# How to Convert KW to Heat L/S Air

The performance of air conditioning and heating systems depends significantly upon air flow. Liters per second (L/S) measures air flow, or the volume of air, produced by an air conditioner or heater. The calculation of liters per second depends on the power of the unit, measured in kilowatts, and the change in temperature of the air flowing into the space to heat or cool.

## Step 1

Determine the amount of kilowatts. Find the kilowatt number on the appliance's label or the specifications page of the operator's manual. If neither the unit nor the manual displays kilowatts, look for the ampere (amp) and voltage rating. Multiply the amperes by volts by 1,000.

## Step 2

Calculate the cubic feet per minute (cfm). Multiply the kilowatts by 3.413 by 1.0 for a 1-phase motor or 3.413 by 1.732 for a 3-phase motor. Record this number as the numerator, or the first number in a division equation. Multiply the difference between the temperature of the air after it leaves the heat source and the temperature before it enters the source by 1.08. Write this number as the denominator, or second number in a division equation. Divide the numerator by the denominator to obtain the cubic feet per minute.

## Step 3

Convert the cubic feet per minute to liters per second (L/S). Divide the number of cubic feet per minute by 2.119 or multiply it by 0.471920717. One liter per second is the same as 2.119 cubic feet per minute.

## Things You Will Need

- Calculator
- Heating or air conditioning unit owner's manual
- Manual S from Air Conditioning Contractors of America

## References

- Florida Solar Energy Center: "Impact of Evaporator Coil Air Flow in Residential Air Conditioning Systems"; D.S. Parker et al.; 1997
- Edisto Electric:Do It Yourself Energy Audit
- City of Seattle: Standard Commissioning Procedure for Packaged Heat Pump (Air-to-Air) & Air Conditioning Units: April 1999
- NCEES: Fundamentals of Engineering Supplied-Reference Handbook, Fifth Edition; 2001
- Energy Codes; Energy Codes 2010 July: Residential HVAC Design; Gil Rossmiller; 2010

## Resources

- Natural Resources Canada: Heating and Cooling with a Heat Pump
- UNC Chapel Hill: How Many? A Dictionary of Units of Measurement: L; Russ Rowlett; 2008
- NIST Guide to SI Units: Appendix B8
- Campbell Scientific (Canada); Flow Conversion; November 2009
- PDH Center: PDH Course 156: Understanding Motor Nameplate Information: NEMA v/s IEC Standards
- UNC Chapel Hill: How Many? A Dictionary of Units of Measurement; Russ Rowlett; 2008
- Air Conditioning Contractors of America: Verifying Manual S Procedures