Usually options are 30 pint, 50pt and 70pt and the bigger it is the more power it needs. I think 50pt is adequate but consider your AC having to compensate and the extra power draw from the plug/panel.They really arent that expensive to buy new.... a 70 pint unit should be adequate.
Frigidaire 70 Pt. Dehumidifier FAD704DWD - The Home Depot
The Frigidaire 70 Pt. Capacity Dehumidifier allows you to control the relative humidity in the room with Effortless Humidity Control. The easy-to-clean washable filter captures dust from the air and keepswww.homedepot.com
They all generate the same amount of heat per amount of water to be removed from the air. Like if your trying to pull one gallon of water from the air, the 70 pint takes 2 hours while the 30 pint takes over 4 hours. So sure, the 70 is putting out more heat while running, but it runs a much shorter period of time and in the end they both put off about the same total amount of thermal energy so long as they are actually regulating the environment they are in. And the bigger the dehumidifier, the bigger the bucket it comes with meaning less emptying.Usually options are 30 pint, 50pt and 70pt and the bigger it is the more heat it generates. I think 50pt is adequate but consider your AC having to compensate.