resistive electric heat.

    Whole-house electric tankless water heaters may not be able to keep up with demand during the winter when the incoming water is very cold. My propane-fired Rinnai tankless will reduce the flow slightly when the incoming water is <50F, but that's with a variable burner which can go up to 180,000 BTU; taking efficiency into account, that's akin to drawing something like 220A at 220VAC -- more power than most homes have available.

    You probably won't be able to re-use the existing 220V drop from the old water heater, as the amperage demand on a whole-house electric water heater that can keep up in the winter is insane --while your old heater might've been 20-30A, a whole-house tankless may need something in the range of +60A.

    Another downside to whole-house electric tankless -- there's no way you're going to run that off a generator or solar, so when utility power goes out, you immediately have no hot water until it is restored. No "one last lukewarm shower" like with a tank.
     
    Last edited: Mar 13, 2018
    Energizer and ToddDubya like this.
  9. arlow

    arlow NES Member

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    Me my wife, my 12 year old son and my 13 year old daughter
     
  10. xcrracer6

    xcrracer6 NES Member

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    A 50 gallon should suffice the rebate for the 50 gallon hybrids is $750
     
  11. Woodstock

    Woodstock NES Member

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    Can you move the freezer to a garage or other outdoor space where it isn't fighting the central heating? Can you shut it down temporarily, or better yet, meter it for a month?
     
  12. JJ4

    JJ4 NES Member

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    Gas/Propane Tankless - If you can get a natural gas or propane this will likely be most efficient. Cons: Will require gas line/access.
    Electric Tankless: Will save you money over a traditional electric tank, but electric is still expensive. Cons: Will require multiple 50-amp circuits to run.

    Depending on where your tank is, I suggest a hybrid heat-pump unit.
    GE Geospring: GeoSpring™ Pro Heat Pump Water Heater Authorized Reseller | GE Appliances
    Rheem Prestige: The All-New Rheem® Prestige® Series Hybrid Electric Water Heater

    These will be much more efficient than traditional resistance electric heating. E.g. they will use 1/3 the electricity. This puts them on a similar cost basis as the tankless units. However, you won't need any new electric or gas circuits to install. They use a compressor to move heat from the air into the water, just like a refrigerator. They do need some space to pull air from, however.

    Tankless or tanked: if you need to wait a long time for water you can get a recirculating pump. Tankless units have a longer tube inside them so you need to wait a bit longer for the water compared to a tank.
     
  13. JoeyD

    JoeyD

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    They are not maintenance free, but are easy to maintain.
     
  14. xtry51

    xtry51 NES Member

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    We installed one at our old house in CT. Stiebel Eltron Tempra 29. It was awesome. Install a separate standard well filter just before it to keep clean. I think I had to clean the screen in mine twice in 5 years. Absolutely worth going this route and I would use a Steibel again in a heartbeat. Don't buy a small unit. Buy the big one and just set the temp where you want it.

    Only obvious downside is it requires electricity to run. So no power, no hot water.
     
  15. sbi

    sbi NES Member

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    But isn't that instantaneous heating and the only water the faucet should receive is between the heater (which is heating the water) and the faucet?
     
  16. W.E.C

    W.E.C NES Member

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    Fast forward to 1:40

     
  17. Kevin_NH

    Kevin_NH NES Member

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    With a bill like that, I suspect that you have a bigger problem than how you make hot water.

    Write down the meter reading, then turn off the breaker to the water heater for a day, then write down the new reading.

    If you want to track your ongoing usage by the hour or minute, there are a bunch of different ways to do this. Your best option depends on the meter you have, how you feel about opening up the breaker panel, and how much you want to spend.
     
  18. ole57

    ole57

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    The copper coil inside a boiler ( mostly oil boilers ) is called a tankless . Very common but not the most effecient . Since you don’t have a boiler but a hot air furnace the best idea would be a tankless water heater . Natural gas or propane . They make electric ones also but they will not work well in New England as the water ground temp. is too cold and Electric tankless water heaters can not recover quick enough . As for that cold water sandwich ( waiting for hot water ) recirculating pumps are available for those that have that problem .
     
  19. Fixxah

    Fixxah NES Member

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    80 gal. is fine for a 5 bathroom house. You are rich, deal with it.

    On demand was a fad. I haven't seen one in years.
     
  20. bigblue

    bigblue NES Member

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    That's a joke right???
     
  21. Rob Boudrie

    Rob Boudrie

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    Nope. You need to flush with white vinegar (or a special cleaning solution you get at plumbing stores) once a year to prevent scale buildup. These are installed with dual valves with fittings to connect a utility pump to cycle 4 gallons of vinegar in a bucket through the coils.
     
  22. namedpipes

    namedpipes NES Member

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    I have a (slightly undersized) tankless electric heater. It definitely uses less power than running the tank heater. It cost around the same to do this or replace the failing tank so I gambled on the tankless.

    The variables are temp of the water coming into the house (colder in Winter) and the volume of water being called for. The heater I have is ample for a hot shower in the winter. It's not really enough if someone is ALSO running a faucet or two.

    I'll probably add back in a tank heater and use the timer to heat it up once a day. Then, the tankless will have very little work to do most of the day, but even when the preheated water is exhausted there'll be SOME hot water.


    I did this for a while and eventually replaced the timer/heater with the electric tankless above. It definitely helped in the meantime.


    Yes. You can plumb in valves and connections to pump vinegar through the heater (with the heating disabled!) for an hour or two a year. Flush afterwards, of course.


    If the tankless heater is located in the same place as the tank heater there is zero difference in how long it takes for the heated water to reach you.

    You can get tiny point of use heaters if you need instant hot water in a location, though.
     
  23. JoeyD

    JoeyD

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    What type of regular maintenance does a Rinnai Tankless Water Heater require?
    There are two types of periodic maintenance that your service technician can perform to keep your Rinnai Tankless Water Heater running smoothly:

    The in-line screen filter should be checked periodically for debris (time between filter checks will be dependent on water quality).

    The unit should be flushed periodically (time between flushes will be dependent on water quality) to keep the unit free of scale and lime. This process should be completed by a professional installer. Please contact an installer near you.

    That’s on their web site but I’m sure many never service them until they break or stop producing hot water, but I wouldn’t do it.
     
  24. Rob Boudrie

    Rob Boudrie

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    I use one of these for the flush: Wayne 1/10 HP Portable Transfer Utility Pump-PC2 - The Home Depot

    All you need in addition to the pump kit is a set of washing machine hoses; 4 gallons white vinegar and a 5 gallon bucket.
    Every professional installation of a Rinnai that I have seen has the valves for vinegar flushing plumbed in.
     
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  25. arlow

    arlow NES Member

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    It is in the cellar which is neither heated nor air conditioned. I imagine it would work less hard in the winter in the garage but much much harder in the summer as ths garage gets quite hot .
     
  26. W.E.C

    W.E.C NES Member

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    Ok guys, I’m schooled , prevention over cure,

    The fat guy in the film gave me bad advice.

    Thanks for the pump tip rob, I have the filter and silcocks installed for flushing
    Will do this week.
     
  27. Johnnyh

    Johnnyh

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    No one installs in line phosphators for on demand units? . Recommended to keep sediment buildup down between cleanings. Cheap insurance for expensive units.
     
  28. JJ4

    JJ4 NES Member

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    A Kill-A-Watt meter ( <$25) will let you check how much power that old fridge/freezer are using. If it's an old one, it could be using 2x as much as newer models. Chucking it (with a utility rebate too) and getting a new one may pay for itself.


    [​IMG]
     
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