Okay! Here goes! I have been brewing for almost a year. I got tired of extract brewing pretty quickly. I moved onto a 5 gallon all-grain system that used a manifold. Currently, I am doing 3 gallon batches BIAB with a five gallon mash tun. For Christmas I am getting a 10 Gallon mash tun with a false bottom. I want to then start step mashing now that I have a couple favorite recipes/home made recipes. So, with step mashing should I remove all of the wort or just part of the wort? I would think it would be easier to just remove all of it, heat it to the desired rest temperature, and then put back into the mash tun. How long do I hold the rests at the different temperatures? Does anyone have a chart of the different rest temperatures, and what the purpose of each rest is?
This isn't the best way to do step mashing. If your tun is not direct fired or you aren't using a heat exchange system of some sort, the only option left is to do infusions of boiling water to raise the temp. Removing all the wort, heating it and then putting it back in the tun with the grain seems like you'd be likely to denature enzymes vital for conversion. I use a direct fired MT and a pump to constantly recirc. I know that if I am not careful when heating (manually) I can end up with a beer that has a high finishing gravity and I have isolated that down to killing enzymes while overheating. Then again, I am sort of super heating wort, where if you were gentle enough maybe your approach would work. Albeit, with a lot of transfers and extra work. Its homebrewing so I'd say give it a try at least. But only after doing a few single infusion mashes first. Then repeat a recipe with your step technique to determine if you like the difference.
Just curious... what kind of improvement are you looking for (or what problem are you trying to fix) by going to step mashing? Have you read "How to Brew?" The old version is available free at www.howtobrew.com . IIRC it describes the purposes of each step, and explains why some of them aren't necessary (or may even be detrimental) with modern malts. FWIW, the vast majority of homebrews, including award winners, are done with single infusion mashes. There are exceptions, but the fact that you're asking about the purpose of each rest suggests to me that step mashing may be a solution looking for a problem. As @warchez said, your practical options for step mashing are pretty much boiling water infusions or a RIMS/HERMS system.
