I realise that this has already been discussed, but one question that hasn't been asked and answered is why do reflux stills you can buy i.e. spirits unlimited or still spirits, have closed condensers. I have the 25lt ss reflux still from still spirits that is not vented and is closed off from the "atmosphere", and works fine, albeit only producing 75% from the wash.
This is why I am making the valved reflux still with the help of my engineering father in law, which should hopefully produce 94-95%. I suppose I am becoming a purist . I have sourced all the parts necessary, which are all stainless steel (including the 25lt boiler, column and condenser). The cloumn on my still will be 1.2m with the tee, nipple and cap added to this height. So I guess what I am asking is what is the difference between these stills to warrant a closed or open air condenser.
Are you talking about the reflux condensers, how they are at the top inside of the column on still spirits, and open on the side in the offset head?
Pretty much the open one is only open because it doesn't need to be closed. It's like a "virtual cap" on the column since it should have the cooling capacity to condense all the vapors. It also provides a little extra safety having it open because it can't build pressure and explode.
The closed one doesn't and shouldn't have the capacity to condense all the vapors. The product vapors have to go past it to reach the jacketed product condenser.
Main reasons for having the offset head are:
1. Much more control over reflux ratio as you are adjusting the actual amount returned, vs the amount of cooling water to a coil you can't see.
2. Only one condenser required, you don't need that separate product condenser.
3. Ease of construction.
. I have sourced all the parts necessary, which are all stainless steel (including the 25lt boiler, column and condenser). The cloumn on my still will be 1.2m with the tee, nipple and cap added to this height. So I guess what I am asking is what is the difference between these stills to warrant a closed or open air condenser.