I had a Goodman GSX140181 1.5 Ton 14 SEER Air Conditioner R-410A installed with a Goodman CHPF3636B6 3 Ton Horizontal A Evaporator Coil installed by a contractor. It came as a kit, along with a Goodman TX2N4A Kit 1.5-2 Ton R-410A Thermal Expansion Valve. Note that it's a 3T evaporator and a 1.5T condenser. That's the way the kit came, and it was priced well, so although the tonnage is different, it was sold as a kit, to be installed together, and was supposedly the way the manufacturer intended for 1.5T worth of cooling to be delivered.
The contractor installed the system and it's cooling nicely, but later I found out that he did not install the TXV (it's still in the box, in the attic). When I asked, he said it was not necessary because he used the piston/orafice that was shipped with the condenser unit. I saw that piston, which was in a bag, stapled to the condenser unit.
Although the system is cooling fine, and I'm getting about a 12 to 14 degree F temperature drop, I'm wondering about efficiency, long-term reliability, warranty, etc.
What's the difference between a TXV install versus an installation with the appropriately sized piston? Will it effect efficiency, reliability, warranty, or anything else? Is it worth the trouble to evacuate, install the TXV, and recharge?