I always put my domestic expansion tank on the cold inlet to my boilermate
with a check valve behind it.
I see a lot of guys just placeing a tee in the domestic cold in any old
location with the tank there. they will have the check valve located back at
the meter. I put 2 check valves, one at meter and one at boilermate. Tanks
sweat here when cold water goes through them big time. I don't like the
idea of a tank of water sitting at a different temp in the cold line. On
the cold inlet to hot water tank it is going to be heated anyway so let it
preheat there. If the tank sweats it will be dried off by the heat
generated. Any comments/sugg. welcome.