Tankless water heaters

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by srdenny, Feb 13, 2007.

  1. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    I've been asked about problems associated with tankless water heater installations by a writer for a trade magazine who's doing research for an article on water heaters. Basically, I'm interested in any quirks in these appliances any of you have found which have caused you to make troubleshooting call back trips. Learning curve stories are also welcome.
  2. You just had to, didn't you...


    In my area they are slowly introducing to the grand scheme. No one to work on them and parts are not available like the common parts found in plumbing.

    Expensive to retrofit in place of a tank water heater due to gas demands/flue requirements.

    Had a customer last year trying to get me to sign off on a set of tankless units that were "supposedly" struck by lightning. The installer didn't use dielectric unions and the current travelled through the units destroying the electronics.

    I get curious george customers all the time trying to whittle my set price ($1000 on up) to begin to make the switch.

    When the efficiency of these units come into play on these, they do good but many considerations are the norm.

    UPDATE:

    I called the customer who needed his endless hot water box on the wall on new years day. The one who was proud as hell to have one because he's better than me because he can take a shower for days.

    No one around to fix it, he ended up getting parts for it a week later and had it up in running, 8 days without hot water.

    The maker of the product sympathized with him since no one around to fix it, gave him major components, basically a whole other unit to fix his problem. Sad.

    I bet the wifey and kids love tankless........until the next time it breaks. He said a tank heater is going back in if it breaks again.



    I'm actually trying to get one of these tankless mfg's to give me one as a demo. I want to be able to cut one of those compartments apart after a year/two years and get true digital pics of the inside of them to see the buildup that the required cleanings don't address/clean. And I will follow the mfg specs to a tee. No one wanna give me a tankless though. :(
    Last edited: Feb 13, 2007
  3. go to PM Enjeneering

    The PM Enjeneering web site has a rather negative
    article on tanklkess water heaters....

    all you go tto do is sign up for the site and then you can search

    for tankless vs tank type heaters....

    its a test that Bradford White did back in jan 05 and

    is not very flattering..

    the link to the PM site is at the bottom of this page

    http://www.weilhammerplumbing.com/houseofhorrors/index.nhtml
    Last edited: Feb 13, 2007
  4. Racer814

    Racer814 New Member

    Messages:
    124
    some are better than others....they seem to be getting more popular and as they work out some of the bugs I think they will become more popular

    The ones I'm installing mount on the outside of the house.

    The biggest drawback other than parts availability is that the flow rate is reduced...
  5. GoTanklessToday

    GoTanklessToday In the Trades

    Messages:
    89
    Location:
    Renton, WA
    We've been out on quite a few calls where a custome can't get the heater to perform well. Only one time in many has it been related to a failed part. The other issues were owner induced, or failure to install the unit properly to begin with. Gas line sizing seems to be the number one issue. Another we have seen is when an installer used a vertical vent termination, but didnt use a condendation drain fitting.

    Shy of the undersized gas line, failure to understand the unit and what it will deliver is probably the worst offense. Over promissing, and under producing. The manufacturers do a great job confusing the world with their performance charts. A unit that is rated at 7.4 gpm will not necessarily produce that. Incoming water temp, desired temperature at the faucet, etc, plays a huge part in reality. For instance.. in Phoenix, the same unit will deliver a whole lot more 120 degree water per minute than it will in northern states. Another thing that is all the rage (here at least) are these "shower wall" setups. I've seen 6-8 shower head systems in these big walk in shower stalls, each of which will rain down 2+ gpm (how do you lather up???). You cant run that system on one tankless heater. In Seattle, you may not run that on 2 heaters. Most of my competitors do not understand the performance of these tankless heaters. It becomes obvious when I go behind them to do an estimate and then spend half an hour educating the customer on the real story. It's frustrating to hear a customer say "I'll just go with that guy, because his heater will give me 7.4 gpm." You all know the customer often times hears what they want to hear.

    For those who are taking the tankless plunge, I urge you to get to know the product inside and out. Get with your area manufacturer's reps, and arrange for some training. The manufacturers all have websites with tons of information. Read the installation manuals and do your best to understand their performance charts. Stay away from articles that are written by companies that dont produce tankless heaters. Of course Bradford White's report on tankless will be less than steller. Just Like Noritz's report will put down the tank. Both heaters are great in their correct environment. Neither is perfect though for every situation.
  6. is OVERSIZEING better??

    Right now in Indiana we have basically
    slush comming into the homes probably
    at around 35 degrees......

    just recently I had to stick my arm down in a meter
    pit with a frozen meter .....it felt like the spraying water was gonna freeze up my veins and arteries before I could get the valve off....

    So ....I am wondering if it is better to oversize the hell out
    of a system to compensate for the cold water
    than it is to give them "adequate" flow...

    Looking at some of these new Rheem units with
    7.5 flow through them and wondering if this would
    be enough bang for the buck???

    series 199 for about 1300??

    of course this still only will do a 3 bathroom home...






    http://wantasub1.stores.yahoo.net/tawahe.html
    Last edited: Feb 14, 2007
  7. much experience in Europe with these

    just a reminder -- gas units have been in use in many parts of Europe for years and years. I saw one in operation six months ago in Paris. I used it for several days. The owner wasn't complaining; although I was not acting like a traveling expert interviewer so I didn't get the low down.

    AFAIK, people there are used to them. There is where I would look for people who can comment after having seen a lot of "experiences".

    david
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,924
    Location:
    New England
    A tankless system generally does two things, puts a restriction on the supply to ensure at least warm water and second, can vary the output radically depending on flow or inlet temperatures. You can mitigate having unreasonably hot water by installing a tempering valve at the outlet,which under ideal conditions restores the flow rate (only if the outlet water temp is hot enough).

    Depending on the inlet temperatures, the flow desired, and how much of a loss you have from the point of use back to the heater, you may not have adequate outlet temperatures unless you can cascade units. Some of them make this easier than others from the limited reading I've done, but it is being addressed.

    There was one of these in the house I rented in Germany nearly 30-years ago. I didn't like it then. I opted for trying one 10-years later here in the USA, it was okay, but maintenance and continued sources of parts became a major pain (recently replaced with an indirect tank).

    Europeans (at least used to) have much different expectations for this type of a system and seem to live with their quirks and limitations more than we do in the land of plenty.

    If your open space is not large enough, since the heat load on a tankless (let alone several in series) will mean that you won't be able to run them without introducing outside air can mean that you will end up with a large unconditioned space. The alternative is building an insulated utility room where you can install the thing so the introduction of combustion air makeup won't impact the (typically) basement. Some of them probably can be run with closed combustion with air piped in from outside which would eliminate at least the air problem. Many people ignore the requirement for makeup air for their combustion products. A gas stove, furnace, gas log fireplace, dryer,etc. all require significant quantities of air, and will be pulling that in from the cracks, gaps, and openings in the house. If they don't get enough, you can run into some real problems. DO NOT DISCOUNT THIS in your choice - newer houses tend to be much tighter than older ones. Much of the newer appliances like boilers, furnaces used closed combustion since they lend themselves to being much more efficient and to overcome some of the makeup air problem but stoves, gas fire places (or real ones) and dryers still don't operate that way.

    Before you decide to go with this type of system, make sure you read and understand the temperature/flow charts AND your local water conditions.

    Where I live, you would be a fool to consider installing a heater outside - the winters are just too cold.

    Look at the physics of it...2.5 gallons per minute for a shower is 1200 pounds of water an hour. Say you need to raise it from 35-degrees in the winter where I live to 105, that's 70 degrees. 1200*70 = 84K BTU. Add a second shower, 168K BTU. Assume maybe 85% efficiency, and raise that to nearly 100K BTU for one shower, and 200K for two. Throw in any additional flow, and the temperature drops, and even though you have the control on max hot, it drops in temperature. Don't even think about having the washing machine or dishwasher running anywhere near the same time or your outlet temperature may drop 5-10-degrees or more.

    So, you may need to make some severe compromises in lifestyle, significantly oversize the thing, and engineer impressive physical plant preparation (air, gas, flue) in order to provide the same output and then you will have more maintenance to perform. Our energy costs still do not make them more efficient at our typical expectation levels in my opinion.

    Since I switched to a tank, I can fill the tub in 5-minutes where it took maybe 25 before (had to almost dribble it out to get enough temperature rise) and have much more pressure to take a shower with. Maybe if I lived in Hawaii I'd think differently, but not in NH!
  9. you are a wise man

    the next questiion I have about them is having to
    change your life style .....pissing off the wife, ect....

    With that heavy duty Rheem #199 I posted

    could it do two showers at the same time or not

    in the Dead of winter, or must everyone take turns and

    stagger their showerrs???

    their is simply NO WAY I would put two of those things
    in just to solve this demand problem....


    you really dont have to do that with a 50 gal rheem


    just wondering
  10. vleespet

    vleespet New Member

    Messages:
    47
    land of plenty

    I am originally from Holland and grew up with tankless heaters on gas in rental appartments. It worked perfectly since 99% of the houses just had one bathroom and mostly just a shower and no bathtub.Taking showers with a family of 4 was not difficult,you just take turns and shower every other day...no problems.

    I think you have to visit different regions of the world and then come back and just enjoy what you have out here.:cool:

    Ron
  11. shower how often in the land of plenty???

    In this country people are so very spoiled...

    I would guass that the average female and
    a large amount of men too actually take two
    long hot baths per day......

    having to adapt to doing a shower only and
    only once every other day would probably not
    even go over too good even for peopel living in the getto....
  12. Dan Pick

    Dan Pick New Member

    Messages:
    62
    Location:
    Speedway, IN
    I've heard of several problems regulating the flow when you have pressure balance valves installed.

    Master Plumber Mark... I see you live in Indy. I live in Speedway, IN
  13. daily shower with tankless too

    for the record

    There is no connection between "habits" and tankless. There is none.

    You can shower every hour with a tankless system.
    You can shower every day with a tankless system.
    Or every other day. :)


    David
  14. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    You can shower every hour with a tank system.

    Just don't make it a long one. :)
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