R 454B Start Up/Commissioning Calculator
* This calculator is a training aid that uses your inputs to suggest practical next steps in an effort to teach how different adjustments and their impact can help dial in a system. It is not intended to be a substitute for journeyman level experience and judgement.
R-454B • TXV/EXV • Subcooling & Superheat Trainer
Training aid: Uses your inputs to suggest practical next steps. Use judgment; not a rulebook.
Important:
Set and verify airflow (CFM) first. Let the system run a minimum of 15 minutes or until pressures stabilize before using the calculator and after any adjustment. R-454B often stabilizes slower than R-410A.
How to use (quick)
- Set blower airflow. Let the unit run at least 15 minutes or until pressures stabilize.
- Enter airflow, ΔT, pressures, line temps, OAT, Indoor Temp.
- Optional: enter Return RH% and Supply RH% for total & latent BTUh.
- Enter Target Subcool (nameplate) and SC tolerance (adjustable).
- Click Calculate. Follow the Primary Next Step.
TXV/EXV systems are dialed in by Subcooling. Superheat is monitored for safety and fine-tuning.
Target Airflow (CFM): —
Actual Airflow (CFM): —
CFM per nameplate ton: —
Subcooling (SC): —
Target SC: —
Superheat (SH): —
Evap Sat (°F): —
Cond Sat (°F): —
BTUh (sensible est): —
Estimated tons: —
CFM per estimated ton: —
CTOA (Cond Sat − OAT): —
Capacity Summary
Total
BTUs: —
BTU ton (total): —
CFM per total ton: —
Sensible
BTUs sensible est.: —
BTU ton sensible: —
CFM per sensible ton: —
CFM apportioned to sensible:
Latent
BTUs latent est.: —
BTU ton latent: —
CFM per total ton: —
CFM apportioned to latent:
Suggestions
- Enter values and press Calculate.
Airflow guidance is from ΔT. Charge guidance is by Subcooling to target. Superheat is safety/trim and can rise on heavier loads.