It's difficult to find a consistent straight answer on this. I asked earlier today on Reddit, and was told "It’s common to upsize the indoor (evaporator) coil to get greater efficiency".
When I search "next size up evaporator greater efficiency", these are the top results:
- "Yes, it’s bad if your evaporator coils are sized bigger or smaller than your condenser coils."
- People arguing 9 years ago on a forum about whether you want the condenser smaller or larger. Little agreement suggests people don't know what they're talking about.
- "Matching Evaporator and Condenser Coils – An Absolute Must"
Number 6 says "Mismatched Coils Can Really Mess Things Up". Number 5 says "I usually go a half ton larger on the evap coil. The added surface area slows airflow and you get better heat and dehumidification.", while the answer to "Can you Oversize an evaporator coil?" says the exact opposite: "After extensive research, we have found that having a matched or oversized evaporator coil will not control humidity enough. Rather it increases the humidity level in the home, especially at night. The reason is that the evaporator cannot get cold enough to properly dehumidify the air, causing your air to feel sticky and humid."
I've tried other search phrases, and the results are generally the same: all over the place. I think this is a representative sample, so I won't bother exhaustively listing them all.
What's the truth? Is there any evidence to back up the claims of a particular side?