Wouldn't using 3/4" for the main run and 'T' off with 1/2" to the loads; Large area supplying small individual runs; act exactly like the manifold?
When you add up the cost of buying 5-6 brass PEX T's, it was cheaper or about same cost to buy one larger copper manifold.
It may work like the premade manifold, but I think it would still be an "in series" system where the first circuit in the series would get more pressure and then the pressure would drop down the line. Using
this larger type of manifold helps keep pressure constant in all lines....IMO.
Is the cost of the 'T's more than running lines to all the individual loads? It just seems to me that
many water lines running side by side would be a nightmare. Again I know nothing just trying to learn.
I found it to be easy to run a line to every faucet. This PEX is flexible and can easily be formed and
bent in a pretty tight curve. You could technically run a single line to a bathroom then T it off and
supply all your bathroom fixtures off the single line. I chose to run a circuit for each one with a
separate valve, I had to re-plumb it all from scratch so that was my preference. Little more cost, yes,
but my manifolds were $12-15 each and I bought a bulk lot of 1/4 turn ball valves on Ebay that ended up being $2.50-3 each. I also just used a sharpie marker to mark what each line feeds, very nice when doing a quick shutoff. A professional would have used a label maker
Three of us on a 30-50 psi well. Never really notice a supply issue unless the toilet in the same bathroom is flushed. Then again it is very seldom more than one of us is using water at the same time.
That's one of the beauties of using a manifold like this, it keeps even pressure throughout the house no matter what gets turned on or flushed at the same time( well as long as pump maintains pressure).
If you are interested in running PEX, how the manifolds work, etc, search youtube. I spent hours
watching videos on install, types of connectors, tools, how to run the pipe, etc before I bought
anything or started planning. I went with the crimp ring and barb fitting type connection system, not a single leak yet, that wouldn't have happened with me soldering copper