New residential 40 gal. electric water heater with new Watts expansion tank. Due to WH location the expansion tank is installed with a T- fitting in the cold water line a couple of feet above. When filling the system with water I know opening a faucet will purge the air from the WH but what happens to the air that is in the pipe entering the Expansion tank ahead of the water since the expansion tank only has an inlet? Thanks
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