Common sense lessons for techs new to the industry. All of these are based on things I struggled with when I was new. This includes how a system actually works, why it's piped or wired the way it is, and what the equipment is doing. Not calculators (those live in Tools). If you have any requests or corrections, feel free to reach out.
PID
PID Basics
What proportional, integral, and derivative actually do on an HVAC loop — with three small sims you can play with one knob at a time.
Hydronics
Hydronic Loops
How water gets around a building — 2-pipe direct vs. reverse return, and why the closely-spaced tees on a boiler aren't a piping mistake.
Hydronics
Load Piping
Two-way vs three-way valves at the load — variable vs constant system flow, when each one fits, and how the choice shapes the rest of the loop.
Drives
VFDs
What a variable frequency drive does, the cube-law energy story, and the run-command vs. speed-reference parameters every controls tech meets — with a widget for the configuration mistake that catches everyone.
Hydronics
Pump Control
How the BMS controls a hydronic pump — pump curves and the operating point, DP control with a remote sensor, and DP setpoint reset. Pairs with VFDs and Load Piping.
Hydronics
Hydronic Balancing
Getting design flow to every load — calibrated balancing valves, automatic balancing valves, and PICVs. With a widget that shows what each one does when system pressure swings.
HVAC
Psychrometrics Basics
The seven properties on a psychrometric chart, what each one tells a controls engineer, and the gotchas that bite — with a pool-room widget that shows why dew point is the number to watch.