Hey chem, I am going to use run to waste for now, my 220v solonoid valve has turned up today, I was thinking about the same sort of idea but instead of capping it maybe using a heat pump and hooking it up to a radiator in my workshop for the wintertime lol just not sure how hot it would get (if at all). I have been and got teh 10m of copper that i am going to use to run a new gas line from outside my kitchen into workshop, I am also going to run a fixed copped waterline at the same time. I am ready to get cracking on the piping, plaster boarding and insulating my room now. I have moved my tents indoors for now so i can get on with sorting out a proper room hehe! Cant wait to see the difference added co2 is going to make.