I have a bore hole / spring water supply from a water treatment plant delivering 4.5bar pressure regulated to 2.5 bar to the house. I am looing to replace an old thermal copper heat store system with an unvented tank. There is a vast cost difference between megaflow systems recommended and others. Do you have a recommendation for system. My reason for changing is the heat store delivery flow is restricted and if we run a bath and shower at the same time the shower stops. many thanks