Air Conditioning - Floor or ceiling vents. Which are best?

Hello, I am trying to decide where to put the ducts in our bedroom/living room addition. I have decided that it will have its own heat pump/air handler system. I want to avoid some of the mistakes made when we built the original house, so I am calling on your experience. What would be ideal? I think I have 4 options. Which is best and why?
1. Floor vents around perimeter for input air. Center of room ceiling vent for return air.
2. Ceiling diffusers around perimeter for input air. Center of room floor vent for return air. .
3. Floor vents around perimeter for input air. Center of room floor vent for return air.
4. Ceiling diffusers around perimeter for input air. Center of room ceiling vent for return air.
Since this is new construction I can do any of these, although some would be easier than others. I don't want to prejudice you with that information, because I really want to know what would be best. Please :) suggest other options I haven't thought of. Your personal experience would be best. Research study references might also be useful Thanks, Bill (Dukes)

First I need to know just what have I got to work with here. Slab , crawl space how much room, how are the truss over head how much room there. Whats the floor lay out. where can I put the air handler or furnace????????? Need all the above then we can say what we think is the best way to go. Where are you. do you need heat or AC the most????????

ED;)

The "best" way? Heat from the floor, cooling from the ceiling. Seriously, like Ed asked, do you need heat or cooling more?

Grady has it, heat vents on the floor and cooling vents on the ceiling.

Generally speaking you want supply at the outside perimeter and returns at the inside perimeter. High returns work fine for both heating and cooliing. I would strongly suggest against any vents/registers in the center of a floor since someone may prefer to place a rug/carpet in that area.

Since from your first post on the other string it appears that you are dearly in need of both heating and cooling (18 degree wintertime and 100 degree summertime) you may wish to look at two separate duct systems for heating and cooling. These could be from the same air handler or completely separate heating and cooling systems. Using the same ductwork for both heating and cooling is always a compromise.

What you (we) need are the heating degree days and cooling degree days figures for an area as close as possible to your home to see which is more needed, heating or cooling.

Hello Ed, Stick construction, 18 inches underneath from dirt to bottom of 12 inch joist, 6/12 pitch 36 foot long trusses gives pretty good attic access. I can walk upright down the center. Insulation is R30 attic, R25 under floor, R21 in exterior walls. In Southern Oregon heating is more important than cooling, because the power bill is twice as much for twice as long during the annual extremes. Living room is 28x15 feet with the West 15 foot end mating with the original house. It has one 9x5 window on the South side, one 9x5 window on the East side, one 3 foot exterior door on the South side, and one 3 foot exterior door on the North side.. Bedroom: 24 x 21 feet gross with the 24 foot length a common wall with a 28 foot length of the living room. Approximately centered along that common wall in the bedroom space is an 8x12 closet where I thought the air handler might go. Also along that common wall is a 8x11 bathroom with the 11 foot side common to the exterior East wall. The bathroom has a 4x5 window on that exterior East wall. The bedroom has a 6x5 window on the East side, a 8x6 window on the North side, and double French doors (6 foot total) on the North side. The only side the heat pump cannot go is the West side. I made a Visio sketch, but I don't seem to be able to paste it in this reply. I see two more posts came in before I could finish this one. Thanks Ed, Grady, and furd. I will have to find out what the heating /cooling days are for zip 97537 I see what you mean now about that being the main consideration for floor or ceiling. Thanks, Bill (Dukes)

Had to call NOAA weather service to get the statistics. The annual (Nov-Oct) numbers are 4537 for heating and 708 for cooling. That is the closest data to where I live. We usually run 5 degrees hotter/ colder in Summer/Winter than where they take the data. Thanks again, Bill (Dukes)

First Id say go to http://aboutsavingheat.com/crawlspace.html
This is the way we do all crawl space. With a 6 mil poly on the ground 2 ft over lap and tape the seams. Insulation on all the walls and insulation in the joist space just on the sill plate all around the home. None in all the joist. No vents.
Now 18" to ground. Have did many this way when the joist are in no ply on them .Put all the duct work and runs just metal ones in. Then the plywood floor. You want 2 small registers in the duct blowing out and 1 in the return duct for air down there . This all works as a heat sink for the home.
ED;)

Ed, that is interesting. You sort of make an 18 inch heated basement below the house. I would expect we can't do that here because of our wet winters. It is almost impossible to keep under house crawl spaces dry. I'll check with the inspector to see what he says. Thanks again, Bill (Dukes)

Did you go to that www about crawl space? been doing them like that for over 30 years. Dont think I can count all the ones we have gone into that had insulation up in the floor joist. Had to pull it all out and re work the whole thing. Had where they put the paper side to the floor and on the down side in the joist. For a time they had a insulation in poly all around .They said it would work in the joist in crawl space HA HA. They have tried to hold the insulation up with everything under the sun. The crawl is like a basement you have to grade the ground so the water cant get in. Gutter and down spouts to help keep the water away from the home.

ED;)

Ed, yes I looked at that web site. I will check it out locally, but I will be very surprised if it is permitted here. When we built the house 11 years ago we had to put in about 8 foundation vents. Of course codes change, as I have realized already this addition is going to be harder to build than the original house. The permit cycle now is 6 months. I am into it 6 weeks now and had to pull my plans back from submission because of a setback error. That gave me the opportunity to rethink the whole heating/cooling concept. I just passed the fire risk reduction inspection that we are now subject to. That was an unexpected expense and about 4 weeks of delay. I was hoping to get the roof on before the rainy season started, but it doesn't look good. I am so sick of working on ducts under the house on damp cold ground. The reason they have to be worked on is a combination of really sloppy (professional) installation and my lack of experience in house design. We designed and built this house ourselves from scratch. Heating and plumbing are the only things we couldn't do in our family and friends network. That is the main reason I started considering other ways to run ducting, and why I didn't go back to the original heating contractor for information on my current system. Bill (Dukes)