You've got an existing compressor that's at end of life — or close to it. The temptation is to just buy the same thing again and have done with it. Sometimes that's right. Often it's not. This is your one chance every 15-20 years to fix everything that was wrong with your old setup.

Before you order: what was actually wrong with the old one?

Check the current pressure and capacity of your old compressor. If your old compressor was adequate, buy a new compressor of the same pressure and capacity. Take a moment to decide whether is a good idea to buy a (slightly) bigger compressor, to account for future expansion of your business.

But while you're at it, ask:

  • Was it big enough? Did you run it flat out most of the time, or was it always cycling on/off with room to spare?
  • Was it too big? A compressor that ran at 30% load its whole life was oversized. You can downsize the replacement and save energy every year for 15+ years.
  • Did it cost too much to run? Energy is roughly 70% of the lifetime cost of a compressor. A more efficient replacement pays for itself, even at a higher purchase price.
  • Was the service responsive? If your local dealer took 3 days to answer the phone or didn't have parts in stock, this is the moment to look at manufacturers with proper direct service.
  • Was the compressor room a problem? Heat, dust, accessibility — if the old install was painful, fix it now while you're swapping the machine. You won't get another chance for a long time.

Opportunities people miss when replacing

VSD upgrade. If your demand actually varies through the day (production starts and stops, night shifts use less, etc.), a variable speed drive compressor can cut your energy use 20-30%. But — if your demand is genuinely flat 24/7, VSD is a waste of money. Fixed-speed is more efficient at constant load. See VSD vs fixed speed for when it pays off.

Heat recovery. Probably didn't make sense at your old plant size or your old utility rates. With today's energy prices, it often does. A 75 kW compressor rejects enough heat to give you free hot water, supplemental space heating in winter, or pre-heat for a process. Payback in 1-3 years is normal.

Step up to a better brand. If you bought cheap last time and regretted it, this is the moment. The cost difference at the original purchase isn't worth a second decade of unreliable service. See quality & manufacturer on the piston side, or the screw guide's service, warranty & downtime.

Two smaller units instead of one big one. Instead of replacing one 90 kW compressor with another 90 kW unit, buy two 55 kW units. You get:

  • Redundancy — if one fails, the other handles enough of your load to keep production going
  • The standard industrial weekend rotation pattern: 1 unit runs in the weekend (low-load aux duty), both run during the week, and you swap priority weekly. This is how most well-run mid-size plants actually operate.
  • Easier to add capacity later (just add a third matching unit)
  • Both units have proper service intervals and you can take one offline for maintenance without losing production

Don't just buy — design

You're not just buying a compressor, you're refreshing a system that should last 15-20 years. Worth spending an extra few weeks on it:

  • Talk to 2-3 vendors, not just whoever installed the old one
  • Get a real energy assessment of your current usage (data loggers for 2-4 weeks tells you your actual demand profile, not what you guess)
  • Look at the piping while the system is down for changeover — fix any restrictions, leaks, dead legs
  • Redesign the compressor room while the old machine is out — better ventilation, dust control, accessibility for service

Where to next