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2 Maintenance Steps for Seasonal Chiller Shutdown

by Patti Althoff - Siwicki | Oct 09, 2019 | Property Manager, property management maintenance, Facility Maintenance, Facility Manager, HVAC Maintenance, Chiller | 0 Comments

chiller maintenance

With autumn temperatures cooling off and winter on the way, it’s important to start thinking about fall chiller cleaning and winter shutdown. Properly cleaning and taking your chiller off-line prevents harmful bacteria and containments from building up in the chiller tank and making themselves known in the spring when you reactivate your system. Here at Althoff, serving Chicago, we want to make sure you know the proper steps to take and the reasons why your chiller should be professionally shutdown in the fall.

2 Steps to Chiller Shutdown

When it comes to properly shutting down your chiller for the season, there are two basic steps. The first step is cleaning and disinfecting your chiller. The second step depends on whether you choose a dry or wet layup.

1. Cleaning and Disinfecting

Once the weather cools enough that you are certain you will no longer need your Chicago building’s air conditioning, it’s time to clean and disinfect your chiller, and you’ll need to clean and disinfect your chiller at the end of the season, regardless of your summer preventative maintenance routine. This is because bacteria, like the kind that causes legionaries disease, can grow in your chiller over the winter. Not to mention, the water that runs through your chiller can also leave deposits that have to be removed prior to shutting the cooling system down.

The HVAC chiller cleaning process starts with adding a biocide and biodispersant to the chiller water. The goal of this step is to kill biological organisms in an effort to reduce their activity. Along with Legionella bacteria, chillers can also harbor Listeria and several different types of fungi, algae and mold. Dirty air conditioners have also been linked to SARS outbreaks. The biocides and dispersants are designed to destroy these organisms and stop the growth of mold and fungi, which can lead to a slimy and biologically hazardous chiller.

Once the biocides have been inside the chiller for the recommended amount of time, the chiller is drained and opened, and the bells are removed. Once the bells have been removed, the tubes must be completely cleaned in order to remove any particulate buildup and to inspect the tubes for corrosion and scale buildup that could lead to leaks and poor performance next spring. If the chiller tubes are mostly through their expected useful lifespans, it may be wise to conduct further testing to determine if there is any pitting, thinning of the pipe walls or hairline cracks that indicate some of all of the pipes should be replaced prior to winter and/or the late spring and early summer cooling season.

2. Wet or Dry Layup?

Once the chiller and its pipes have been thoroughly disinfected, cleaned and inspected, it’s time to either perform a wet or dry layup of your chiller.

Dry Layup

Most chillers in Chicago should probably undergo a dry layup. This is recommended when the chiller will be offline for many months. Since Chicago’s winter temperatures typically start around the beginning of December and end during the beginning of March, but winters in the area have been known to last from November through March. Because there can be months where your cooling equipment and chiller are not needed, we usually recommend a dry layup, which involves draining the chiller, making sure it is dry and clean and leaving it dry for the entire winter. By not having water in your chiller, you are preventing the growth of harmful pathogens in the offseason.

However, performing a dry layup depends on the type of chiller and your building’s winter cooling needs. Some chillers and commercial HVAC units are not designed for dry layups, and some industries and buildings may need supplemental cooling even during the colder months. In this instance, the only option is a wet layup.

Wet Layup

A wet layup is exactly what you would expect. After the disinfecting and cleaning process is complete, the endcaps are reinstalled, and the chiller is filled with new water. Prior to the refilling process, it’s important to double-check the manufacturer’s flooded water volume for the specific chiller because biocides and anti-corrosion chemicals must be added to the water. Once the chiller is full and all the required chemicals are added, the chiller water must be circulated via a water pump. The water can be circulated continuously throughout the winter, or it can be set on a timer to circulate the water for a certain amount of time every six hours in order to prevent stagnation and the buildup of harmful pathogens.

Don’t Forget to Cycle as the Temperatures Cool This Fall

As the temperatures start to cool, the air conditioning portion of your HVAC system will operate less often. Most buildings in Chicago may hear the air conditioner running periodically during the day while the sun is out and the temperatures are high, but at night, the HVAC system may be off for hours. This can result in the chiller water stagnating. Unfortunately, when stagnant water sits in your chiller, it can damage the system and the connected plumbing pipes, even if the system is only off for a few hours. For this reason, we recommend ensuring that you activate your circulation pumps at least once every six hours in order to eliminate the possibility of the water in your chiller stagnating during the decreasing temperatures of the fall season.

Why You Don’t Want to Skip Fall Chiller Maintenance and Winter Shutdown

To save money, you may consider skipping the fall chiller maintenance and shutdown procedures. After all, there’s a lot to do to get ready for the colder months. You have to remove or cover outdoor furniture, shutdown and winterize all outdoor spigots and sprinkler systems as well as any piping that is located in unheated sections of your building, have your roof inspected for leaks and damage and ensure that your building’s envelop is airtight so that you do not experience any leaks or drafts.

Once you consider everything you need to do to get ready for winter, chiller maintenance may find itself on the bottom of your winterization list. Unfortunately, this could spell disaster come spring. Turning off the cooling portion of your HVAC system without disinfecting and cleaning it can lead to all sorts of nasties building up in the water, like bacteria, mold, algae and fungus. Not to mention, any particulate matter in the water will settle to the bottom. When you turn on your air conditioner in the late spring and summer, all those containments will circulate through your pipes and through your HVAC system. This can cause damage to your chiller and the associated piping as well as make people in your building sick. In the best-case scenario, individuals inside your building will merely experience an increase in indoor allergy symptoms. In the worst-case scenario, you could find your building at the center of a Legionaries or SARS outbreak.

Chiller Cleaning and Shutdown with Althoff

Here at Althoff, we can perform all your fall preventative chiller maintenance, including the cleaning and wet or dry layup of your chiller for the winter. If you aren’t certain if you need a wet or dry layup, our HVAC technicians can evaluate and inspect your chiller and take into consideration the need for cooling during the warmer days of winter and spring in order to help you make a decision. If you do need a wet layup, we can create a winter chiller maintenance program to ensure your chiller does not grow mold, fungi or algae or develop a bacteria problem. If your chiller is nearing the end of its useful life, we can assess your current chiller and recommend a replacement plan that meets your timeline and budget.

To learn more about our HVAC chiller services and to schedule maintenance, call us at 800-225-2443.

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