Your expansion tank pressure should match the highest water pressure you have up to 80 psi.
The expansion tank should be inflated with the water off and the residual water pressure bleed down. Then air up the tank to match the highest pressure up to 80 psi.
If you have over 80 psi then you need a pressure reducing valve.
The expansion tank should be inflated with the water off and the residual water pressure bleed down. Then air up the tank to match the highest pressure up to 80 psi.
If you have over 80 psi then you need a pressure reducing valve.