No HVAC tech here just a homeowner. I have an older home that was designed for heat and AC but it was made with all supplies in the floors except in the living room where they are in opposite walls near the floor. I would rather have cold air from the ceiling and hot air from the floor. Since you don't have to worry about heating from these vents I would try to get them from the ceiling. That said my system works well. I think the thing with it is that there are air return ducts in every room(none in the bathroom) and in each hallway on each floor of my house. The rooms on the 2nd and 3rd floors have the returns near the ceiling and all large rooms have more than one return; one in the wall near the floor, the other in the wall near the ceiling. Also from what I can see and what my neighbors say, is that the supply ducts are large which allows plenty of air flow. The outlets from the floor throw the air directly up into the room, not from side to side. This works well in the summer and winter. In the winter the living room that has the outlets in the wall blow the air in front of and across the outer wall which contains floor to ceiling(13FT) windows and french doors. In the summer I place directional louvers over these which direct the cold air up into the room. Even though this works If I had a choice I still would rather have that cold air coming from the ceiling.

well Dave, I see that the contractor posted his findings so I wouldn't worry too much about upsetting or offending anyone. it isn't unusual for there to be conflicting opinions, but the fact is that you and he are the only ones who have seen the ductwork. his discription of your return air setup is suspect. I see he is advising you to wait out the summer to do any duct/return modifications. if you can, do. it is awfully hot to be modifying ductwork this time of year. a rushed job isn't a good job. better someone take the time to properly install and seal ducts. it kinda bothered me that no mention of duct or return sealing was mentioned. of course the discussion is pretty technical. but I find that leaky ducts/returns are often overlooked. when you talk about the kids rooms and the 3-4 temp difference, you mention west facing windows. how many & what approx size are in each room? what type of windows do you have? single pane, double pane? metal frames, vinyl frames? clear glass or low-e glass? if the temp difference is due to the west windows..and it would be here in my area, then there are a couple of things you could try. block the afternoon sun from the exterior for a day or two and see if this evens out the 3-4 degree temp difference. wouldn't have to look great, or be permanent, just stop the solar gain. if you can keep the heat from entering the house, then the a/c doesn't have the added load to temper. exterior shading is the best route. rather than interior shades & curtains. beat the heat before it gets inside. if this works then invest in solar screens. yes they are darker than normal screens, but they will minimize heat gain. if windows are double paned..you can't install window tints as it will increase heat between panes and blow the seal. awnings and bahama shutters are other options but to me..at this point solar screens would be more cost effective. right now you have more time than solutions, so give it a try. don't worry about riling those guys up..they live for that stuff. Shophound & the guys have a good handle on things, so let them talk themselves around. I have to admire your restraint & patience. you are aware that 1" pleated filters are very restrictive? for now I'd change to a less restrictive filter. at least then more air will return to the unit. hang in there. best of luck.

You can get some metal foil duct tape and tape them up if you want. Just have to remove it whenever the doors need to be opened. Some small air leak is common but still not desirable. How cold is the air coming out of the ceiling vents? I use a cheap meat thermometer on a cable with a digital readout. While your at it, measure the temp of the air going into the return vent and the outside temp and the temp of the exhaust air coming out the top of the outside unit. You can even stick the probe under the insulation on the big and on the small copper lines behind the outside unit and measure those temps. Then report all that here.

We just installed a new shower unit in a guest ensuite bathroom. Now, whenever we turn on the bath/shower in the master bedroom ensuite (a different room), water leaks from the shower head in the guest room (for as long is the water is running in one room, it will drip in the other!). Is this a venting issue? Appreciate any ideas>