•Brett Wetzel and Kevin Compass open theadvanced Refrigeration podcast with complaints about constant travel and terrible hotels, including broken blinds, bad smells, and cockroaches, plus a rule for avoiding sketchy areas. Kevin recounts a brutal week on a jobsite with an electrical contractor who miswired coils, phases, and controls, causing repeated troubleshooting, power trips, and a major shutdown when rooftop unit drainage spilled into an electrical trough. He then describes training in Chino, California on a Hussmann CO₂ rack with redundant valves, a suspected stuck oil solenoid causing overheated oil lines and high bypass activity, and how correcting it reduced compressor speed. They debate ejectors and parallel compression control, flash tank instability, oil pressure issues, controller limitations, and note miswired electric defrost heaters and CO₂-to-CO₂ heat exchanger failures.

Brett Wetzel and Kevin Compass open the advanced Refrigeration podcast with complaints about constant travel and terrible hotels, including broken blinds, bad smells, and cockroaches, plus a rule for avoiding sketchy areas. Kevin recounts a brutal week on a jobsite with an electrical contractor who miswired coils, phases, and controls, causing repeated troubleshooting, power trips, and a major shutdown when rooftop unit drainage spilled into an electrical trough. He then describes training in Chino, California on a Hussmann CO₂ rack with redundant valves, a suspected stuck oil solenoid causing overheated oil lines and high bypass activity,and how correcting it reduced compressor speed.

They debate ejectors and parallel compression control, flash tank instability, oil pressure issues, controller limitations, and note miswired electric defrost heaters and CO₂-to-CO₂ heat exchanger failures.

Brett Wetzel and first-time guest Kevin Compass kick off the Advanced Refrigeration Podcast in a chaotic mood after tech failures, traffic, and a rough week on a large grocery-store refrigeration job where electricians are slowing progress, skipping work on energized circuits, and delaying rack startup. They talk about traveling, hotel safety concerns, sleep deprivation, and returning the following week because verification is only partially complete and the rack couldn’t be started. The conversation shifts into Danfoss case control and pack controller details, including correcting earlier misunderstandings about fan shutdown logic being handled automatically by the pack controller if programmed correctly. Brett walks through Danfoss thermostat control settings (on/off vs modulating), notes recommended minimum modulation percentages (around 3.6–4), and discusses guidance from Brian Rogers about avoiding modulating on dual-temp islands unless using an EPR, especially on CO2 systems due to potential icing issues. They explain S3/S4 sensor weighting (inlet vs discharge air), caution against using weighted control where return air can be blocked (turkey, produce, beer cases), and discuss how modulating control can reduce cycling and improve rack stability—especially on low-temp circuits that affect medium-temp load and BGV stability. They debate CO2 ejector versus high-pressure valve operation, with Brett noting updated information that ejectors run as primary until high utilization before the HPV opens. The episode also covers Danfoss network scheduling for case enable/shutdown staging, group-based defrost schedules, why long stage delays can cause short cycling after power blips, the value of adding minimum loop protections, and the confusion of chained controller calculations. They end by noting a potential wiring/relay issue on ejector solenoids (not all on solid-state relays), joking about communication challenges with a Scottish colleague, and signing off as Brett heads to sleep before an early flight.