Welcome! Here are the website rules, as well as some tips for using this forum.
If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
The factory rep tells me that no one else is has trouble with the A.O. Smith Cyclone water heater model #BTH-199A 200. This is the super fancy modulating water heater. Since day one this has been a problem locking out on blower prover error. That was three years ago. Symptom is the water heater work fine until the blower starts to surge as it runs. it will work in this state but starts to lock out. Also sounded like bearing noise when the blower stopped working correctly. Change the blower and it was good for another 6 months. at $800 a blower I could have heated the water burning dollar bills and been more cost effective.
I have replaced everything on this water heater, had the rep out, and had other Techs look at it. the A.O. Smith rep blamed the blower failures on humid air from our marine environment. So I disconnected the outdoor air intake and drew combustion air from the mechanical room. Problem solved, right?
6 months later. "blower Prover Error"
Another $800 combustion blower. This one was good for 2 months.
With out a new spare on hand and the hot water down all I could do was check to see if the last one I replaced would run for a couple days. Before going through the trouble of installing it I plugged it in to see if it would spin up.
I've been changing these so much I stopped changing the whole blower housing and started just changing the plate that the motor and impeller are mounted on. Much easier to get to those screws.
The used blower spun up fine. But when it turned off the impeller kept spinning. I checked the other blower and the same thing happened.
A little destructive testing made the problem obvious. The motor shaft is completely smooth! No spline, no flat, no key! the impeller is just friction fit on the shaft. Over time this gets loose and the impeller starts to spin on the shaft. The motor is surging because is over revs and does no see the right amp draw.
I cut a few slots in the end of the shaft and in the impeller. Then built up a good weld with Rapid Fix. Now it is working like new.
I still don't trust it and I'm going to replace the water heater. I'll never buy one of these again. It's a manufacturing flaw. No matter how many inducers I get they will all be built the same.
Sharing this so someone else can avoid all the stress.