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Thread: Tankless WH

  1. #1
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    Default Tankless WH

    I'm considering installing a tankless water heater to replace my existing 57 year old (no joke) 40 gallon tank. I'm interested in some pros and cons that you may have come across, as well as if any of you have any personal experiences with particular brands.

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    Jim Robinson
    New Mexico, USA

  2. #2
    Terry Sandmeier's Avatar
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    Default Re: Tankless WH

    Wow! 57 year old water heater!! Why do you want to replace it? They don't build things like they used to. As for on demand water heaters, if you are not cost prohibited they are a great system. Seisco makes a good electric heater, and there are multiple gas fired appliances, I only have a bias of Tagaki, bad experience with them, if your heater goes down, to get warranty you have to ship your unit to them in California and let there tech diagnose the problem to determine if they will cover the repairs or replacement.


  3. #3
    mathew stouffer's Avatar
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    Default Re: Tankless WH

    They are geat. The only problem I have seen is the limitations regarding vent requirements. The BTU's are greater than a regular water heater so sometimes it is difficult to install the vent.


  4. #4
    Bob Spermo's Avatar
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    Default Re: Tankless WH

    I have a gas on-demand direct vent water heater. Great! I would not get an electric on-demand one. The new direct vent ones can be placed on an exterior wall and the venting expense is greatly reduced. Mine is a Rheem 6.5 gals a minute! It uses less gas than a fireplace pilot light because I have conducted an experiment. Turned off the pilot light (closed the gas valve) and installed my gas on-demand water heater. Monthly gas cost went down!


  5. #5
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    Default Re: Tankless WH

    I wanna see pics!


  6. #6
    Brent Simmerman's Avatar
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    Default Re: Tankless WH

    They are great unless you have really hard water.


  7. #7
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    Default Re: Tankless WH

    I have a Takagi TK-1 whole house water heater. I have had it about 7 years and it's been pretty good. I Never run out of hot water and I have 6 kids, only 4 at home right now. My only complaint is that it sometimes makes unusuall sounds and I can not figure out what the problem is. I would not recommend an electric unit, I have heard that they draw so much electricity that the utility companies are having to upgrade transformers, and making the property owners pay for the transformer. I am not convinced that the tankless units save as much money as they claim to.


  8. #8
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    Default Re: Tankless WH

    Rinnai R75LS or Rinnai R85E depending on your size and demand anticipation.
    Can't go wrong with either.

    We know why you fly: because the bus is too expensive and the railroad has a dress code...
    www.atozinspector.com

  9. #9
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    Default Re: Tankless WH

    Definitely buying gas if I get one. I was thinking I might bring in a combustion air vent or buy a direct vent. We're remodeling and adding on, so I can configure the combustion air pretty easily. Thanks for the tips. It looks like 4 to 5 GPM are about the top end unless you spend bigger money. Anyone run two showers or a shower and washing machine / dishwasher simultaneous with no problems on theirs?

    Jim Robinson
    New Mexico, USA

  10. #10
    Jerome Cartier's Avatar
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    Default Re: Tankless WH

    Rinnai is the most common whole house tankless gas w/h I inspect.
    I have recently inspected 2 properties with electric tankless w/h units at each bathroom and kitchen area. They were Eemax and CEC Power Stream.

    Jerome Cartier
    Cartier Fine Home Inspections
    Mobile, Alabama
    (251)490-3212
    http:CartierInspections.com



  11. #11
    Gary Wilson's Avatar
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    Talking Re: Tankless WH

    Quote Originally Posted by Brent Simmerman View Post
    They are great unless you have really hard water.
    I too have been looking at a gas unit. Our water is so hard we have to use plastic glasses! We do have a water softener, will that compensate for the hard wtaer? Thanks


  12. #12
    Brent Simmerman's Avatar
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    Default Re: Tankless WH

    Yes, around here there is no trouble if you have a water softner, those that don't wish they did after about year.


  13. #13
    RANDY NICHOLAS's Avatar
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    Default Re: Tankless WH

    I've had my electric tankless for 6 years. I will never buy another, unless it's gas.
    I saw no increase in my electric bill. BUT
    I've changed the elements twice. The elements get a lot of mineral deposits or other stuff (cooked water) built-up on them. The stuff comes loose and clogs the aerotors at the sinks and clogs the faucet mixing valve, probably helped destroy the dishwasher. The wife usually washer the clothes with cold water or the $900.00 clothes washer would also be ruined.


  14. #14
    Ed Voytovich's Avatar
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    Default Re: Tankless WH

    Outside of this list, the people who like tankless water heaters are usually the people who manufacture and sell them. In my experience, the installers are less enthusiastic.

    It is unlikely, despite increasing gas/electric prices, that energy savings from cutting down on stand-by storage tank losses will off-set the much higher cost of the original tankless equipment. We can do the math.

    If you are replacing a +/-40K BTU water heater with a 160K tankless, you may well need to increase the size of your gas lines. We can do the math.

    On-demand water heaters in many areas of the country require descaling annually. This means disconnecting the incoming and outgoing lines and back-flushing the internal tubing to remove accumulated minerals--the equivalent of flushing a conventional water heater, but often requiring chemicals to loosen/dissolve the scale. At the International Builders' Show in January of this year, at least one vendor was marketing a device to attach to one's copper pipes and use some voodoo to prevent scaling. We never saw that before tankless heaters came on the market. Having a plumber provide this descaling may cost $150+/-. We can do the math.

    Servicing this equipment may create some issues. There are several brands, and they are all way more complicated than a conventional tank or an indirect-fired tank used with a boiler. The service guy's bookkeeper can do the math.

    I know they use on-demand water heaters in Europe and Japan, and they have done so for years. In my experience in Europe (I have not been to Japan), they do not worship long showers, home laundry facilities, and dishwashers. And they drive small cars. The European use argument does not convince me. This country is different. Do the math.


  15. #15
    Robin McCaslin's Avatar
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    Lightbulb Re: Tankless WH

    You have to keep in mind a thing or two when you get an On Demand Water Heater.

    There are two types, "Whole House" and "Single Station".

    The Whole House heater is usually gas fired, and the Single Station heater is usually electric. . . And you already know this as well, but I'm trying to get the groundwork understood for what I'm going to talk about.

    Full House Heaters:
    The size and type / brand matters greatly due to the "Minimum Flow" requirements of each particular unit. The small, under the counter single units trip on with a much lower flow rate than the whole house units will. There are houses I've been in that a single facet with the standard flow restricting aireator did not offer enough flow to allow the water heater to fire up. In example, to wash the dishes at the kitchen sink, one had to go into the bathroom and turn on the hot water at the vanity or in the shower in order to gain enough flow for the heater to come on.

    Single Station Heaters:
    The obvious problem, they service only one outlet. and usually have a very low flow rate. You see these mostly in public restrooms nowadays. . . They keep your hands from cramping in the cold water as you wash, and that's about it.

    And the Hot-Shot or HotSpot beverage heaters are not considered viable in this statement. Just so you know. (There's always are a few wize-guys trying to stir up the muck.)

    The next issue with ether type is the level of the water's temperature. Up to a certain point, the flow rate, the heater will continue to perform well, After that, and I believe the general and usual threshold of the All House heaters usability is close to 4 GPM, the temperature falls off very fast.

    An example is if someone is taking a shower, the washing machine is running, and then somebody in the kitchen turns on the faucet, . .. Instant cold in the shower. However, the heat will return instantly when one of the three shut off.

    I've given these issues a lot of thought, and unless you are willing to live with it and Work Around the unique issues inherent with On Demand heaters, then this is worth consideration:

    Place a small, "ultra high recovery" gas hot water heater next to your On Demand, and feed the tank heater from your On Demand heater, and insulate the tank to the maximum. Just a little 5 - 20 gallon tank. Something to take care of the constant Low-Flow issues, and a buffer against the momentary Over-Flow freeze-outs while singing in the shower.

    If you're going to do it, make it as seamless as possible, There's no need for mommy hating you because of it. Please don't get me wrong, they do work, and they save a lot of money. However, like all things, they have their issues, and in this case, a hybrid system will, (excuse the pun), keep you Out of Hot Water!


  16. #16
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    Default Re: Tankless WH

    I had the same problem that Fritz had. Bought mine in the early 90's. I'm on a well and the pressure drop would shut the unit off. I had to keep it on the lowest heat setting and keep the faucet set on all hot. If someone turned another tap on, on the cold side it would shut the unit off. They are not suited for wells unless you have great pressure. I replaced mine 3 weeks ago with a regular electric tank.
    Also I saw no cost savings using tank-less. They are also 3 to 4 times the cost of a conventional tank (installed). Savings I doubt it.

    Mike Schulz License 393
    Affordable Home Inspections
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  17. #17
    Joshua Hardesty's Avatar
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    Default Re: Tankless WH

    Here's some thoughts:

    A tankless gas-fired heater isn't *that* much more efficient than a standard tank water heater, at least according to those little yellow badges they all get.

    You will want to ALSO get a small water heater to put after the tankless. Why? The dreaded cold water slug. This may have been touched upon already, but basically a certain amount of water has to go through the heater before it fires. If you were to pop open the T&P on one, the water would get hot quickly. Let it close fully, and then open it up again. A small bit of unheated water makes it through the heater before it senses the flow and fires. In most instances this isn't a problem, but if you have the kinds of showervalves that have seperate controls for temperature and flow, OR if you have one of those showerheads you can cut off so you can conserve water, when you flick that shower back on in about a minute you'll get a brief but very unexpected slug of cold water. Putting a standard heater in-line lets the slug of cold water mix in with a full tank of hot water so the effect is lessened.

    There's a higher initial cost, which will eventually be negated by the savings you'll see, but it'll take a while to get there. There needs to be other changes as well -- they take a larger gas line than a standard gas-fired heater.

    They do have a much smaller footprint than a typical waterheater.

    They're not freeze-proof, even the outdoor ones which are sort of supposed to be. They have built-in pumps and heaters that circulate and warm the water inside the unit but they can fail. I replaced 6 little ceramic heaters on a couple of 240,000btu tankless heaters recently. I also replaced two heat exchangers in there too because they ruptured once the heaters failed. Actually, I don't know if the copper burst because the heaters failed, or if the heaters failed because of thermal shock after the water sprayed on them. Also, if you lose power, and it's exceedingly cold out, you've basically got a large amount of unprotected copper pipes sitting out in the open. Of course, this only relates to outdoor units.

    "Instant hot water" means the cold water that goes into the heater is instantly heated before it comes out the other end, it does NOT mean you can turn on a faucet at the other end of the house and get hot water instantly to that fixture. I'm sure that's obvious, but you'd be surprised how many homeowners were dissapointed after their contractor talked them into buying one.


  18. #18
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    Default Re: Tankless WH

    Quote Originally Posted by Joshua Hardesty View Post
    You will want to ALSO get a small water heater to put after the tankless. Why? The dreaded cold water slug.

    "Instant hot water" means the cold water that goes into the heater is instantly heated before it comes out the other end, it does NOT mean you can turn on a faucet at the other end of the house and get hot water instantly to that fixture. I'm sure that's obvious, but you'd be surprised how many homeowners were dissapointed after their contractor talked them into buying one.
    When I read the top part I thought you were going to get to the bottom part, and then this - but you stopped short of this:

    When you have a water heater with a built in (or separate) storage tank instead of those 'on-demand' water heaters you can reduce your water usage (there is a water shortage in many parts of the country and all codes call for the installation of water-saving toilets which you have to double flush, but that is for another thread) by installing a circulation pump in the hot water system to either continually or periodically circulate hot water through the hot water lines, reducing the cold water slug the size of the water lines from the water heater to the point-of-use which would otherwise have to be pushed out through the now open hot water faucet.

    I've never seen a circulation pump on an on-demand type whole house water heater installation.

    If the building you are inspecting is not a one- and two-family dwelling or a townhouse, then the IRC does not apply - the IPC applies. In the IPC recirculating pumps and systems are required where the developed length of the hot water piping to the farthest fixture exceeds 100 feet.

    From the 2006 IPC.
    - 607.2 Hot water supply temperature maintenance. Where the developed length of hot water piping from the source of hot water supply to the farthest fixture exceeds 100 feet (30 480 mm), the hot water supply system shall be provided with a method of maintaining the temperature in accordance with the International Energy Conservation Code.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  19. #19
    Bob Spermo's Avatar
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    Default Re: Tankless WH

    Jerry,

    I have seen on demand water heater systems with an activation switch that starts the system. Instead of waiting for a faucet to be turned on to start the system you can use a switch (or motion sensor) to start the hot water circulating. As soon as you engage the faucet the switch turns itself off as now the faucet is the on/off switch. The object is to have hot water at the faucet when you call for hot water. It takes a little extra plumbing but you do not waste water waiting for hot water. I have seen this in two high end "green" houses.


  20. #20
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    Default Re: Tankless WH

    Jim,

    I have gas fired tankless water heaters at my home, my office and at 3 of our rentals. They can work well, but we encountered a number of issues when installing them.

    Iíve put up this page describing some of the installation issues we encountered, and how to resolve them:

    Tankless Water Heater Installation FAQ - Paragon Real Estate Inspections Evanston / Chicago

    Michael Thomas
    Paragon Property Services Inc., Chicago IL
    http://paragoninspects.com

  21. #21
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    Default Re: Tankless WH

    Bob,

    Interesting setup, does it also have an automatic time out for the 'on' switch (motion sensor of whatever)?

    What if you triggered the 'on' switch and then decided not to use the water, or maybe you accidentally triggered the 'on' switch? Would the recirculating pump keep running until a hot water faucet was opened, or would it shut down after a set amount of time?

    I would hate to pay for all that gas just keeping it blasting away to keep the water hot, of course, though, you did say "high end "green" houses" and they would not be concerned about the cost of the gas as long as they are thinking they are 'saving water'.

    Kind of like some of the houses I used to inspect, they had their own standby generator, some 60 Kw and larger, and the amount of gas those things suck is frightening to most people. At 7 gallons per hour costing $3 per gallon times 24 hours equals $500 per day of operation, and you might not have power after a hurricane for (in some cases at those subdivisions they lost power for) 4 weeks, that's $15,000.

    Heck, other places lost power for that long too. Same thing with the winter storms which went through Kentucky and that area recently, no power for several weeks. Most we lost power for down in South Florida was 4 days, and that cost $500 for propane for our whole house generator.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  22. #22
    Bob Spermo's Avatar
    Bob Spermo Guest

    Default Re: Tankless WH

    Jerry,

    Damn good question! I did some research and still couldn't answer your question. I know that activating a faucet will turn the switch/pump off. Since the switch turns on the pump which starts the water circulating and then starts the water heater maybe after a set time if no hot water is demanded by a faucet it turns itself off! I now have to find the answer!


  23. #23
    Robin McCaslin's Avatar
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    Default Thankless Tankless WH

    After reading other interesting issues about the `Tank-Less Water Heater, it seems that if you don't -Have- to have one, then you don't need one. And, the best use for it would be for heating up a swimming pool, or a in a home heating scenario. Any closed loop system would be a pretty nice fit for it.


  24. #24
    Joshua Hardesty's Avatar
    Joshua Hardesty Guest

    Default Re: Tankless WH

    Quote Originally Posted by Jerry Peck View Post
    I've never seen a circulation pump on an on-demand type whole house water heater installation.
    Check these guys out:

    -:- Kyung Dong America -:-

    Click on their Products, and scroll down a bit. They have a tankless heater with a recirculation pump built in, and a very small "buffer tank" to dilute any hot/cold/hot stacking. I've never installed them, so I can't speak to their quality, but from an installer's standpoint it's great. Normally when I install a recirc on a whole-house tankless setup I need the tankless, the recirc pump, the aquastat, the storage tank, check valves, etc. etc.

    Last edited by Joshua Hardesty; 03-04-2009 at 04:28 PM.

  25. #25
    Robin McCaslin's Avatar
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    Default Re: Tankless WH

    Going to such lengths seems less than fruitful. Much like a Rubix Machine from the comic papers long ago.


  26. #26
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    Default Re: Tankless WH

    I'm convinced. I'm going with a conventional 50 gallon water heater. We may add a solar pre-heating system in the future. We've roughed in the lines to the roof, so it will be pretty easy to add later when cash flow or gas prices make it an easier decision.

    Jim Robinson
    New Mexico, USA

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