Problem with Noise from Tankless Hot Water Heater

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,

Further Information

• How to Choose a Hot Water Heater (article)
• Energy Efficient Tankless Water Heaters for Your Home (video)
• Is Water from a Tankless Hot Water Heater Hot Enough (article)