"umm.... What's an RCD?"

A Residual Current Device - the new Official mumbo-jumbo name for what used to be known as an ELCB Earth Leakage Circuit Breaker (IMO, a far more meaningful name to the average user!)

"My computer is im my left, and the central heating system is about 40-50ft away,"

you seem to be suffering severe data corruption just between KB & PC - are you sure you want to go that far...?!! ;-)

(but yes, a suitable 1-Wire interface can go several hundred metres - one of its applications is in building environmental control)