Will 3/4” pex with an inside diameter of .68 inches have enough capacity to supply a 3/4” manifold with 1/2” supply lines to a bathtub, washer and toilet and sink with no pressure drop?
I plan on running 3/4” pex from water meter to the house. Once inside the house the 3/4” will branch off using a 3/4” Tee. The (1) 3/4 supply line will run to a hot water heater then as hot water leaves the heater from a 3/4 supply to a hot water manifold with dedicated 1/2 supply lines to each fixture. The second 3/4” from the tee joint will deliver cold water will also run to a manifold. Every fixture will have its own dedicated 1/2” supply. The outdoor faucets will have dedicated 1/2” supply lines as well.
Plumbing – Does 3/4” pex supply enough water for a house
bathroompexplumbingshowerwater
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Best Answer
Not a calculated method, but if that home is yours and you're planning to spend a good few years in it, I would put in the 1" main PEX to water heater and as you go to edge water outlets of the house, convert that 1" to 3/4". The cost of 1" vs 3/4" isn't too drastic and having the extra capacity, especially to the water heater will help with pressure issues. 3/4" post water heater is good, unless you have 8+ hot drops.
If that home is a builder home and used for investment or you're trying to minimize the cost, do the calculation on needed flow and capacity. Most of the time 3/4" is good for smaller homes.
Regarding manifolds, all builders that I've seen do not use main manifolds and just use tee's and split off the main pex. It appears, labor wise, its less work and less cost since the manifold adds a few hundred to the project and creates further runs but you lose the ability to shut off each drop.