I read there is pex-a and pex-b. I believe hd and lowes sells pex-b. I want to re-do my plumbing under single wide trailer but need something to withstand the cold. will the insulation sleeves be sufficient to protect below 32 degrees? I cannot afford the high quality pex-a. also need to know if I should increase from 1/2inch to 3/4 inch as I have a 2 bath trailer with sink, washer and hot water heater. thanks!!!!!