Hot Water Heater Odor

I battled with an odor, mine smelled musty. tried everything, finally pulled the heater, and found rust under the Styrofoam. replaced heater, no smell

Terry, I'm betting you have a Suburban water heater. If you read in owner's manual, Suburban recommends draining the water heater whenever it's not being used. Suburban uses an anode rod that reacts with sulfur in the water to produce hydrogen sulfide (sewer gas) and it's hard to get that stink out. I've gotten in the practice of draining my water heater after every weekend's use to avoid that problem and make the anodes last much longer. I even use a siphon hose to get that last 1/2 gallon off the bottom of the tank - that way, no water comes in contact with the rod between outings.

Maybe a good time to change your Anode rod if you have one.
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after the bleach then pump a gallon of white vinegar thru the system. That usually gets rid of most taste/smells.

With the heater off and the water cool try lifting the relief valve at the top of the tank. You could have a big air bubble that is causing the problem. Also a flush with a light bleach mix and again popping the relief to ensure the solution is getting to all surfaces. Sometimes city water has enough to clean and disinfect the tank but sometimes it needs a boost.

Sanitize the system using 1/4 cup bleach per 15 gallons

Next time you winterize bypass the water heater so anti-freeze doesn't go into it. No need for anti-freeze in WH just draining