NORITZ Tankless Heater--water temp fluctuation

Discussion in 'Tankless Water Heater Forum' started by shall, Feb 13, 2008.

  1. shall

    shall New Member

    Messages:
    16
    Location:
    Sacramento
    NORITZ N069M TANKLESS Natural GAS WATER HEATER

    We installed a NORITZ IN March of 2007. We have had water temp fluctuation ever since. We have had several opinions on cause of problem to no satisfaction. First we reran 3/4 line direct to gas supply about 5'. Second we contacted PGE and they resized the meter upward to 630 btu which is almost twice the size needed. I contacted NORITZ and went through the test procedure and all results were well withing operating ranges for supply and demand of water including outlet temperature. The flow through the heater during shower use was registering 1.5 gpm so have plenty of capacity. The temperature rise is from 58 to 120 degrees. A 60 degree spread and the heater should provide 5.5 gpm at that level.

    The water pressure at the residence shutoff is about 60 to 70 during the day and does fluctuate a little within that range. At night the pressure has registered as much as 80 to 85 on the "WATTS'" Regulator Test Guage.

    The NORITZ people felt that the problem was likely in our plumbing --like the MIXET valve in the shower. If the shower is in use the temp fluctuates slightly. If water is used any other location a dramatic change occurs. Not very pleasant.

    I was about ready to remove the NORITZ and install a storage water heater to resolve the problem. Seems like a step backward so am looking for ideas.

    The MIXET shower valve is a mechanical setting so don't see how that could be changing hot water flow. The only thing that I see is the input pressure change but no one seems to click on that.

    Stan
    Last edited: Feb 13, 2008
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    A tankless system may or may not have a modulating burner - some do, some don't. If it does have one, it takes it a little time to adjust (not much, but it does), if it doesn't, then the temperature of the outlet will change, sometimes radically, when the volume through it changes. Think about a pan of water on the stove. Put an 1/8-cup in the pan and let it sit for a minute on a hot pan, it may be boiling. Now, redo it and put in a quart of water. After a minute, it will be hotter, but no way as much.

    In the shower, you might be much happier changing the shower control valve to a temperature controlled one. But, even those can take up to a second to follow the and respond to the change in water temperature.

    I think what's happening, is any use of hot water elsewhere is not being responded to quick enough by the tankless system, and the temperature of the shower drops because the temperature of the hot water drops.

    Some tankless systems are better than others. They work best as single use devices, some are okay for multipoint use.
  3. fidodie

    fidodie New Member

    Messages:
    94
    Location:
    new jersey
    are you on well water?

    i have a cute two temperature reading thermometer which i have hooked to the input and output of my tankless - and i can see the output shift with input temps - i have a well, so the expansion tank is "colder" than the well water - the well cycles, and i get temperature cycles.

    i think it is an azel unit - runs on a battery.
    i also have a fluke dual probe thermometer (about $100) which i could do the same with.

    both temp gages attach to the pipe with foil tape, so there is a delay, and buffering effect, but it is obvious that input effects output. the fluke is fast sample, the azel is slow.

    if you have a unit that is supposed to create constant temp output, and you are feeding the input water temp in their "temp range" and "flow rate", then it is their unit...
    Last edited: Feb 13, 2008
  4. shall

    shall New Member

    Messages:
    16
    Location:
    Sacramento
    NORITZ Tankless

    The NORITZ system has an internal temperature monitoring setup that can be accessed with the control panel. When we went through the check program we could see that the water temp at the input was 58 degree steady. The output also remained constant within a few tenths. So at least the check system sez it is operating oK. Will re-test and watch output temp while changing demand at two or three faucets.

    The local water supply is from wells and stored above ground. The delivery system is all underground for quite a distance. Could the pressure fluctuation at the input cause the output temp to vary? Would the addition of a pressure regulator be a reasonable thing to do? Where would a pressure regulator be installed and what does one look like?

    Do I just have to accept this water heater as a marginal single use device? NORITZ continues to say that the unit is sized properly and will supply two or more showers or appliances.

    Thank you for the thoughts about monitoring the input and output temp simultaneously.

    Stan
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    You'll need to try the varying load and see what happens. Note, until you test, you won't know how fast the temperature readouts will respond. What does the spec sheet say for response to a varying load? It's hard to get either an electrical or gas valve to modulate very quickly - there is likely some hysterisis built in which will slow the response.

    A thermostatic shower valve typically responds in 1-second or less timeframes, and might be able to track the variations faster. I don't get big ones at home, but used the same valve in a hotel. The temperature stayed the same, but it also compensated by pressure changes by decreasing the flow; IOW, it used both pressure balance and thermostatic controls to ensure a consistant temperature.

    Someone turning on another hot water tap might not change the pressure enough, so the pressure balance function wouldn't adjust to keep the balance between hot and cold, but as the device lags in adjusting the hot water at the source, you notice it.

    If the sensors at the tankless unit are covered with mineral deposits, they won't respond as quickly as they should. Your system may need a good de-liming.
  6. gmt

    gmt New Member

    Messages:
    26
    Location:
    Pennsylvania
    I assume that you can check on the output temperature at the Noritz. Have you tried flowing water at normal use and when the problem occurs check the output temperature.

    I am not sure about Noritz, but on Rinnai's we can get the outgoing temperature from the control pad.

    If the output temp is at the desired temp. then the problem is most likely with the plumbing.

    Are there any roughed in valves in the house that are not trimmed out? I've found that before, causing a cross connection between hot and cold. And that issue was occasional.

    Just a thought.
  7. pressure flux in system.....

    This might sound stupid, but here goes....

    Occsionally we get water mixing at the laundry outlets....

    Now that you have installed this new system their might
    be something mixing and fluxing at the washing machine...

    WHO KNOWS WHY, it just t happens.....


    try a very simple test and turn of f the hot and cold going to the laundry
    and then take a shower and see what happens......


    if that dont work,
    you might want to change out that crummey Mixit valve
    and install a good 1700 delta.....
  8. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    Have you asked Noritz to send out a service tech? Did you install it yourself, or did you have a licensed plumbing contractor do it? If the latter, have him go through the diagnostic procedure GMT recommends. It does sound like a cross connection, but checking the output temp at the heater would at least answer whether or not the problem is the heater.
  9. shall

    shall New Member

    Messages:
    16
    Location:
    Sacramento
    NORITZ TANKLESS temp flucuation

    Well--Sure have some ideas and things to check now. I will be busy setting up some tests and checking temps and flow.

    I did install this heater myself but with the advise and consent of a licensed contractor who has installed quite a few systems and has resolved problems encountered.

    Consensus at this point in time is that the Noritz is working properly and that there must be mixing taking place somewhere. Still wondering about the water pressure flucuation at the input. So will check this all out as best I can. Thank you much for the suggestions. Will let you know resolution.

    Stan
  10. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    If you have pressure fluctuations, check the filter at the cold inlet of the tankless unit. It may be partially clogged.
  11. shall

    shall New Member

    Messages:
    16
    Location:
    Sacramento
    NORITZ Tankless temp fluctuations

    Well----did a lot of testing and other work over the 3 day weekend. Replaced the cartridge in the MIXET and tried a new shower head in the 2nd shoower. I find the 2nd shower works better than the MIXET one so there has to be some undesired temp variations from the MIXET. Alst feel that the water temp seems to follow the inlet pressure variations so the MIXET is more sensitive to that too. The suggestion to set at lower temp on the heater and use more volume also seems to help some. Seems that every thing we touch has impacts on the water temps so everything has to be perfect for the system to be static.

    I looked at the Takagi specs and they are much the same as the Noritz. So if the Takagi seems to be static and works ok for a 2 1/2 bath home then we should be able to make this work. Replacing the MiXET valve is a major project but may be something that we have to consider. Did not anticipate tearing out the wall to get at the plumbing.

    Thank you all for the suggestions and thoughtful replies.

    Stan
  12. Tankless perks

    Shall, learning everything about your plumbing system

    is one of the side benefits of a tankless water heater....

    having to totally "fine tune" the house to accomidate
    the tankless heater and eventually getting to tear
    out that MIXIT faucet is like a perk...

    look at all the "invaluable experience" you got ..



    I honestly hope that you dont have to get into fooling
    with that Mixit valve and everything settles down for you....
  13. shall

    shall New Member

    Messages:
    16
    Location:
    Sacramento
    Noritz Tankless temp fluctuation.

    Yes I have learned a lot since I started this project. Little did I know how complex plumbing could be. A storage tank evidentally covers up a lot of possible sins in piping, sizing and fixture selection. Fine tuning is the understatement of the day. I will replace the Mixet valve soon. Will go ahead with the bathroom re-do a little sooner than originally scheduled. Looks like about 15 years sinc the last time so will look at a few estimates.

    Will also have the whole system evaluated again at that time.

    Thank you all for your patience and indulgence, Stan:)
  14. smokey9015

    smokey9015 New Member

    Messages:
    1
    Location:
    Illinois
    anyone know how to put Noritz in to diagnostic/test mode?
  15. icemaniceman1111

    icemaniceman1111 New Member

    Messages:
    1
    Location:
    Massachusetts
    strange smell and taste from new noritz

    I am getting a strange smell and taste from a new noritz 931 DV

    A distinct smell of concrete dust/metallic mix

    Upon rinse of mouth with warm water, an odd taste and astringent feel to teeth and gum, almost like a weak acid.

    Anyone else having this problem?

    Noritz denies every having heard of this and so does my plumber and supplier.

    Suggestion from supplier, run it for a week or two and then if we still have it they will send a rep out.

    any thoughts?

    thanks

    david in mass.
  16. gregsauls

    gregsauls Homeowner

    Messages:
    56
    Location:
    Texas
    We have two Delta 1700 valves and a Rinnai tankless with no problems regarding desired water temps. We never notice items such as washing machine or dishwasher filling up when in the shower.
  17. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    The tearing it out and putting a tank type heater back in would definatly solve all of the problems once in for all. Fluctuating water pressure and temperatures, Pressure Balance valves that are not quite up to snuff. Water piping that may be undersized or long runs, fluctuating gas pressures and suspect water conditions are all things that can and do cause tankless heaters to give less than advertized results. But hey, it does save 4.4% annually. :rolleyes:
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    Whenever you do some soldering, you use some flux. If you are a little overgenerous with it, you'll have some inside the pipes and it can take awhile to rinse it all out. Flux doesn't taste too good. Also, the insides of the WH should have been clean, but there's no guarantee that it didn't have some contaminants inside...again, it may take some flow to flush it out.

    You could turn it off, then let a hot tap run for an hour or so...no need to heat all that water. See if that makes any difference.
  19. Salty Marsh

    Salty Marsh New Member

    Messages:
    1
    Location:
    Alabama
    I just had a Noritz installed a couple of days ago and today, I innocently typed in fluctuations in water temperatures....and poofs...the first Google result is...here! The Noritz Tankless forum. Wow! I mean, ouch.
    Sigh.
    Hey, after reading thru about 127 posts with EXCELLENT information, I find yours. I gotta say, your reply passes the smell and taste test. Short, wisdomful, and to the point. Copious here here's to you and everyone else here for the great info. I can't say I feel better about the subject, but I'm a lot smarter! Also resigned. I will place a note in a sealed bottle and shove it up that Noritz unit for the people of the future to find with my recommendation to replace the faulty Noritz with a tankful water heater. Yes! Or maybe, in 10-20 years, el yesso!
    Tanks from Salty Marsh




  20. dcpete816

    dcpete816 New Member

    Messages:
    20
    Location:
    San Francisco
    That seems a little unfair. I have a Noritz tankless and it works flawlessly. I've had it for less than a year now. It replaced a 50 gallon tank water heater that also worked just fine. I have no regrets at all. I haven't noticed any temperature fluctuations, but I haven't done any scientific analysis on it. I have city water, no well.

    For me, the tankless made my entire bathroom remodel possible. I was able to get rid of the hot water heater closet and reclaim the space for the bathroom project. I installed an exterior Noritz tankless unit and couldn't be happier. If I have a plumbing problem with the unit, water will leak outside the house rather than inside the house. Plus, I am not using any space in the house to heat water. I live in California, so I'm not really concerned with pipes freezing (although they are insulated anyway).

    I did read the original poster installed a 3/4" gas line, but it was for a short distance. That may be ok, but it was definately not ok for me. I ran a dedicated 1" gas line from the meter to the tankless unit. But the distance is to the other side of the house. I didn't need to upgrade my meter.

    I love my Tankless Norwitz, thank you very much!

    Chris
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