Electric Tankless Water Heaters


Note: This post has been expanded and updated for 2009!

Tankless water heaters only heat water when it is needed. About 8% to 30% of the energy consumed by a standard water heater goes to keeping the water hot while it’s not being used. New tankless systems heat the water instantly when you turn on the faucet, rather than keeping a tank full of hot water 24/7 whether you’re using it or not. Tankless heaters run on either electricity or gas, just like regular heaters. They start out at about $300 for electric and $600 for gas.

There are two main brands of whole-house electric tankless water heaters: Stiebel Eltron and Powerstar. They come in various models, which are rated on the “gallons per minute” that they deliver.

The online store Low Energy Systems has a good selection of tankless water heaters, both electric and gas-powered. You can also find tankless water heaters reviewed on Amazon–this is one of the few places you’ll find reviews from owners themselves.

See more information about water heaters and electrical savings at Ask Mr. Electricity

153 thoughts on “Electric Tankless Water Heaters”

  1. I find out that Carlos Cabrera’s company is out of business again. There goes my warranty on my American tankless water heater. Anyone need one for parts

  2. Am looking at buying one tankless for my new double shower master bath and replacing the 50-gal tank unit (that has has trouble keeping up from day one) with a second tankless.
    I am considering either a Titan or Stiebel units.

    Has anyone had any experience with either ?
    What are your thoughts.

  3. I recently purchased two American Heat AH27’s 27kw tank less water heater. One of the units seems to work fine and when the temp is set at 140 it puts out a steady 123-124 degrees when there is not too much flow. The other unit is frustrating the crap out of me as a contractor. The output on the unit when set at 140 degrees it fluctuates from 104-11 degrees. I have wasted 12 hrs. trouble shooting this unit already. American Heat has worked with me, answered my calls and sent parts but they cant fix the problem. I replaced the input and output sensors and the circuit board and it still does the same thing at every tap. The next week I replaced the flow meter and it still doesn’t give a consistent temperature. Ive adjusted valves and water flow and now they are telling me that these heaters wont work with pressure sensing mix valve that are commonly used in showers and sinks throughout the country! The pressure sensing valves reduce hot water to the mix of water at the shower head when the water gets hot enough. This causes the output flow at the heater to decrease which in turn makes the flow switch turn off the element.

    How the heck can they claim these heaters wont work with these valves when over half the homes in the country use them???

    I am so frustrated with this company right now.

    Any help with this situation would be outstanding!

    1. John,
      We talked yesterday about upgrading the “Guts” of your American Tankless to Hubbell controls. Please call Hubbell at 203.378.2659 Ext.136. Ask for Sam Wellington. Based on my experience working on competitors products I feel we can help you. Thank you.

      Sam Wellington
      Technical Advisor
      Hubbell Electric Heater Co.
      PO Box 288
      Stratford, CT 06615-0288
      Tel 203-378-2659 x 136
      Fax 203-378-3593

  4. I’ve had a SETS 210-3 since 2004. Had some problems at the very beginning but the tech (David?) talked us through a wiring problem we had . Then it was hot-warm-hot-warm for a while. We lived with it until it started going from hot to cold and back to hot again. Another call to the tech (same guy) and he talked us through adjusting our well pump pressure switch settings to 60 pis and 80 psi. He also suggested we remove the flow restrictor on the shower head. Worked pretty good after that. We still have some fluctuations but nothing like before.

    Fast forward a few years and I “discovered” that the well manager system that we use had an adjustable pressure regulator. When I increased the pressure from 35 psi I didn’t adjust the pressure regulator. Once I adjusted it our temp fluctuations in the shower ceased. We still have some issue with temp flucs at the kitchen sink.

    I’ve had to remove the water heater a few times to flush it of hard water deposits. I’m thinking about purchasing the service valve kit but $200 seems like a lot a money for it. For now I’ll continue to pull it off the wall once in a while.

    I’ve been considering upgrading my heater. From what I’ve read here it seems to have really helped. I’m really excited that the upgrade includes an inlet water temp switch since I’ve been working on a solar hot water system that will provide water hot enough to use as-is. Without the inlet temp switch I think the old SETS will turn on and then sense an overheat condition and turn off. I think it’ll continue to do this until I’m done using the hot water. With the inlet temp switch it shouldn’t turn on at all if the incoming temp is high enough.

    After I do the upgrade I’ll let you know if I’m as happy as the rest of you that have gone with the Hubble. I expect I will.


  5. I like the compactness and energy efficiency of a Tankless Electric Water Heater. I was not happy with the performance of my old SETS unit, andwhen it failed I replaced it with a Hubbell. The Hubbell temperature controller has everything the SETS unit lacked. Using an input thermistor, it measures the temperature of incoming cold water. Rather than activation by a flow SWITCH, the Hubbedll has a flow METER, which constantly tells the processor how much water is passing through the unit. The processor then calculates the duty cycle of the heating elements necessary to heat the water to the selected temperature. If then samples the temperature of the outgoing hot water to make any necessary adjustments to keep the water at the selected temperature. Temperature selection couldn’t be easier. There is an UP button which raises the set temperature, and a DOWN button which lowers it. In case of a power interruption, the unit remembers what the set temperature was, and retains it when power is restored.
    The Hubbell Tankless provides everything a home owner can want. It is easy to install and use, and as long as it has water and power, it will deliver unlimited hot water at the selected temperature. For people on wells and pressure tanks, this product is ideal. Water temperature gain is directly affected by how fast the water flows over the heating elements. Flow normally increases and decreases as the well pump cycles on and of on well-and-pressure-tank systems. On simple flow switch activated units, this results in fluctuation of the water temperfature. The Hubbell’s flow meter solves this problem by feeding constant water flow information to the processor which continually adjusts the operation of the heating elements to keep the hot water temperature constant, even as the flow might fluctuate. I really don’t think it can get any better.

    I bought a SETS unit about 6 yrs. ago. It had a lifetime waurratee. Well, they went out of business and so did the waurrantee! Then they started a new company called American Tankless. I have one of these because they sent it to me as a waurrantee for the SETS. It worked for about 4 yrs., not too bad. But, American Tankless went out of business TOO! No waurrantee! The SAME GUY who started those 2 companies, now started a new company called EcoSmart. From the pictures, it looks like the same unit as the last 2! I called EcoSmart to see if they would help troubleshoot my heater. The lady who answers the phone would not connect me with Carlos. I know that he doesn’t have any legal obligations to help me, but thats bad public relations! I’m not saying the new unit is, or, is not any good, but, with the track record of this guy I would be reluctant to purchase anything that this guy is associated with. If you want to contact me, feel free!

    1. I was wondering about that. I’ve had an ‘American Tankless’ heater for four and a half years. It worked great for a year, then started acting really flaky, not turning on, or turning off mid-shower, etc. Seems to go through spells however now it seems like one of the elements has quit working and we’re ready to replace it. Found the ECOSmart on Amazon and was ready through it but then saw the picture and it looks 95% the same as the guts to the American Tankless I have. I’m not going to buy a unit through them, even though their pricing is much below the others, I’m sure there is a reason for that.

  7. I had a SETS for 8 years and it worked fine. It did take forever to heat up.

    As for Hubbel/SETS. Keep in mind that there are two departments, sales and the other tech support. The tech for SETS isvery short. If you don’t get it right first time, you’re out of luck. The sales, Sean, have been more helpful, but don’t expect miracles.

    What you need is the troubleshooting guide. I know, because they wouldn’t give me written instructions either, called, but it is posted on their website. Also, the tech just confused me with statements like, “The order doesn’t matter.” Followed by, “that one goes first.” The troubleshooting guide will walk you through connections, since you have to test them for the guide.

    Also, you can just buy the exact parts from several different electronic stores for half the price and if you know what you are doing even cheaper. It took me about week of research and comparisons, but I found my triacs for $1.90 each. SSG, not some generic. Same with the other components, with similar, if not so dramatic price drops.
    In the end I purchased a cheaper tankless since it seemed less of a hassle.

    1. Rigo, I also have had a SETS Model 240-3 for the past 8 yrs and only now experiencing problems. It appears that I need to replace one of the triacs however there are no markings on the parts in my unit. Can you please share your research (ie. part no.) on the $1.90 SSG triacs you found. Thank you. Peter

  8. We live in New Jersey where the winters are not severe. We have well water so during the winter the water temperature from the well can get down to 45 degress F. I started with an Envirotech tankless water heater. It worked great for 2 years and then stopped heating the water. The company was out of business by then. I then made the mistake of buying an American Heat unit and had nothing but problems for 3 years. I took a chance with a Hubbell model 280-3 this March 2010. So far the unit has performed as advertised. The temperature control has been flawless. Hubbell gave me a 10% credit for sending back the old American Heat unit. My advice to anyone is to buy the Hubbell unit. It has been upgraded and performs great. Hubbell also sells refurbished SETS and American Heat units for less money, but the person I spoke with in the technical group said they do not contain the upgraded parts that the Hubbell unit does. I can vouch for that. Every part in the Hubbell is an upgrade from the American Heat.

  9. Thanks for all the postings! Glad I’m not the only idiot with the SETS garbage. I have had a model 280 for years, and have dump hundreds back into it…most likely all I’ve saved and then some. It is leaking now. I was told the last time I talked to Hubbel, that they wouldn’t sell me the control unit to do the swap on my own. So if they maintain that position it is cheaper for me to buy a Stiebel. Now for the question:
    I have noticed recently that the water gets so hot and pressurized in the unit, that when the hot valve is closed (after open for some time), the pressure builds up so high, that it pushes extremely hot water backward (out of the cold inlet) into the filter 3 feet away from the heater. The copper gets too hot to touch and getting drips from the threading on the filter (melting plastic). Thought there was some kind of one way ball/check valve to prevent backflow. If I spend the extra dough to upgrade….again…am I wasting it? Most everything in there is new.
    Thanks for your input.

    1. In response to the SETS 280 post of September 7th, you may contact me directly (Sean) via telephone 877-649-8589 or via the web buytankless.com It would appear that your hot/cold issues are related to the highlimit engaging and resetting. Although we are not associated with the old SETS product we welcome your call to troubleshoot and offer some solutions.

    2. Our SETS unit model 220 came to my attention after working for 3 years without a problem by a loud BOOM and water leaking through an inside wall. The cold water feed 3/4 inch PEX plastic pipe 18 inches distant from the SETS unit had swelled under pressure and heat and burst, likely from the mechanism you described of the unit heating the water to steam and pushing it back through the cold water inlet. I heard the water boiling within the unit as I turned the water off.
      The plumber and I discussed how to prevent the backflow and we decided our first idea of putting a check valve at the cold water inlet would create a BOMB. Imagine if the 3/4 inch PEX wasn’t there to act as a pop-off as it did for us. PEX is rated to 180 degrees F and 100 psi. It could be a larger explosion, depending on the weakest point – ordinary annealed copper tubing may fail at 300-600 psi and 200 degrees F. More likely a coupling would open up sooner, but still I would strongly recommend against using check valves on SETS units or any other inline water heater.
      I am now looking for a way to replace my SETS units due to this tendency to boil water within the unit. After reading the discussion hear, I am going to try Hubbell.

      1. Frank,

        Sounds to me like yours was doing the same thing mine was before it died. I could hear the boiling water when no one was using water. My pipes did not burst, however; The steam found relief by blowing past the seals on the heating elements.

        Though I’ve not determined everything that has failed thus far, I have figured out that the “Flow Switch” magnetic trigger is hanging up in various positions and that one of the two reed switches (one to operate each board in mine) is stuck in the “on” position, causing the elements to be powered up when there is no water flow. This symptom can also be caused by a triac or board failure (which I may also have).

        I believe that the best failsafe plan for these or any other units is to install a pressure relief valve (just like a tank type unit has) in the water line on the output side and plumb its discharge into a drain somewhere.

  10. Quintin Kittle

    Tony, I know it sounds easy to do this job, but if you need instructions above what you can find on Hubbel’s website, then your not qualified to do this swap. No-one suggested to call Hubbell for instructions… they are paid big money to know what they know. All I say is, go to Hubbell for the parts. Their website has the literature for the old SETS and the new Hubbell. Study, Study, Study. By the way, I never changed my Limit Switches, mine work fine. Likewise on the Triacs, I did buy new ones but my old ones are still working great.
    Just remember one thing, if you yourself don’t understand the complete electrical theory on this controller, and why and how it should be done, it can KILL you. I have a degree in electronic maintenance, and years of experience with programmable logic; this isn’t for everyone.

  11. Does anyone have the assembly instructions and connection diagrams for steps 1-5? The tech at Hubbell didnt seem interested in providing that kind of information.

      1. I am wanting to upgrade a SETS 240. I called into Hubbell as indicated to get instructions on how to do the the steps shown in Sean’s post.
        1. Replacement of the control board and adding a digital display.
        2. Replacement of the L50 High Limit to the L60.
        3. Replacement of the Thermistor.
        4. Adding of 2nd Thermistor.
        5. Removing flow sensor/reed switch, Replacing with Flow Meter.

        The tech department wasnt exaltly willing to send the info.. they gave multiple excuses.. Looking at prior posts I have put together a probable parts list but cant confirm. I also do not have info on replacement of components and connecting them together.

        one TKD2000 (TKD2000) Digital Display $24.00
        one TK2000 (TK2000) Temp Controller $85.00
        one VTY10 (VTY10) Flow Meter $48.00
        two USP9509 (USP9509) Thermistor $19.00 ea
        one L60 (L60) Hi-Limit $26.00
        Total: $221.00

  12. Here at Hubbell we are committed to quality. So we do recommend when trying to upgrade your SETS unit to a Hubbell that you replace all the electronics and components. I can explain why:
    1. Replacement of the control board and adding a digital display. – This is necessary to run the new flow meter. The new display is alpha/numeric and will show set point, inlet/outlet temp along with any error codes.
    2. Replacement of the L50 High Limit to the L60. -The L50 high limits trip at 50°C and could cause nuisance tripping.
    3. Replacement of the Thermistor. – The SETS Thermistor is a 15% accuracy thermistor, A large error factor. Hubbell new Thermistors are accurate to +/- 2%.
    4. Adding of 2nd Thermistor. – This transforms a non-intelligent SETS unit that only reads outlet temp into an intelligent machine that could read inlet and outlet temperature.
    5. Removing flow sensor/reed switch, Replacing with Flow Meter. – Transforms machine from on/off operation to full staged modulation.
    6. Replacement of the Traics. – SETS Traics were hand soldered that often left them permanently heat damaged, shortened life cycle. Hubbell High quality traics are 40 amp spade connected traics with a large heat sink. This makes the traic run cooler and prolong the life of the component.
    7. Elements. – SETS used a copper water heater element. The high sheath temperatures in a tankless hot water made these elements susceptible to heat damage and corrosion. Hubbell tankless use’s a copper/incoloy element that better handles the high sheath temperature and has much better corrosion resistance.
    8. New style power block. – The SETS heater uses a long white 5 or 7 position power block. It was very common for this power block to overheat and melt. New Hubbell tankless uses a power distribution center that can handle up to (4) 1 OWT wires. (Does not come with referb unless specified)
    9. Replacement of all wiring. – SETS System used a variety of wire types through the years. Hubbell only uses quality THHN wire rated to 105°C.
    10. Modifications to Tankless cover. – Since your SETS heater doesn’t have a digital display we need to cut the cover and pop rivet an overlay.

    As always we welcome your calls to our technicians at the factory 877-649-8589

  13. Quintin ,

    What parts they tell you that you needed to get it to work? Do you have to replace the controller board to get the new flow switchn to work? If you triacs are working why did they recommend getting new ones? I am into this thing about 1200.00 now so if I could get it fixed for under 100.00 I would be willing to give it another try. It has not worked ever for more than a few seconds. Sets had it once which cost me $80 for the round trip ticket to Florida. Right before they were sold they sent me a new controller and new heating elements as the unit I received was not the unit I had ordered.


    1. The parts you need are outlined in my previous posts. The flow switch requires the new controller ..Yes. it tells everything you need to know as an electrician in what I wrote before. They recommend updrading the triacs because they need upgrading for reliabilities’ sake. Mine just happen to still be good yet, so I didn’t change them. If one burns out, I’ll swap out all three for the new spade type. The triac itself is sinked better, and the spade connectors are a hell of a lot more convenient than stiff soldered connections. I just didn’t want to pay $30.00+ for them when you can get them from the manufacturer for 1/3 the price. Just google the part# off the triac and you’ll find them. For what it’s worth, if you can’t figure out just what it is you need to do to upgrade everything, and how it all works, maybe you should find someone that is very good at electronics to help you.

  14. Quintin Kittle

    Dennis, talk to Sean as he requests. I just made the transition on my unit by buying the parts from him and doing the swap myself, and I should have done it a long time ago, it works awesome. No more cold water! I bought the triacs seperately but haven’t installed them yet. I wanted to try the new flow meter and see if it worked before taking out the old triacs and they work fine with the new controller. You will have to buy the new reed switches(temp sensors), they tell the new controller whatthe temp is coming and going. Ever since I made the swap my controller is set to 110degrees and the water is a constant 105 for as long as I need. The controller is programmable and I have ours set to alternately flash the preset H2O temp, and the actual output temp. That way I can see the temp rise to the limit as it’s heating,,,ya can’t beat it. I think the techs at Hubbel thought I was nuts for doing and suggesting this, but I explained to them that I’m a poor guy with 3 kids. I can’t afford to pay someone that kind of money when I’m smart enough to do the work. I’m sure there are others like me out there too. I told them that I would call if I had any issues with starting it up after bolting in the new control and they said they would help if they could, but it was not a problem. The controller bolts right up where the old one is, same bolt holes except for one and it’s predrilled also so no problems there. The new reed switches wire tie to the pipes at the incoming and outgoing connections, and the flow meter simply needs a sharkbite, (or gatorbite if you shop at Lowe’s) connector to screw into the H2O line.

    1. I now bought a Steibel eltron Tempra 24 and had electrician come and install another breaker 60 amp for the water heater. I already had a 70 amp breaker in the panel so left that one. I am once again having problems with the heater blowing the breaker. Do you think the 70 amp breaker with 60 amp is the problem? Or do you think the 70 amp breaker is bad? Really like the water heater but man we have spent so much money on heaters and electricians and plumbers this is getting ridiculous.HELP??

  15. I have had some interesting reading on this site. I have a titan SCR 3 N160 tankless water heater and I love how it heats water, but you get the shower running for about 5 minutes and the breaker cuts out. I have had an electrician come in and replace the 70 amp double pole breaker once and then the unit worked without problem for about 2 months now it is back at it again. Other than buying a different unit does anyone have any ideas on my issues.

    1. Quintin Kittle

      Have an electrician check the amperage draw of the unit for about 10 minutes at full heat. Then have him check the amperage rating for each circuit, one circuit may be bad, like a loose connection and such. If the unit checks good, go to a higher breaker, but only slightly, say….5-10 amps over what his test showed.

  16. In response to the SETS 220 post, you may contact the staff at Hubbell via telephone 877-649-8589 or via the web buytankless.com It would appear that your hot/cold issues could be related to the highlimit engaging and resetting. We welcome your call to troubleshhot

  17. Dennis LeBoeuf

    I own a sets 220 I have had for 10 years, I have the same hot – cold issue. How do I get in touch with the Hubble people and order parts for the flow control circuit board and triacs?

  18. We live in an 1850 sq ft apartment and are having a problem with the anode rods in our present hot water tanks causing “gunk” to build up around our filters creating low water pressure and long waiting time and not so hot water. At the moment we have (2) 20 gallon tanks due to space availability (we only need 2 person capacity)- Thinking of switching to a tankless system and wondering if anyone has any advice on where to begin. Our top of the line contractor has been unhelpful- initially replaced a “cartridge’ on our kitchen faucet for $850 dollars to fix our problem and now tells us it’s the anode rods – the replacement will be well over $3,000 due to placement etc. I think we are being ripped off?
    Looking for any advice!

    1. From everything I know,read,talked to, the top ones would be, Steibol Eltron, Hubbell and maybe Bosch. Stay away from EcoSmart! It’s a SETS and American Tankless in new sheet metal! Same people, same people, same service!

  19. I purchased a SETS Model 220 in November 2006 and experienced the same temperature fluxuations others have reported. In my case, I have a unique application where the water going into the tankless heater comes from a 40 gallon pre-heat tank. The water in the pre-heat tank is heated by a geothermal heat pump and varies in temperature between 45 degrees and 120 degrees, depending how much the heat pump has been running. I did extensive experimenting with the power level of the SETS heater, and the temperature of the water in the pre-heat tank, to determine which power level was “best” for a given input water temperature. I then had to adjust the power level of the SETS heater every couple of days, based on the temperature of the water in my pre-heat tank. All this resulted in barely tolerable showers.

    I actually thought the problem I was having with the oscillating hot water temperatures was caused by my unique setup, until I found this website and read all the other SETS owner’s similar stories. It made me feel better knowing I was not the only one who fell for SETS blatantly deceptive explanation of how their flow switch worked and how the system regulated the outgoing water temperature. Shame on SETS!

    Based on the positive feedback of SETS owners who upgraded to Hubbell, I decided to purchase a refurbished Model 220 in April 2009. I have deliberately waited until now to post my experience because I wanted to have a full 12 months of experience with my new system before commenting. I am happy to report that the heater works exactly as it should. I have the temperature set point set to 115 degrees, and when the incomming water is above this, the Hubbell unit does not overheat the water, but as the incoming water temperature drops, it kicks in to maintain the outgoing water at 115 degrees (+/- 3 degrees). I no longer have hot and cold showers, and no longer have to adjust the power level of the unit. I have had absolutely no problems with the Hubbell after 1 year of ownership. Congratulations to Hubbell for getting the control system working the way SETS should have.

    I want to thank all of those who previously posted the good experience they had upgrading to the Hubbell units. Without your positive comments, I would probably not have made the switch and would still be suffering with hot and cold showers. I also want to let anyone out there who might be considering using a Hubbell as an auxillary heater for either a solar or geothermal system, the Hubbell heater will works like it should.

    A Happy Badger

  20. For those of you who have a SETS unit and want to upgrade to a newer Hubbel, I suggest you do your homework first. Returning your $1000.00 unit to them and paying them another $800.00 for your unit back, with $200.00 worth of upgraded parts is ridiculous. Just call the tech, and tell him what you got, order the parts, and install them yourself. The Triacs can be bought online from the manufacturer, of which you’ll need three,for $13, not $30. The rest must come from them and the total you pay out is only $212.00, not $1800.00
    The difference in the units is not the hardware, but the control, and to switch from flow switch to flow meter control only requires a new flow meter and sensor, controlboard, digital readout, and the three upgraded triacs. Install these in the spots where you have the old control components in your old sets unit, and you’ve got a refurbished Hubbel unit!

    1. I have had a titan and would not recommend them…I have had the one(think its scr-2) that is 60 amp one breaker. It has two heating chambers….I have had 2 go bad on me…One where one of the heating elements burned out in on of the chambers; the other something happened to the control electronics..Would recommend Stiebel single power source…Can’t remeber model number but it’s the one that only requires one 60 amp breaker (240V)..

  21. I installed the Hubbell after years of frustration with the SETS unit. The Hubbell works as advertised! It works like you wished the SETS did. Since it knows the flow RATE, not an on and off switch (SETS), it accurately delivers just the amount of power needed for the temperature that YOU desire. The quality of the unit is apparent when you open the box and see the neatness of assembly. I plan on adding a solar heated hot water system (SunWard) before the Hubbell heater for the most efficient system and backup for sunless days. I will also be adding a recirculation system for instant hot water at the taps that is also sun powered. Both units (Hubbell and SunWard) will allow tax Credits, which is better than deductions. This set up makes everybody in the house happy since trying to train everyone to only “turn on” the hot water when needed is a fruitless effort unless they really understand how it all works. There is a huge waste of power when guests (and the untrainable) use the hot water for just hand washing, out of habit. and never getting the benefit of getting hot water due to the length of pipe from the heater even though their using the power. The combination of the three units keeps everybody happy.

    D Frank

    High Point, NC

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