I have installed a new water tank... and a new federal pioneer panel. I put in a two pole 20 amp breaker as the specs said from the water tank. (3000 watt) no heat but both elements have 115 volts... did I use the wrong breaker?

Federal Pacific panels have an unusual staggered buss. You may have to move the breaker down a space to get the breaker on both buss bars.

Thank you so much Missouri bound... it worked like a charm... if you ever come to canada you have a place to stay at our house
Murray