Shower and bath mixer

18 Dec 2013
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United Kingdom
Hello all im installing a new bath etc in my bathroom and the mixer valve does both the bath and the shower. The connections onto the mixer are 22mm. Cold water is from the mains (good pressure) and the hot water is from combi. All current pipe in the bathroom including the current bath feeds are 15mm. Can I run 15mm hot and cold to the mixer then step up to 22mm for the mixer connection? I know the bath will fill slower on 15mm than 22mm but are there any reasons why this will not work?
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The hot actually comes in on 22mm and reduces to 15mm at the start of the bathroom so I can do the hot on 22mm and the cold is 15mm only. Im thinking hot all the way in 22mm and cold mains good pressure in 15mm then step upto 22mm?
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Just to clarify what Terry said - he means step up to 3/4" at the mixer so use a 15mm x 3/4"tap connector on both.

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