How to Prepare Your Glycol Closed Loop System for Winter

When the temperature drops across Ontario and Quebec, a facility’s heating and cooling systems are put to the test. For many commercial, institutional and industrial buildings, glycol closed-loop systems are the backbone of winter operation. Whether they’re tied into HVAC water treatment, process cooling, or heating systems, these loops protect critical equipment from freezing while ensuring efficient performance.

But without proper preparation, glycol systems can quickly become a liability. Scale, corrosion, leaks, or improper glycol concentration not only drive up operating costs but also create risks for downtime and equipment damage. A proactive water management program is the key to keeping your closed loops reliable all winter long.

Why Winterization Matters

Glycol closed-loop systems don’t usually draw much attention, they’re designed to run quietly in the background. The problem is that when they’re neglected, issues tend to surface at the worst possible time. Frozen lines, pump breakdowns, or weakened glycol that can’t handle a cold snap can all bring a system to a halt. The fallout is more than just an inconvenience: it can mean costly shutdowns, equipment damage and uncomfortable conditions for anyone relying on the building.

Getting the loop ready before winter isn’t just a box to check. Proper winterization protects the investment you’ve already made in your equipment, keeps energy use in check and helps you avoid the stress and expense of emergency repairs when the system is needed most.

Essential Winter Start-Up Checklist

Here are practical steps every facility manager should follow before winter arrives:

• Test Glycol Concentration

Use a refractometer to confirm the glycol concentration. If it’s too low, the system won’t have adequate freeze or burst protection (too high, and you risk reduced heat transfer efficiency and increased pumping costs). Adjust as needed to maintain the proper balance.

• Check Inhibitor Levels

Glycol blends contain corrosion inhibitors that shield metals from rust and scale. Over time, these protective additives deplete, leaving your system vulnerable. Test inhibitor levels and boost them to prevent corrosion damage to pumps, piping, and heat exchangers.

• Verify pH Range

pH directly impacts corrosion rates and the stability of the glycol solution. Ensure the fluid is within the manufacturer’s recommended range (typically slightly alkaline). If the pH drifts too low or too high, it can accelerate corrosion or degrade the glycol itself, shortening the system’s life.

• Clean Strainers and Flush Debris

Closed loops often accumulate rust, dirt, and scale in strainers. If these aren’t cleaned out, they restrict flow and undermine the effectiveness of your water treatment program. Flush and clean strainers to restore proper circulation and maintain overall system health.

• Inspect the Glycol Feeder

Take a close look at the glycol feeder before the cold sets in. Make sure it’s running smoothly, topped up with the right mix, and free from cracks or wear. A feeder in good shape helps keep the loop at a steady level and saves you from topping up manually all season.

• Check Pump Seals and Expansion Tanks

Pump seals are small parts with big consequences: if they fail, leaks and air can get into the loop. Expansion tanks also deserve attention: check that the fluid level is right and that the tank can handle pressure swings without stress on the system.

• Look for System Leaks

Walk the loop and carefully inspect all piping, fittings, and heat exchangers. Even minor leaks dilute the glycol concentration and raise operating costs over time. Early detection is far less costly than repairing a burst pipe or replacing damaged equipment mid-winter.

• Replace Side Stream Filters

Side-stream filtration helps remove suspended solids such as iron oxide, corrosion products, and debris. Replacing these filters before the season ensures clean glycol circulation, improved heat transfer, and reduced fouling on system components.

• Record Baseline Readings

Before winter starts, write down the key numbers: glycol concentration, inhibitor strength, pH, and conductivity. Having a clear baseline now makes it much easier to spot changes later and catch problems before they turn into downtime.

The Bigger Picture: Industrial Water Treatment and Risk Management

Your glycol loop is only one part of your facility’s overall industrial water treatment program. Boilers, cooling towers, and closed loops all work together to support safe, efficient building operation. A weak link in one system often creates strain elsewhere. That’s why comprehensive boiler water treatment, cooling tower water treatment, and closed loop maintenance all need to be part of a unified strategy.

Partnering With Experts

WMC Water has been helping facilities across Ontario and Quebec protect their systems for decades. From routine water testing to full water treatment programs, we help facility managers reduce downtime, extend equipment life, and manage costs with confidence.

If your glycol closed-loop system hasn’t been reviewed ahead of winter, now is the time. Proactive water management is always less expensive and far less stressful than reacting to a mid-winter emergency.