The expansion/pressure tank gets pumped full of water,under pressure.
It allows you to run water for a while before the pump kicks on---without it you would be turning on the pump each time you needed any water at all.---Think of it as your own in house water tower.--Mike---
It allows you to run water for a while before the pump kicks on---without it you would be turning on the pump each time you needed any water at all.---Think of it as your own in house water tower.--Mike---