Save energy by recovering heat.

The amount of heat that is generated by an air compressor is one of the most important things to understand as a compressed air system auditor, technician, installer, and most importantly, as an end-user.  

The reason for this is that as much as 90% of all of the energy that goes into an air compressor is lost as heat. Since compressed air is an expensive utility, this presents a considerable opportunity to save energy, and even be eligible to receive an incentive from a local utility company for doing so.

Note: Many regional utility companies offer compressed air and heat recovery incentives. Find a comprehensive list of programs in Canada on the Natural Resource Canada website here. For programs in the United States of America, view the Database of State Incentives for Renewables & Efficiency (DSIRE) website here.

Estimating heat in BTUH's

The following is a simple rule-of-thumb formula for approximating how much heat is generated by an air compressor. This rule-of-thumb formula is applicable to all air compressors, both rotary screw and reciprocating:

  BTUH = Air Compresso Horsepower x 2,520

Here are some examples of various air compressor horsepower sizes and their approximate BTUH ratings:

  • 100 HP = 252,000 BTUH (100 x 2,520)
  • 50 HP = 126,000 BTUH (50 x 2,520)
  • 25 HP = 63,000 BTUH (25 x 2,580)
  • 10 HP = 25,200 BTUH (10 x 2,520)

To put this in perspective, the average 2,000 square foot home uses a 60,000 BTUH furnace, or in other words...a 100 horsepower air compressor can heat 4 houses.```

Heat management is critical to compressed air.

For compressed air systems to operate the way they should,  heat exhaust must be managed.  We cool compressors with fresh air or water to allow them to operate correctly, if we do not provide enough cooling then air compressors suffer, and so does compressed air quality.

So what does this mean to the compressed air auditor?

  • The rejected heat from air compressors is recoverable and a substantial source of heat energy.  In many regions, programs and incentives exist to help promote these opportunities.
  • Hot compressor rooms mean hot air compressors – look for compressed air quality problems such as oil and water in the compressed air. Look for air compressor and air dryer maintenance concerns.
  • Air compressor efficiency is improved by providing cooler inlet air and so a hot compressor room is an inefficient one.