I have a well with a 40 gal Welxtrol pressure tank. It is a closed system. I am installing a new high efficiency electric water heater (heat pump). Do I need a thermal expansion tank if I already have a pressure tank? Won’t the pressure tank absorb the added hot water pressure in the same way an expansion tank does?
And, with the above, if the water heater already had a pressure relief valve built in, with drain, why do we need expansion tank or thermal pressure relief valve? Won’t the pressure just come out the built in valve and drain accordingly?