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Tankless Water Heaters

lthiesen
lthiesen Member Posts: 19
Interesting article in this months PM Engineer magazine about tankless and tank type water heaters. According to this article there is only a small difference in operating costs, only about $50.00 a year. Any thoughts on this, anyone?

Comments

  • Scott Gregg
    Scott Gregg Member Posts: 187
    Operating cost

    Operating cost difference is relative. So is the overall cost of ownership and this is one of my favorite subjects! First, narrow the field to the better products in tankless capable of doing a whole house not home center models: Noritz/Rennai/Takagi. If you compare a tankless heater with a 50 gallon tank heater also gas fired there will be very little energy savings. This however is an apple and an orange.

    Noritz and Rennai heaters (Not as sure about Takagi but probably similar) have a 20 year expected life v/s about 8-12 for a normal tank type fired heater. (Yes I know there are plenty that go 20+ but we are talking averages here and the stats are in)

    Secondly, the tankless heaters by these companies produce better than 300 gallons per hour of hot water that you can not run out of.

    Third, they are self diagnosing to help you service them if you do have a problem.

    Now, All that said, lets compare a little more fairly. A 75 gallon power vent tank heater cost about $450 A tankless we’ll say for sake of this discussion cost $1200. (I went a little low on the tank and a little high on the tankless for fun)

    The 75 gives you 91 gallons first hour delivery. Then you are out. The tankless gives you 300+ (Closer to 400 most of the time) and you can never run out.

    The energy guide sticker on the 75 shows about $365/year operating cost, the tankless is $150 because it is always off waiting for you instead of the other way around. (That's about a 3.5 year payback if you only consider energy)

    You will probably have to replace the 75 long before the tankless adding to your actual cost difference of ownership when both products are subjected to the same conditions.

    If ANY part of a tankless fails you can easily replace it, if the tank fails you throw it in a dumpster.

    If the HX of the tankless gets stopped up with lime or calcium in bad water conditions you get an error code and can flush it out renewing the heater. With a tank, you find out about the deposits when the bottom blows out flooding the place...and you toss it in the dumpster.

    If all you have is a 50 and all you care about is energy savings then the tankless might not be your first choice. If these other factors are things that matter to you then they probably are the best option.
  • Scott Gregg
    Scott Gregg Member Posts: 187
    Oops double post

  • jim sokolovic
    jim sokolovic Member Posts: 439
    For direct-fired domestic water source...

    this is good logic. But an indirect water heater, piped off a high efficiency boiler, really makes the most sense to me.
  • Scott Gregg
    Scott Gregg Member Posts: 187
    I went and read the article...

    First let me say that I like BW and their products. I was a bit disapointed in the article though. I read the article and I find the test parameters...interesting. As I thought about it seemed more like propaganda than a real test. I wonder if a tankless MFGer set up a test how they would set the parameters. Here are things that stood out to me and bugged me a bit:

    They do not tell us how long they ran the test.

    Hardness was set intentionally to lime up the HX of the tankless. If they let both the tankless and the tank go for a few years (possibly just one at that level!), watch what happens to the tank! Oh yeah, get a big wet vac ready.

    A quote from the article"(Tankless #2 was rated 4 gpm at 77¢ªF rise)". This is interesting. By their own test they were only requiring a 62* rise. (58* incoming water set at 120*) Their¡± tankless unit can provide about 5.2GPM at this level! Why did they leave that out? Hmmm?

    Why do they not give us the first hour rating on tested products? Could it be that the tank is about 75 gallons and the tankless is about 300 and they make more profit selling tanks?

    Here is some other evidence to consider:

    They began their "Article" by siting the "The ongoing, recent fascination with tankless water heaters"
    Would the words Recent or Fascination apply to the rest of the world that has been using these things for 20+ years?

    This "test" was produced by a TANK water heater Company. They don't make tankless heaters. Would anyone care to guess who makes the Everhot...Hmmm?

    Now that they are getting their product private labeled do you think the REAL manufacturers are stupid? How do you think they have the pricing set up?

    Here is what I think. The tank guys are scared to death! They should be. (Not just BW either!) They have a 9 million unit market per year (collectively) and are quickly loosing market share by a product they know very little about. They do not have 20-30 years to develop their own technology so they scrambled to buddy up with the manufacturers to try to protect the market as best they can...for now to buy them time to figure it all out. If it were only a "fascination" they would not have bothered.

    They are not going to roll over and let the invaders take over the residential water heater market. They need to discount tankless as much as they can until they figure it out themselves. It's interesting to watch.
  • Scott Gregg
    Scott Gregg Member Posts: 187
    Jim...just an option

    High Eff boiler Munchkin. Great unit. With 60 Gallon Indirect it's a great system. But...

    You can get about 204 first hour. Looking at cost and space. for less money and a lot less space adn instaltion, you could purchase two Noritz N-069M units with the Quick connect cable and provide from a minimum of 492 Gallons/hr (8.2GPM) to a max of 948GPH (15.8GPM)Depending on incomming water of 45* - 75*

    No not right for everything but a dang good option for a lot less $$$.
  • Jim Wy.
    Jim Wy. Member Posts: 43


    If you have kids like I do (9&11) you won't save one penny going tankless. Since they never run out of hot water in the shower they dont come out of the shower until they're practicaly sick from the heat every night.But my wife is very happy so it's all good. We used to have a 50 gallon waterheater w/ 60MBH which is no comparison to a Rinnai.
  • jim sokolovic
    jim sokolovic Member Posts: 439
    The cost of...

    purchasing and installing 2 tankless units of that capacity is less than a single indirect tank? The boiler is there for space heating, too - so I assume you cannot include that cost? I am not familiar with these units - how do they vent (sidewall, I assume)? With 2 tankless units and a space heating boiler, that's 3 combustion appliances to maintain? I may be stuck in my thinking about what works best for the average Joe homeowner - but it is interesting to learn more about these tankless units, thanks!
  • FHHO
    FHHO Member Posts: 6
    Can takeless use circulating lines?

    Can circulating lines be connect to the tankless heaters?

    I would like to convert to tankless, but afraid my circulating lines would become obsolete.

    The reason I got the circulating lines is because I have a large home and it used to take a while for the hot water to push all the stagnat cold water out of the lines.
  • Scott Gregg
    Scott Gregg Member Posts: 187
    No comparison is right

    Jim, you are right. A 50 gallon is NOT a fair comparison to the Rennai! It is too bad though that some (Normally tank companies)will want to compare energy between a 50 and a tankless and ignore the fact that one gives about 65 gallons (if your lucky) and the other gives you over 300. If you compare the energy with a tank heater that can put out a larger amount of hot water, the savings get a lot better.

    On caviat though. I think a good indirect would probably compete well with a tankless on both counts. Only thing a lot of people here don't have boilers.

    To get your kids out of the shower quicker, there is a cool tankless valve set on the market. 1/4 turn, and they'll come on out. ;-)
  • Mr T    Elmira NY
    Mr T Elmira NY Member Posts: 1
    Brands of Tankless

    I was reffered to this site from someone @ the FHB site.
    I am very interested in upgrading my DHW to a tankless.
    I am trying to do my research BEFORE my 9 Y.O. A>O>Smith unit craps out.
    I have seen the Bosch units at Lowes and I am familiar with Rinnai from my work in remodeling.
    Is the Bosch a Reliable unit?
    or is it just a DIY catcher?
    I know Rinnae makes good stuff, what otherbrands should I be researching?
    I have Natural gas (so does my house):)
    Thanx in advance for the advice

    Tony
  • Jim M
    Jim M Member Posts: 29
    Tankless

    It is funny to me how emotional people are about domestic water heating. "water heaters are best, why spend all the extra money up front"; boiler and water maker are the only way to go"; "tankless can't handle a whole house". All these statements are true for some and false for some.

    As professionals we need to know how to apply each of the options and when best to apply them. as homeowners it is your duty to do due diligence, dont buy a 117MBTUH tankless unit and expect it to do more than one outlet, and don't expect it to do a good job on that outlet.

    The best thing proffessionals can do is become good consultants and match the best products for the customers needs. The best thing a home owner can do is find that professional and rely on him and his expertise.

    Yes you can circ a tankless but be aware of the "cold water sandwich" and make sure that piping and equipment are applied to elimanate that problem.

    Areas of high water hardness are are great places for tankless. My first experience with tankless, about 4 years ago, was brought to me by a homeowner who was going through two to three elements a year because of water hardness, after installing tankless he hadn't had one water hardness alarm.


    Jim
  • Scott Gregg
    Scott Gregg Member Posts: 187
    Yep

    If you already have a boiler an indirect is my prefered way to go...always.

    In my area though boilers are almost no-existant for new houses.

    This leaves tankless as the best way to go.
  • Scott Gregg
    Scott Gregg Member Posts: 187
    Bosch v/s Rennai

    I think the Bosch is just shy of a DIY catcher. They work, but for a smaller application than most have. They are nowhere near the capacity, quality or technology of the Rennai.

    Look at Noritz while you are at it.

    My advice on tankless is if you are going use one, do not purchase on over another based on price. You might be sorry later.
  • Mad Dog
    Mad Dog Member Posts: 2,595
    Definitely easier on your....................................

    back! Mad Dog

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • jbplumber
    jbplumber Member Posts: 89
    for the installer

    That the whole game Mad Dog. j.lockard
  • Rodney Summers
    Rodney Summers Member Posts: 748
    New Home Tankless Water System

    Hi:
    We are building a new home, full basement and two stories above; 6000 square feet in all with 4.5 baths. We have 3 baths on second floor, half bath on main floor and one bath in basement. Questions I have:

    1) Two Rinnae system located on opposite sides of house to service all areas within 25 feet. I am told that this will work well without the need for a recirc pump. Any suggestions?

    2) Two Rinnae system in tandem in one location with recirc system and small electric water heater as reservoir. I am told that this would handle our capacity for the whole house and provide instant on hot water. Downside is that Rinnae's with recirc pump and hot water heater are leaning back to the same characteristics of a traditional hot water heater system. Any opinions on this one?
    3) Single boiler system: Would this be even a better option with use for home heating as well?

    Thanks for all your comments and advice
  • Plumdog_2
    Plumdog_2 Member Posts: 873
    Localize them

    and forget the re-circ lines; it gets too complicated. Make sure you have adequate gas supply to each location and investigate the venting situation. BW and Rinnai have concentric direct venting capability that works real slick. You also need to provide an approved drain for service valves and T&P; check with local building authority.
  • JackFre
    JackFre Member Posts: 225
    My view (www.rinnaisolutions.com)

    I represent Rinnai in New England, but am also a licensed plumber and was in the mechanical contracting business and installed tanklesses (on-demand is my preferred term...never call them instantaneous unless your showerhead is at the HW outlet of the unit)back in the late 70's,early 80's. I've not read the P&M article. Yes, the tank manuf are scared and they should be. With the modulating gas valve technology in the newest units the on-demand water heaters time has come. The tank people have not done a damned thing to improve the efficiency of their units and now they are like the deer in the headlights. I understand the attraction to indirects off the boilers but on my system (Buderus G224., 40gal Bud ind, Ecomatic) when I shut the boiler down (spring/summer)my gas consumption for hw dropped over 60%. Same load, same people and in fact I didn't tell my girls that I had changed the system over. The boiler/ind is an excellent system but in my opinion should only be used with a HW priority control to prevent boiler oversizing. I've been doing a lot of commerical systems with the Rinnais. Just fired up a system with two banks of four to two 200 gal ASME tanks for the Worcester County Jail (gotta take care of those inmates, eh). As a mechanic, it is just so impressive watching these start and run and bring those tanks up in a hurry. They balanced their own flow and none of the eight varied more than .1gpm from the others. We created a storage room with the space saved over the original PVI system. Please look over the Rinnai solutions web site. There is just a massive amount of good info there.
  • Brian (Tankless)
    Brian (Tankless) Member Posts: 340
    Great Scott (both of you:)

    You both hit on ALL of the reasons why tank makers should be scared.

    Scale & lime buildup: That is the # 1 argument I have heard plumbers use, to talk customers out of on-demand heaters, especially gas. And in the process, have talked themselves right out of a sale, and a potentially great relationship with a new customer who will tell more people.

    Note: In 14 yrs, I have never had to descale or flush a tankless water heater, period!

    But, in the presence of the plumber who wanted to install a tank (she wanted us to meet) I told the customer that in the time it takes to replace a tank, I can descale & flush a gas tankless at 1/3 the cost. She has now had a Takagi TK-2 for 5 yrs and is very happy. No sediment in the tank she doesn't have, and has endless hot water.

    She has sent me five new customers, I love it :O)

    Use the scaling issue as a sales tool.

    Knock 'em dead in 2006 Guys & Girls.

    Tankless in Swampland.
  • Brian (Tankless)
    Brian (Tankless) Member Posts: 340
    Commercial Laundry

    I did a similar install in a nursing home laundry, Scott.

    Hot water needs were two commercial "Milnor" washing machines which run 18 hr's/day.

    We took out a 299Mbtu, 70 gal gas dinosoar (sp), which recirc'ed into an uninsulated 500/ish gallon storage tank.

    We put in a wall mounted ELM AquaStar AQ-170-HT, and circ'ed into a 70 gal Ruud, well insulated storage tank.

    Oh joy & bliss, the building is on it's own gas meter. The next month's gas usage went down 40% from the previous month. I timed a heating cycle after a machine took out 25 gal's of 150* water...1 min 55 sec's.

    In 11 years I have changed out the burner/water valve ****'y, approx 35 minutes. Not bad, eh?

    Water heating is a Tankless Job.

    Later guys, keep up the good work.

    Brian.

  • Dirk Wright
    Dirk Wright Member Posts: 142


    I have a Toyotomi oil fired tankless water heater with a 5 gallon heat exchanger. When I installed this in place of my tank type electric water heater, I had to move it some 20 feet away, so now it takes too long to get hot water at the furthest tap. The other problem is short cycling. I suppose the modulating gas type tankless heaters don't do this, but my 150,000 btu/hr Toyotomi is constantly short cycling when hot water is demanded. It also keeps the water in the heat exchanger at the set temperature. Short cycling is really not good for any unit.

    So, I bought an Ergomax to solve these 2 problems. I can locate the tank much closer to the points of use, and the large energy reserve of the Ergomax means that there should not be much if any short cycling. The downside is complexity with the required closed loop circulation system. The only other problem with this is that the Toyotomi is limited to 155 F output temperature, meaning that the Ergomax can only be kept at about 145 F. The domestic water in the Ergomax is in the coils, not in the tank, so there is no legionnella issue there.
  • JackFre
    JackFre Member Posts: 225
    Avoid the recirc, split them up!

    Having said that, what are the actual fixtures that you have in the various bathrooms. If you have a "mega-shower" with a bunch of bodysprays and a high flow shower head you may have to put them together and recirc. My view on recirc is to avoid it if at all possible.
  • Tony_23
    Tony_23 Member Posts: 1,033
    Suggestions

    Stay away from Bosch. I installed one in a VERY good customer's home, and removed it 6 months later after numerous trips back for lockouts that had no published code. It flashed a code, just not a published one. The factory tech guy promised the parts to correct their design issue in a week and it took almost 2 months. Their highest output model is supposed to do 6+ GPM but requires .8 GPM just to fire up.

    I'd go with Rinnai, Noritz or Takagi.

    Since you're in Elmira, call Northrup Supply and see who they recommend as an installer. I think they handle Noritz now.
  • Dave Stroman
    Dave Stroman Member Posts: 763


    I am the first to admit that I am a hydronics guy and favor indirects. I am also a plumber and have never thought much of the tankless for the following reasons.

    Can't retro fit into the existing flue. Most houses have a 3" or 4" flue conections. Many vent into an old brick chimeny. You can not simply swap out a tank for a tankless. Sure, you can vent through the wall, but I hate sending a flume of vapor out the side of a house. Sure, we could line the chimney, maybe.

    Gas line size? Can not assume that the gas line is sized for a larger Btu unit.

    And if you do put in that larger Btu unit to handle that big tub or multiple showers, what happens when you need a very small flow of water to just wash your hands. Will the thing even fire?

    I am not disagreeing with any of you about how practical tankless may be in some applications, and after reading these postings, I have softened my distaste for them and will bit the bullet and attend one of the training meetings that my suppliers give from time to time.

    If I am way off base on this, I am sure if will find out shortly.

    Dave in Denver
    Dave Stroman
  • Joe_8
    Joe_8 Member Posts: 32
    Love those Rinnai

    Hey Jack,
    I just engineered and installed 8 Rinnai heaters at the Worcester County Jail too. What building did you do?
    Joe
  • Joe_8
    Joe_8 Member Posts: 32
    Love those Rinnai

    Hey Jack,
    I just engineered and installed 8 Rinnai heaters at the Worcester County Jail too. What building did you do?
    Joe
  • Joe_8
    Joe_8 Member Posts: 32
    Love those Rinnai

    > Operating cost difference is relative. So is the

    > overall cost of ownership and this is one of my

    > favorite subjects! First, narrow the field to

    > the better products in tankless capable of doing

    > a whole house not home center models:

    > Noritz/Rennai/Takagi. If you compare a tankless

    > heater with a 50 gallon tank heater also gas

    > fired there will be very little energy savings.

    > This however is an apple and an orange.

    > Noritz and Rennai heaters (Not as sure about

    > Takagi but probably similar) have a 20 year

    > expected life v/s about 8-12 for a normal tank

    > type fired heater. (Yes I know there are plenty

    > that go 20+ but we are talking averages here and

    > the stats are in)

    >

    > Secondly, the tankless

    > heaters by these companies produce better than

    > 300 gallons per hour of hot water that you can

    > not run out of.

    >

    > Third, they are self

    > diagnosing to help you service them if you do

    > have a problem.

    >

    > Now, All that said, lets

    > compare a little more fairly. A 75 gallon power

    > vent tank heater cost about $450 A tankless

    > we’ll say for sake of this discussion cost $1200.

    > (I went a little low on the tank and a little

    > high on the tankless for fun)

    >

    > The 75 gives you

    > 91 gallons first hour delivery. Then you are

    > out. The tankless gives you 300+ (Closer to 400

    > most of the time) and you can never run

    > out.

    >

    > The energy guide sticker on the 75 shows

    > about $365/year operating cost, the tankless is

    > $150 because it is always off waiting for you

    > instead of the other way around. (That's about a

    > 3.5 year payback if you only consider

    > energy)

    >

    > You will probably have to replace the

    > 75 long before the tankless adding to your actual

    > cost difference of ownership when both products

    > are subjected to the same conditions.

    >

    > If ANY

    > part of a tankless fails you can easily replace

    > it, if the tank fails you throw it in a

    > dumpster.

    >

    > If the HX of the tankless gets

    > stopped up with lime or calcium in bad water

    > conditions you get an error code and can flush it

    > out renewing the heater. With a tank, you find

    > out about the deposits when the bottom blows out

    > flooding the place...and you toss it in the

    > dumpster.

    >

    > If all you have is a 50 and all you

    > care about is energy savings then the tankless

    > might not be your first choice. If these other

    > factors are things that matter to you then they

    > probably are the best option.



    Hey Jack,
    I just engineered and installed 8 Rinnai heaters at the Worcester County Jail too. What building did you do?
    Joe
  • Scott Gregg
    Scott Gregg Member Posts: 187
    Here's my $.02

    If you are going to be able to heat the house with a radiant or hydronic system, go ahead and use a good indirect.

    If not, I like the twin Tankless feeding into about a 6 gallon 120V electric tank heater. Recirc back between the tankless set and the tank with a couple of check valves. The little tank heater handles keeping your loop hot and saves the tankless warranty without breaking the bank or giving up too much in standby losses. Pipe them parallel. Works great. Plus, you have the redundancy of the second tankless. (If one goes out, the other will keep going.)

    If you do not have a big hot water load like a body sray sytem or some other high flow outlet, you probably only really need one Rennai.
  • Rodney Summers
    Rodney Summers Member Posts: 748
    But Dirk

    You just turned your instant HW heater into a regular boiler with indirect! Technically, if you have the 148 model, it's not approved for closed hydronic heating systems.
  • Dirk Wright
    Dirk Wright Member Posts: 142


    It IS a boiler, in reality. It's functionally equivalent to a boiler. It basically a boiler with a really small heat exchanger and a really large burner. The water heater has a 5 gallon capacity stainless steel heat exchanger coupled to a 148,000 btu/hr burner, and it keeps that water in there at the set temperature all the time. This is different than the gas and electric tankless, which turn off completely when there is no demand. The only difference between the Toyotomi and a boiler is that the temperature is adjustable over a wide range and it can take very cold water on it's inlet. The Toyotomi also responds to temperature change, not flow like the other tankless types. It really is a kind of a boiler, so I do not believe this will be a problem. The only down side is that this unit can only make 155F water, limiting the heat storage ability of the Ergomax.

    The new Toyotomi boiler is different only in that it is set for 180 F and what is adjustable is the temperature differential. Otherwise, they are the same.
  • JackFre
    JackFre Member Posts: 225
    Joe, YOU did the WCJail!!!

    I helped and enjoyed it. It is a cool system though, eh?I've been talking about since start-up. Sorry for the delay in respose!
This discussion has been closed.