It's fine as long as the jars are covered with the water and the lid is left loose in place. You'll find many discussions here about doing it as it is a fairly common practice for many of us with the Presto 23 quart model.

Dave

PS: I wouldn't try the double stacking tho. JMO

Thanks very much!

Why does the lid need to be loose? I usually leave mine on to limit the steam in my kitchen when using it for BWB. Should I be afraid of developing pressure and blowing the lid off?

Chris

I'm new here, but I recently looked up the question of double stacking. NCHFP actually says that you can double stack both in pressure canning as well as boiling water canning, if you use a rack in between layers. For boiling water canning, the top layer of jars still needs to be covered by 1-2 inches of water.

Here is a link to the Canning FAQ's of NCHFP. Double stacking of both BWB and PC is discussed about 8 down under the General section. Hope this helps.

Here is a link that might be useful: NCHFP FAQ's for canning