As with any trade you have good and bad regardless of qualifications. I've put on here a few times my trades, plumber,part 'p' spark to name two, i also had a business @23 yrs,, now i'm just leisurely doing handyman work, everybody wants half a dozen little jobs doing, if your stuck with one trade you find as many 'single trades' they are struggling for work or **** rates. Multitrades/ handymen are not cowboys , some might be though as there are in any trade. So you know how to take a rad off, what if a rad valve starts to weep or theres an air lock in the rad or you open the rad and no air comes out could you sort it?