I figured it would take about 2 hours of continuous water heater operation and recirculation to reach the required temperature of 130 degrees F. 15 minutes per 6 gallons, 35+6=41.I don't have a thermometer to measure that but I figure I'll run the system till the water heater reaches temperature and shuts off. That should be about 2 hours to hit that tempAt the 2 hour point it is Hot to touch. I have a total of 2.5 gallons of vinegar in the system.
I kept the recirculation going about 15 m8 ures after the water heater shut off. It did not restart. I rocked the TC side to side pretty good, loud sloshing sounds, then drained the system completely. I refilled and there is no order of vinegar but there is the slightest vinegar tartness taste in the water. I'm going to leave it sit overnight then drain and refill in the Azm. I expect it to be fine after that.
It seems to have worked well especially due to the hot water recirculation. I'd call it a success. A bit more expensive than bleaching and time consuming but if you don't want nasty chemicals in your system, vinegar and hot recirculation is a great alternative.
