why would the air handler change between 410A and 22?? the coil temps are the same.
airflow is the same. the diff. would be efficiency i.e. coil size, and the metering device. 22 and 410 are no diff. other than pressures to reach the same temps.
^ this, and if you're hooking up to an older unit efficiency most likely isn't a huge concern on the job so just match the metering device. I understand what your saying about what the customer paid for but in the end it's the same result. You could have saved a lot of labor just by matching the txv or piston. Hell whenever we do a coil replacement we have to change the txv because our coils come out of the box ready for 410a.
Ok but a 3 ton air handler and a 2 ton condenser, even if you replaced the metering device, there still is a couple of other problems: we are in south Florida and the units are only straight cool so at 3 tons it is typical and we did install a 10kw heater and requires a 60 amp circuit with #6 wire. We pulled out a 2 ton and usually has and had a 5kw heater that requires a 30 amp circuit with #8 wire. So now we have a 10kw heater on a 30amp circuit with #8 wire so you can guess what would happen when the client operates the unit in heat mode. I know we could of just changed the heater to a 5kw heater but even if you lower the fan speed you will still have a problem of not enough temp rise adequate to heat the area "properly" even though we don't use heat all that much but when you want it you should have it. And on cooling a 2 ton duct system with a 3 ton air handler even with the fan speed lowered you still will have a higher static pressure and the unit will sweat in the attic even if it doesn't sweat and the static pressure wasn't that far off and the heater was the correct size, you still have the problem of he was under the impression that he was getting a 2 ton Trane air handler and we did not install that. I wish I could tell you openly here what his cost was to have it installed was. But the biggest in my mind screw up is that we would and still didn't do the right thing for the client. I wish he would of chosen the coil replacement vs the new unit.
You see it is and always should be about doing the right thing and do what you tell some one you are going to do and that is where we as a company failed him.
Ok I know the air handler is technically a Trane because it is made by the Trane company but it is really called tex fan or something like that, real bottom line and the name to me is more than a name it isn't what he paid for.
Oh one more thing think of the price he paid was like the song "my next THIRTY years" I know you have herd that song like a HUNDRED times!!! Lol you get it?
AFAICT as long as you have a metering device that is correct for the compressor tonnage and 350-400cfm per ton you can run a larger evap coil, with a caveat, a too far over-sized coil won't have enough vapor velocity to properly return the oil so it will load up with oil and drain the compressor sump. It also increases the required refrigerant charge weight.