How difficult is it to install a combi central heating system with eight rads? I want to attempt as much as possible. Can't pay the 3000 for a full installation, so I want to give it my best shot. Are there people out there who may have been in a similar situation, or any pros who can spare a moment and give some guidance/advice. I know I'm probablly off my head for contemplating this but I can't resist the challenge - and because my fireplaces are all bricked up!