Unless you want to spend $1450, or more for a 3 gallon distiller they are 1 gal distillers [6 Gal per 24 hrs.
I just bought another 4000 model to go with the 4000 that I have had for years. It started acting weird, so I took the fan assemby apart on the top, took it out to the garage and used the air comporessor to blow a bunch of dust that had collected.
That helped, but since I have had it for many years I figured it was time to get a new one. They said they will recondition it for a $100, so if it gets any worse that is what I'll do. Living alone I get get by with all my water needs. Wouldn't be enough for a family.
I don't think any of them have alluminum. The only one that mentions the cooling condensor is the model 7000. It has stainless steel. Ask if you call, let me know. The 4 water filters I mentioned in that earlier post claims the waterwise eliminates Aluminum.