Losing my mind w/ Noritz tankless

Discussion in 'Tankless Water Heater Forum' started by Ricker, Apr 3, 2017.

  1. Ricker

    Ricker New Member

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    Replaced a 14 year old 75 gal hot-water heater about 6 weeks ago. We decided to go tankless. Did a bunch of research and landed on Noritz. Found a local 5-star recommended installer on Noritz website, got his quote, and went for it.

    Ever since the very first day it was installed, we've heard our pipes bumping and thumping at pretty much all hours of the day and NIGHT (omg, the night). The pattern is very irregular. You might hear nothing for 5 minutes and then 3 thumps in a minute. It's a fairly muted thump but it might as well be a sledgehammer after 10 pm when the house is dead quiet. I've heard real "water hammer" before this is not as bad.

    My installer has insisted that I have crossover in my hot/cold pipes and this has the Noritz unit in a frenzy trying to keep up with the fluctuations in temperature. I've replaced all 5 single handle shower cartridges and isolated the crossover problem to the kitchen sink. I turned off the water supply below the kitchen sink a few nights ago...which meant, "no crossover anywhere in the house". Still, the thumping persisted. So much for that theory (at least, in my opinion).

    This weekend, I got the Noritz manual out and figured out how to disable the recirculation function altogether (and disabled it). Guess what? Silence, wonderful silence. The bad news is that we have to wait 10 minutes for a hot shower (completely unacceptable waste!!).

    My installer basically refuses to believe that the problem is due to the Noritz unit. As if they're infallible or something. Installer believes the hot/cold "crossover" at my kitchen sink single handle faucet is the source of the noise in the pipes. The crossover existed before the Noritz install so why was there no thumping in the past?

    My opinion is the Noritz unit is defective in some way and needs to be replaced. Please help...I really don't want to go back to a big dumb tank.

    Some background data that might help:
    Noritz NRCP982-DV NG (w/built in recirculation pump)
    House is fully plumbed with recirculating hot water line throughout house.
    House is 14 years old. 2 stories (no basement). 5.5 baths.
     
  2. Terry

    Terry Administrator Staff Member

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    I don't know about defective, but I do know that when I switched to tankless, there was more noise(s) involved.
    I don't have a recirc on my basic unit, but I would consider it to be a good option to have.
    There is a lot more going on with a tankless than with a standard tank. I haven't been doing very many. What are other people noticing.
    I'm considering moving my tankless closer to my three bath core just to shorten up the lag time.
    And then I wonder about the adding sounds moving it closer too.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Depending on how the pipes are run, if there's any friction as they pass through the walls, etc., and how they are anchored, thermal expansion factors could be causing them to make noises when the unit runs to restore the temperature. Because of the recirculation, and to keep the thing from running constantly while it is going on, it will cycle on/off periodically. A tank type unit might create similar noises, but only initially when you start to run hot water, and those cold lines heat up and expand. It would happen again when you stopped, but would occur slower as the water in the pipes cooled off.
     
  5. Ricker

    Ricker New Member

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    Update: I believe we have found the culprit. The installer did not install a thermal expansion tank on the cold intake side of the unit. Any time the recirc pump was running hot water through the system with no demand, the heated water had nowhere to go...hence all the noise during the recirc hours. Installer is coming tomorrow to install the expansion tank and then we'll know for sure (but I'm 99.9% sure this is issue).

    Needless to say, I'm both relieved (no pun intended) and p'ed-off. How did such a simple/basic thing get overlooked?! The installation guide even notes that an expansion tank is required (but not included). A tremendous amount of undue stress has been put on our plumbing for the past 6 weeks. Should I be concerned about pipes about to fail? Is my new Noritz unit life expectancy now diminished? Finally, is there a Plumber's licensing board in California I can report him to? I wouldn't normally make a stink but this could have led to *serious* damage to our house and potential safety issues for my family.

    [​IMG]
     
    Last edited by a moderator: Apr 4, 2017
  6. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    you are not going to have any serious damage done to your house because this
    dumbass did not install a thermal expansion tank... most homes do not have one
    and it will not hurt your unit either...

    I assume he came back out and
    installed one without much hassle or did you have to threaten to sue him??


    Do you wish you would have stuck with a 75 gallon heater and stayed
    away from all this hassle??
     
  7. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    Terry, I am suprised that you went to a tankless unit ..... I have thought about doing one in my own
    home to get up to speed on them but I still think the over all benefits are nill. and it might piss my wife
    off in a serious fashion. I do not want to be
    in the cross-hairs of some pissed off customer or wife a few weeks the road when
    they begin reveal all the "quirks" you have to accept and live with
    FOREVER DOWN THE ROAD...........

    You claim you are gonnna move it closer to your shower units,
    does this mean you are sort of dis-appointed with the tankless experience??
    so overall on a scale of 1-10 being would you say your are happy or not
    with its performance...??
     
  8. Terry

    Terry Administrator Staff Member

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    I do sometimes think about adding a small gas tank back where the old one sat, and using the tankless to refill it.
    I spend way too much time waiting for hot water in the morning. I put the tankless where I did because it was close to the gas meter and the outside wall for venting. But it's a long way from where I shower.
     
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Note that unless you have a 'closed' system (and this is noted in the install instructions), you do NOT need an expansion tank. A closed system could be created if you have a check valve (often installed by your water utility at or before the water meter), or you've installed a pressure reduction valve. If you have neither of those, you do NOT need an expansion tank, but it won't hurt to have one. If the system is NOT closed, then adding one will not stop the noise issues you have. With an open system, any thermal expansion just pushes the excess volume back out into the supply line to the street, it does nothing internal to the house. The possibility that you could be pushing potentially polluted water back into the utility's supply system is why many places are adding check valves to protect their supply from inadvertent pollution - a rare, but possible consequence of a system without one.
     
  10. Ricker

    Ricker New Member

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    A moderator was kind enough to edit my reply (post #4) but included the wrong diagram from the installation manual. The image shared was of a system without the recirculation line. I've included the correct image from the manual which omits the idea of a back flow preventer. In both cases however, the manual clearly depicts an expansion tank as part of the install (per local code).

    Anyway...

    The installer came by this morning and did 2 things:
    1) Lowered the water pressure to 50 psi (according to him, it was at 75 psi).
    2) Installed the expansion tank.

    I've set my Noritz back to normal operating schedule; the recirc pump will run tonight from 5-10 pm. I'll either have a 20 piece orchestra to listen or the problem will be solved. Let's hope for the latter.

    A few notes:
    1) I asked the installer, "Hey, are you going to pump this expansion tank up to 50 psi to match the water pressure? The tank comes pre-charged to only 20 psi." He looked at me like I was from Mars and said he "never does that" and "it doesn't matter". I was like, "That's interesting because the tank instructions say you should do it...and I watched a couple YouTube videos last night where they did so as well." I managed to convince him we should pump it up to 50 psi. :)

    2) The words "per local code" in the installation guide regarding the expansion tank. Does that mean (a) you should install the tank according to how local code recommends it is done or (b) you should install the tank only if local code requires it? I know I'm splitting hairs here but my installer was like "Well, I didn't install it originally because it's not required by code." I said "It's like $40-50 bucks, just price it into the job. Cheap insurance that you never have to come back."

    3) I think (although I'm not sure) that our home is new enough that there is a back flow preventer installed at the curb where the water meter is. I know our hose bibs on the outside of the house have them installed as a safety measure.
     

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  11. Ricker

    Ricker New Member

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    PS Thanks for all of the replies. And yes, if the noise persists after today, I will totally wish I had just replaced my old 75 gal tank with a new one and been done with it.
     
  12. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    It sound like your installer is a total doof if he does not
    even know you should attempt to match the pressure in your home
    for the thermal tank...
     
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  13. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    Ok, from your statement it sounds like you are having regrets....
    but you have not given me a rating of from 1 -10 yet..

    With you being a plumber you can always get your hands on a
    water heater for cheap and just tear the thing out if it gets too
    annoying...


    Being the owner of this site,
    are you just trying to stay neutral on the subject??

    I suppose you could give it a rating of "5" and be a real dick about it......lol
     
  14. Ricker

    Ricker New Member

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    Welp. The pipes are still barking. To add insult to injury, I have found water on top of the expansion tank (something is leaking).

    When I disable the recirculation feature on the Noritz, there is no noise in the pipes (the big downside is that it takes forever to get hot water to some corners of the house). So, what about installing an external recirc-pump and leaving recirc disabled on Noritz? We had an external recirc pump with our original 75 gal tank and never had an issue.
     
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Can you isolate the noise to the actual tankless device, or is it coming from the pipes, and maybe distributed? When they installed the unit, check the pipes and how they are anchored. Some clamps allow the pipe to smoothly slide through as it expands and contracts, some are just a clamp, and when things expand, once they get enough tension, it jumps through the clamp and can make some nasty sounds.

    FWIW, hose bibs are required in newer construction to have vacuum relief valves, but that is not the same thing as a check valve to protect the supply line of the utility. It does, but in a different manner than a check valve. If you have a PRV, which it sounds like you do, then you should have had an expansion tank installed. IF the T&P valve was not leaking on the old one, then there was a leak somewhere that bled off the excess pressure when the water was expanded during the heating process. Having a PRV creates a closed system, and therefore should have an ET installed regardless of the type of WH, at least in MHO.
     
  16. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    woof woof woof...... is it that kind of bark, ???
    or is it more of a long howl in the night like you hear from a wolf..???
    I myself , hate getting woke up from those small squeaky sounding yappey dogs that bark at nothing all night long...LOL

    You are probably going to have to find someone else to work on this pig if your installer does not know
    what he is doing.. If he does not come back out to check the leaking I suggest you give him a bad review
    on Google ..... good luck
     
  17. Ricker

    Ricker New Member

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    The noises are far away from the tankless unit - most prevalent in the furthest (from the tankless) corner of the house which happens to be the Master BR. Perhaps we need air-column(s) installed in that corner of the house?

    I'm not sure how the pipes were anchored throughout the house but we never (in 14 years) had this issue before. The only thing that changed was replacing hot water tank with tankless (and removal of external recirc pump).
     
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  18. Ricker

    Ricker New Member

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    Now I'm wondering if we might have air trapped in the recirc system. Potentially dumb question but how does one bleed the recirc line? Supply lines are easy, turn on the faucets and the water pushes the air out...but the recirc line?
     
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A recirc line will bleed itself...no action required. As opposed to say boiler heating lines where you may only have 12-14# of water pressure, typical house pressure has enough oomph to purge any air out on its own. Since the water pressure will drop 0.43#/foot, if say your boiler was in the basement, and had to go up 20', the pressure would be only about 3# up at the top...not enough pressure or volume to push the air out without some hassles...not the same with a supply system for potable water at typically 50psi or there abouts.

    Typical recirc systems rely on an aquastat and either use that to turn the pump on/off, or to open/close a crossover valve. If you have a dedicated return line, then there may not be any cross-over valves, but there might be throttle control valves. Without more info on how your recirc line(s) were hooked up, I can't think of much of anything else. It would help to be there and observe.

    If it is thermal expansion of the lines, and the pipes 'jumping' through tight clamps or holes in joists/studs/walls, rather than moving freely as it expands and contracts, unless you can isolate where that's occurring, your choice is live with it, or run the recirc only on demand, or on a timer so you don't experience the issue at night while you're sleeping. I know I've got mine on a timer, and if I get up earlier than my norm, instead of a few seconds to get hot in the shower, it takes over 2-minutes, but, do not notice noises from my pipes at any times. Seeing what the builder did...I doubt he use any clamps!
     
  20. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    jadnashua could have a point about the water lines perhaps you ought to loosen them a little and see if the
    noise stops... it could be something as simple as expansion of the water lines going "bark" or "woof" in the night
     
  21. Muffichka

    Muffichka New Member

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    We have the SAME nightmare issue- loud knocking noises in the pipes when the recirculating pump of the Noritz tankless WH turns on. No noises when hot water is running without recirculating pump on. It’s driving us crazy. Has there been any resolution? We have expansion tank, all kinds of check valves & the knocking noise is still there most heard in the wall of Master Bedroom shower. It’s not water hammering. The knocking noise is strictly limited to when the recirculating pump turns on (actually, when there is NO water being used!). Plz help. Several plumbers (including the installer) don’t know what’s causing it. I’ve already paid thousands of dollars. 3 Noritz WH were changed- all the same! :(((
     
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