Knight Lochinvar Model 210 with new noise

Bossboy302

Installed 2011, regularly maintained and serviced. Has performed perfectly since new. Just recently began to make noise. Has ocurred 3 times. Seems to be combustion fan. Happens when hot and running, lasts 30-40 seconds or until we shutdown boiler. Not a howling noise, more like fan is rubbing. Rubber isolator mounts feel worn, maybe getting soft when hot allowing blower to move around and make contact somewhere?

Any ideas? Thanks

Bossboy302

Any thoughts,?

It has happened 4 times now. Seems to occur after having run a long time. I had removed, checked, and re-installed the combustion fan, all normal. Yesterday, during the iccurance, I felt the fan and seemed secure and operating normally. Don't think that's the problem. I did smell propane, and wonder if I have a combustion problem? A leak, or otherwise an inadequate gas supply?

The noise definitely can be heard through the air intake piping.

GGross

https://forum.heatinghelp.com/discussion/comment/1832637#Comment_1832637

I would do a combustion test on the boiler, and then check the intake piping for flue gas recirculation, you would do the recirc test while the boiler is running, checking the intake pipe with your combustion analyzer for any products of combustion, if there are other flues near the intake piping at all I would also run that equipment. This won't fix the issue mind you, just point us to a cause. If the flue is recircing I would recommend relocating the intake pipe, if the fan fails it would need to be replaced though. Possible it's just bad luck, but usually there are site condition factors that take out things like fans etc. After 14 years though I'd say whatever caused it to fail is likely a minor issue

EBEBRATT-Ed

Surely it needs to be serviced if it has not had any attention