Hi Chris and yes you can do it yourself if you got the skills, the tools and are confident enough you wont flood entire place. I'll strongly recommend hiring a plumber, it seems to be a simple straightforward task yet only if know exactly what is required. Whole CH system might need drained and refilled, inhibitor added, balancing and bleeding probably also required. There are quite a few complications that may occur, depending of CH system type, like vented or unvented, I'll definitely hire a plumber. Good luck.