Refrigeration Condenser Airflow Calculator
Air-cooled condenser CFM from heat of rejection.
Enter your values
Enter the total heat of rejection in BTU/hr.
Enter the allowable air temperature rise in F.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Required condenser airflow
- 1,235 CFM
- Fans at 3000 CFM each
- 1
- Approx condensing temp margin
- 16.2 F above ambient
Quick answer
Air-cooled condensers typically need enough airflow to keep the air-side temperature rise around 15-20F above ambient.
CFM = (THR in BTU/hr) / (1.08 x dT)
At a glance
| What it does | Air-cooled condenser CFM from heat of rejection. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Total heat of rejection, Allowable air temperature rise |
| Main output | Required condenser airflow |
| Formula | CFM = (THR in BTU/hr) / (1.08 x dT) |
| Cost | Free — no sign-up, no download |
How to use the Refrigeration Condenser Airflow Calculator
- 1Get total heat of rejection (compressor work plus evaporator load) from equipment data.
- 2Choose an allowable air-side temperature rise, usually 15-20F.
- 3Divide by 1.08 x dT to find condenser fan CFM.
Inputs explained
- Total heat of rejection(BTU/hr)
- Enter the total heat of rejection in BTU/hr.
- Allowable air temperature rise(F)
- Enter the allowable air temperature rise in F.
Worked example
Using the values the calculator loads with:
Inputs
- Total heat of rejection24000 BTU/hr
- Allowable air temperature rise18 F
Results
- Required condenser airflow1,235 CFM
- Fans at 3000 CFM each1
- Approx condensing temp margin16.2 F above ambient
Frequently asked questions
What is total heat of rejection?
It is the evaporator's cooling load plus the compressor's added heat of compression.
Coil fouling?
Dirty coils reduce effective airflow — increase design margin 10-15% for real-world dust and debris.
What do I need to enter into the Refrigeration Condenser Airflow Calculator?
Just 2 values: total heat of rejection, allowable air temperature rise. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Refrigeration Condenser Airflow Calculator work out the answer?
Air-cooled condensers typically need enough airflow to keep the air-side temperature rise around 15-20F above ambient. It applies the formula CFM = (THR in BTU/hr) / (1.08 x dT) and shows the working so you can check each step by hand.
Is the Refrigeration Condenser Airflow Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.