New 10SEER condenser with existing 8SEER Coil?

[vrocrider]

Any problem installing new 10SEER 5 ton condenser with existing 8SEER Evap coil? Thanks.

[skippedover]

I can't imagine anyone having a new 10-SEER unit still in inventory. What I can tell you is that if it's an AC only unit, it will work but the SEER rating actually achieved will probably somewhere in the 8.5 area. A new evap coil is highly recommended. However if the unit is a heat pump, I wouldn't do it without replacing the indoor coil. An R-22 heat pump with an undersized coil will blow the high side pressure up over 500 PSIG when you switch to heating and the internal pressure valve will open in the compressor. Simply put it probably won't work on a heat pump.

[smokin68]

Add a txv. It should dehumidify well. Seer rating is tossed out the window, but if you're in an area with inexpensive electric and a cooler climate, why not use it. This isn't saying I don't prefer a new matched system.....

[vrocrider]

Why add TXV? Thanks

[smokin68]

Why add TXV? Thanks

With a mis-matched system, this controls the system's superheat, and adjusts according to the load on the coil, running more effeciently while preventing floodback to your compressor(slugging).

[vrocrider]

Thanks. This is installed at and outside the coil? Rough cost for part for 5T?