This isn’t a manufacturer-approved configuration, and Roman is upfront about that. But two years in, the system is holding steady — no fan motor failures, stable space temperatures, and a noticeable drop in energy bills compared to the old straight-cool, electric-resistance setup it replaced. He breaks down the engineering behind it: how the stacked units share ductwork without cross-talk under normal operation, the plan for handling backfeed if one unit ever fails (block-off strategy, similar to fan wall arrays), the MERV 15 filtration and CO2 demand control built into the design, and why static pressure and undersized 30-year-old ductwork are the next things on the punch list to improve.

Topics covered:

• Why the church’s tiny attic access ruled out a standard 20-ton replacement
• How four 5-ton VRV/VRF units were stacked into a cube configuration on shared ductwork
• Running multiple indoor units off one common thermostat
• MERV 15 filtration, CO2 demand control, and a humidity-based outside air damper
• What happens if one unit in the cube fails — and how backfeed is handled
• Two years of real-world performance data: energy savings, motor life, and static pressure
• Roman’s take on when it’s okay to build outside the manufacturer’s playbook

If you’ve ever stared down a retrofit where every “normal” option was physically or legally off the table, this one’s worth watching. Roman’s not telling you to go improvise on your next job — he’s showing what it looks like to understand the science well enough to take responsibility for a creative solution and make it work for the client.