Review Of Tankless Water Heaters

Inside a Tankless Water Heater
Interior Of A Tankless Water Heater

Tankless water heaters have been used in Europe and Asia for 50 years, and they are gaining popularity in the US. Right now they represent about 8% of new sales in the US. Tankless heaters, also called on-demand, flash or instant water heaters, qualify for a $300 federal tax credit.

How efficient are tankless water heaters?

Tankless water heater are about 10%-20% more efficient than tanked heaters, depending on circumstances. The problem with tanks is that heat leaks out of the tank, and the heater has to constantly reheat the water, 24 hours a day.

Tankless water heaters are available in propane (LP), natural gas, or electric models. They come in a variety of sizes for different applications, such as a whole-house water heater, a hot water source for a remote bathroom or hot tub, or as a boiler to provide hot water for a home heating system. They can also be used as a booster for dishwashers, washing machines, and a solar or wood-fired domestic hot water system.

Woman Enjoying the Benefits Of A Point-Of-Use Water Heater
A Woman Using A Point-Of-Use Water Heater

Some statistics: Water heating accounts for 20%-25% of an average household’s annual energy use. The American Council for an Energy-Efficient Economy determined that total cost for a tankless water heaters is less than for standard water heaters over a 13-year period. The U.S. Department of Energy site states that you can save up to 30% of the energy you currently use with a tank heater. But the American Council for an Energy-Efficient Economy says to expect only a 10%-15% reduction in water heating energy used.

Gas-powered tankless water heaters are the most efficient, but are the most difficult to install and require venting.

Electric tankless water heaters are somewhat more efficient than tank electric heaters (about 8% more efficient), but are generally less efficient than gas-heated tank water heaters. Since electric tankless heaters are less powerful, their flow rates are generally limited to 1-3 GPM. Point-of-use electric heaters (see the WaiWela mini heaters below) are great for a remote faucet or bathroom where usage is minimal and the flow rate is small.

However, when comparing water heaters, a number of factors have to be weighed: the cost of installation, how hot you like your water, the number of people in your household, and the cost of gas and electricity in your area.

Let’s quickly review the advantages and disadvantages of tankless water heaters:


  • Uses less energy (eliminates heat loss in tanks and through pipes)
  • Continuous hot water (hot water doesn’t run out)
  • Long life-span (20 years versus 13 for a tank heater)
  • Compact size


  • Some tankless heaters have difficulty coping with large households
  • More expensive than tank water heaters
  • Owners may wait longer for hot water to arrive at a faucet (depending on installation)

With tankless water heaters, there is a short delay between the time when the water begins flowing and when the heater’s flow detector activates the heating elements or gas burner. In the case of continuous use applications (showers, baths, washing machine) this is not an issue. However, for intermittent use applications (for example when a hot water faucet is turned on and off repeatedly) this can result in periods of hot water, then some small amount of cold water as the heater activates, followed quickly by hot water again.

Installing a tankless system comes at an increased cost, particularly in retrofit applications. They tend to be particularly expensive in areas such as the US where they are not dominant, compared to the established tank design. If a storage water heater is being replaced with a tankless one, the size of the electrical wiring or gas pipeline may have to be increased to handle the load and the existing vent pipe may have to be replaced, possibly adding expense to the retrofit installation.

Here is a round-up of the best tankless water heaters:

Takagi T-K3 Tankless Water Heater

Takagi Tankless Water Heater

Takagi heaters were the first tankless water heaters available in North America, and they’ve been manufactured in Japan since 1946. Their current indoor model, the Takagi Flash T-K3  delivers 258 gallons per hour of hot water every hour.

It’s capable of handling water flows ranging from 0.5 – 7.0 gallons per minute, with heating capability of 11,000 to 199,000 BTU (the widest range on the market). It’s all controlled by a computer board and sensors checking for flow, temperature and demand.

The only complaints about Takagi heater we’ve seen are the same as those about tankless water heaters in general– that it takes a while for hot water to flow, and that flow rate is reduced when inlet water is cold, or when many people are using the hot water at once.

The Takagi Mobius model is capable of producing a rate of flow approaching 10 GPM, making it ideal for central water heating. You can link up to 20 Mobius units together using one main control system. Note that with most gas-supplied demand heaters, significant input BTU is required to ensure proper and safe operation

You can find Takagi heaters at Amazon and  Low Energy Systems.

Stiebel Eltron Tankless Water Heaters


The Stiebel Eltron company was established in Germany in 1924, and they’ve been selling their quality heaters in the US since 1980.

Like Takagi’s heaters, Stiebel Eltron’s gas or propane tankless water heaters are equipped with temperature sensors that continuously monitor the incoming and outgoing water temperatures, and the temperatures can be controlled to within one degree by using the digital controls provided.

Inside A Stiebel Eltron Tempra Tankless Water Heater

Stiebel Eltron heaters are warranted for three years, and sell for about $700-$800.

Stiebel Eltron heaters are available from Low Energy Systems and Amazon.

Paloma Tankless Water Heaters

Paloma On-Demand Water Heaters

Paloma began operation in 1911 in Japan, and they are a major gas appliance company in Japan. The Paloma Group also owns the US company Rheem.

Paloma makes large capacity heaters, which can serve large households and even small businesses. They work well in homes with low-pressure, or in homes where there no electrical power or intermittent power. For example, the Paloma 28c model is said to be able to serve “the needs of a small restaurant kitchen, a school shower facility, or a large National Guard training base”.

Paloma claims to have unique safety features built into their heaters. All of Paloma’s indoor tankless water heater models are equipped with a system to monitor and correct combustion conditions that could lead to carbon monoxide production. These models are also equipped with an Overheat Limiter Film Wrap designed to detect overheating all around the heat exchanger.

Paloma heaters are available from Low Energy Systems.

WaiWela Mini Instant Water Heaters

Waiwela Mini Tank Heaters

Waiwela heaters are made by Paloma. They are compact electric heaters which actually contain a small tank. These point-of-use heaters are usually installed under a sink. They plug into a regular 120V household electric socket, and provide instant hot water, thus saving water because you don’t wait for the hot water.

There are two models available: 2.5 gallon Waiwela, and 4 gallon Waiwela. Both are 110 VAC, UL approved, and they are warrantied for six years.

They are available from Low Energy Systems.

Solar Water Heating and Tankless Heaters

What would be the most efficient way of heating water? Using direct solar water heating, in combination with another renewable source such as wood and biomass (cleanly burnt), and biogas. Biogas can be used in a LP gas water heater, but it is not commonly available in the US.

Solar Water Heater

A solar water heater can reduce your hot water heating bill by 60 to 95 percent, potentially saving hundreds of dollars a year. However, upfront and installation costs can be high, anywhere from $1,500 to $5,000, although there are federal tax credits available.

A tankless heater will also work as a backup, as long as it is designed to accept hot-water input (not all of them are).

88 thoughts on “Review Of Tankless Water Heaters”

  1. The local natural gas company has sent a letter suggesting that we replace our 80 gallon electric heater with a Rinnai tankless unit. They are offering a $600 rebate and imply that I might be eligible for a tax credit of up to $1500. This all sounds attractive, but after reading the postings on this website I am becoming suspect that this might not be the time to leap into this plan. Our home is only 2 years old and my incentive is only to make it more green, but not at the price of some of the problems I have read about. Also, why would a gas company recommend a manufacturer with a poor customer service record. I plan to talk to the gas company about these issues, hear the “other side” and ask for references before making a final decision.

  2. We’re considering a tankless for a slightly different reason than most. We live in a condo in a city with extremely hard water. Our tank water heater and furnace are in a small utility closet on the 2nd floor. We would like to get a water softener, but there’s no room to put one. (No basement either).

    We were thinking of removing the tank water heater and putting in a tankless. We would then have room to put a water softener in, before the tankless heater. We realize we would have to run an additional vent through the roof.

    Comments? Thank you.

  3. I prefer Navien tankless water heaters over all other brands for two reasons. One the Navien is 98% efficient (the highest you can get on earth as of 11/09). Their units also have been engineered differently than others, and require only PVC for ventilation piping, which is very inexpensive. Where as other brand requires acid resident stainless steel ventilation piping which is extremely expensive. If any readers here need a estimate on a new tankless water heater installation my partner and I have installed dozens in Connecticut. check us out on URL Mr-WaterHeaters
    Best Regards-

    1. Nothing but problems with our Navien Tankless. Company has a problem with Public Relations. All work done by licensed plumbers. Which has cost a small fortune.

  4. I used to have a SETS, now I have the same model, redesigned by Hubbel, and couldn’t be happier. It is so good, I crank down the temperature so I don’t waste energy. I live in NC.
    I haven’t noticed a spike in my electricity bill, and I get constant hot water.
    Even I was about to go back into the tank heater road when I chanced upon this site and saw positive comments on the new Hubbel heater. Glad I did.

  5. Wow. The more I read about tankless, the less I want one. It seems like every single brand has an issue. Even the “reputable” ones. I am now reconsidering my desire to go tankless, and just buy the best tank model available….and be done with it! Maybe I will go down this tankless road again, when the technology is more developed and the companies that are worthwhile will still be around.

  6. Does anyone know if any legal action has been taken against the scam artists that sold me a faulty model 280 under the name of American Tankless (with a lifetime warranty) then closed up shop and opened American Heat, probably fleeced people there and now are operating as EcoSmart? DO NOT BUY FROM THEM.

  7. I have a leaking tank heater and am considering going tankless … one concern I have is that I am on a well … are there any issues with using tankless with a standard domestic well? The house is ~3000 sf w/ 4 bathrooms … there are 3 of us now, but my parents will be moving in soon … will tankless be able to keep up with demand?

  8. After 13 years my natural gas power vent 40 gallon water heater is leaking. so long old friend. never a problem, always hot water. consistent, reliable, trouble free. I considered shortly a tankless, but in my house i have enough to think about besides how to feather the control at the sink to save 15 dollars per year. The annual cost to heat my water is less than 225.00 I have 3 females living here and anything that keeps my life on an even keel would be worth 10 fold the monetary savings. and as far as being green there is not much difference in an he tank unit compared to a tankless .

  9. We installed an AquaStar gas tankless water heater 4 months ag0….so far, so good but have not seen any decrease in the amount of gas usage on my bill…we’re also concerned about the temperature of the water entering from the outside lines during winter…we live in northwest Indiana…would it help to have an indoor storage tank for water during the winter?

  10. I’ll recommend a SEISCO again. Mine’s still working fantastically, haven’t had a problem with it yet. I have the 28 kW version and I use a Bricor 1 gpm shower head. I believe they make a 32 kW version as well if you need more power. The only other thing I’d recommend is to have a bath tub faucet where you can regulate the flow of the hot water separately from the cold. In the deep of winter, it helps to slow the water down a little bit when running a bath so the water gets heated completely.

    If you are staying within Oregon, remember Oregon has the best incentives for solar in the whole country. Might be an option to think more closely about.

  11. I have a Bosch on-demand tankless, I’ve had it for almost five years and have never had a problem with it; I love it! Living in Oregon, it was the perfect solution, but it is natural gas, so I did have a bit of an increase in gas bill, but not much.

    I am moving now and looking at an electric as we are going out in the country and no gas around! Recommendations are much appreciated!

  12. I have had my Titan tankless water heater N-120 model in for 7 years and it was worked great. I am in Miami and it is good to see a home town company make it big. Also I was looking online and found that the titan was rated the top selling electric tankless water heater….Good work guys

  13. I have been using the Titan brand units and I highly recommend them to anyone. Not only are the small they are very powerful. I myself have the N-160 in my house and it works great even on my Jacuzzi. The company has 25 years of experience in building the units, why would you go anywhere else. Get one of these units you will not regret it.

    Bryan Tavarez
    General Contractor

  14. I’ve had a tankless (Takagi) for a few years, and the ONLY problem I have is that our energy-efficient dishwasher pulls water in at too low a rate, so the hot water doesn’t kick in. Thus, the dishwasher has to heat all that cool water up, causing a lot of strain on it (which it can’t handle – it’s a BOSCH). Solution, I run the water in the sink next to the dishwasher until it is hot, then I turn on the dishwasher and don’t turn off the sink until I hear that the dishwasher is pulling in water. It is far from perfect. And I would probably have to do this at the start of the rinse cycle, too, of course (which I don’t).

    and washing dishes with luke warm water does not do the job. The soaps are not designed for that.

    I may need to install a small instant-hot electric water heater under the kitchen sink to feed the dishwasher.

    I won’t buy a BOSCH dishwasher again. Parts are expensive and tough to obtain, and they break down quite a bit. But the hot water problem has also increased the service problems (because the panel for the on-board heater has burned out twice, likely due to overuse).

  15. Does anyone have any experience about the reliability of Richmond tankless water heaters? They are manufactured by Rheem. My wife and I are considering having one installed, but the more I’ve been reading about some of the problems people have had with tankless, I’m becoming less sure we’re doing the right thing.

    I’ve tried searching for reviews for the Richmond line of tankless heaters, but so far I’ve found very little.

    We’re having a local contractor do the install, and he recommended the Richmond brand because it was affordable. Price isn’t an issue with us, the number one thing we need is reliability. I checked with a Rinnai dealer, and what he said sounded good, but I just confirmed what someone else here posted earlier – Rinnai has had their standing revoked by the BBB due to consumer complaint issues! 🙁

    So, has anyone had experience with the Richmond brand? If not, is there something sold at the bigger home improvement stores such as Home Depot, etc that is known to be reliable?

    Any suggestions/input/advice is very welcome!! Thanks!

  16. I had a Bosch AE 125 electric tankless water heater installed October 2008, it is now June 12, 2009 and I have not had hot water for 48 hours now and can’t see having any until the 15th. On a mild June day in New England the unit began pouring water out, I shut off the breakers and called the plumber who installed the unit. Luckily he was able to come out a short time later because he arrived as the Bosch representative I had on the phone needed information, how many amps on the breakers, the gauge of the wire all the “important” leak causing information. The plumber said the leak was from a vertical crack in the heating exchange which has a 10 year warranty (not to mention this is all occurring under one year of the purchase). Unfortunately it was after 5pm so there was no tech support at Bosch so I was given a customer number and told to call back the following day. I did so while at work (lucky to have a job in this economy) but I was told to have the plumber come out and remove the top part of the heat exchange to check for “scaling” caused by hard water. I do not have a plumber in my family, nor do I have one “on call” so this would take another day or more so when I got home from work I called tech support again to get assistance so I can remove the part. This technician wanted to know why I was doing this so I explained the situation, he told me to e-mail him pictures of the crack that scaling should not have occurred in this time frame and with New England water not being very hard, and he would have the tech supervisor take a look and possibly get a replacement sent overnight the following day. No such luck, I come home to a voice mail telling me they need to have that part taken out and pictures of that sent. Even if I did have immediate access to a plumber everyone knows how expensive they are. I paid what to me as a single parent, a small fortune to have this installed less than 8 months ago. I had to pay for the initial emergency call to find out what was leaking. I am going to have to pay to have them come out and install a replacement unit (if the warranty is honored) or have them install a tank that I might have to go purchase this weekend. My intentions when I had this installed was to save energy and money by using less fuel on water sitting in a tank not being used. Warning to anyone contemplating a Bosch purchase the name may sound familiar but Google the item first and see what other consumers have experienced first before digging yourself into this hole I am finding myself in. I am doing that now and cannot believe how many people have experienced the same issues, shoddy product no wonder they put you through hoops before they even consider honoring a warranty. BUYER BEWARE!

  17. My Takagi has not worked correctly since new. I am the second owner; the first had the plumber to the house numerous times. Problem not solved. The water in the shower will go ice cold almost instantly. Stays cold for 30 seconds to 3 minutes and will do this 3-4 times during the shower. It is not pleasant. Yet Takagi has stated that this shouldn’t happen, the plumber stated it was connected properly….so I guess there’s nothing wrong with it. When it’s hot, it’s hot. The ice water is what I have a problem with.

  18. I read about all these problems with tankless water heaters and the companies, etc.

    Most of these companies were sold, the new owners in turn though they could handle the business, they made changes on the warranty, staff etc. and on the units themselves. They quickly learned that it takes knowledge of your product, not just money and advertisement. This was the case with SETS bought and closed 18 months later, supposedly HUBBEL has taken over , but they are worst than the last owner of SETS, JMorabito.

    Another company that comes is American Heat, going down same road, no knowledge of tankless water heaters, many of these companies are having the units manufactured under private label, they request design chnages without really knowing the effect of the changes and once done, the problems start.

    When considering buying a tankless call the company ask a lot of questions and make sure they know what they are talking about, so you do not end up dissapointed.

  19. We had the Rinnai R85 installed in a home we were having built in 2006. We stated to have problems in mid 2008, when the unit started to flash a code 12. This has been ongoing since then, and now, we have been out of hot water for a complete week. The plumber has dismantled ever part trying to solve the problem. Rinnai to date, refuses to replace the heater, and wants us to continue to pump more money into it (we’re up to ,500 now). After a review of the BBB yesterday, I see that the BBB has given them an F in their consumer ratings, and has revoked their accreditation as of March 25, 2009.
    I think it’s time to buy another brand and give up the ship.

  20. Hi there,
    Thanks for all your time and effort to provide an informative site for people like me.
    I’m renovating my home in Long Beach,NY and I’m trying to decide whether I should go Tankless or solar powered for water heating. it’s a two family home, my apt upstairs is 1300sq/ft. Estimates given so far are $3000 for tankless heaters only for one floor, or $9000 for solar (after rebates) for entire house with tankless backup. Any advice or ideas?
    Thanks very much.

  21. I have a Bosch 1600H natural gas tankless water heater. We have one full bath in our rowhouse. Since installing this heater, we have seen issues with the temperature of the output water being too hot. This unit has a hydro-ignition (no standing pilot), and requires a minimal amount of flow to start heating water. In our shower, the water coming out is usually VERY hot to start. Then when you adjust the shower faucet to a lower temp, the flow rate demanded for hot water drops below the minimum required to ignite the water heater.

    So what’s the result? We either have extremely hot water, or it’s ice cold. There is a very narrow band on the faucet that is cool enough to shower in and produces enough flow to ignite the water heater. This has been very frustrating for us.

    I have all of the settings on the unit set to produce the lowest temp output and also to allow for the minimum ignition flow rate. Our shower has an 8″ rain shower head.

    Has anyone else experienced this? Is there a solution, like installing a mixing valve to regulate the water heater output temp? Very frustrating, and potentially dangerous for children and guests staying with us.

  22. Cleo,

    you are correct about SETS and American tankless it is the same owner with his lifetime waranty and his new technology. Know they are back again with another unit and another “lifetime warranty” How long will people fall for it. The new one is ecosmart

  23. We’re considering replacing two older tank heaters with one tankless. Our bathrooms are on the far side of the house from the heaters. My concern is the heat of the water. I tend to take hot showers, and would be very unhappy if the water wasn’t hot enough. Can I adjust the heat on tankless as we can on the tank heaters so that the water is hot enough?

  24. In response to Walter Law:
    Is your tankless heater from American Heating? If it is, your key word may be “trouble.”
    In the Megaefficient archives (Archives Index>Heating>Electric Tankless Water Heaters) there is another article written by Justin, dated Sept 2006. At the bottom of the article are many letters from 2008 about a company called SETS; complaints about the poor quality of their tankless heaters, the operational problems, lack of service, and rating with BBB – an F. According to the letters, the SETS company suddenly went out of business last year; however, one of the letters includes a “heads up” message stating the SETS owner has apparently resurfaced and is operating as American Heating.
    You might find the letters an interesting read.
    ps – I have the Bosch AE125. My ground temp is less than 50 degrees, we have 2.5 baths and it works beautifully.

    1. Cleo,

      Thanks for the information. We purchased a SETS in 2001 and had nothing but problems. After we complained numerous times they finally gave a replacement – same problems. We’re still struggling with the replacement, and assumed it was due to the fact that it’s an electric tankless. We have been planning to bite the bullet and install a gas-fired unit, but it appears from the posts here that there are electric units that would work. That’s great news, as we spent a considerabl amount of money for the installation that we would save on a replacement.

  25. I just had an American Model AH26 electric tankless installed in a cabin. Can’t get it to work. Two electricians (installer and Second Opinion) both swear the unit is properly installed. When I press the buttons to set the heat, nothing happens. No “lights”, no nothing. Doesn’t seem to be getting electric power, but the three-wire 240V circuit breaker is according to specs.

    Anyone have any knowledge about trouble-shooting this model?

  26. Electric Tankless

    SEISCO is the only tankless that works in HARD water, its also the only one that works well with solar because it has no flow meter. It senses flow by a change in temperature. It also is the only true WHOLE HOUSE ELECTRIC TANKLESS. Other units like Steibel Eltron restrict the flow to maintain temperature. The SEISCO has huge chambers, doesn’t restrict flow and holds a gallon of hot water so there is no sandwich effect like gas. It is 99% efficient. Saves power AND water. It also has contact points so your electric company can turn it off during high demand. Check with your company, you can get big discounts for this sometimes. I called the company direct and they gave me a great deal and shipped it direct to me. Its so easy, I installed it myself. This thing uses off the shelf parts, so if you are handy you can service it yourself and they say it lasts for 20 years! Two showers going full blast and ENDLESS HOT WATER, just like they advertise

  27. I am about to purchase an electric tankless hot water heater. Gas is not an option as I would have to run a line to the house or buy/lease a huge tank, either way it is cost prohibitive. The house is 4000 sqft with 4 full bathrooms. Normally, only one shower is going at a time but on occasion two maybe running. Of course I have the usual other water users such as laundry and dishwasher. I don’t want to have to wait for hot water so I would like to know what people would suggest in my sitation. By the way, electricity is rather cheap here in San Antonio, TX and the climate is usually warm to hot except for a couple of months when it can get into the 40s to 50s. I am torn between a Seisco RA 32 or Seisco RA 28 and a Stiebel Tempra 24 or Stiebel Tempura 29. Can anyone advise me on the following:
    1: Which brand is more energy efficient? 2: Which controls water temp more evenly? 3: Which will raise water temp fastest? 4: Which will cost me less on my heating bill each month? 5: Can either brand/model work in tandum with an electric TANK water heater? 6: What water softener works best with which brand as our water here is harder than nails!
    Thanks – Keith

  28. Ditto on the posting, something’s wrong.

    I have a Bricor, I really like it. It suits my Seisco quite well. I wish I had put in the plumbing with two separate knobs so I could run the hot water slower when filling the tub. Still works great except in winter time when the water is just hot, not piping hot like I like it. My wife has no complaints whatsoever.

  29. I posted on 2/16 about problems with the Eemax EX190TC. It appears the unit can’t keep up with my 2.5 gpm shower head (or the 2.2 gpm kitchen sink) – the incoming water temp is just too cold. The plumber adjusted the flow on both, and it helped with the sink but he advised that I get a low flow showerhead for the shower. I bought a showerhead with variable gpm at the hardware store (from 0.5 to 2.5 gpm) so I could experiment and that seemed to do the trick. I enjoy my high pressure hot showers but the lower flow is not so bad, and I suspect if I get a fancy low flow like Bricor or something it’ll be better. I’m very happy with the new unit and the extra space it’s opened up in my tiny apartment, though it definitely takes some getting used to and developing new habits for water use. But now I’m saving electricity AND water (I hope), so it’s all good.

    Anyway, just wanted to post about the resolution to my problem in case anyone else stumbles on here with a similar issue.

  30. Hello,
    We just got a tankless installed. I can say really short it is the greatest thing I have ever had. With old one we were only were able to take one 5-8min shower, forget about filing the tub with hot water. We got Noritz 751 series. This thing is incredible, it has a remote control so that you can change the temperature and our installer explained to us if there is going to be any problems it will give us an error code. We did lot of research with which brand to go and we find out that Noritz was the best. Also when the installer came he reinsured us with the that info. The installer was good too, he was certified and had really good point about not installing recirculation pump we wanted. Also we moved the heater outside on the wall so it doesn’t use any space at all. If you need a good installer around the Los Angeles area you can try they are really good. And once again I recommend Noritz if you thinking tankless.
    Hope it helps. Be well

  31. I just had an electric tankless – Eemax EX190TC – installed on Friday and I’m having trouble with it. I get plenty of very hot water to the two sinks (one in the kitchen and one in the bathroom), but the hot water doesn’t last more than a minute or so in the shower. It then goes warm to cold, and nothing I do (short of turning it off/on again) brings back how water. I also think I smell something burning when I try to take a hot shower. (My apt is very small – I can pretty much see the tankless unit from my bathroom door.)

    I know electric tankless units can be problematic, but I also know it’s possible for them to work well – you just have to be patient and keep at it – so I’m hopeful this will all resolve itself (the plumber who installed the system is coming back tomorrow to check it out). However, does anyone have any experience with this model or this problem on another brand? I’m just trying to collect as much as info as possible so we can diagnose this properly tomorrow.

    For what it’s worth, I live alone in the washington DC area in a very small apartment with a standing shower only (no tub), so I figured a tankless unit would be perfect for me. (Gas was not an option.) I’ve read of others in this climate being happy with electric tankless (even read a positive review of the same Eemax model from a guy in Wisconsin), so again, I’m hoping I didn’t make a huge, expensive mistake opting for the tankless. All advice welcome. Thanks.

  32. Ah yes, like the above poster I installed a bosch model 2400OE exterior tankless gas heater on a house I built for my father in law. Despite the sensors, heat tape and the clear posting on the box and in the manual that said “freeze protected to 5 F” it froze and broke a plastic part at 20 degrees F one winter day. Bosch, with stunning disregard for the damage I can do by merely telling the facts of the story, flat refuses to honor their advertising claim and responds only that “our warranty expressly excludes freeze damage of any sort”. Then why use frees resistance as an advertising ploy? The small plastic part which broke costs $300, the heater costs $999 it will take a hell of a lot of gas saved to recoup the $1400. Bosch is scum, boycott all of their crappy products.

  33. I have a Seisco too. Love it.

    I’d prefer to have a solar setup with an air source heat pump water heater to top it off. Must have very efficient tank for it though. While my electric on demand heater will do 99% efficiency, a heat pump will do the equivalent of 300% or better. Beat that gas.

    That really is the problem with water heaters, the tanks are inefficient. The reason why I got the Seisco was that my old water heater (one whole inch of insulation) sprung a leak. Newer ones made of plastic with several inches of foam should do the trick. Especially when tied to a heat pump water heater and a solar setup. Throw in some hydronic heating to the whole system and we don’t need a separate heating system either.

    Oh, one last thing, you can get away with a small tank if you have a low flow shower head. I have a heat pump heater and air conditioner, electric range, electric water heater, electric dryer, and I still run about 73% of the electricity usage of the average home. It’s all about how you do it.

  34. I have a Seisco too. Love it.

    I’d prefer to have a solar setup with an air source heat pump water heater to top it off. Must have very efficient tank for it though. While my electric on demand heater will do 99% efficiency, a heat pump will do the equivalent of 300% or better. Beat that gas.

    That really is the problem with water heaters, the tanks are inefficient. The reason why I got the Seisco was that my old water heater (one whole inch of insulation) sprung a leak. Newer ones made of plastic with several inches of foam should do the trick. Especially when tied to a heat pump water heater and a solar setup. Throw in some hydronic heating to the whole system and we don’t need a separate heating system either.

    Oh, one last thing, you can get away with a small tank if you have a low flow shower head. I have a heat pump heater and air conditioner, electric range, electric water heater, electric dryer, and I still run about 73% of the electricity usage of the average home. It’s all about how you do it.

    1. waw! I like to know how to go with my house water heating needs.
      I live in Arizona USA and in the summer will have suficient solar power, but how to find ythe right system?

  35. Matt the tankless guy

    Of course there are electric units that will suffice for a dishwasher and shower at the same time but instead of using therms to heat the water which convert natural gas to actual flame energy your relying on wattage which will only convey heat through friction, in so many words. At this point its a matter of logic, when you rub your hands together it takes a lot more energy to heat them up than it does if you just take a lighter to them. Now if its a question of efficiency think of it this way when you wanna wash your hands at a half gallon a minute the amount of energy needed to do that is only about 6-11000 btus depending on how hot you want the hand wash to be and how cold the water is coming in. If you wanna take a shower and run the dishes and do a load of laundry your looking at 120000 btus roughly and flow sensor is what will determine the flame size and with constant flame you will keep constant temperature, not to say electric cannot do the same but the amount of energy you will need in comparison with each other is like comparing apples to oranges. The energy cost for electric tankless to keep a constant supply of tempered water is astronomical in comparison. If you think your not saving money going with gas tankless, you might as well throw your money out the window if you want to heat any kind of water. An example of this very situation would be like a gourmet chef using an electric range…….. wait a minute there are no gourmet chefs anywhere that use electric ranges…… thats why any restaurant you go to has all gas fired appliances, because there is much more cheap energy in natural gas and even propane than electric energy can even touch. Electricity, even though Benjamin Franklin discovered it over 200 years ago, is still harvested as efficiently as natural gas and you get 6-7 times more energy out of natural gas……. So in a nutshell never even think that an electric tankless water heater is going to be a better idea even if there is no way for you to get any type of gas supply to your property, you would be better off with cold water. Electricity sucks.

  36. Matt the tankless guy

    I have installed over three hundred tankless units for residential domestic hot water application in every brand there is. Noritz is the best brand of tankless or as the noritz people will call it briefcase water heater. they have units that will fit every application, and i even helped on the install at the Wynn resort in Las Vegas where they have no boilers no storage tanks just one wall with 24 noritz units on it and they can keep up with more than the demand…… were talking 500 rooms or more that never run out of hot water and is about 300% more efficient than the old boiler and storage tank routine. not to mention when the tank goes out you have to replace the whole water heater. with a tankless or briefcase whichever you call it the entire unit as a whole will never need to be replaced……. of course it is a machine and like all machines parts wear out but with noritz and goHot which another brand of briefcase every part is interchangable and can be taken out with a phillips head screw driver, so if you were so mechanically inclined yourself you can work on them with out a lot of technical mumbo jumbo. And if your worried about temperature rise in states like colorado which is where im from and where i’ve installed a majority of the units i’ve worked with that’s good your worried about that. Rinnai, Noritz, goHot, and Paloma would be the prime choices for areas with water coming in at 50 and below. Of course as long as you size it right any heater will work you just might be spending more in maintenance and installation for proper application and maximum efficiency. and for the super green home owner that is looking for the most efficient model Noritz and goHot are the only heaters right now that offer 93.3% efficiency. Any other questions feel free to email me

  37. The only drawback to a gas tankless is your gas supply (as I very sadly found out)…going from 30,000-50,000 BTU on a tank gas water heater to 180,000 BTU may require a big enough boost that its not cost effective.

    Heres my question–if I went electric, are there units that could supply enough flow for a shower and dishwasher to run at the same time? If I assume 2.5 gpm for any major appliance, I dont see how an electric tank would work for more than 1 appliance at a time.

    Any suggestions?

  38. I bought a house from the man that was the head of the electric department for a major US City and this is how he built the house for himself and 4 family members. The house had a solar water system with a huge, non-powered holding tank that usually had 125 – 170 degree water. This tank fed into an electric, 80 gal. water tank with a $5 timer that turned the electric heater on for 2 hours at 5am and then again at 5pm. It also had a small pump that sent the water continuously through the 2200 sq. ft. ranch home. I never had a problem with hot water or the electricity bill. So the electric only ran for 4 hours per day and a household of 3 always had hot water (two of us used a lot of hot water) though we were on a well and not city water, so we were green (took it out of the earth and returned it to the earth.

    I would like a gas fired tank that can turn on and off for only 4 hours per day just like the system I used to have, but do not know if one exists. Electric yes, gas no. Most people try to use less electricity but I don’t know how to get around using Tessla Electricity (he created A/C, not that scoundrel Edison).

    Sometimes old technology, used wisely is more efficient than new.

  39. I am interested in getting a tankless,but I don’t know which kind. I was told the LP tankless heaters do not have a long life and are a problem because of the LP. I also have solar electric for my whole house and would electric be better and less money? What should I do? My tank is on its last legs and I am running out of time. Please help.

  40. We have a solar boosted tankless (called continuous hot water system here) hot water system on our house in Melbourne Australia. They are standard on most new homes here.
    The Solar panel warms up water during the day which is stored in a conventional hot water tank (with no heaterelement). This then feeds the water heater, reducing the amount of energy required to produce hot water.
    Our house was specifically designed to have the hot water system equidistant from all hot water usage points – a massive energy saving.

    1. I live in Arizona, with very hot summers , when the water runs hot from the cold pipe line, Yet we do not have solar system to heat the water.
      I would like to get pictures of your solar system heating device, and how much did it cost you .

  41. Matt the Engineer

    That would just be a matter of sizing. There may be limitations on sizing electric heaters (mostly limited by your voltage and circuit amperage), but there are no real limitations on gas-fired water heaters.

  42. My concern is that where I live here in Colorado, the tap water is freezing cold, I would estimate less than 50 degrees. I’ve been worried that these won’t heat it enough to make a good shower.

    1. Matt the tankless guy

      hey matt?,
      i’m the tankless expert. i live in co. call me at 3035009087 and i can educate. or email me if your not comfortable

  43. Interesting that while North Americans are moving towards this technology (which I lived with as a teenager in France and now live with in my home in Costa Rica), much of the world is moving away from on-demand hot water heaters, especially electric ones.

    On-demand electric heaters are a nightmare for electricity suppliers because each one creates such a huge electrical draw, and if everyone decides to wake up and shower at 7am that’s a big spike in demand. Suppliers prefer level loads and slowly rising and falling loads. The only way for them to meet a sudden spike in demand is to anticipate it and build up generation capacity so they are producing enough when the spike hits.

    In Japan the government now gives out tax credits for people who install electrical storage hot water heaters. These heat the water overnight or at other times when the utility has excess capacity and electricity is cheap. With a really well insulated storage tank, this makes more sense than on-demand heating.

    I’ve heard that even natural-gas based on-demand heaters create problems for the gas company – again, if everyone turns on the shower at 7am, there could be a sudden drop in pressure in the utility company’s gas lines. But that sounds like a bit of a stretch.

    On the other hand, even the on-demand gas heaters have their pitfalls:
    – Friends of mine installed a Bosch unit – supposedly top of the line – and on a very cold Canadian winter day, cold air flowed down the exhaust vent and froze the heat exchanger solid. When the gas kicked in later that day as they turned on the hot water, the flames thawed the water in the frozen (and cracked) heat exchanger, and they had a flooded basement. They could not convince the company who sold them and installed the heater to take any responsibility for this. They’re back to a tank.
    – My sister installed a new heating system for her rad-heated home, where the boiler heats water both for the rads and for on-demand hot water. I have spent many an evening there dining with them and then helping with the dishes, and if you are the energy-conscious sort who likes to use as little hot water as possible to do dishes, you’ll find it quite a challenge with on demand hot water. After five years they are still not used to it, and are eager to go back to a tank. Also they have broken the system twice – once themselves, once their cleaning woman – because it is very sensitive to on/off/on/off actions such as one typically does when washing dishes or, say, rinsing a sponge while wiping sections of kitchen counter.

    Glad to hear some people have positive experiences. I certainly had no trouble with the one I used as a teenager. But there are downsides to them too – especially electrical ones – and I suspect most of us could accomplish more, in terms of saving energy on hot water, by switching to cold-water clothes washing, putting an insulating blanket around our hot water tank, lowering the tank temperature from 140F to 120F, putting pipe wrap such as Armaflex insulation around the hot water pipes, and just trying not to use as much hot water.

    Robin from Green Energy Efficient Homes

  44. Justin,

    Thanks for the information. I was wondering if I could couple one of these tankless heaters with a solar heater. But was not aware that there could be a problem with hot or warm water at the inlet. Supposedly, if this was the case, the tankless heater would not turn on its heating element or keep it energized for less time. Please comment on this.

    Also, I plan on installing POU smaller tankless heater. Near or under the bathroom lavatory & shower, under the kitchen sink and another near the washing machine. The solar heater would in turn supply the whole house providing preheating (at worst conditions) or already hot enough water.

    After all, we never use very hot water directly unless doing laundry or washing dishes. We mix it with cold water to obtain lukewarm water for comfort. So, I think a tankless water heater would suffice.

    Again, thanks for your excellent website.

  45. This all sounds great – I wish you had added a discussion about desupersaturators . This can only be used if you have geothermal heating – but you get free hot water all summer long and very inexpensive hot water in the winter. It basically uses the geothermal system to heat the water in winter and dumps the heat from the house into the water in the summer.

    Great savings! Well worth the cost if one is going to go with geothermal.


    I’ve got a Seisco electric and I wouldn’t go back to a tank or gas if you paid me. I pay about $8 a month for hot water. I can get, and do pay extra for, green power. Where your electricity is all coal fired, I would probably not go electric. But, anybody considering it shouldn’t be discouraged by what people say about performance on them. Size it right and it performs beautifully.

  47. For myself, I’m mainly interested in which is cheaper – as we all should be if the externalities are properly encoded into the price by taxes and whatnot. And I’ve noticed that so-called payback periods often don’t take account of the cost of the loss of use of the extra money in the meantime.

  48. great post. I have a Rinnai tankless water heater that also is connected through a heat exchanger to my hot water radiators in my 100 year old house, trading in an old furnace and a water heater for one little wall-hung unit.

    My dirty little secret is a 1500 watt tiny little electric hot water heater that my supplier insisted on installing because of that “short delay”- it provides a little kick of hot water when you just need a bit for washing hands etc.

    1. Lloyd,

      your solution of trading in a water heater and an old furnace with a tankless water heater sounds very good, but I am not sure how it works. Can you please give me more details about it?

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