Illinois Licensed Plumber
When you do the first in last out method, the tees pretty much automatically space them selves out equally. The idea is the first tee on the cold supply is by the first heater so it gets the cold water first, and the second heater has the other tee on the hot side, the distance between the tee's and the other heater will be the same, and the second heater is the first one out which makes the one getting the water in first to be last out.Ron,
Don't the tees have to be equally spaced between the WH's to draw equally?
Do not ask me the physics behind it, I am not that good at explaining it. All I can tell you is it works.
Here is another diagram from ao smith with three heaters, and you can do this all day with as many as you want.
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