Navien Tankless Water Heater Comments and questions

Discussion in 'Tankless Water Heater Forum' started by willl, Dec 28, 2008.

  1. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas

    Interesting you bring this up... A couple of the upper end tankless units have a communication cable option so up to three units can be paralleled together so they can "talk" to each other and provide a greater flow rate. We are about to install just such a parallel set up at a Boy Scout camp here to supply 6 showers and ditch the 50 gal electric water heaters in favor of propane. Being on the camp inspection cmty, getting those once a year maintenance descalling done will not be an issue! :D
  2. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    And pray tell what was the cost of that compared to th one 50 gallon tank?. Do you guy's really ever sit down and run the numbers?

    What does 2 Rinnai's, the installation materials, the electronics to "talk" to each other plus installation cost with nothing donated or discounted ?

    If you were getting a price from me it would be in the 5 grand range.

    And the cost of a 50 gallon electric? Around 300 bucks for the takn and maybe another 250 to put it in.

    So $550.00 against $ 5,000.00.

    And once again the payoff is --- Drumroll please

    NEVER
  3. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    You just don't get it and probably never will. Keep in mind "our" plumbing supply connection at cost. So, cost to the camp for two units will be about $2k total (free install by pro-plumbers already lined up) and we get unlimited hot water. Get this, UNLIMITED HOT WATER for our campers. Something the current system can't offer. Six showers in use by two hundred campers at Winter Camp 3 weeks ago showed we had to change something when we couldn't keep up with hot water demand. Please note,I never said cost benefit, savings, ROI, nada!


    UNLIMITED HOT WATER
    Last edited: Jan 19, 2009
  4. Ladiesman271

    Ladiesman271 Homeowner

    Messages:
    221

    It would be interesting to try to follow NHmaster's advice. One little 50 gallon electric heater for six showers in a camp. Funny how you already have multiple electric water heaters and they can't keep up with the demand.


    I notice that you have followed some of NHmaster's advice.:D

    "The world is full of stupid people. Try not to be one of the crowd."
  5. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    So you base you undying love for this crap on the fact that you can get the stuff and labor donated. Great, wonderfull, good for you. What about everybody else. I get it just fine. In fact I get paid to GET IT.

    If one 50 gallon heater wouldn't do it you could put in 3 more and still have it cost less especially if your gracious plumbing supply sold them to you at cost also.

    I'm done with this thread. It's an illogical total waste of time for anybody that is actually considering purchasing a tankless. 99.9% of folks can't get the equipment at cost and 95.9% of folks don't have the skills or tools to install the thing. Basing cost comparisons on essentially "free" equipment is rediculous. However free or not free the operating cost doesn't change and even at "cost" a 4% savings just breaks even. Good by..... Oh and when you start having problems with the thing(s) you only have to answer to a whole campground full of angry campers not just the wife and childdren. :D
  6. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois

    If you have the right physical layout, this would be the ideal situation for drain heat recovery units (lots of showers, high fuel cost). Preheat the incoming cold water with warm drain water. It is easy to get a 20 degree rise in incoming water temp (45 to 65) and has an actual payback.

    2.2 gal/min x 6 showers x 20 degree F x 8.8 lbs/gal = 2323 btu/min

    Propane is 91600 btu/gal x 80% water heater efficacy / $3 gal= 24400 btu/$


    2323 btu/min / 24400 btu/$ = 9.5 cents/min, (When all 6 showers running)

    200 campers/6 showers x 6 min/shower =200 minutes of showering

    200 mins x 9.5 c/min = $19.00 a showering cycle.

    I would assume $1500 in capital costs w/free labor. Thats about 79 shower cycles for full payback, so it depends on how often the camp is used. You also get the benefit of increased capacity and no maintenance issues.
  7. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    I have to agree with NH on this issue. I looked at the Navian website and was suitably impressed. I was actually thinking about going that route when my water heater dies, until it came to finding out the price and local distributors. The link to the distributors didn't work and through a bit more Googling I found prices of $1500 and up, plus shipping, of course.

    I can purchase THREE tank-type water heaters for the price of that Navian. Sure, I'll lose a bit on efficiency and pay a bit more in natural gas purchases but damn, I still think that I'll come out ahead by the time I die by going with the old tank-type.

    And just in case someone wants to know, figuring ROI is what I did for a living for too many years.
  8. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    Never heard of such.... Neat idea. Concerned about servicability with a 70+ year old "non-tech" camp ranger.
  9. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    One of the best things about them is they are essentially idiotproof, since there are no moving parts. It is usually just a copper pipe in the drain stream with a coil of copper pipe around it, which acts as a heat exchanger. Here is a goverment webpage on them. DHRU. They become more attractive with high volumes of hot water use, high energy costs and colder cold water temperatures. I would geuss they start to become viable for residential use with households averaging more than 30 minutes of showers a day and avg cold water temps of 55 F (possibly less with high energy costs). Crunching the numbers at my house I save about 1 cent per min of showering x 30 minutes a day (4 people) x 365 days = ~$110 per year. Capital costs were $500 DIY or probably $800-1000 if professionally installed. The DIY numbers are no-brainers with 20+% ROI. Even 10+% ROI is good for some and below the cost of capital. They are obivously not viable for every application, but have good potential in some applications, such as your camp scenario.
  10. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Is this device code approved because it presents a very real possiblity of cross contamination should the exchanger be breached.
  11. sjsmithjr

    sjsmithjr Geologist

    Messages:
    295
    Location:
    Knoxville, Tennessee
    "Double-walled heat exchangers meet most local plumbing codes for potable water. Double-walled heat exchangers are covered by the Uniform Plumbing Code, Section 603.3.4; 1995 CABO (Council of American Building Officials) One and Two Family Dwelling Code, Section 3402.3.1; 1998 ICC (International Code Council) One and Two Family Dwelling Code, Section 3402.4.2.1; and the 2000 and 2003 ICC International Residential Code, Section P2902.4.2 - Heat Exchangers."

    At least that's what they tell us...
  12. jchaters

    jchaters New Member

    Messages:
    2
    Tankless Hot Water Heaters

    I have read all the posts in this discussion and I am quite amazed. I had a Rinnai tank less providing heat and hot water in my home for 8 years with grea success. Bought a new home with a tank. 5 year rental before I can get rid of it. The day the rental agreement ends (62 DAYS FROM NOW) I will be replacing it with a tank less. Savings whatever they are are great, enviroment benefits excellent I guess, but when I want to fill my beachcomber hot tub, or have a shower after my two girls are done showering, the tank sucks. I want tank less because I want endless supply of hot water and a quiet little box that sits on the wall, takes no space, uses outside air for combustion and is never an issue. Yes I also distribute tank less, Navien as well as Noritz. We have well over 1500 in the market. We have had issues but unfortunately 75 per cent of them are caused by sales reps under sizing and over promising. I have also been called by end users who can not fill their bathroom tubs or fancy showers with their 50 gallon tank and have no room for another. Two tank less and they thank the contractor and myself every time very. Their are many reasons to purchase a tank less as well as not to.The most interesting part of this thread in my opinion is the one that picks on foreign products whoever may make them. Korean cars are winning car of the year awards, Japanese cars seem to have taken over the market maybe it is time for us North Americans to get our head out of the sand and start embracing and producing better products rather than calling them crap as they take over the market. European and Asian countries have paid much higher utility costs for years thus they produce more efficient products as a way to keep their costs down in the long run. When you talk payback don't forget oil, natural gas, propane and electricity are artificially low in price right now and will be going up in the very near future. PS no yelling or screaming is required as these are just "my thoughts"
  13. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Bradford white makes a nice tanked water heater that can fill your beach comber tub. Also can supply enough water for your two daughtersas well as you. A Bradford White's standard 50 gallon water heater only provides 90 gallons of hot water in the first hour. This unit in their 25 gallon model can provide 155 gallons of hot water in the first hour, the 55 gallon unit can supply 200 gallons of hot water in the first hour..

    Here is the Spec sheet on the units.
    [​IMG]
    [​IMG]
  14. JJplumb

    JJplumb Plumber

    Messages:
    1
    Location:
    British Columbia
    I find you guys very funny with all the back and forth between your opinions from a home owner to a contractor. The contractor has a boiler put is his house and can make adjustments to his systems very easily because he has been to the training seminars and has used the same basic principles of these systems for years and is comfortable with them. The home owner does not have the same resources and relies on a contractor for the advice (with or without research) tank less water heaters are a proven asset from efficiency and life expectancy. both of these installs are better then a hot water tank. The tank less is 3 times more expensive then the hot water tank but also last 3 times longer then the tanks. Keep in mind that they are 3 times more expensive then hot water tanks based on todays prices, we all know that prices only go up!!!!!! hot water tanks also lose their energy factor as they get older do to insulation breaking down and sediment build up. Tank less water heaters don't have problems with either of these, yes you will have to de scale them every so often depending on how hard your water is. Tank less will be the only thing that is logical for domestic hot water in the near future and if you are not a contractor that is a part of this then you will be left in back of the crowd because majority of home owners will want to get rid of the bulky systems for something is more efficient then a boiler. Navien at 98% efficient is better then any boiler has better warranty and is half the price with the same life expectantcy.
  15. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Navien is the worst tankless unit out on the market. It has the highest consumer complaints out there on its performance and reliability. The performance issue is the huge temperature fluctuations it has. They needed to have that buffer tank that they promote so much to help stabilize the fluctuations, but it does not help that much.

    If you really want a good quality Tankless unit I would go with a Noritz or a Takagi unit. I myself like the Noritz for their duel flame burner, it has the most stable temperature output of all the tankless units. Also do not be fooled by the claims of energy savings. Tankless systems are more a luxury item if properly sized and installed, as it will provide endless amounts of hot water. Many that went tankless have stated that they take longer showers now, which eats into the so called energy savings.
  16. ChuckS

    ChuckS New Member

    Messages:
    96
    Location:
    Aurora, CO
    I would like to throw the unit I have into the mix. We have the Paloma 7.4 and so far it's solid. It also has a duel flame burner, very stable temp output and did cut our energy bills way down.

    http://www.tanklesswaterheaters.com/waiwelaph28ri.html

    I agree my wife and daughter take longer showers but that doesn't negate not heating water through the day and overnight. Not to mention if you go away for the weekend etc... Will it pay for itself is another question all together since ours was $2600 installed but I will say we're very happy with it and I don't miss running out of hot water in the mornings (I am the last in the shower).
  17. Scott D. Plumber

    Scott D. Plumber In the Trades

    Messages:
    67
    Thoughts

    At one time the Wright Flier was a “Fadâ€, Henry Ford was wasting his time with motor cars and copper pipe was for amateurs who could not cut and thread Galvanized. Everything happens in stages and the first stages are more expensive…at first. Remember the first flat screen TV’s?

    The Consumer report piece is so obviously a hit piece it’s not funny. One day, I’ll take the time to go through it and blow it up, but not today.

    As for Navien, it’s an ok product but plagued by temperature swings at low temp rises. It makes a better boiler than a water heater IMHO. Rinnai is my favorite with Noritz a close second. You might think you are saving $200 in vent with PVC but the unit cost $200-$300 more than a comparable Rinnai and then you have to cut/prime/glue the ugly PVC. Unlike the low profile, single concentric, push-joint Rinnai vent. So what have you gained? Plus the Rinnai gives more hot water and so does Noritz.

    The Navien is 90+ Really? If I have a car that gets 50mpg and a car that gets 38mpg in the driveway, and they are both “OFF†which ones is getting better mileage? We are talking about equipment that only runs for a fraction of the day anyway. I would think actual energy difference is negligible.

    That said, the there is only one product with a nationwide network of trained Authorized Service Providers, a 24/7/365 tech support (in the USA, Not India) and a highly trained Rep network. That’s Rinnai. Nothings perfect, but some things are better than others.
  18. Dana

    Dana In the trades

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    2,986
    Location:
    01609
    :):):):)

    Yeah, I too get a bit of a laugh out of the "98% thermal efficiency" numbers for Naviens, in much the same way that I do with the overzealous mod-con boiler advocates.

    An on-demand hot -water heater almost BY DEFINITION short-cycles on most of it's burns. Anything less than 5 gallons would be an efficiency-robbing short-cycle for tankless, condensing or otherwise, and even though the bulk of the water use is indeed bathing/shower draws greater than 5 gallons, the numbers of short-cycles, the fixed-losses per burn (flue purges & ignition sequences) add up- they aren't anything LIKE 98% efficient, or even 90% in real-world situations, no matter what their EF number is. (An EF test takes 10+ gallons at every draw, enough to signficantly inflate the performance of a condensing tankless.)

    What determines the real as-used efficiency is how well the unit manages the fixed losses on short-draws of 2 gallons or less, not whether it's condensing/non-condensing. Depending on real world use patterns and the fraction of large/small volume draws, a non-condensing tankless will run anywhere from 75-80% efficiency, whereas a condensing unit might run 75-85%, no more.

    Used as a condensing space-heating boiler a condensing tankless can indeed hit 90%+, but only if the return water entering the tankless is below 110F. In order to hit 98% the return water would have to be under 70F. While not-too-likely in a heating system, 98% efficiency possible for high volume hot-water draws, since the water from street is typically well below 70F. But the average efficiency as a hot-water heater will always be considerably lower than it's steady-state thermal efficiency.

    Tankless HW heaters see a huge number of ignition & flue-purge cycles, robbing efficiency as well as wearing out some of the sub-systems. Even a small well-insulated buffer tank can cut the number cycles by more than half and increase the overall efficiency (while getting rid of the "cold-water sandwich" issue) for the efficiency cost of a small standby loss (less than 1%). From a fuel-saving point of view it's not always cost-effective for just water-heating, but in a combi space-heating/DHW system it can be. (Systems using a reverse-indirect like a ThermoMax or ErgoMax as a heating system buffer while acting as a DHW heat exchanger tends to work well for homes with low/moderate design-day heat loads of 25-75KBTU/hour. But if it's an already high mass low temp radiant-slab heating system where lower than 110F temp heating water is typical the reverse-indirect-as-buffer approach is less than ideal.)

    The best selling point for a condensing tankless is when it can use a cheap PVC vent stack instead of stainless/Z-vent for the standard-efficiency model. In installations with long vent runs the installed cost of a condensing tankless + PVC vent sometimes works out to about the same or less than a standard-efficiency unit + Z-vent. In those cases taking the (very modest) efficiency savings offered by the condensing unit seems fair.
  19. Bring on the heat

    Bring on the heat New Member

    Messages:
    2
    Adaboy

    Love the way "NHmaster" layed into the whole environmental solar, windfarm, hybrid, et al & etc. things and ALL the other useless crap good money is being wasted on - to control what? - carbon emissions! To save a polar bear? Crapola!

    Don't buy it!:p If we continue to allow the powers-that-be to regulate US (and I mean all the USA) for carbon emissions, we grant them the power to legislate US all out of existence. We're all made of carbon and exhale it all day long. If it were not for us, the trees would all die and we wouldn't even have a "geen" planet to worry about.

    I WAS considering a tankless WH, but it sure don't make $ense to me. Maybe in 10-15 years when I need a WH again, I'll look into it again. That is, if we haven't destroyed the plannet and I am still here TO look into. Don't get me wrong, I am not damming the innovative spirit. I just prefer to spend MY money on something that has proven its self, rather that gamble on something that may not be better and may be less reliable.

    Maybe 10 or 15 years from now, will see that Hybrids and windfarms were the answer. However, I suspect they will go away quietly and we'll not hear from them for much longer.

    :)Nice to chat with you guys!
  20. Dana

    Dana In the trades

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    2,986
    Location:
    01609
    Yeah, and maybe oil will go back to $6/barrel before it hits $120/barrel again (and electricity is going to be too cheap to meter any day now, eh?) ;-)

    With or without carbon taxes, unless the worldwide recession becomes permanent, energy prices will be rising before your recently installed tank HW heater craps out- count on it. North of $4/gallon people using the ubiquitous F150 as their commuter car are going to be looking at hybrids, high-efficiency diesels, compressed natural-gas vehicles, ANYTHING to keep from forking over their paycheck at the pump.

    A decade from now any purchased-efficiency will be more cost effective than it is now no matter how fast we drill, even if all carbon-taxes get repealed. The developing world won't stop developing just so's we can have cheap energy. By 2040 China alone will add another USA's worth of energy consumption. It's been great while it lasted, but you can kiss cheap oil goodbye even in the intermediate term. In the short term coal-seam natural gas drilling over the past decade is starting to pay off for the US though- enjoy the prices while they last. (If Boone Pickens gets his way, cheap natural gas will be history too.)

    What makes you "...suspect they will go away quietly and we'll not hear from them for much longer", anyway? Wishful thinking isn't a very good analysis of energy markets, and the effect of carbon taxes is still quite small compared to the larger market forces.

    But whether & where a tankless makes sense depends on more than just the installation cost or the price of energy though.

    F'rinstance...

    For moderate flow, low volume (and particularly) intermittent users even a cheap low-efficiency pilotless ignition like the Bosch 1600H can make sense. (The basic unit under the cover is now a well-evolved better working variant on the E.L.M. Aquastar from 20+ years ago, many of which are still in use with 15+ years of USA-family type loads on them. The modulation feedback is better, and the ignition system changed, but the heat exchangers & burners are nearly identical.) It's efficiency is only a few percent lower than the whole-house forced draft burners, but higher than the raw combustion efficiency (let alone EF test numbers) of a atmospheric-drafted tank. But it's still low enough that it can be vented into pretty much the same chimney as you would a tank- no need for special vent-pipe materials, and since it's a water-flow-powered magneto type ignition you don't even need to run electrical power to it.

    All of this adds up to a very CHEAP installation as a tank-replacement- you may have to run fatter gas line to it, but beyond that it's about the same, and you gain the benefit of no rust-out leakage (I suppose it could happen in high acidity water), and zero standby loss, and somewhat higher combustion efficiency. I'd rather have one o' them in a weekend condo or vacation cabin than a tank- ANY tank. The downside is somewhat limited flow- in a New England winter you can't run both the dishwasher & laundry while someone is taking a shower and not hear about it. (Output is only ~100KBTU/hr- plenty for a shower even with 40F inlet water, but don't push your luck!)

    An atmospheric drafted tank with a standing pilot is going to run over 75 therms/year in standby losses. The cheapo Bosch loses less than 10 (and then only if used regularly- in long term standby the standy loss is truly zero.) And when in use, well over 70% of the energy ends up in the hot water, compared to ~60-65% for a pretty good tank, if (and only if) there's 60gallons/day running through it. It doesn't take high math to figure out how long it has to last to have paid for itself in fuel-savings alone.

    Then when you figure that you can have 5 or even 10 people in succession taking showers without running out of hot water... There are plenty of situations where they make sense, independently of globule-warming carbon-crap or nickel-squeezin' on fuel. Zero recovery time is nice!

    I've recommended this very unit to several people for these very reasons, with the same caveats to boot. None of them have tracked me down to complain... ( ...yet. :) )

    Tankless water heaters aren't new (they're about ~100 years old), just new(er) to the US market. In Europe they became the standard primarily for space-savings. For decades many had to be lit by hand and didn't automatically modulate flame to flow, but modulating versions with mechanical feedback have been around for at least 30 years. It's the 80%+ efficiency high-output versions with all of the electronic controls that try to serve multiple simultaneous & significant flows that are (relatively) new, but even those now have a decade of track record behind them with few nightmare scenarios.

    I'm not say they're for everybody, but I've yet to meet anyone who switched over from a tank to a tankless and regretted it later.

    But me, I'm still for using bigger-burner tankless heaters as heating system boilers, getting the hot water from an indirect-fired tank that also acts as the heating system's buffer tank. Most components of the tankless will last longer with far fewer ignition & burn cycles per day/year/decade (you may not get a full 25 years out of the heat-exchanger though), and with very low mass it's standby & cycling losses are far lower than cast-iron boilers. Properly designed & set up, you'll get significant modulation efficiency benefits out of them too, further reducing cycling losses. Again, not for everyone (but not a terrible option for many.) But just retrofitting an indirect-as-buffer-tank onto an existing hydronic boiler would usually be a cheaper & more efficient option than adding a tankless (or tank) hot water heater.
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