Problem with Noise from Tankless Hot Water Heater

By: Danny Lipford

I have sounds coming from our tankless water heater. Should I be concerned? -Nora

Hi Nora,

Gas tankless hot water heaters all make noise when firing up and heating water, but the levels are usually less than 90 decibels. A decibel meter can be used to find out how loud your tankless water heater actually is. If you have a smartphone, you can download a free decibel meter app called SoundLevel and measure the decibel output yourself.

If the noise occurs when hot water isn’t being used, there’s a good chance that another source is siphoning water from the line and creating a vacuum. If you hear a weird groaning sound from the pipes or the tankless hot water heater when you flush the toilet, that could be the culprit.

Even though a toilet only uses cold water, I have seen some toilets do this. In that case, you need to have a plumber install a check valve in the water line.

Good luck with your project,


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3 Comments on “Problem with Noise from Tankless Hot Water Heater”

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  • Irina Says:
    October 9th, 2014 at 4:19 am

    Last night the water was way too hot and I woke up because of the very loud noise the water heater made, it sounded like the system was under high pressure, kind of laud singing pipes . I turned it off. What should I do?

  • donna Says:
    July 6th, 2014 at 4:20 pm

    Our water heater is considerably noisier than when we had it installed five years ago. Should I have a plumber check it? What could be causing this?

  • Roland Jugandi Says:
    March 23rd, 2014 at 10:22 am

    90 dB is very loud.

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Problem with Noise from Tankless Hot Water Heater