I'm renovating an area in my home and would like to move a gas water heater. The existing location is in a hallway between two bedrooms and I'd like to place this unit in the garage. Venting and adding gas is not an issue, but I'm concerned about water flow. I'm attaching a PDF that I'm using for illustration purposes. The blue lines are all 3/4" copper lines and have 1/2" lines tapped off them to the devices in the room. My intention is to disconnect and cap the 3/4" line at the manifold in the wall between the two bedrooms and run 3/4" lines (red) to under the kitchen sink and make my connections there. This would free up the existing water heater location for other use (a larger closet). Would there be any water flow issues in this scenario since there are several 1/2" taps on the cold water side leading to the water heater? The length of pipe from the manifold to the new water heater location is about 45-50'.

Check code. I think a water heater in the garage needs to be 18'' above the floor. They make stands for them.

I'll place the water heater 18" off the floor, but the real question is water flow. The coldwater side will be feeding all devices including the hot water heater (at the far end). The flow will also have to feed all hot water devices. I guess it should all work as it essentially had to feed everything before, just from a different location.

One thing to keep in mind is to keep the runs short to the most frequent points of use.

Also, the air intake must be screened. Newer hot water heaters all have that.