Hi, I just moved into house with a Navien tankless NPE-240A. Whenever I start the washing machine, the tankless would make a VERY loud banging noise (see video link below). The tankless works fine otherwise for my showers, etc. It is just this annoying sound when using washer. I have also installed 2 new "water hammer" valve but they didn't help.
Does anyone have any idea what could be the cause? Thanks.
Does anyone have any idea what could be the cause? Thanks.
