Make sure your chilled water systems are protected this winter

Winter is a troublesome time for building owners and managers as the cold weather creates additional pressure on chilled water systems, and can bring on-going issues to the forefront.

Once temperatures drop below zero, the water in chilled systems can freeze and cause a decrease in their efficiency, as well as a risk of burst pipes –potentially causing thousands of euros worth of damage.

The stress of having to find someone carry out emergency, out-of-hours repairs can mostly be avoided by carrying out planned, preventative maintenance, particularly on equipment at the mercy of the elements.

You should take every precaution possible to prevent this from happening. Here’s all you need to know about chilled water system maintenance in the winter.

Why are chilled water systems at risk?

The pipes of chilled water systems are often exposed to low ambient temperatures for their water to freeze. If this isn’t kept in check and the frozen water is allowed to expand which leads to blockages, leaks and burst pipes.

The simplest and easiest way to treat this is to dose the system with glycol.


Glycol is typically blended with special corrosion inhibitors to help ensure long life for system metals. Many times, a secondary corrosion inhibitor such as nitrite or molybdate may be added on-site to further increase protection levels.

The amount of glycol you need in your system should be specified in the documentation issued with the unit; these levels should be checked and maintained on a regular basis during the cold snap.

Ethylene glycol is the most common chemical used to combat freezing in chillers

What happens if my glycol levels aren’t correct?

As water begins to freeze in your chilled water system, there’ll be a decrease in water flow and your pumps will have to work harder to push water through the pipes. Your energy bills will skyrocket, as will your carbon emissions.

Once the water has frozen, the overbearing pressure willl cause the pipes to burst. At this point, the system will fail and you may be forced to close down your premises until the problem is resolved – a catastrophic outcome for many firms, especially retail and hospitality firms in the middle of the holiday season.

The cost of repairing a chilled water system after a failure can get very costly, even before you consider the damage to your premises caused by leaks.

What’s more, the warranty for your equipment may be voided – most manufacturers will discredit their warranties if you fail to maintain the correct levels of glycol in their chilled systems.

How much glycol do I need in my chilled water system?

Ethylene glycol is the most common chemical used to combat freezing in chilled water systems. The amount of gycol you need in your chilled system depends on temperature, so facilities managers (or water treatment professionals do on their behalf) need to make informed judgements on dosing levels based on how low they expect the mercury to drop.

Other maintenance checks for the winter months

Corrosion protection is required because as heat or oxygen is introduced to the system, the glycols over time can break down into various organic acids. Severe damage to systems from low pH can occur if left unchecked. For this reason, routine testing of the glycol should be done to ensure your systems are maintained up to standard.

Clean coils

Coils can be put under strain during the winter months due to the likely build-up of dirt, mould, pollutants, and more. This build-up accumulates gradually, but over time forces your chiller to work harder, reducing airflow, cooling capacity and pressure.

This results in a loss of performance and efficiency, and therefore increased energy consumption and running costs. For each 10% reduction in airflow, the efficiency of the chiller drops about 5%.

This can all be avoided by regular cleaning and maintenance of the coils. To help the coils remain clean, remove any waste, rubbish and general debris from the surrounding area of the chiller.

Look out for pipe fractures & leaks

Leaks lead to a lot of wasted energy and money, something every business is trying to avoid. Water leaks are generally obvious, and when noticed should be repaired immediately.

As mentioned previously if piping is damaged or fractured as a result of changes to weather conditions and low glycol levels, piping can burst and cause unwanted leaks.

Give your system a frequent winter health check and spot those pipe fractures and take remedial action before it’s too late.

Examine insulation

It’s important to ensure the thermal insulation is in good condition and properly fixed to the vessel/pipework – no one can afford to be losing heat in the winter months. It should be checked to make sure there are no condensation leaks, repair and replace the insulation wherever necessary.

Other parts to clean and examine

  • Unblock strainers & filters

Scale, corrosion, biofilm, weld slag, dirt, iron oxides, and suspended solids can cause serious operational problems when trapped in strainers. Blocked strainers will cause pipe blockages, failed pumps and then potential freeze issues. Prevent this harmful clogging by cleaning the strainers regularly.

  • Protective condenser fin/coil coating

After the fins and coil have been cleaned up, examine the fin coating. The condenser fins and coil may have been treated with an anti-corrosion protective spray, so check to ensure this isn’t damaged.

When cleaning the coils don’t use a hard or wire brush, a soft hand brush or purpose made narrow coil brush should be used to prevent damage to the coating.

  • Panels and steelwork

Wash down all panels and steel work and repair/treat when necessary. Ensure there isn’t any water accumulation around and under any supporting structure. Any dirt or mould left untreated or cleaned off will become permanent and may


Get the protection you need for this winter.

If you have not had your glycol system tested recently, want to validate your maintenance program or maybe just have a few questions, get in touch with us today.