A chiller winter maintenance checklist

Winterising your equipment properly not only protects it from costly damage but also keeps your production running smoothly. In this article, our cooling experts share a comprehensive chiller winter maintenance checklist to help you protect your assets, optimise efficiency, and extend your equipment’s lifespan.

Why winter maintenance matters for your chiller

Industrial cooling systems work hard all year round. During the colder months, the risk of freezing and expansion in water-filled components increases dramatically. If left unchecked, this can cause burst pipes, cracked coils, and internal leaks.

Cold ambient air also affects lubricants, sensors, and control systems, leading to potential downtime, energy waste, and expensive repairs. By carrying out a few proactive maintenance steps now, you can avoid major disruptions later and ensure your process cooling equipment is ready for reliable, efficient operation.

Step 1: Drain and isolate water lines

When preparing for winter, one of the first steps is to remove water from systems that could freeze. For adiabatic coolers, this means:

• Turning off the adiabatic pad distribution system.
• Draining and flushing all supply lines completely.
• Ensuring the system is fully empty before storage or shutdown.

For external chillers or free coolers, make sure all non-circulating water is drained from tanks, pipework, and heat exchangers. Standing water expands by around 9% when it freezes, which can rupture copper or plastic lines and cause costly leaks once thawed.

If your system will be inactive for an extended period, isolating and draining it is the simplest way to prevent frost damage.

Step 2: Check glycol concentration

For chillers that will operate through the winter, using the right glycol mix is vital to prevent freezing. Glycol acts as an antifreeze agent and ensures smooth fluid circulation at low temperatures.

Maziak recommends a minimum 30% glycol concentration, which protects against freezing down to approximately –15°C. This can be easily verified using a refractometer.

Low glycol levels increase the risk of freezing, while too much can reduce efficiency. Always follow manufacturer guidelines and monitor the mix regularly throughout the season.

Learn more about our water chillers and how they’re designed to perform efficiently across all ambient conditions.

Step 3: Inspect insulation and trace heating

Pipework, valves, and fittings exposed to the cold should be properly insulated to prevent heat loss and ice formation. Check that:

• All external lines are wrapped with appropriate insulation materials such as foam rubber or fiberglass.
• Trace heating cables are in good condition, with no corrosion or breaks in the connections.
• Power to trace heating is maintained even during shutdowns, unless systems are fully drained.

A proactive inspection before temperatures fall will save you the hassle of repairing frozen pipes or replacing damaged sensors.

For large or exposed systems, Maziak’s cooling solutions team can advise on suitable insulation and protection for your site layout.

Step 4: Clean and inspect coils

During autumn and winter, coils can accumulate dirt, leaves, and debris. This restricts airflow, forcing chillers and coolers to work harder, which increases energy consumption.

To maintain efficiency:

• Remove debris from the area surrounding the unit.
• Clean condenser coils with a soft brush or purpose-designed coil cleaner (avoid wire brushes to prevent coating damage).
• Check for corrosion, dents, or coating damage - and reapply protective spray if necessary.

This step is especially important for dry air coolers and air blast coolers, which rely on ambient air for efficient heat rejection. Regular cleaning ensures optimal airflow and heat transfer throughout the cold season.

Discover more about Maziak’s dry air coolers and their energy-efficient design.

Step 5: Check for leaks and pressure drops

Leaks in water or refrigerant lines can cause serious efficiency losses. During cold weather, any moisture around leaks can freeze, expand, and worsen the problem.

Check for:

• Visible water leaks on joints and fittings.
• Refrigerant leaks using approved detection equipment (by a qualified engineer).
• Unusual pressure drops or performance changes.

Fixing leaks early prevents downtime and reduces running costs, helping your cooling system operate at maximum efficiency.

Step 6: Maintain system heaters and controls

Most chillers and coolers are equipped with crankcase and evaporator heaters to pre-warm components before startup. These prevent oil thickening and protect the compressor from damage.

Before winter:

• Test all heater elements for correct operation.
• Replace any that show signs of wear or failure.
• Verify that thermostats and control settings are calibrated for cooler ambient conditions.

Regular heater checks are a small but essential part of keeping your system in top condition.

Step 7: Don’t leave untreated water in the system

Never leave plain water in your system during long winter shutdowns. As temperatures fluctuate, freezing and thawing cycles can damage copper coils, expand joints, and cause leaks once the ice melts.

If you must store water temporarily, ensure it’s treated with glycol or drained entirely. This small precaution can prevent major repairs when restarting in spring.

Learn how our free coolers and adiabatic coolers are engineered to handle seasonal variations safely and efficiently.

Step 8: Plan a professional inspection

Even the most thorough in-house maintenance can benefit from a professional review. Maziak offers full inspections and servicing for process cooling systems to ensure safe, efficient winter operation.

A typical winter inspection includes:

• Checking refrigerant and glycol levels.
• Inspecting insulation, heaters, and control panels.
• Verifying pump performance and flow rates.
• Cleaning coils and filters.
• Testing start-up and shutdown sequences.

Partnering with a trusted service provider ensures your equipment continues to perform at its best, even during the harshest winter conditions!

At Maziak, we’ve supported UK industries with reliable process cooling solutions since 1958. Through our partnerships with Atlas Copco and Eurochiller, we deliver cutting-edge chillers, coolers, and system support designed for energy efficiency, sustainability, and long-term reliability.

From specification and installation to servicing and preventative maintenance, our engineers are here to keep your cooling systems performing all year round.

Get winter-ready with Maziak

Taking time now to prepare your process cooling systems for winter can prevent costly breakdowns and production delays later. Whether you’re operating a single chiller or a multi-system setup, following this checklist will help you stay efficient, safe, and ready for the season ahead.

Our friendly experts are always happy to help you get the best performance from your cooling equipment this winter!

FAQs

How often should glycol levels be checked in a chiller?

At least once a month during winter. Extreme temperature changes can alter glycol concentration, so regular checks ensure your system remains protected.

What temperature does a 30% glycol solution protect against?

A 30% glycol mix protects down to approximately –15°C, ideal for most UK winter conditions.

Should I run my chiller during winter?

Yes, many industrial chillers are designed to operate year-round. However, regular inspections, insulation, and heat trace systems are essential to prevent freezing and maintain performance.

Can I use plain water in my process cooling system?

Not during winter. Plain water expands when frozen, causing cracks or leaks. Always use a glycol mix or drain the system completely before shutdown.

When should I schedule professional chiller maintenance?

Schedule a pre-winter inspection, and another in early spring to prepare for increased loads and warmer conditions.