I have a question about the house I bought and the piping for the boiler system. Coming into the boiler is 1/2 feeding the baseboards is 3/4 and there is some 1 inch I am assuming in there in certain spots. I want to know if everything should be 3/4? I am having trouble on getting air out of the system and thought this maybe causing the issue with all the different piping in the system. The sound of water rushing in the pipes is driving me nuts. Also can I re pipe everything with pex and just have copper at the baseboards? Thanks for any help you can provide on this.