Smith Vent Damper Buzzing

jmichalski0604

Hello there. I've been troubleshooting issues with a Hydrotherm steam boiler, old home purchase, for the past year. Our recent issue is with a Smith Automatic Vent Damper, PN 6946. Since our last service visit about three weeks ago, the damper motor has had an intermittent buzzing. It appears as though the damper is getting stuck, intermittently, just before it fully closes. This hasn't been a concern until this morning when we woke up to no heat. We found that the damper was buzzing. We were able to work around this by manually turning the shaft a bit to complete the close/ circuit. After a few seconds, the damper opened back up and the boiler kicked on.

Does anyone think that this could be a function of the motor starting to go bad or could there be something possibly stuck in the flue? We recently had this side of the chimney lined. Could this be something as simple as greasing the shaft, if that can be done as I assume it's probably a sealed unit? Otherwise, if I look to replace it, what consideration do I need with respect to finding a replacement? I'm having a hard time finding this 20+yo part from Smith Cast Iron Boilers.

Steamhead

The motor assembly is going bad. I don't know if Johnson sells replacement motors like Field does- if not, time for a new damper.

jmichalski0604

Great, thank you. That was my thought as well. I got a hold of the tech who serviced the unit and he mentioned that it could possibly be the damper itself. I took the flue apart and found the "fingers" that rub up against the pipe. He mentioned that they sometimes make the motor stick. I noticed that a couple were rubbing up against the pipe so bent them back a tad. That's shot number one but, like you said, shot number two is getting a new unit.

Thank you for the help.

ChrisJ

I thought the entire point in the "fingers" was to rub against the pipe and create a better seal?