I was torn between two tier and single. This is gonna sound silly but even though I was going to recirc with a pump, I wanted to gravity feed into the boil kettle, plus, I figured that would put the boil kettle at a much lower/ safer height. RIght now I am only using one pump, one of the things I had considered was a bar so I could slide the pump beneath the kettles, should I mount gang boxes on the stand? If I do do I then need to ground the stand as well as the kettles, or just ground the kettles to the wired ground?
I have the same design dilemma. Even though I have the pumps, would like to be able to gravity feed HLT to MLT for fly sparging and quick dumps for dough in and not be limited to pump max flows. I am goiung to run 3/4" hose (FDA/NSF) and may have better flows without the pump or both in parallel as you are limited by pump displacement.
I also have a two story garage but not much floor area. Easier to go up then single tier.
Pluses from current system; RIMS and Pump cobmi good. Cooler so far the best MLT even though I have keg and Minibrew options. Cooler has perforated custom false bottom ILO manifold, but also uses a 3 screen (Zymico) manifold setup for any grain bypass. Love the Minibrew HLT. Went electric on the RIMS and HLT (240V, 1.5Kw and 4/5Kw respectively). Would not go back to gas fired for those two at all. Still gas fored for BK, happy with that. Conical fermentor - no carboys ever again.