Heat Pump Airflow Calculator
Airflow checks for a heat pump in both modes.
Enter your values
Enter the system size in tons.
Enter the cfm per ton in CFM/ton.
Enter the auxiliary heat in kW.
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.
- Design airflow
- 1,200 CFM
- Heating airflow
- 1,260 CFM
- Aux heat rise
- 26.3 °F
- Supply temp with aux at 70°F return
- 96 °F
- Aux capacity
- 34,120 BTU/h
Quick answer
Heat pumps generally need 400 CFM per ton in cooling and slightly more in heating to keep supply temperatures comfortable.
CFM = tons x 400; strip rise = kW x 3412 / (1.08 x CFM)
At a glance
| What it does | Airflow checks for a heat pump in both modes. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | System size, CFM per ton, Auxiliary heat |
| Main output | Design airflow |
| Formula | CFM = tons x 400; strip rise = kW x 3412 / (1.08 x CFM) |
| Cost | Free — no sign-up, no download |
How to use the Heat Pump Airflow Calculator
- 1Enter the system tonnage and target CFM per ton.
- 2Add the auxiliary strip heat capacity in kW.
- 3Verify the temperature rise with strips on is inside the air handler's listed range.
Inputs explained
- System size(tons)
- Enter the system size in tons.
- CFM per ton(CFM/ton)
- Enter the cfm per ton in CFM/ton.
- Auxiliary heat(kW)
- Enter the auxiliary heat in kW.
Worked example
Using the values the calculator loads with:
Inputs
- System size3 tons
- CFM per ton400 CFM/ton
- Auxiliary heat10 kW
Results
- Design airflow1,200 CFM
- Heating airflow1,260 CFM
- Aux heat rise26.3 °F
- Supply temp with aux at 70°F return96 °F
- Aux capacity34,120 BTU/h
Frequently asked questions
Why does heat pump air feel cool?
Supply air is typically 95-105°F, below body temperature, so it feels cool even while heating effectively.
More airflow in heating?
Slightly higher airflow improves capacity and keeps head pressure sensible.
What do I need to enter into the Heat Pump Airflow Calculator?
Just 3 values: system size, cfm per ton, auxiliary heat. 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 Heat Pump Airflow Calculator work out the answer?
Heat pumps generally need 400 CFM per ton in cooling and slightly more in heating to keep supply temperatures comfortable. It applies the formula CFM = tons x 400; strip rise = kW x 3412 / (1.08 x CFM) and shows the working so you can check each step by hand.
Is the Heat Pump 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.