I saw a post about recirculating pumps being used with AO Smith Vertex water heaters. I built my house in 2008 and I am now on my 3rd AO Smith Vertex and the main control has been replaced 5 times between the 3 units. The problems just started again and this latest control board is less than 6 months old. I've had half a dozen plumbers look at the system and setup over the years and no one has been able to tell me why these keep failing. Everything has been double and triple checked but I now think it is related to the recirculating pump that was installed about a year after my house was built. Any suggestions? I need someone who knows about these units to fix this problem once and for all.

If this is a power vent, it could be something as simple as a draft problem. And what I mean by that is a clog on the exhaust pipe or the intake is clogged. If it's in an enclosed room you need to take care that there is a louvered door or grate in the wall for fresh air. Have you tried trouble shooting with the techs at the factory?

The Vertex heaters are nothing but problems. In theory the idea of a down fired heater works great in the real world they burn out igniters and flame rod sensors too easily