Howden Screw Compressor Maintenance: 6 Steps I Learned the Hard Way

I've been maintaining industrial compressors and refrigeration equipment for about nine years. In that time, I've personally made and documented 14 significant maintenance mistakes totaling roughly $63,000 in wasted budget. My first year? I didn't know a screw compressor from a centrifugal. I learned by breaking things.

This article is the checklist I now use for our Howden screw compressor units. If you're responsible for one of these machines, or any rotary screw compressor, this is the list I wish someone had handed me in 2017.

Who this is for

If you're a maintenance engineer, plant manager, or reliability tech dealing with a Howden screw compressor, and you're not 100% sure you're catching issues before they become repair bills, keep reading. Six steps. Each one ends with a concrete checkpoint.

I'm not going to give you theory. I'm going to tell you what happened when I skipped each step, and what it cost.

Step 1: Establish baseline readings before anything else

Most people skip this. I did.

In 2019, we took over responsibility for a Howden screw compressor package from a previous contractor. I assumed "running fine" was good enough. I didn't record suction pressure, discharge pressure, oil temperature, or vibration levels. Eighteen months later, we had an unexplained high-discharge temperature trip. The OEM support asked me a simple question: "What's your normal discharge temperature?" I had no answer.

We lost eleven days waiting for the previous contractor to dig up old service records. Those records showed the compressor had been running 10°C above its original commissioning temperature for at least six months. The oil cooler was fouled. The fix was a $4,800 service that we could have scheduled as planned maintenance instead of emergency repair.

Checkpoint: For the first month after commissioning or handover, log suction pressure, discharge pressure, oil temperature, discharge temperature, and vibration levels weekly. After that, compare monthly readings to the original baseline. A change beyond 10% deserves investigation.

Step 2: Check the oil level and the oil condition—separately

Oil level is the easy one. Check the sight glass with the compressor off, not running. I once assumed the frothy reading at idle was accurate. It isn't. Foaming gives you a misleadingly high level. Let the compressor sit for 30 minutes and check again.

Oil condition is the one I actually got burned on. In September 2022, the oil analysis report came back with elevated copper particles. I acknowledged it in an email and did nothing for six weeks. I was busy. The bearings failed a month later. That $85 analysis became an $8,700 repair, and I had to explain to the plant manager why I'd ignored a warning I'd paid for.

Checkpoint: Check oil level cold every 500 operating hours. Send an oil sample for wear metal analysis every three months. If the report shows copper, lead, or elevated iron, treat it as urgent. Don't wait for the next scheduled service.

Step 3: Clean the condenser coils the right way

If you've searched "how to clean condenser coils" before, you've probably seen the pressure-washer approach. That's exactly what our contractor did for years. That's also why we replaced the coil in 2023.

Blasting a coil from the outside with high-pressure water bends the fins, drives debris deeper into the core, and reduces heat transfer. The compressor then works harder, discharge pressure climbs, and your energy bill goes up 10–15% without anything "looking wrong."

Here's the method we use now:

1. Lock out and tag out the unit. Coil cleaning involves water and electricity. Not a good mix.
2. Dry brush the surface first. Soft brush and a vacuum to remove loose debris. Most people skip this and just spray.
3. Apply a foam coil cleaner from the inside out. Spraying from the outside pushes the gunk deeper into the coil.
4. Wait 10–15 minutes for the cleaner to break down the oils and dirt.
5. Rinse from the inside out with low-pressure water. Keep the nozzle at least 12 inches from the coil, angled to follow the fins.
6. Straighten bent fins with a fin comb.
7. Verify airflow after the coil is dry. Check supply and return temperatures across the coil.

I don't have hard data on industry-wide coil damage from pressure washing, but based on the failed units I've inspected, my sense is that aggressive cleaning destroys more coils than neglect does. We now clean coils twice a year, minimum, and inspect them monthly.

Checkpoint: Monthly visual inspection. Coil cleaning twice a year in normal conditions, quarterly in dusty environments. Never with a pressure washer.

Step 4: Don't ignore the hot water side of heat recovery

A Howden screw compressor produces a lot of waste heat. In food plants and chemical facilities, that heat is often recovered for process hot water or space heating. That's where I learned a humiliating lesson.

In late 2023, discharge temperature was creeping up on our compressor. Not enough to alarm, but enough to notice. I checked the compressor side thoroughly: oil, filters, refrigerant, condenser coils. Everything looked fine. I ordered a new temperature sensor—$310. The sensor wasn't the problem.

Turns out the hot water storage tank on the heat recovery loop had scaled up. Flow was restricted, the heat exchanger couldn't shed heat, and the compressor was suffering because the auxiliary loop was failing. The scale issue cost us $3,100 in diagnostic work and a week of anxious monitoring.

If you're doing a hot water heater replacement on a recovery system, match the flow rate to the compressor's heat rejection. Add a strainer before the heat exchanger. And if you have hard water, budget for descaling as part of your planned maintenance—not as an emergency.

Checkpoint: Every six months, check the temperature differential across the heat recovery heat exchanger. A narrowing delta means scaling or flow restriction.

Step 5: Think about what your diesel heater is doing to the compressor

Cold climate operators fall into this trap. In winter layup or off-hours, you put a diesel heater in the compressor room to keep things from freezing. I've done it. Most people have.

The problem: diesel heaters produce water vapor, carbon monoxide, and particulates. When the compressor starts, it pulls that combustion-laden air into the intake. Moisture creates acidic condensation in the oil. Particulates clog intake filters fast. One operator I know went through three intake filters in one winter before figuring out the heater was the cause.

If you must use a diesel heater for freeze protection:

• Vent the exhaust outside. "Vented" heaters that still discharge into the room don't count.
• Monitor relative humidity in the compressor room. Keep it below 60%.
• Inspect the intake filter after any extended diesel heater use. You'll be surprised what you find.

This was accurate as of Q1 2025. Heater designs and building codes change, so verify current venting requirements before installation.

Checkpoint: Audit your compressor room's winter heating plan. If any combustion-based heater is present, verify venting and add intake filter checks to the weekly winter list.

Step 6: Document everything—and know what your insurance covers

I used to treat documentation as an administrative chore. Then the 2022 bearing failure happened.

We submitted a warranty claim, and the manufacturer asked for service records. We had records, but they were incomplete: missing dates, no oil analysis report for the relevant quarter, no photos. The claim was denied. That's when I learned that maintenance documentation is a financial instrument, not a bureaucratic one.

What does a maintenance log have to do with your commercial insurance? More than you'd think. I had a conversation with a Howden Group commercial insurance services broker who asked: "Can you prove this unit was maintained to the manufacturer's schedule?" I couldn't. Based on their experience, maintenance records are the difference between a paid mechanical breakdown claim and a denied one.

Schedule a yearly coverage review with your broker. Ask explicitly whether mechanical breakdown due to wear and tear is covered, and what documentation the insurer expects at claim time. A few photos and a spreadsheet are often all it takes.

Our maintenance log is a spreadsheet with columns for date, person, readings, oil changes, coil cleaning, and any abnormalities. We also date-stamp photos of anything unusual. It's not glamorous. It's survived one warranty claim, one insurance review, and zero arguments.

Checkpoint: Create a maintenance log if you don't have one. Include the last 12 months of service history. Before filing any claim, photograph the equipment and attach the maintenance records.

Common mistakes I still see

Even with this checklist, I keep seeing the same errors repeat.

• Using the compressor package as a shelf. Rags, tools, spare parts sitting on top of the unit block airflow and hide oil leaks. The top of the compressor is not a workbench.
• Overtightening drive belts. A new belt should deflect about 10–15mm in the center under thumb pressure. I ran one too tight and destroyed a bearing. The bearing didn't fail dramatically—it ran hot for two weeks and then made a grinding sound nobody could ignore.
• Trusting remote alarms completely. SCADA says the unit is fine. Meanwhile the room temperature sensor has failed and the condenser fans are cycling endlessly. Remote monitoring is a tool, not a replacement for walking over and looking.
• Skipping the oil separator pressure drop check. Replacing a clogged separator early is maybe a $600 job. Replacing it after oil carryover contaminates the system is a much bigger number. I didn't bother writing that one down; the invoice still reminds me.

This checklist costs less than one mistake

Honestly, this checklist is just a list of my own failures organized into steps. Every item is a lesson I paid for. The total is $63,000 and counting. Is this the definitive best-practice guide for Howden screw compressor maintenance? Probably not. But it's the list that has caught 47 potential failures for our team in the past 18 months, and it's saved us far more than the $63,000 I spent learning it.

The cheapest maintenance approach—doing nothing—turned out to be the most expensive one. Take ten minutes today and write down your baseline readings. That single step, done now, is more than most operators ever do.