Navien NR-240A-NG rattling / knocking sound from internal recirc. pump

[rlavs]

Hi All,

I have a Navien NR-240A-NG installed by previous owner in 2013. We recently had issues with the water going from hot to luke-warm within a minute of turning it on.

Replacing the internal check valve near the pump fixed the issue, and for the past ~2 weeks all has been fine.

Last 2 days however, we've heard a knocking / rattling sound from upstairs and tracked it down to the water heater. The sound is coming from the pump area I worked on when replacing the check valve. Also, occasionally the hot water issue from before has returned.

Has anyone heard a sound like this before? Unsure if the pump is dying and it is coincidence, or if I need to dismantle and look at the check valve again...

Here's a link to a video with the sound in it.

Thank you!

 

[GReynolds929]

I would replace or be prepared to replace the pump. Sounds like the bearings or bushing are going.

 

[Sponsor]

 

[Fitter30]

Have you ever done the yearly maintenance or more with vinegar? Let hope it's the pump or the heat exchanger being mineral up and the the water is trapping the minerals flashing to steam.