Radiator in the barrel maybe not, outside better idea. Mine currently heat my apartment, only a 1 bedroom but still. Water cooling is amazing because it works in any orientation. I wasn't aware you're using one of those self contained units. I'm not a huge fan but I have owned one, they're extremely simple to use. Never worry about adding coolant or bleeding the system proper, as for actual life mine was fine for the year I owned it. The only reason I wish I was 100% water cooled is the 10 fans running for my miners. Do a google search and you can find what I assume is the water system they used in the minirigs. A lot more coverage, kinda wished this was an aftermarket option.