Learn
High-quality, field-first guides that match the calculators. Real measurement steps, common mistakes, and OEM-first safety notes.
How to Measure Superheat and Subcooling (Field Workflow)
10 minA practical step-by-step workflow for getting reliable SH/SC numbers in the field: probe placement, steady-state checks, and the mistakes that cause “chasing your tail.”
Understanding Your PT Chart (Saturation, Dew vs Bubble, and Pitfalls)
9 minWhat “saturation” actually means, how to read a PT chart fast without mixing units, and when dew vs bubble matters for blends in real field measurements.
Duct Sizing Basics (Friction Rate, Velocity, and Tradeoffs)
11 minA duct-sizing primer for real jobs: what friction rate and velocity represent, how constraints change the answer, and how to avoid common “looks right but performs wrong” mistakes.
Refrigerant Charge (Additional Charge): What It Is, How to Estimate It, and What It Isn’t
10 minA field-first guide to “additional charge” estimates for line set length/diameter changes: what you’re actually calculating, where techs get burned, and how to keep OEM procedures in charge.
- If you’re charging: start with measuring superheat and subcooling so your numbers are trustworthy.
- If your PT numbers feel “off”: read understanding your PT chart (units + dew/bubble pitfalls).
- If airflow/duct changes are on the table: read duct sizing basics to frame friction/velocity tradeoffs before you cut metal.