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Thread: Advice - Tankless Water Heaters !

  1. #16
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Default Bubble, bubble, boil and trouble

    No, it's a straight all-water system -- an extra inlet/outlet pair in the storage tank. There's no control system at all -- just a PV panel to generate the 12V to run the pump. Simple and elegant -- no sun, no heat, no pump -- but as an engineer, I'd like some dials and knobs. We made it through last summer with no apparent problems, but God knows how hot things got -- I'll find out this summer. I'm on a well with a bladder tank, so there's no overpressure problem, but I'll be testing the temperature limit of the CPVC (ASTM rated for continuous service at 100 psi and 180 degrees F; for through 6 pipe, the limit is 239F/115C).

    As for coils in attics and heating boilers, I thought about that (the attic, anyway), but even Florida has some mighty cold nights, and I've only seen 130F in the attic in the summer. After my next re-roof, that should drop significantly; in Florida, the objective is to keep as much heat outside the house as possible.
    Last edited by Mikey; 03-30-2008 at 08:54 AM.

  2. #17
    Plumber Cass's Avatar
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    Quote Originally Posted by robertsmu View Post
    water damage caused by a leaking water heater.

    The heater before this unit must have leaked as well, because the whole structure underneath is rotted beyond repair. Complete replacement of all joists and subfloor. Insects in Texas love moist wood. Need I say more?
    Had there been a drip pan installed... there would have been no damage.

  3. #18
    Master Plumber master plumber mark's Avatar
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    Talking Cant Tankless water heaters leak too????

    Quote Originally Posted by Cass View Post
    Had there been a drip pan installed... there would have been no damage.


    It amazes me how many people will opt not to get
    a 15 dollar pan put under their new heater..
    and then when they have a good flood or just a
    very slow un-dectable leak that does tons of damage
    they still are too damn cheap to get a pan for their new one...


    water heaters dont flood people out...
    people flood themselves out by being cheap tightwads.

  4. #19
    Plumbing Contractor srdenny's Avatar
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    [QUOTE=SourKraut;131628]I'm curious if this technology is just a fad that it only" here in America do we know how to heat water". yet the systems have been used and PROVEN to work for over seventy years!. But what do those yurupeans know, why this is the land we can can make a car last as long as the payments before things start to fail. Maybe the failures we have over here are ignorant installers putting it in the way [I]they [I] think it should be installed instead of how it was designed to be by the manufacturer.
    If it's a problem with the water then it's a problem for everything regardless the technology.
    "green" is not a fad, it's a social responsibility to make things operate as efficiently as possible [I]always[I]. The "good enough" attitude is partially the reason why we're paying $110/barrel for oil now. They know we need it.


    Michael
    Yurupeans use tankless heaters as point of use appliances, not whole house. The problem is not ignorant plumbers, it's consumers who want the new technology to perform like their old technology, which tankless was not designed to do. As for green, as my previous post notes, in certain applications tankless heaters do save energy. In many, many others their savings, if any, are not a viable ROI and are not, in my opinion, green. But, they are working on new models that will be condensing (95+% efficient) and be set up to handle recirculation better than present models. Hopefully, this will greatly help their adaption as a whole house appliance while achieving the energy and water savings prescribed by the green movement. Now, if they could just make them a little less sensitive to varying water conditions, or, better yet, self cleaning, then maybe people like Mark will give them a second look.

  5. #20

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    Sure, had the drip pan been installed 35 years ago!! The heater that recently failed didn't drop its water. There was decades of damage there, my friends.

    When I replaced the water heater on the other side of my house a couple of years ago, I put a drip pan under that one. All nice and pretty.

    The point is, and we are off track here, that tankless heaters for all their shortcomings, won't cause that kind of long-term damage.

  6. #21
    DIY Junior Member
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    SR denny. Thanks for your reply.What do yurupeans use to heat their homes? I realize a lot of them do live in multi-family units with a common heat source. But there are a large number of single family dwellings as well. I remember visiting my grandmother in Germany back in the 80's having a tankless heater for the domestic water and cast iron radiators for their heat source.
    I'm curious as to what sort of maintenance is required for the tankless. I feel a little foolish for finding this site after the fact of installing a Rannai unit. I live on Long Island where the water is very good. I am not aware of any contaminants that would clog our plumbing. If so what sort of precautions should I take as the system is only used for heating the floors so half the year it won't be operating.
    I also interested as to what "extra plumbing"(other than a gas line) is needed for the tankless vs the tank type? Outside of the floor heating loops there seems to water in, water out, gas supply.
    -Michael

  7. #22
    Retired Defense Industry Engineer jadnashua's Avatar
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    Many of the tankless systems are not specified for use as area heating devices...unless that one is, you may not have a warranty.

    When used to heat domestic water, you are constantly supplying new water with its dissolved minerals in it. The intense heat in the heat exchanger can cause those minerals to be deposited on the insides of the heat exchanger. If the coating gets deep enough, it acts like an insulator and your heat transfer can suffer radically. I don't think your system when used to heat the house in a closed loop system will run into those problems...wearing out the unit that wasn't designed for potentially 100% duty cycle is.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  8. #23
    DIY Member Squ1rrel's Avatar
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    I would agree with Jad on the duty cycle thing. Seeing that copper heat exchanger burned through like someone took a cutting torch to it from overuse is NOT a pretty sight. I wonder if some of these new, stainless steel systems are going to run into the same problems?

  9. #24
    Plumbing Contractor srdenny's Avatar
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    to the others debating merits of tankless technology versus tank technology - I consider the "newfangled, more complicated, and not yet widely adopted" tankless technology as compared to the older, more widely adopted tank heater technology to be analogous to computer-controlled fuel injection technology when it came strongly into play in the automotive industry around the 1980's, displacing the previous carburator / air-fuel fuel mixing technology. Fast forward 20 years since then, and sure the technology is still more complicated than carburation, but has been made acceptably reliable and the knowledge of maintenance procedures and repair has become widespread enough to allow nearly all automobiles manufactured nowadays to employ the new technology. In fact there may now be more mechanics / auto-technicians now knowledgeable in servicing fuel injection vehicles than there are who are able to rebuild and repair carburators. We may see a similar market adoption trend with water heater technology in the future. In this case the new technology will become more widespread and accepted, as the price comes down to purchase and maintain it, and it becomes better "tested" and improved, etc.[/QUOTE]

    Your analogy may come to pass. If it does, I'm sure there will be some product variation as the manufacturers adapt to the marketplace, as well as incorporate evolving technology.

  10. #25
    Plumbing Contractor srdenny's Avatar
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    "I live on Long Island where the water is very good. I am not aware of any contaminants that would clog our plumbing. If so what sort of precautions should I take as the system is only used for heating the floors so half the year it won't be operating. The water where I live is very good as well, but it still has inpurities. I would recommend checking the filter on the incoming cold side of the heater on a by yearly basis, at least for the first year.
    I also interested as to what "extra plumbing"(other than a gas line) is needed for the tankless vs the tank type? Outside of the floor heating loops there seems to water in, water out, gas supply." The flue requires Cat III (stainless steel) pipe, with a condensate drain.
    __________________

  11. #26
    In the Trades plumbernj's Avatar
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    Quote Originally Posted by jakeru View Post
    to the original poster - I think the Takagi and Rinnai brands are both exceptionally high quality tankless heaters. The Takagi TK-3 has a low .5 gpm turn-on flow. I am very happy with mine. I saved a bundle buying it all on secondary market (craigslist) or wholesale and installing it myself.

    to the others debating merits of tankless technology versus tank technology - I consider the "newfangled, more complicated, and not yet widely adopted" tankless technology as compared to the older, more widely adopted tank heater technology to be analogous to computer-controlled fuel injection technology when it came strongly into play in the automotive industry around the 1980's, displacing the previous carburator / air-fuel fuel mixing technology. Fast forward 20 years since then, and sure the technology is still more complicated than carburation, but has been made acceptably reliable and the knowledge of maintenance procedures and repair has become widespread enough to allow nearly all automobiles manufactured nowadays to employ the new technology. In fact there may now be more mechanics / auto-technicians now knowledgeable in servicing fuel injection vehicles than there are who are able to rebuild and repair carburators. We may see a similar market adoption trend with water heater technology in the future. In this case the new technology will become more widespread and accepted, as the price comes down to purchase and maintain it, and it becomes better "tested" and improved, etc.


    Yeah, I heard this same jargon in 7th grade about the metric system.

  12. #27
    DIY Member Squ1rrel's Avatar
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    And yet, the US is one of the only countries remaining to use the Imperial Standard measurement..but measurement changes requires the entire system to change, technology alters gradually, as it increases in reliability and availability, and people replace their older systems...just look at cell phones and laptops. Convenience and durability exceeded problems as the technology progessed.

  13. #28
    Master Plumber Redwood's Avatar
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    Many of todays cars with all these newfangled electronic fuel injection, electronic ignition are routinely going 100,000 miles before they ever have a mechanic do anything more than an oil change and other required maint.

    I don't miss those 15,000 mile tune ups a bit! Seems like there is none of that getting the choke right either. What I really like is being able to do a performance tune with a laptop or after market plug in box! One of my buddies has a one ton GM diesel van that will make a corvette owners eyes bug out when he gets left behind at a traffic light!

    Technology is a wonderful thing!

  14. #29
    DIY Member jed1154's Avatar
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    I have three electric tankless water heaters. I like them.

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