関連ワード:  1/2 vs 3/4 pex flow rate    1 2 vs 3 4 pex flow rate    1 2 copper vs 3 4 pex flow rate    3/4 pex flow rate    3/4 vs 1 pex    1/2 vs 3/4 pex    should i use 1/2 or 3/4 pex