hot & cold proper pipe size help

[playersc]

I am planning to replumb my house with pex and have a question about pipe sizing. Coming into the house is 1 1/4" PVC, my thoughts were to tee off the 1 1/4" PVC to 2 3/4" pex pipes one hot and one cold. Would it be ok to run all 3/4" pex in the attic and drop down to 1/2" from the attic to the fixtures. Note there will be a kitchen sink, 4 toilets, 4 bathroom sinks, 3 showers, and a garden tub. I this a proper design, if not what would you do. I also plan to install a recirculating system. All suggestions are welcome.

Thanks playersc.

[Bob NH]

I am not a tree-hugger and my greatest interest in the environment is finding good places to hunt and fish, but recirculating hot water systems waste energy and contribute to global warming. A small point-of-use electric heater at the end of a long run, just before the major demands, is much more efficient.

Do your bit to save the polar bears and maybe help to keep the courts out of the carbon dioxide business.

[Terry]

A four bathroom house needs to be sized better than that.
The 1-1/4" coming in is okay.

This chart should help on your sizing.
http://www.terrylove.com/pipe.htm

I like the idea of a recirc line if the house is large.
The line is insulated there and back, and you don't wind up dumping so much hot water down the drain. I mean cold water until the hot finally gets there.