I am installing a new bathroom and need to replace some of the plumbing. The pipes coming from the mains and the combi boiler are 15mm. The bath however branches off of this in 22mm. What i want to know is can i use 15mm up to the bath tap and then use a 15mm to 22mm connector to connect to the taps, or should there be a run of 22mm pipe leading to the bath. Thanks very much