From a practical point of view I would agree with Ed.
My expansion tank line is 1/2" copper and drops from ceiling to bottom of tank which is about 7&1/2'. By the time the water gets to the tank the temp has dropped considerably. Depending on the size of the expansion tank(s) volume, the incoming hot water will be diluted with existing tank water and would cool it more as well.
My expansion tank line is 1/2" copper and drops from ceiling to bottom of tank which is about 7&1/2'. By the time the water gets to the tank the temp has dropped considerably. Depending on the size of the expansion tank(s) volume, the incoming hot water will be diluted with existing tank water and would cool it more as well.