It would be in your best interest to let your HVAC contractor handle the demo of your existing HVAC system. Certification is required for the handling of refrigerants. All refrigerants must be recovered. An intentional release of refrigerants can lead to a fine of $10,000. This has been discussed before, see the link. Here is a link that might be useful: Gardenweb string on Refrigerants

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.

If you were me, you would run away from Trane hi efficiency heat pumps. I have had the new unit, air handler, new lines for almost 3 years. The installer is certified by Trane and the unit has a 10 year extended warranty. When it was sold to me I was told everything is covered. I now have a 850 dollar bill on my hands because Trane refuses to pay the installer for work that had to be done on the unit last month. They have worked on the unit 5 times in 3 years. I can email you the documents that show that Trane will not back up the warranty, if you send me your email. By the way the unit does not currently work and I am not sure who to call, other than my attorney. Trane seems to not care when issues are pointed out. They go on selling the units like hot cakes and ignore those such as myself that have units that do NOT work. eddie_brown@yahoo.com

If the thru the wall unit is rated for 20A, then yes, use the existing 12/2 wire for 240V. Simply take out the 1 pole breaker and replace it with a 2 Pole breaker, making sure the new double breaker is attached to different legs in the panel. If you don't know how to do this, check a wiring book. Then attach the black wire to one breaker of the pair, and the white wire to the other breaker. Place some black electrical tape on the white wire at the panel and the new unit. If the new unit is 15A, then use a 2 Pole 15A breaker. If the new unit is rated at 25A or more, you will need to rewire as well as bigger breakers, assuming you now have 12/2.