PEX Design Question

[RcambellSRQ]

How many fixtures can reasonably be ran off a 3/4" hot loop with 3/4 to 1/2" reducing T's running to the various fixtures? I have included a photo of my preliminary design below. Also, do I need the check valve between the hot and cold connection tee back into the water heater?

Thank you in advance for any feedback

 

[Tuttles Revenge]

Sizing is a matter of fixture usage/volume and capacity/pressure/diameter.

plumbing code has charts for sizing the water needs of a house based on the total number and types of fixtures.

pex manufactures also should have published flow rates for their product, whichever you're going to install.

Your main is determined by the total number of Fixture Units based on your code and the longest length of pipe needed to supply that fixture. Each branch is based off the same calculation.