I can see from your replys you know what your doing and are experienced. I did hating and cooling work back till 83. I am now trying to get back into the trade and enroled in a adult ed. School. I have to say it was a waste of $5000.00. All I really got out of it was an EPA certificate. Controls (elect) are no problem, its this new super heat etc which we never used back then Basically a more precise charging method to me. My question. In my own home I'm getting ready to install a new a/c unit. It's a 3 ton, but I needed a 2-1/2 ton. I plan on changing the compressor to a 2-1/2 ton, figuring that's actually what seer is, a larger coil. I also want to install a heat exchanger, change the piston type orfice to a TXV, and install a receiver. The receiver only because it will help not being so precise in my charge. What do you think? I'd appreciate any input.

Superheat and subcooling have been around since the first refrigerant it is just that only real pros new what it was and how to use it. It was always easy to just dump the refrigerant in until the suction line got beer can cold LOL.

I had a ace in the hole all my life. My Grandfather came to this country with a guy named Doctor Carrier and helped to develop modern refrigeration and A/C. My father learned from him and I learned from my father. I guess we kind of kept it in the family.

One of the first things I learned was superheat and subcooling because you cannot charge a system properly without it period especially today when a one ounce difference in a charge can cost you up to 1 SEER worth of efficiency.

I suggest you get the proper tools and learn how to use them correctly. Articles on superheat subcooling are all over the net just use Google.

Sounds like some extra work to change the compressor out for just ½ ton but if you have the parts it is only your free labor that counts.
I do not believe you will want to use a receiver. I think what you are talking about is a suction line accumulator to help in an over charge condition to help save the compressor from taking a liquid slug down the suction valves where only gas should be. A receiver is OK if you plan on pumping down your unit and all the refrigerant will not fit in the condensers coil other wise it is a waste of time on a central A/C unit.

SEER is a lot more than just a bigger coil. Many higher quality/less current draw system components are used to create a higher SEER system. The A coils are also different among other things.

Remember to include a hard start device and a time delay if you are going to use a TXV.Compressors do not like to restart against the pressure that most TXV's trap in the system. On item you might try is a liquid eye or sight glass in the liquid line going to the A coil inside. Not only will you be able to see if there is a moisture problem with your system but you will also know when the systems liquid line is full to at least the sight glass.

This info is just the tip of the iceburg but it is a start for you.

Learned something re: accumulator vs receiver

Thanks a million HVAC1000