My basement walls had to be opened anyway, and last year there was a pinhole leak upstairs, so I'm thinking of replacing the copper main in the basement with PEX. The copper is 1/2", with 6 branches - 4 apartments (each with 1 kitchen 1 bath) + a shared laundry + a garden hose tap. No one has complained about low pressure since I upgraded the service line from the street to 3/4" copper 7 years ago. I know PEX A connects by expanding the pipe which then tries to return to its original shape, and PEX B requires crimping around connectors that slip inside the pipe, thus reducing the pipe diameter, i.e. introducing bottlenecks. Since PEX B adds bottlenecks, I've been told to upsize my pipe for the main - at least for the first 2 apartments. Should I use 3/4" or 1" PEX B?
(The copper is at least 33 years old. Both hot and cold are type M copper, which has a life expectancy of 20-50 years. "M-type piping is the thinnest residential copper piping variety, and typically lasts for 20-50 years. L-type copper pipes are of medium thickness and can last for 50-100 years. As the thickest variety of copper piping, K-type pipes can last for over 100 years." - repipenow.com)
(The copper is at least 33 years old. Both hot and cold are type M copper, which has a life expectancy of 20-50 years. "M-type piping is the thinnest residential copper piping variety, and typically lasts for 20-50 years. L-type copper pipes are of medium thickness and can last for 50-100 years. As the thickest variety of copper piping, K-type pipes can last for over 100 years." - repipenow.com)
