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. I have a 25 year old Rheem 50 gallon electric water heater in my house and my wife keeps saying I should replace it. Normally I would say she right. But, I’m a plumber and in my 30 years experience I’ve found Rheem water heaters last longer than other brands. So, until it starts leaking I’m going to leave it alone. Rheem, best in my book.

  2. We live in the northern Piedmont/triangle of North Carolina and are considering a tankless water heater for our 2400 sq foot ranch style home. We need it for baths/showers and washing some linens. There are 3 of us in our home occasionally a 4th on weekends here and there. We are total electric.

  3. Till now the best value for money are the Titan tankless water heaters. I have been using them for years without a problem. I recently replaced one that was over 15 years. Can not top that

  4. We bought a paloma @ Home Depot a little over 2 yrs. ago. Nothing but trouble with this. Customer service really doesn’t want to know much. Blame myself for not doing a little more home work on this brand. Service man out here at least once every two months. Advise anyone who is thinking of buying this brand to talk with someone who has one.

  5. I live in florida, have a 80 gal electric hot water heater.. thinking of switching to a natural gas tankless.. have 2 kids (that take long showers) and spouse..
    any recomendations ?? (brand, size) etc… or should I go with another 80 gal. again ??

  6. We live in the northern Piedmont/triangle of North Carolina and are considering a tankless water heater for our 2400 sq foot ranch style home. We need it for baths/showers and washing some linens. There are 3 of us in our home occasionally a 4th on weekends here and there. We are total electric. Des anyone have a reccomendation for a particular brand. What is the difference between “point of use” and say 4 gpm tankless water heaters?

  7. Can a tankless heater be used for radiant heat in a three car garage (approx. 1200″ of 5/8 pex tubing) and if so what size would be recommended. The line is filled with anti-freeze so would be a closed system with return back to the tankless heater. Has anybody tried this sort of thing?

    1. Yes, but only certain electric ones. You’ll need one that senses the incoming water temperature and adjusts accordingly. I know SEISCO and Stiebel Eltron units operate that way.

      You probably also need a pressure reservoir.

      As far as the size, you’ll have to figure that out based on your heating demands. I’d imagine too big would be better than too small, the only thing you’d lose is purchase price.

  8. I live in a 2 story single family home. It is time now for me to replace my gas-fired water heater and I am still debating whether to buy a tankless one. I do not know much about this system. Can anyone please email me if it is feasible, economical, and efficient to replace the gas heater with a tankless heater. Would I have to do any retrofits? I would appreciate a quick response, ideally from someone in Souther California using tankless system.

  9. I have a 2 family home that will be fully rented. I am redoing the entire heating system without a chimney. Have placed radiant heating lines in the newly poured basement slab. Each unit, a 2 bedroms apt downstairs and 3 bedroom apt upstairs, will have their own separate meters for gas & electric.
    I am serious about placing solar on the roof. I am considering solar thermal to go into a heat exchanger that will then feed into each of the two apt’s separate tankless water heaters to provide an initial boost to the water temperature.
    Should the tankless units be gas or electric? I have read conflicting articles on the internet as to which is better to purchase. SEISCO has been mentioned as a good source for an electric tankless. Takagi and Noritz were mentioned on the tankless gas unit side. Can anyone clear up the confusion as to which way to go? Also, for the space heating, the downstairs apt will have radiant heat and upstairs water circulating within radiators. What units would be recommended to heat the water for the space heating and can the solar from the roof handle both the domestic hot water boost as well as the space heating boost at a reasonable installation cost that would be worthwhile?

  10. anybody in CA as dissatisfied with their Tankless performance?
    I hear there is a groundswell of unhappy people and a class action may be forming.
    I have the details if you want them.

  11. I have been reading about a new supposedly revolutionary microwave tankless hot water heater and am trying to learn if this would indeed be superior to the current tankless units on the market. Does anyone have any insight on this? Thanks in advance.

  12. Clarence, again, I’ll recommend SEISCO. I’ve my 28 kW unit for two years today and have not had a single problem with it. I live in a single family 1236 sq. ft. house with all the normal stuff (but with low flow fixtures.) I have never had a shower go cold, I’ve never been out of hot water, and I’ve never been happier with a water heater.

    For your home, a 28 kW should do with low flow fixtures since you don’t live in a cold winter area. I get quite a bit colder in the winter, so there’s a difference because the water is heated as it flows through and if it’s too cold at too high a flow rate, it won’t get as hot. If you want to play it safe or with higher flow fixtures, you might try the 32 kW, it will do a 40 degree rise at 5.5 gpm or 109 degree rise at 2 gpm. I recommend low flow fixtures, I have a fantastic Bricor .98 gpm shower head which I love. Remember, if you use more water, it takes more energy to heat it.

    You can check out my experience at

  13. My wife and I live in Southern California (lLos Angeles County) and are considering changing to a tankless and/or solar water heating system.

    Our home is a flat roof 1,100 sq. ft. single family residence facing north north. We require hot water for 2 full bathrooms, a kitchen w/dishwasher and a washer and drying.

    Please advise where I can get more information (in layman terms) regarding purchase and installation costs, size needed, a comparison of the two systems and just what would be involved in replacing the current approx 40 gal. tank water heater.

    I’ve perused the internet and am currently on technical information overload.

  14. I tried buying a Titan Tankless. Won’t ever make that mistake again. In less then a year, it was sent for repair three times.

    The first time, the flow switch stopped working after 1 week of use.

    The second time, it stopped heating water after three months.

    The third time, it still didn’t work right after I got it back.

    After I got it back after the third time, it still doesn’t work. Now I have a 40 gallon tank water heater and I don’t have any problems.

  15. Stay clear of Niagara Industries (Titan Tankless Water Heaters). I bought one from them less than a year ago. It has failed four times since then. The first was within a week. The second time it lasted almost three months. After that, it was dead on arrival. They stand by their warranty so long as you don’t want your money back because it doesn’t work and they’re nothing actually wrong with it.

  16. I had a Bosch 2400E it started having problems 2 months after the instalation. I was told to hire a gas technition to fix it, but no one within a hundred miles or more of my house would even touch the thing. So I have a 1500.00 wall hanging in the basement right next to my new 40 gallon hot water heater. If your going to spend the money make sure you can get it fixed.

  17. Can someone please give me some info on a “ecosmart” water heater? I do not know anything about tankless water heaters, bu their price is very inviting and their warranty is very impressive. The features seem nice. I talked to representative today and they tell me they have been building this system for 18yrs. This is for my camp, and will prob be there about 50-80 days a year. Any input is greatly appreciated.

    1. I’d stray away from Ecosmart. While their reviews on Amazon are good, the company has only been around a few years. Before Ecosmart they were ‘American Tankless’, and before that they were ‘SETS Systems’. They offered lifetime warranties with the American Tankless brand as well, but a year after I bought the unit the company dissolved, screwing all warranty holders. I will be surprised if they don’t do the same with Ecosmart. Sounds like they’re in the business of undercutting the other companies with mediocre units and jumping ship. While the units may work well for a few years they don’t seem to be built to last.

  18. I am in the process of planning/building on the SE coast of North Carolina. I am considering designing in a hybrid tank/tankless system with a small high efficiency storage tank (6-12 gallons) being fed by a tankless unit. The tankless unit would only be turned on at high usage times. This would temper the water temp, eliminate cold water sandwiches, and provide some hot water even during a power failure.

    Alternatively, a thermostatically controlled tankless could be installed downstream from the small tank and would only kick-in when the small tank ran out of hot water–or as a booster (keeping the smaller tank at a minimum temp, providing consistency for the input temp on the tankless and possibly allowing for a smaller tankless).

    Has anyone tried any of these hybrid tank/tankless solutions? Am I killing the efficiencies for the sake of more consistent hot water?

    1. Scott, the answer to your last question is yes.

      For the price you’ll be spending, there is virtually no benefit to your proposed system. Firstly, if you put the tankless before the tank, you’ll be heating the tank water needlessly before it gets heated by the tank. It would make much more sense to put the tankless after the tank so when the tank runs out, the tankless would kick in to finish the job. To do this, you’d need an electric tankless with the top off capability such as a SEISCO.

      But finally, what’s the point of adding a tank anyway? No matter the tank’s efficiency, it’s still a fair shake less efficient than the tankless and that’s the prime reason for getting a tankless in the first place.

      Your only benefit would be the power failure scenario, but only if you plan on taking a shower very soon after the power goes out as all tanks lose heat, and only if you take 1-2 minute showers with that size tank. Since it sounds like you have an electric setup, just go with an electric tankless of sufficient size and consider upgrading to low flow shower heads, the real kind like Bricor (can vouch, good stuff) not the 2.5 gpm nonsense that they sell in home improvement stores. I’ve had a SEISCO 28 kW unit for almost two years now and am very happy with it. It is coupled with a Bricor .98 gpm shower head and I can heat water from freezing to scalding forever.

      1. Based on the descpription and not directly said is “Scott” wants to have “Instant” hot water, incorporate a recirculation system, and have no cold water “slugs” with endless hot water. He is lookng for comfort.

        The majority of efficency ratings I see on Tankless systems horn blow “No Loss” because they are eliminating the recirculation system and tank loss. Though this may be good selling point on efficency, it does nothing for comfort.

        Scott, there is no balance between comfort and efficency. So for comfort, put the small tank infront of the “Tankless”. Set your circulator to just less than the flow switch GPM setpoint on the tankless and the temp for the tank type 10 degress less than the tankless delivery setpoint. This will not increase your overall efficency due to maintaining the circulation system, but you will be able to benifit from all the other aspects of a tankless system, longer life, endless hot water, generation efficency, elimination of sandwiches and wait times. Lastly, since it will be a new house, if you properly design your piping system, insulate properly, purchase a 92% plus gas instant heater you will have the best of both worlds. The most efficent system to deliver the comfort you want.

  19. connie c.:

    Consider using a nuvoH2O water softener as I am and keeping your tank water heater. After reading these reviews, I am sticking with my tank–for now. But, my softener has crapped out after 9 years (Culligan) so I was looking at a non-salt replacement and thought why not reduce the size of the water heater, too. I still have to find some decent reviews for the nuco, though.

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