I am currently heating around 2800 s.f. with central air and another 1000 s.f. with hot water modine in the garage. I have a tarm solo 40 with a buderus oil with 80 gallon indirect hot water tank. Im am considering having some type of storage tank installed only becuase it is recommended by everyone i talk to but I dont quite understand how the whole concept works. Could someone breifly explain this to me. And rough costs for purchasing and installation. My system is currently less than 6 months old.