Makeup Air Heating Load Calculator
Heating capacity needed to temper makeup air.
Enter your values
ⓘ Live results
Results
- Heating capacity required
- 162,000 BTU/hr
- In tons of heating equivalent
- 13.5 tons
- Temperature rise
- 60 °F
- Gas furnace input (80% AFUE)
- 202,500 BTU/hr input
Quick answer
Tempering makeup air uses about 1.08 BTU/hr per CFM per degree F of temperature rise, which quickly adds up to a large heating load for kitchen-size airflows.
BTU/hr = 1.08 x CFM x (indoor temp - outdoor design temp)
How to use the Makeup Air Heating Load Calculator
- 1Enter the makeup air CFM that must be tempered.
- 2Enter your indoor design temperature and winter outdoor design temperature.
- 3Read off the required heating capacity, converting to furnace input if needed.
Worked example
Using the values the calculator loads with:
Inputs
- Makeup air CFM2500 CFM
- Indoor design temp70 °F
- Outdoor design temp10 °F
Results
- Heating capacity required162,000 BTU/hr
- In tons of heating equivalent13.5 tons
- Temperature rise60 °F
- Gas furnace input (80% AFUE)202,500 BTU/hr input
Frequently asked questions
Why is makeup air heating so large?
Every CFM of cold outside air needs continuous heating whenever the exhaust runs, and kitchen exhaust systems often move thousands of CFM.
Can heat recovery help?
Yes — an energy recovery ventilator or heat wheel can recover 50-80% of this load from the exhaust air stream.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.