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Tankless water heater for kitchen

LMM170
January 13, 2012

I am looking for a good tankless water heater for my kitchen area. Anyone have one they really like?

Comments (12)
  • CEFreeman

    I 2nd that, although I am looking for a recommendation on an electric one for my bathroom.

  • live_wire_oak

    Tankless are not the miracle solution to everything that the buzz would have them be. I've lived with one for 16 years, and while the technology has changed a bit, basic physics has not.

    If you want one merely for the 2.5 gallon output of the kitchen sink, then you need to figure out the coldest temperature that your incoming water starts at. Ours will raise 45 degree water by 60 degrees at 3 gallons per minute, and we live in the South, where winter water temperatures are not that cold. Tankless gas heaters use a LOT of gas all at once. Ours needed a 3/4" dedicated gas line to run it and that's usually standard across the board, but it will depend on your local utilities gas pressure and your pipe size. Some people need 1" or even 1 1/2". That means an all new dedicated gas line for it from the meter. It also meant about $600 in stainless steel venting materials in addition to the $600 heater. Our labor was free, and this was 16 years ago. The heater, black iron pipe, and stainless flue alone will approach 2K nowadays, and the labor to install a new gas line and flue, well, that's probably at least $800 in a cheap location. I don't even want to think about what it would be in a high labor market.

    You're talking 2K just to have hot water in your kitchen, and that's if you DIY. A small one like we have that can do 3-5 GPM (winter vs. summer) can actually do the whole house, as we do, but you have to make adjustments in how you use your hot water and only use it sequentially. You can run the DW after you take your shower or run the load of clothes. Not at the same time. There are models that have higher BTU capacity and can run multiple applications at the same time, but they will also come at a higher costs for both material and labor. The energy savings on a gas model run around 13%, so the payback period is very long and if you have to add labor into that, it will take 30 years before you see any real savings to just replacing a tanked heater. It's only in a new build situation where you do not have to retrofit that tankless makes any financial sense. Or if your utility is running some type of rebate to factor into the calculations.

    The electric tankless need a LOT of amperage in order to heat water. A tank unit uses a little bit of electricity over time to create that 110 degree water. A tankless uses a LOT of electricity at once to be able to get the same temperature rise. An electric unit that could take my same 45 degree water and give me 110 water at 2 GPM will need at least 120 amps to be able be installed. Modern homes have 200 amp services. Do the math. If you want to have hot water at the same time you have lights and run your refrigerator, you'll probably have to have an all new electrical service run to your home and a new panel installed. If you are OK with a trickle of lukewarm water, the small 60 amp ones that they jokingly sell for "point of use" will give you exactly that: no flow and not really hot water. They only really give warm water in warm areas of the country where the incoming water temperatures are in the 60's. And since modern electric tank heaters are 97-100% efficient, the paltry 1% gain in efficiency of tankless will NEVER be paid back, even to your children should they keep the house.

    For most people who aren't building new, the best solution for a short wait for hot water is better plumbing design. Locate the heater centrally to all usage points and avoid the daisy chain effect. Home runs with PEX are more efficient at delivering what is produced in a minimum of time. If you aren't replumbing your whole house though, redesign isn't a financial winner either.

    That leaves recirculating systems that use a pump (or gravity) to have hot water at a fixture always. They will cost you more in energy usage to be able to do this. And unless you live in an extremely water expensive location, the energy used to keep the hot water always at the faucet will far outstrip just running the taps and waiting on the cold to purge. You can put the systems on a motion detector, which helps with the energy usage, but if you have to pay labor to have these installed, you are right back at them being a cost prohibitive luxury for most.

    I will have to say, if we had to do it all over again, yes, we would install our tankless again. A thousand times over! We replaced a leaking tank in the attic that caused damage below it when it rusted out. (The overflow was blocked, so that safety measure didn't work.) It took us 3 days to put in the gas line and install the vent through the roof correctly and the new water piping for the new location of the heater, but it has been worth the effort for us. We can take endless showers if we so desire. Not two at once, but if I'm feeling yucky and want to steam it out, I can be in there for 40 minutes and when I'm done, I could still shower the entire Kitchen Forum one by one if needed. It's space saving compared to a tank. It's the size of a suitcase and hangs on the wall in the utility room and even has room for a cat box underneath. And it's still going strong 16 years later with only a single instance needed of the replacement for the pressure sensing diaphragm that induces the burners to light. We have never needed to clean the burners, but we have great water. (It's actually bottled to sell elsewhere.) If someone was on a well and had minerals in their water or pH problems, the maintenance would have been more involved.

    In other words, I do not recommend tankless as a point of use solution at all. I do recommend switching to a whole house tankless if you have the DIY ability and are a household where one of the smaller units can handle your needs after you do the math with your incoming water temperature and required flow. If you live far enough north that you need one of the really big BTU monsters just to get 3 gallons of flow, then it will not be worth it to you in any circumstances.

  • Linda

    Wow, thank you LWO. What a great explanation. That is another one of the decisions I have been wondering about. It's great to cross off at least ONE decision made (sticking with tank for our needs!)

  • babushka_cat

    because i had to remove a cabinet with a flue venting the old tank water heater during the kitchen remodel, i was forced to go tankless for my whole house. it sits in the sub-basement and is takagi. have been very satisfied. they are not cheap to install but was able to get it done while obama was handing out tax credits which helped. mine is gas, needed to run a dedicated 1" gas line for it. it takes a bit of time to get going but once it does, oodles of hot water! would recommend, very satisfied.

  • clinresga

    live_wire: fabulous post. Really gets to the heart of the issues with TWH. For even more concerns with them, see this site:

    Pros and cons of tankless

    They also have some really fascinating information on how to get a standard issue 6 or 9 year warrantied tank heater to survive for 20 years or more.

  • jscout

    Oh, I interpreted the OP as looking for a tankless instant hot water solution. Nevermind.

  • CEFreeman

    Nice.

    Electricity isn't an issue for me. I augment with 32 solar panels. I also have a solar water system that works beautifully. It's just getting the hot water 65 feet under the house to the shower and sink at the other end.

    Not sure what I want to do. I'm considering a marine hot water heater just there, because they're small and I don't use that much water.

    Another project.

  • MIssyV

    Okay, I can't help but post my own questions about this topic. I posted about it on the plumbing forum about a month ago and only got a snide comment :(

    For whatever reason, we do not get hot water to our kitchen sink. We are on a slab, so the idea of checking the water line is out of the question. We get hot water to every other location in our house, even the half bath that is the furthest distance from our hot water tank.

    We bought my grandparents home after they both passed, and grandma had a small little hot water tank under the kitchen sink. However that never got hot enough for my liking and found I ran out of hot water quickly. So we removed it a few months ago when re doing our kitchen. I always thought she put it in because it "took too long to get hot water" but am now finding its because "you can't get hot water to that sink." Ugh....regrets. So, now I too am wondering if we should put in a tankless hot water tank or re install the small one we had (which took up a lot of space under our sink). Talk about eating crow ...I hate to ask my hubby to re install that hot water tank!

    Not sure what qualifies as "expensive water" but our water bill is typically $90 a month...we are a family of 5

  • live_wire_oak

    A small electric tank heater will be under $200 and give you hot water, certainly not unlimited, but enough to wash hands and prime the DW. A small electric tankless heater will cost you about the same and give you only lukewarm water----IF your electrical panel can handle it. It will need more electrical power than a tanked model. Gas would not be an option unless you relocated it somewhere with more space and the possibility of ventilation. It would also be quite a bit more costly.

    A better solution would be to abandon the possibly damaged line in the slab and just run a new hot water line from the heater through attic down through the wall to the sink. That's a pretty simple job to do DIY and is often the solution to corroded and leaking pipes in slab. I would also be concerned about potential damage in other pipes in the slab, doubly so if they were copper. Copper only has a finite lifespan in copper, and if the water is bad, it can eat it away in as little as 8-10 years. My own home had it's copper pipes in slab replaced with PVC 20 years after it was built due to pinhole leaks in the copper.

  • LMM170

    Wow, thanks for the long informative post. Based on my calculations, and the other areas it will serve, I need a 100 amp unit. Anyone have a good brand to consider?

  • live_wire_oak

    Do you have any open breakers in your panel? What size is your panel? You did read that one that size would use about half of your home's electrical service, didn't you? A service that is mostly likely already dedicated to other home uses?

    A Rheem RTE 27 is available generally for around $700 and will get 45 degree winter water up to 115 with a flow rate of 2.6 gallons at that temperature rise. That is a single application usage. It will require 2 60 amp breakers in your panel, or 120 amps of a 200 amp panel and two brand new 6 gauge wire circuits run to it's location.

    The spec sheet is linked below, but they bury the important chart all the way at the bottom. What is important is temperature rise and GPM flow. THe RTE 27 is their top capacity model and the one they sell for "5 GPM whole house usage" even though it will barely do one faucet.

    The funny thing is, if you read the chart, the RTE 3 "single point of use" model that they tell you will work under a single sink to give you got water will only give you a 20 degree rise with 1 GPM usage. 65 degree water, and only a trickle of it is not my idea of being able to wash my hands with hot water. It wouldn't even be adequate for decent flow if you had solar hot water preheating the feed with 90 degree water.

    Even the next model up, the RTE 7, which they rate at 2.5 GPM will only give you a 20 degree rise if you are using a normal faucet. You have to shut the flow down to .5 GPM to get reasonably hot water.

    A small $200 tank heater will do the same job with much smaller electrical requirements, as will running a $150 recirculation pump from your existing heater.

    Here is a link that might be useful: Rheem Spec Sheet

  • DaveLinde

    We are starting a kitchen gut/remodel and considering a point-of-use electric tankless. I found this forum searching for info on brands and sizing and was surprised by the amount of negatives for on-demand heaters. We replaced our electric tank with a propane whole-house tankless and it is great. However the time to run the cold water out of the line to our kitchen sink is a nuisance so I was going to put a point of use unit there while all is open. I cannot easily get propane there but I can put in any reasonable size electric service.

    With the gripes about the smaller units only making tepid water I was wondering if it makes sense to cascade the point of use heater off the whole house heater? or does this risk scalding when the hotter water kicks in?

    Our whole house propane is a Rinnai and it has done well by us.

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