Navien Vibrating Squeak when it is cold out

cj5

Hi,

For a few years now my Navien NCB-240 Combi has been making this vibrating squeaking noise when it is starting up space heating. Its like the bearings in the circulating pump needs to warm up. It will do this for about an hour each time the space heating turns on.

It only does it when it is cold outside perhaps <30F.

The past couple years I was thinking it had something to do with flushing the boiler and air being trapped since it would start soon after a flush, but it just started doing it today and I haven't flushed it yet.

I'm pretty sure the noise is from the circulator pump but not absolutely sure.

It's not coming from the inducer fan at the top.

Wondering if this is a sign of pending part failure and which it would be. Since it goes away in warmer weather maybe it is a thing these boilers do…

Any thoughts on this?

Thanks

yellowdog

Who is telling you to flush your boiler?

Intplm.

It might be your circulator squeaking at start-up. Take a long screw driver, place the handle at your ear, and the other end on the circulator to get a better idea.

Maybe post a video here so we can hear it too?

cj5

cj5

Here's a video of the noise.

https://youtube.com/shorts/U2kffScgkes?si=WntxeKyCof8YI5Cp