Air register locations and more

[tom31415926]

Greetings, all. I'm new to this forum, and I'm impressed by both the wealth of knowledge here and by the clarity and authority with which it is expressed.

If my questions are already answered elsewhere, please give me links to the answers. I don't mind a bit of reading.

As part of an overall home remodel, I'm considering some options for the HVAC. The present system is old, and will probably have to be replaced at some point.

I have been doing some reading about air supply register locations. Ceiling registers are the most practical in my situation, I think. The present supply registers are located on the wall right over the door to each room, along a central, low-ceiling hallway. The only return register is on the ceiling of the hallway. The rooms do not heat evenly, the registers over the doors do not "throw" the air across the rooms to the exterior walls. I would not mind replacing the supply registers with new ceiling registers as part of the new system.

I have read about air velocity at the register, and the fact that mixing with room air occurs at some distance away from the register. What I read suggests that a ceiling-mounted register that deflects the air towards the exterior wall (or walls, in the case of the corner rooms) would work well. The air mixing would take place along the ceiling, and the exterior walls would be reached with tempered air.

For cooling, I can see where this would provide cool air along the warmest surfaces in the room, and that the cooled air would move downward in the vicinity of the exterior walls. For heating, I suppose it would be better to have floor registers so that warm air would rise along the exterior walls. I'd rather have only ceiling registers, however. I can imagine that warm air blown towards the exterior walls would cool somewhat as it hits the exterior walls and travel downwards there.

Does this location seem right? Feel free to tell me that I'm not asking the right questions! Just tell me where to look in order to gain a better perspective.

The rooms are about 12 X 15 feet, How far back from the wall should the register be? Or, on what factors does this depend?

My reading suggests that I would need to find a good ceiling register to direct the air along the ceiling, probably something better than stamped louvers. It would be great to find a register (diffuser) that has a sort of semi-circular pattern. circular paterns are easy to find, but it seems that I want to direct much more of the air towards the exterior walls. Any suggestions on where to look for registers?

What if there is a window at the middle of the exterior wall? I'd have the air directed towards the window (or above it). Is that bad? the windows are upgraded double-pane.

I have not yet looked at heat load (or "cooling load"). Is it possible to make some starting assumptions on the air flow (in cfm) that is needed in each room? I do not anticipate that there will be extraordinary loads (unless two computers and a soldering pencil create an extraordinary situation).

Thanks for any information,

tom31415926