Drizair 2400 and Drizair 2000 are 140 pints and 110 pints AHAM per day, respectively.
My understanding is both the 2000 & 2400 are discontinued, as R22 Hydrochlorofluorocarbon is being phased out as per compliance with the Montreal Protocol. R22 systems are no longer manufactured after 2009, but can be serviced until 2020.
The 2800i and 3500i use the more efficient R-410a high pressure systems.
Listed in order of rated output:
Drizair 2000 - 110 pints -Discontinued R22-
Drizair 2800i - 130 pints New R-410a
Drizair 2400 - 140 pints -Discontinued R22-
Drizair 3500i - 170 pints New R-410a
I don't want to oversimplify. There is more to the 2800i & 3500i than just the output differences of the new systems. The new units feature intelligent control panels displaying inlet/outlet conditions using an on-board thermo-hygrometer, and interface with Hygrotrac's remote monitoring systems. Better performance per amp than the older systems as well. Easier cleaning and maintenance design.