Episode 5: Seasonal Maintenance Checklist for Centrifugal & Rotary Screw Air Compressors

In this episode of Beyond Compression, we share a combined perspective from the compressed air experts at FS-Elliott and FS-Curtis on how seasonal temperature changes impact compressor performance, efficiency, and reliability. From summer heat and humidity to winter cold and condensation risks, we explore how shifting ambient conditions influence both centrifugal and rotary screw compressors—and what operators can do to stay ahead of them.

We also discuss why following a structured, OEM-recommended maintenance approach is critical to maintaining performance year-round, and how proactive preparation helps reduce risk, extend equipment life, and avoid unplanned downtime.

In this episode, you’ll learn:

•  How temperature and humidity changes affect compressor performance and system stability 
•  The four critical factors that influence reliability: cooling, lubrication, filtration, and moisture management 
•  Key maintenance practices to prepare for both summer and winter operating conditions 
•  Why seasonal challenges are predictable—and how to prevent them before they impact your operation 

Depending on your location, you may be preparing for peak summer heat or transitioning into colder winter conditions. In either case, your compressed air system is facing known challenges that require attention.

👉 Learn more about seasonal compressor maintenance by reading our blog: https://www.fs-elliott.com/blog/seasonal-maintenance-for-centrifugal-and-rotary-screw-compressors

Follow FS-Elliott on LinkedIn and Facebook for more insights from our engineering and service teams, and join us as we explore smarter, cleaner, more reliable compressed air systems.

Transcript

SPEAKER_00 0:10

Hello, everyone, and welcome back to Beyond Compression, the podcast where we share ideas, stories, and practical insight around compressed air systems. Each episode brings you conversations with the engineers, product experts, and industry professionals working behind the scenes to improve reliability, efficiency, and performance. I'm Barbara, your host for today's episode, and today we're talking about something every facility deals with but doesn't always plan for: seasonal changes and how they impact compressed air system performance. From summer heat to winter cold, these shifts affect everything from efficiency to reliability and even downtime risk. And joining me today are two experts who see this play out in the field every day. Dave, director of aftermarket sales at FS Elliott, focusing on centrifugal compressors, and Ray, Senior Warranty and Technical Services Specialist at FS Curtis, bringing the rotary screw perspective. Thanks for being here, guys.

SPEAKER_01 1:14

Thanks, Barbara. I'm always glad to be here.

SPEAKER_02 1:16

Happy to join. This is one of those topics where everyone knows it matters, but it usually doesn't get attention until something goes wrong.

SPEAKER_00 1:24

Yeah, it doesn't seem like something that people really think about until their compressor starts to act up, right? Now let's start big picture. Seasonal changes, and why do they matter so much for compressed air systems?

SPEAKER_01 1:37

At the core of it, compressors are heavily influenced by ambient conditions. Temperature and humidity directly impact air density, cooling efficiency, and overall system performance. For centrifugal compressors, inlet conditions are everything. When temperatures rise, air density drops. That means less mass flow and lower efficiency right out of the gate. So even if your machine hasn't changed, your performance just took a hit because the environment shifted with the seasons.

SPEAKER_02 2:04

And on the rotary side, it's not about air density as much, but the effect is still there. Rotary systems depend heavily on lubrication and cooling. So when temperatures increase, oil breaks down faster, and the system has a harder time rejecting heat. So what you see is higher operating temperatures, more stress on components, and shorter oil life. And like I always tell people, the compressor will keep running until it doesn't.

SPEAKER_00 2:31

Yeah, and unfortunately that's always how it goes. So we're talking about different compressor technologies, but same outcome: efficiency loss and reliability risk. But are there common factors across both?

SPEAKER_01 2:44

Yeah, three things consistently show up, actually. Cooling effectiveness, lubrication behavior, and moisture management. If any one of those starts drifting, you'll see it in performance. And if two or three drift at the same time, that's when you start getting calls.

SPEAKER_02 3:00

And most of the time it's not a sudden failure. It's gradual. A little more energy use, a little less capacity, a few more alarms, until someone finally says, something's off with the machine's performance.

SPEAKER_00 3:14

Great insight so far. Thank you. And now let's break it down by season and start with summer. What are the biggest risks you see?

SPEAKER_01 3:22

Summer is all about heat and compounding effects, and one of the most common issues we see is fouled cooling equipment. Intercoolers and aftercoolers collecting buildup over time. When that happens, heat transfer drops and internal temperatures rise and efficiency declines. For centrifugal compressors, that also reduces air density through each stage, which impacts flow and turndown capability.

SPEAKER_00 3:46

So it's not just a temperature issue, it's affecting how the compressor actually operates.

SPEAKER_01 3:51

Exactly.

SPEAKER_02 3:52

And on the rotary side, that same heat hits the oil system. Oil starts degrading faster, which leads to varnish, reduced lubrication effectiveness, and increased wear. You might also see more carryover, which creates downstream problems. So it's not just the compressor, it's the entire system feeling it. And humidity plays a role here too, right, Ray? Big time. Higher humidity means more moisture entering the system. If your dryers or drains aren't keeping up, that moisture ends up traveling through the system. And that's where issues start stacking up. Alright. Now let's flip to winter.

SPEAKER_00 4:30

What changes?

SPEAKER_01 4:32

Winter brings colder air, which is denser, so in theory you get better efficiency. But moisture becomes the bigger concern. Condensate increases, and if it's not properly removed, it can accumulate or freeze in the system.

SPEAKER_02 4:46

And frozen condensate is where things get real annoying real fast. Block drains, frozen lines, startup issues. It can shut things down if it gets bad enough.

SPEAKER_01 4:56

And for centrifugal compressors, if drains aren't working properly, that moisture doesn't just disappear, it stays in the system and impacts performance.

SPEAKER_02 5:06

And lubrication plays a role here too, right? Yeah. Cold temperatures cause oil to thicken. That reduces flow and makes startups harder. So now you've got moisture issues and lubrication issues at the same time, and not a great combo.

SPEAKER_00 5:20

This is a good time to bring in a real-world example. Dave, you mentioned a service visit that ties directly into this.

SPEAKER_01 5:27

Yeah, this was a good one because it shows how small issues can turn into bigger problems, especially if not detected during regular maintenance and when seasons are changing. So, I was on site visiting an existing compressor installation, and the customer was dealing with inconsistent performance. Nothing major, but enough to cause frustration and confusion as to what was causing it. Things like moisture showing up in the system and occasional alarms.

SPEAKER_00 5:54

So, kind of issues seen all around the facility?

SPEAKER_01 5:57

Exactly. When we looked into it, the compressor itself was fine. The issue ended up with how the condensate drains were installed. Multiple drains were tied into a single discharge line, which created back pressure and prevented proper drainage. So instead of removing moisture, the system was basically holding onto it.

SPEAKER_02 6:15

That's such a common install mistake that I've seen during my visits too. It looks clean and then causes problems for years.

SPEAKER_01 6:22

Yeah, you're right, Ray, and it didn't stop there. The piping runs were long, not properly sloped, and had extra fittings restricting flow. So now you've got condensate building up instead of draining, which gets worse in colder conditions. So what did you do to fix everything that was going on? We reworked the installation. Each drain was routed independently, piping was shortened and properly sloped, and we added isolation valves and unions for serviceability. And honestly, it wasn't a huge job, but the results were immediate. Moisture issues cleared up, alarms dropped off, and the system stabilized.

SPEAKER_00 6:58

That's always satisfying, with a simple fix, but big impact.

SPEAKER_02 7:03

And I'll add, on the rotary side, this gets even more critical because of oil. You're not just dealing with water, you're dealing with oil-contaminated condensate. If that's not handled correctly, you can run into environmental issues and problems with separators and downstream equipment. So this is bigger than just performance. Way bigger. It's performance, maintenance, compliance, and cost. And one thing I see a lot is timer-based drains being used where they shouldn't be. They either dump air unnecessarily or don't remove enough condensate. So you're either wasting energy or creating moisture problems, sometimes both.

SPEAKER_00 7:41

So, moral of the story: drains matter more than people think.

SPEAKER_01 7:46

A lot more, actually. They're one of the most overlooked components, but they play a huge role in system reliability.

SPEAKER_00 7:53

Alright, now let's zoom out a bit on this topic for a minute. If someone wants to stay ahead of seasonal issues, what should they actually be doing?

SPEAKER_01 8:01

From a centrifugal compressor standpoint, focus on the fundamentals. Keep cooling systems clean, monitor lubrication, and make sure airflow is unrestricted, and test condensate drains during your regular scheduled maintenance plan, not just assume they're working. And also, like we discussed today, keep seasonal changes in mind too.

SPEAKER_02 8:21

And same idea for rotary systems. Watch oil condition, keep heat exchangers clean, and make sure moisture is being removed properly. And I'd add, don't treat maintenance as a once-a-year thing ever. So it's really about staying proactive.

SPEAKER_01 8:36

Exactly. Seasonal issues aren't random, they're predictable. If you prepare for them, you avoid the bigger problems.

SPEAKER_00 8:43

And if you don't, the system will remind you. Not gently, I assume. Not gently. Alright, final question for you both. If there's one takeaway for listeners, what would you each say to them?

SPEAKER_01 8:56

Well, I would like to emphasize that compressor performance is directly tied to your operating environment, and if conditions change, your system has to be ready for that. And follow proper installation and have a maintenance schedule program in place per OEM guidelines. All good advice, Dave.

SPEAKER_02 9:13

And I'd like to also add, don't overlook the basics. The simple things, drains, oil, and airflow, are usually what cause the biggest problems.

SPEAKER_00 9:22

Dave and Ray, thanks for joining us today. Great insights from both of you as always. And to our listeners, thanks for tuning in to another episode of Beyond Compression. If your system hasn't been evaluated recently, now's the time to take a proactive approach before seasonal changes turn into performance issues. Check out the resources in the show notes, and don't forget to follow us for more insights and future episodes. Until next time, thanks for listening, and thanks for letting us be part of your journey toward more reliable and efficient compressed air systems.