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Thread: tankless water heater...circulator

  1. #1

    Default tankless water heater...circulator

    hi..

    looking for opinions on wether a circulating system is necessary with tankless water system.

    bathroom would be two floors above heaters...prob 20 feet. and outside walls in nj.


    tks

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default heater

    The location of the heater, not its type, determines whether you could need a circulation system. The advantage of a tankless heater is that it can be installed near the point of use and thus give rapid temperature response. If the heater is going to be installed in the same location that a tank type would have been then if the tank type would have needed a circulator, then the tankless does also, except a tankless is a a bit more complicated and you have to follow the manufacturer's directions to install it.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    If not installed exactly per the instructions (and some probably don't allow it), the tankless would be running all the time the circulator was running, and your costs and wear and tear would be excessive.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4

    Default agree

    yes ive read the use of a recirculator vs an on demand system nearly voids ur warranty.

    is that "warm up" time it takes to get hot water from a tankless that much more than tank?

  5. #5
    DIY Member TheOak's Avatar
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    It really depends on the length and diameter of the piping. At a bare minimum you are it is probably safe to assume that it is going to take at least 10 seconds longer.

    Recirculation and instant hot water is definitely a convenience, at least in my books. How much is 10 seconds of water worth compared to the cost of recirculating your water to keep it warm? You are going to spend A LOT more trying to keep that water hot.

    Yes, it would be nice to save the water and the environment and all that stuff ... you just need to pick your poison

    Waste natural gas, or electrical or whatever you use to heat your water, resources to keep your water hot in recirculation, or waste water in waiting to get hot water ... again, you just need to pick your poison ...

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    SOmebody did a study and said that if you recirculate on demand (say with a timer or occupancy sensor or manually activated switch), use for up to two hours per day saves money verses the water and sewer costs for the waste. Used longer than that starts to cost money (but not a huge amount in a normal residential situation). I've got mine on a multiperiod timer - runs in the morning, then again in the evening, and most of the day during the weekends. the electrical use to run the pump is minor - I'd bet mine doesn't cost more than $0.25/month electricity to run, if that. If the pipes are insulated, the heat loss isn't that much either.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    DIY Member TheOak's Avatar
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    Here is a little calculator that can give you an idea of the purge times.

    Once you click on the link, then click on "Cold Water Purge".

  8. #8
    Master Plumber Redwood's Avatar
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    Another part of your post no one seems to be picking up on is the plumbing in an outside wall in NJ...

    That doesn't seem like to good an idea to me...

  9. #9
    Moderator & Master Plumber hj's Avatar
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    Default tankless

    The "warm up" time is exactly the same for a tank or tankless heater. It is a function of the piping, not the water heater.

  10. #10
    DIY Member TheOak's Avatar
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    Quote Originally Posted by hj View Post
    The "warm up" time is exactly the same for a tank or tankless heater. It is a function of the piping, not the water heater.
    It will take the tankless about 10 seconds to get the water up to temperature no?

    Where, the water in a tank will be up to temperature already.

    Therefore, the cold water in the pipes will need to be purged, plus the water that goes through the tankless (about 10 seconds worth) before the temperature is up to snuff.

    Or ... am I missing something?

  11. #11
    Master Plumber nhmaster's Avatar
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    There is talk of making recirc manditory. The reasoning has to do with the propagation of legionella bacteria. The new procedure will call for the water heater to be set above 140 degrees with a recirc pump, regardless of length of pipe run. Individual tempering valves will have to be installed within 18" of all fixtures requiring tempered water. This method insures that legionella bacterial can not hide in piping that has not been used for awhile and is allowed to stagnate. If and when this code ammendment gets ratified it will not only add considerably to the cost of piping a home, it will also put a bit of a crimp in the installation of tankless water heaters.

  12. #12
    Master Plumber Redwood's Avatar
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    It will probably do a number on PEX Homerun Systems as well.

  13. #13

    Default Tankless Hot Water Circulator Pumps

    Temtrol deltaT. Inc. recently released our tankless hot water circulator pumps. We expect to have additional researched compatibility info on our website in the near future which should answer most questions. Any questions we don't have answers for we'll research to find the answer and call you back. Our Tankless hot water optimizer series of hot water circulators are built for an easy install and are engineered with extra features that matter to those concerned with efficiency and comfort.

    These include:

    A relocateable water contacting stainless steel temp probe. On a closed loop install this allows strategic temperature probe installation at the last hot water usage point on the loop while the tankless hot water circulator pump can be installed where it's most convenient. Why waste energy heating the whole loop when you don't have too.

    The RJ11 phone jack on the control panel makes for easy multi-point-of-use pushbutton installs throughout the home using 5 to 1 phone connector available at most 99 cent stores. The RJ11 makes wiring simple by using a standard phone cord (again, available at 99 cent stores) and operates using any momentary contact switch or non-illuminating doorbell button to activate the system for a single-cycle, override or on an as-needed basis. When activated through the RJ11 port the system will run until the water in the hot water pipes equals the owners chosen temperature which they previously set on the control panel, then stop.

    For those seeking an even more sophisticated configuration, the Tankless hot water circulators can be sensor activated using occupancy, sound or motion.
    More info on this can be found at http://www.redytemp.com.

    Tankless water heater problems occur when unique requirements or limitations are not followed. Exceeding a specified flow rate can wear down a tankless water heaters internal piping as well as void a warranty of some models. Finding out the specific's for your particular model should take no more then a phone call to the manufacturer. Good manufacturers tend to welcome calls not just from potential customers but also from owners of their products.

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