Basement Dehumidifier Woes: Even AlorAir Isn't Good Enough?

Basement dehumidifiers seem to be treated as disposable appliances. You buy one, run it for a year or two, and then replace it when it stops pulling water out of the air. I was hoping to escape that cycle when I bought an AlorAir Sentinel HD55 (paid link) from Amazon in September 2022. It was marketed as a commercial-grade dehumidifier. I expected that to mean it would be more durable than the usual big-box-store models, or at least more repairable if something went wrong. For a while, it was great. From Icing Up to Unusable After roughly a year and a half or two years, though, the coils started icing up. At first it was only occasional. Then it happened more and more frequently. I did the usual research and troubleshooting. I cleaned the filter, replaced the filter, checked the coils and fins, made sure the room wasn’t too cold, and tried to rule out airflow problems. The Sentinel HD55 supposedly has an automatic defrost system, but whatever was happening kept getting worse.…